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Natural Rubber Research Volume 24 z Number 1 z 2011
CONTENTS
RESEARCH PAPERS
Impact of climate warming on natural rubber productivity in different
agro-climatic regions of India
P.R. Satheesh and James Jacob 1
Evidence for climate warming in some natural rubber growing regions of South India
Shammi Raj, P.R. Satheesh and James Jacob 10
Over-expression of MnSOD and related drought tolerant traits in MnSOD
transgenic Hevea brasiliensis
R. Jayashree, S. Sobha, K. Rekha, R. Supriya, M. Vineetha, S. Sushamakumari,
R.G. Kala, P.K. Jayasree, A. Thulaseedharan, K. Annamalainathan, D.B. Nair,
S. Sreelatha, R. Krishnakumar and James Jacob 18
Ecosystem flux measurements in rubber plantations
K. Annamalainathan, P. R. Satheesh and James Jacob 28
Application of remote sensing and GIS in determining erodibility of rubber soils
Shankar Meti, B. Pradeep, M.D. Jessy and James Jacob 38
Yield of modern Hevea clones and their response to weather parameters across
diverse environments
T. Meenakumari, J.R. Meenattoor, T.A. Soman, S.K. Dey, Gitali Das, Shammi Raj,
T. Sailajadevi, Ramesh B. Nair, K. Anitha Raman, T. Gireesh and Kavitha K. Mydin 44
Rubber yield of certain clones of Hevea brasiliensis and its relationship
with climate variables
T. Gireesh, Shammi Raj, Kavitha K. Mydin and V.C. Mercykutty 54
Physiological evaluation of a few modern Hevea clones for intrinsic drought tolerance
K.V. Sumesh, P.R. Satheesh, K. Annamalainathan, R. Krishnakumar,
Molly Thomas and James Jacob 61
Physiological traits for identification of potential drought tolerant accessions from
wild Hevea germplasm
D.B. Nair, M.A. Mercy, K. Annamalainathan, R. Krishnakumar and James Jacob 69
Juvenile growth response of selected wild Amazonian accessions and hybrid
Hevea clones of Wickham origin in a drought stressed environment
M. A. Mercy, Kavitha K. Mydin, T. Meenakumari and D. B. Nair 76
Patron
Ms. Sheela Thomas IAS
Editor-in-Chief
Dr. James Jacob
Editor
Mr. Sabu P. Idicula
Guest Editor
Dr. R. Krishnakumar
EDITORIAL BOARD
Secretary
Dr. C. P. Reghu
Associate Editors
Dr. R. Krishnakumar
Dr. Kochuthresiamma Joseph
Dr. Siby Varghese
Dr. Sherin George
Dr. Jayashree Madhavan
Dr. Thakurdas Saha
Editorial Committee
Members
Dr. D. Chaudhuri
Dr. Kavitha K. Mydin
Ms. Binni Chandy
Treasurer
CA. Zachariah Kurian

Comparison of root trainer and polybag grown planting materials of Hevea
T.A. Soman, M. Suryakumar, Kavitha K. Mydin and James Jacob 84
Some good agricultural practices for adapting rubber cultivation to climate change
Sherin George,V.K. Syamala, Sabu P. Idicula and N. Usha Nair 91
Exchange properties of soils in the traditional rubber growing tract in South India
Mercykutty Joseph 97
Performance of some Hevea clones under the changing climate of
sub-Himalayan West Bengal
Gitali Das, R. S. Singh, S. Meti and D. Chaudhuri 106
Seasonal variations in yield and associated biochemical changes in
RRII 400 series clones of Hevea brasiliensis
S. Sreelatha, Kavitha K. Mydin, Sheela P. Simon, R. Krishnakumar,
James Jacob and K. Annamalainathan 117
Critical weather factors influencing the incidence and severity of Corynespora
leaf fall disease in Hevea
Shammi Raj and Annakutty Joseph 124
Is climate inimical to the development of abnormal leaf fall disease in
natural rubber plantations in North East India?
C. Bindu Roy, T. Sailajadevi, Shammi Raj, Nripen Kr. Gogoi and Jacob Mathew 132
Reduction in carbon dioxide emission in block rubber production by biomass gasification
N. Rajagopal and Thomas Sebastian 140
SHORT SCIENTIFIC COMMUNICATIONS
Climate uncertainties and early establishment of young rubber plants
in traditional rubber growing regions of India
M. D. Jessy, R. Krishnakumar, K. Annamalainathan and James Jacob 145
Potassium and silicon help young rubber plants tide over transient drought
P. Prasannakumari, M.D. Jessy and K. Annamalainathan 150
Variations in leaf fatty acid composition of different clones of Hevea brasiliensis
Molly Thomas and Jayasree Gopalakrishnan 155
Studies on the performance of Hevea in the changing climate of Garo hills (Meghalaya)
A.P. Thapliyal, R.P. Singh, M.J. Reju, D. Chaudhuri, R. Krishnakumar and James Jacob 159
Drought tolerance of modern Hevea clones grown in the North Konkan
region of Maharashtra
S. Ravichandran, Meena Singh, James Jacob, R. Krishnakumar, and K. Annamalainathan 165
Influence of climate change on rubber honey production
S. Devanesan, K.S. Premila and K.K. Shailaja 170
GENERAL ARTICLE
Impact of climate change on insect pests, pathogens and their natural enemies
Suseelendra Desai and M. Srinivasa Rao 174
Cover Page
Eddy covariance system for ecosystem level CO2 and water vapous flux measurements
See Annamalainathan et al., pages 28-37
Figure in the inset shows long term change in maximum temperature at Kottayam.
See Satheesh and Jacob, pages 1-9

In this issue
Natural Rubber Research is coming out for the first time with a special issue
and the theme is Climate Change which is of topical relevance. The articles
appearing in this special issue are important on two accounts: (i) According to
the fourth assessment report of the Intergovernmental Panel on Climate Change,
countries in South and South East Asia where most of the world’s natural rubber
(NR) is traditionally grown are highly vulnerable to the adverse effects of global
warming and climate change. (ii) Due to the increasing global demand for NR,
its cultivation is being extended to hitherto non-traditional areas that are often
agro-climatically less congenial for its optimum growth and productivity. Thus,
NR cultivation will increasingly experience climate stress, both in the traditional
and non-traditional areas in the years ahead.
Several articles in this issue give evidence for climate warming in both the
traditional and non-traditional areas of NR cultivation in India. The article by
Satheesh and Jacob (page 1) shows how this will have a profound adverse impact
on NR productivity. In parts of North East India where severe cold during
winter is presently a limiting factor for NR cultivation, climate warming has a
stimulatory effect on NR productivity. Moderate warming could make more
areas in North East India suitable for growing NR in future.
The article by Jayashree et al. (page 18) explains the successful development
of a transgenic rubber plant that over-expresses MnSOD, imparting protection
against water deficit stress in nursery studies. This is the first such report in
natural rubber. Several articles in this issue discuss agronomic practices for
managing adverse climatic conditions in the field. These independent studies
suggest that clone RRII 430 may have an edge over the other clones in the RRII
400 series in terms of survival under hot and dry conditions. The paper by Nair
et al. (page 69) explains a fast and efficient method for screening large number
of plants for intrinsic stress tolerance traits.
Carbon dioxide sequestration and water flux rates of a young NR plantation
estimated by the eddy covariance technique is reported by Annamalainathan
et al. (page 28). This is the first such report from a perennial crop grown in
India. The article by Meti et al. (page 38) used satellite images for the first time
to estimate the vulnerability of rubber soils to erosion. Extreme rainfall events
are a likely fallout of climate change and rubber plantations which are generally
grown in slopes need to take special care against soil erosion.
James Jacob MSc (Ag), PhD, DIC, PhD
Editor-in-Chief

Natural Rubber Research, 24(1): 1-9, 2011
IMPACT OF CLIMATE WARMING ON NATURAL
RUBBER PRODUCTIVITY IN DIFFERENT
AGRO-CLIMATIC REGIONS OF INDIA
P.R. Satheesh and James Jacob
Rubber Research Institute of India, Kottayam-686 009, Kerala, India
Received: 12 January 2011 Accepted: 20 May 2011
Satheesh, P.R. and Jacob, J. (2011). Impact of climate warming on natural rubber productivity in different
agro-climatic regions of India. Natural Rubber Research, 24(1): 1-9.
Long term changes in climate of major natural rubber (NR) growing tracts of India were quantified and
their impact on NR productivity was estimated using multiple linear regression models. Day-to-day
variations in productivity in terms of dry rubber yield per tree per tap (g/t/t) could be best explained based
on the variations in daily maximum temperature (Tmax) and daily minimum temperature (Tmin) and
variations in other weather variables did not contribute much to the variations in daily productivity. For
unit rise in Tmax and Tmin, NR productivity was affected differently in different agro-climatic regions. If
both Tmax and Tmin rose by 1 0 C, NR productivity will reduce by 9-16% in the agroclimatic conditions of
Kerala and by 11% in the hot and drought-prone North Konkan region. On the other hand, in the cold-
prone North Eastern India, there is hardly any reduction in NR productivity if both Tmax and Tmin went
up by 1 0 C. Our analysis show that if the present warming trend continues, NR productivity in Kerala could
be reduced by 4-7% and that in North East India could go up by as much as 11% in the next decade. North
Konkan region may also register about 4% reduction in NR productivity in the next decade if the present
warming trend continues; however, absolute yields will continue to remain high in Kerala.
Key words: Climate warming, Maximum temperature, Minimum temperature, MLR models, Natural
rubber productivity.
1

Natural Rubber Research, 24(1): 10-17, 2011
EVIDENCE FOR CLIMATE WARMING
IN SOME NATURAL RUBBER GROWING
REGIONS OF SOUTH INDIA
Shammi Raj, P.R. Satheesh and James Jacob
Rubber Research Institute of India, Kottayam-686 009, Kerala, India
Received: 31 January 2011 Accepted: 15 May 2011
Raj, S., Satheesh, P.R. and Jacob, J. (2011). Evidence for climate warming in some natural rubber growing
regions of South India. Natural Rubber Research, 24(1): 10-17.
Long-term temporal changes were analyzed with respect to important climatic factors influencing rubber
cultivation in the traditional rubber growing regions of India. Rainfall, temperature and sunshine hours,
being the major climatic factors influencing rubber growth and yield, were analyzed at four rubber research
stations in the traditional rubber growing regions of Tamil Nadu, Kerala and Karnataka having daily
datasets ranging from 11 to 53 years. No significant trend was noted in the annual rainfall amount and
total number of rainy days over 53 years at Kottayam. Annual maximum and minimum temperature
trends were not significant for stations other than Kottayam. Increase in maximum temperature was
observed in Kottayam while minimum temperature decreased in Parliar and Nettana. The daily bright
sunshine hours showed a decreasing trend in Kottayam. Extreme rainfall events increased in Padiyoor.
Long-term decadal means in maximum temperature showed an increase of 2 0 C over 53 years in Kottayam
while it was 0.5 0 C in Parliar. Increase in temperature, decrease in bright sunshine hours and skewed
rainfall were observed at some of the traditional rubber growing locations.
Keywords: Climate, Mann-Kendall, Natural rubber, Seasons, Sunshine hours, Trends.

Natural Rubber Research, 24(1): 18-27, 2011
OVER-EXPRESSION OF MnSOD AND RELATED
DROUGHT TOLERANT TRAITS IN MnSOD
TRANSGENIC HEVEA BRASILIENSIS
R. Jayashree, S. Sobha, K. Rekha, R. Supriya, M. Vineetha, S. Sushamakumari,
R.G. Kala, P.K. Jayasree, A. Thulaseedharan, K. Annamalainathan, D.B. Nair,
S. Sreelatha, R. Krishnakumar and James Jacob
Rubber Research Institute of India, Kottayam-686009, Kerala, India
Received: 25 January 2011 Accepted: 6 May 2011
Jayashree, R., Sobha, S., Rekha, K., Supriya, R., Vineetha, M., Sushamakumari, S., Kala, R.G., Jayasree, P.K.,
Thulaseedharan, A., Annamalainathan, K., Nair, D.B., Sreelatha, S., Krishnakumar, R. and Jacob, J. (2011).
Over-expression of MnSOD and related drought tolerant traits in MnSOD transgenic Hevea brasiliensis.
Natural Rubber Research, 24(1): 18-27.
Two transgenic plants (L1 and L2) of Hevea brasiliensis (clone RRII 105) integrated with the manganese
superoxide dismutase (MnSOD) gene were developed from two independent Agrobacterium mediated genetic
transformation events. Six month old bud grafted plants of clone RRII 105 (control), non-transgenic somatic
plants (control) and transgenic plants (L1 & L2), growing in polybags were subjected to water stress and their
drought tolerance traits were evaluated through molecular, physiological and biochemical tools. MnSOD
transcript abundance, leaf water potential, PS II activity, photosynthetic oxygen evolution and respiratory
oxygen uptake rates, H 2 O 2 content and superoxide dismutase and peroxidase enzyme activities were studied.
Northern analysis indicated a higher MnSOD transcript level in the stressed transgenic plants. The maximum
potential photochemical efficiency of PS II was not altered under drought stress. On the contrary, the effective
quantum yield of PS II and mid-day leaf water potential were reduced in all the plants, however, the extent of
reduction was small in L1 plants. Similarly, the drought mediated reduction in photosynthetic oxygen evolution
rate was smaller in the SOD transgenic L1 plants than in the other plants. The SOD activity was 35 and 31 per
cent higher under normal and drought conditions, respectively in the transgenic plant L1 than the bud grafted
plants of clone RRII 105. Though there was an increase in SOD activity and H 2 O 2 content in L1 plants,
corresponding changes were not observed in the case of peroxidase activity. The results indicated that the
transgenic plant L1 is superior to all other plants in terms of drought tolerance. Development of transgenic
plants for abiotic stress tolerance, integrated with genes like MnSOD is a significant step in extending rubber
cultivation to marginally suitable areas in the present scenario of changing climate.
Key words: Drought tolerance, Genetic transformation, Hevea brasiliensis, Mn superoxide dismutase,
Transgenic plant.

Natural Rubber Research, 24(1): 28-37, 2011
ECOSYSTEM FLUX MEASUREMENTS
IN RUBBER PLANTATIONS
K. Annamalainathan, P. R. Satheesh and James Jacob
Rubber Research Institute of India, Kottayam- 686 009, Kerala, India
Received: 6 February 2011 Accepted: 28 April 2011
Annamalainathan, K., Satheesh, P.R. and Jacob, J. (2011). Ecosystem flux measurements in rubber plantations.
Natural Rubber Research, 24(1): 28-37.
Perennial trees like natural rubber plants sequester large quantities of atmospheric CO into biomass and
2
therefore, mitigate the increase in greenhouse gas (GHG) emission. In the present study measurements of
CO and water vapour flux of a natural rubber ecosystem were attempted for one continuous year. An eddy
2
covariance (EC) flux measurement system was installed on an 18 meter tower inside a rubber plantation (4-
5 years old) at the Central Experimental Station of the Rubber Research Institute of India (RRII) which is
situated in the traditional rubber growing region of Kerala. The daily net ecosystem exchange (NEE) of CO2 by the rubber ecosystem was in the range of 1-25 g/m
2
2 /day during the study period. Most of the days
recorded a net CO sequestration. However, a few days recorded a net CO efflux (R ) from the plantation
2 2 eco
to atmosphere. The mean annual NEE of the 4-5 years old rubber plantation was 11 g CO /m2 /day which
works out to 33.5 tons CO /ha/year indicating that rubber plantation is a potential sink for atmospheric
2
CO . The amount of carbon sequestered by the plantation as calculated from the EC data was compared
2
with carbon sequestration of the trees calculated from biomass inventory method. The annual mean
evapotranspiration was 3.5 mm/day as calculated from the EC data indicating the high efficiency of
sequestering carbon per unit amount of water consumed.
Keywords: Atmospheric flux, Biomass, Carbon sequestration, Eddy Covariance, NEE.

Natural Rubber Research, 24(1): 38-43, 2011
APPLICATION OF REMOTE SENSING AND GIS IN
DETERMINING ERODIBILITY OF RUBBER SOILS
Shankar Meti, B. Pradeep, M.D. Jessy and James Jacob
Rubber Research Institute of India, Kottayam-686 009, Kerala, India
Received: 20 January 2011 Accepted: 6 May 2011
Meti, S., Pradeep, B., Jessy, M.D. and Jacob, J. (2011). Application of remote sensing and GIS in determining
erodibility of rubber soils. Natural Rubber Research, 24(1): 38-43.
Climate change studies involve interaction of many factors and for meaningful interpretations, integrated
analysis is essential. GIS is an ideal platform for this. In the uncertain scenario of climate change, our
decisions need to be prioritized and for this multi-criteria decision analysis provides a very good tool. An
attempt has been made to assess the vulnerability of rubber plantations to soil erosion as a result of heavy
rainfall and runoff in Kozhenchery taluk of Pathanamthitta district of Kerala, India. Analysis has indicated
that the major portion of rubber plantation (81%) is distributed on locations that have medium adaptability
to rainfall variability and least (0.9%) on areas showing low adaptability. Spatial analysis of rubber
distribution map with soil erodibility map has indicated that 60.5 per cent of rubber area is distributed on
land with highly erodible soil with moderate slope followed by 37 per cent on less erodible soil with moderate
slope. Maps highlighting the areas vulnerable to rainfall variability and soil erosion will serve as an ideal
tool for planners, researchers and extension people to develop suitable strategies for enhancing NR
production in India.
Key words: Erodibility, GIS, MCDA, Remote sensing, Runoff.

Natural Rubber Research, 24(1): 44-53, 2011
YIELD OF MODERN HEVEA CLONES AND
THEIR RESPONSE TO WEATHER PARAMETERS
ACROSS DIVERSE ENVIRONMENTS
T. Meenakumari, J.R. Meenattoor, T.A. Soman 1 , S.K. Dey 2 , Gitali Das 3 , Shammi Raj, T.
Sailajadevi, Ramesh B. Nair 4 , Anitha Raman, K 5 ., T. Gireesh and Kavitha K. Mydin
Rubber Research Institute of India, Kottayam-686 009, Kerala, India
1 Hevea Breeding Sub-Station, Rubber Research Institute of India, Kanyakumari-629 851, India
2 Regional Research Station, Rubber Research Institute of India, Agartala-799 006, India
3 Regional Research Station, Rubber Research Institute of India, Nagrakata, West Bengal-735 225, India
4 Rubber Board, Kottayam-686 002, India, 5 International Rice Research Institute, Philippines
Received: 3 January 2011 Accepted: 27 April 2011
Meenakumari, T., Meenattoor, J.R., Soman, T.A., Dey, S.K., Das, G., Raj, S., Sailajadevi, T., Nair, R.B., Raman,
K.A., Gireesh, T. and Mydin, K.K. (2011). Yield of modern Hevea clones and their response to weather
parameters across diverse environments. Natural Rubber Research, 24(1): 44-53.
A total of 12 promising clones, including the newly released RRII 400 series clones were evaluated in three
geographically diverse locations across the traditional and non traditional rubber growing tracts in India.
The present paper reports the yield performance of these clones for the 4 th to 6 th year of tapping. The response
of the clones to changes in meteorological variables in different locations in the same period was also
examined. In Kanyakumari, RRII 105, RRII 430 and RRII 203 were on par. In Agartala, RRII 422 and RRII
429 were the top yielders and registered significantly superior yield to both the controls, RRII 105 and
RRIM 600. In Nagrakata, RRII 429 was the highest yielder and RRII 417 and RRII 422 also recorded
significantly superior yield than the controls. Genotype Environment Interactions (GEI) for rubber yield
was analysed from the trials with a view to identify clones with wide adaptability as well as specific
adaptation. AMMI model was selected to quantify GEI and the analysis revealed that environment (E) and
GEI together contributed to the major proportion (72.8%) of the variations in rubber yield. Twenty seven
percent of the total variation was attributed to genotypes (G). Genotype means ranged from 35.31 g/t/t to
56.24 g/t/t. Clones RRII 429, RRII 422, RRII 417, RRII 430 and RRII 105 were high yielding ones across
environments. RRIM 600 was found to be the widely adapted clone. RRII 429 showed the highest interaction.
Weather parameters viz., maximum and minimum temperatures, RH, sunshine hours and rainfall were
studied in relation to rubber yield in the three locations. Maximum temperature was negatively correlated
with yield in Kanyakumari, irrespective of clones. In Agartala and Nagrakata the results were however
inconclusive.
Key words: Environments, Hevea clones, Weather parameters, Yield.

Natural Rubber Research, 24(1): 54-60, 2011
RUBBER YIELD OF CERTAIN CLONES OF
HEVEA BRASILIENSIS AND ITS RELATIONSHIP
WITH CLIMATE VARIABLES
T. Gireesh, Shammi Raj, Kavitha K. Mydin and V.C. Mercykutty
Rubber Research Institute of India, Kottayam 686 009, Kerala, India
Received: 1 February 2011 Accepted: 30 April 2011
Gireesh, T., Raj, S., Mydin, K.K. and Mercykutty, V.C. (2011). Rubber yield of certain clones of Hevea brasiliensis
and its relationship with climate variables. Natural Rubber Research, 24(1): 54-60.
The relationship between long term yield of seven Hevea clones and climatic parameters such as minimum
temperature (Tmin), maximum temperature (Tmax), sunshine hours (s), rainfall (R) and relative humidity
[RH1 (morning) and RH2 (afternoon)] was studied under a typical tropical humid climatic regime. Of the
seven genotypes, RRII 105 was significantly high yielding (68.0 g/t/t), while Gl 1 (40.5 g/t/t) and RRIM 600
(43.8 g/t/t) registered relatively low yields. Climatic parameters were regressed on yield. Tmax was found to
be the most important influencing factor with a negative relationship in each clone (slopes from -7.299 to -
3.353). Tmax showed less monthly variability when compared to RH in the corresponding period. RH was
seen to be low during the winter and pre-monsoon seasons. Yield was found to be the most important
function of Tmax (R 2 = 0.21). Most of the clones showed an increase in yield with time mainly during the
monsoon season (slopes from 4.94 to 2.56 per year). The R 2 ranged from 0.30 (RRII 105) to 0.76 (RRII 203)
during the monsoon season. The clone RRII 208 did not show any increase in yield, while RRIM 600 showed
a varied response of yield with time over different seasons. The study indicated the moderate level of
decrease in yield with increasing Tmax. However, rising temperature in the long-term climate change scenario,
the yield decline in rubber clones need to be evaluated further in large scale.
Keywords: Hevea clones, Rubber yield-climate relations, Selection.

Natural Rubber Research, 24(1): 61-67, 2011
PHYSIOLOGICAL EVALUATION OF A FEW
MODERN HEVEA CLONES FOR INTRINSIC
DROUGHT TOLERANCE
K.V. Sumesh, P.R. Satheesh, K. Annamalainathan, R. Krishnakumar,
Molly Thomas and James Jacob
Rubber Research Institute of India, Kottayam-686 009, Kerala, India
Received: 8 February 2011 Accepted: 8 May 2011
Sumesh, K.V., Satheesh, P.R., Annamalainathan, K., Krishnakumar, R., Thomas, M. and Jacob, J. (2011).
Physiological evaluation of a few modern Hevea clones for intrinsic drought tolerance. Natural Rubber Research,
24(1): 61-67.
Water deficit stress will be one of the most important environmental factors that will affect crop productivity
in the coming years and prolonged drought conditions will have adverse effects on photosynthesis and
growth of plants. In this study, five modern Hevea clones and three check clones were compared for their
intrinsic tolerance to water stress conditions. The results indicated that the clone RRIM 600 grown in open
condition had the least decline in CO 2 assimilation rate followed by RRII 430, fifteen days after drought
imposition while RRII 414 was found to be severely affected. Similar trend was noticed in the glasshouse
grown plants 10 days after drought treatment. The effective quantum yield of PS II (Φ PS II) was maintained
better in RRIM 600 and RRII 430 while other clones showed drastic decline in PS II activity with drought
stress. RRII 430 and RRII 422 showed stable Φ PS II activity under drought conditions. PS I activity was not
much affected in stressed plants both in the glasshouse as well as in PEG solution. Among the modern
clones, RRII 422, RRII 429 and RRII 430 showed high PS I activity under moisture stress, probably indicating
an increased rate of cyclic electron flow around PS I when the PS II function is impaired. Gas exchange and
fluorescence data revealed that the clone RRII 430 was more likely to endure drought stress than the others
in the RRII 400 series. Gen-Next clones should have better tolerance to changing climatic conditions and the
results of the present study help in this direction.
Keywords: Chlorophyll fluorescence, Drought, Photosynthesis, PS I, PS II, Quantum yield.

Natural Rubber Research, 24(1): 69-75, 2011
PHYSIOLOGICAL TRAITS FOR IDENTIFICATION
OF POTENTIAL DROUGHT TOLERANT ACCESSIONS
FROM WILD HEVEA GERMPLASM
D.B. Nair, M.A. Mercy, K. Annamalainathan, R. Krishnakumar and James Jacob
Rubber Research Institute of India, Kottayam- 686009, Kerala, India
Received: 7 January 2011 Accepted: 8 May 2011
Nair, D.B., Mercy, M.A., Annamalainathan, K., Krishnakumar, R. and Jacob, J. (2011). Physiological traits
for identification of potential drought tolerant accessions from wild Hevea germplasm. Natural Rubber
Research, 24(1): 69-75.
In vitro experiments were carried out to identify the most intrinsic tolerance traits for abiotic stresses like
drought, temperature, light etc. using two contrasting Hevea clones. Combination of stresses was found
more deleterious than single stress causing an increased membrane injury, leaf chlorophyll bleaching and
reduction of PS II photochemical activity. Attempts were made to identify a few vital drought tolerance
traits using poly ethylene glycol (PEG) with known drought tolerant (RRIM 600) and drought susceptible
(RRII 105) clones. Leaf samples of clone RRII 105 upon incubation with PEG (60%) and light together (350
µmol m -2 s -1 ) exhibited more membrane injury in the drought susceptible clone RRII 105 (60.5%) than in the
known drought tolerant clone RRIM 600 (44.2%). Experiments with in vitro drought and light stress decreased
the chlorophyll content of leaves and enhanced chlorophyll bleaching more in clone RRII 105. Similarly the
dark adapted Fv/Fm ratio in exposed leaf samples of clone RRII 105 was found more inhibited than clone
RRIM 600.
The drought tolerance traits thus identified in laboratory were validated in young plants grown in nurseries.
In young plants under acute drought stress, the reduction in chlorophyll content (24%) and mid-day water
potential (25%) were more in clone RRII 105 than in clone RRIM 600 (8% and 15%, respectively). In similar
stress condition, the PS II quantum yield declined by 41% in clone RRII 105 and 17% in clone RRIM 600.
Under extreme drought, the greenish nature of leaves diminished and turned yellowish due to photo-
bleaching causing reduction in total functional leaf area of plant leading to drying and senescence of leaves.
Intrinsic drought tolerance traits thus identified were employed to screen large number of Hevea germplasm
collection.
Leaf traits such as leaf yellowing and senescence that normally occur in summer under acute drought and
high light stress in field were empirically scored in 3772 wild germplasm accessions. Accessions that were
exhibiting less senescence and yellowing were ranked top as the most drought tolerant ones. From the large
pool of wild germplasm 165 accessions were identified as intrinsic drought tolerant ones and 121 as most
susceptible ones. The leaf samples of selected accessions were exposed to in vitro drought assay using PEG
with light and an inverse relationship was observed between percent leaf yellowing under summer drought
in the field and leaf PS II activity measured under in-vitro drought and high light stress. Thus, leaf yellowing
is an easy proxy measure of PSII activity during drought and high light stress.
Keywords: Drought tolerance, Germplasm, Leaf yellowing, PS II activity.
Correspondence: D. B. Nair (E-mail: bhuvanendran@rubberboard.org.in)

Natural Rubber Research, 24(1): 76-83, 2011
JUVENILE GROWTH RESPONSE OF SELECTED
WILD AMAZONIAN ACCESSIONS AND HYBRID
HEVEA CLONES OF WICKHAM ORIGIN IN A
DROUGHT STRESSED ENVIRONMENT
M. A. Mercy, Kavitha K. Mydin, T. Meenakumari and D. B. Nair
Rubber Research Institute of India, Kottayam – 686 009, Kerala, India
Received: 1 February 2011 Accepted: 26 April 2011
Mercy, M.A., Mydin, K.K., Meenakumari, T. and Nair, D.B. (2011). Juvenile growth response of selected
wild Amazonian accessions and hybrid Hevea clones of Wickham origin in a drought stressed environment.
Natural Rubber Research, 24(1): 76-83.
Natural rubber cultivation in India faces adverse effects of drought and cold stresses, especially in the non-
traditional rubber growing areas. As the genetically divergent germplasm accessions are an excellent
repository of various useful traits including stress tolerance, systematic screening of wild germplasm for
drought and cold tolerance with the ultimate objective of developing location-specific clones for non-
traditional rubber growing areas holds much importance. With this objective, during the year 2007, a field
evaluation of 30 Hevea clones comprising Amazonian accessions and Wickham clones was initiated at
Regional Research Station (RRS), Dapchari located in the North Konkan region of Maharashtra state in
India. This region experiences high temperature (exceeding 40 0 C in April-May), high light intensity and
very low soil moisture during the summer months. The check clones in the experiment were RRII 105, RRII
430, RRII 414, RRII 208, RRIM 600 and Tjir 1. Growth parameters along with annual and summer girth
increment were worked out. Leaf yellowing and drying were also used as criteria to assess drought
susceptibility. Based on this data, the growth response of wild Amazonian clones and hybrid Wickham
clones were assessed and compared with that of the check clones. The growth performance of the modern
clone, RRII 430 and RRII 414 was assessed for the first time under Dapchari conditions. Clone RRII 430 was
found to be more suitable than RRII 414 for establishment in a drought prone region based on juvenile
growth performance.
Keywords: Amazonian accessions, Drought tolerance, Wickham clones, Wild germplasm.

Natural Rubber Research, 24(1): 84-90, 2011
COMPARISON OF ROOT TRAINER AND POLYBAG
GROWN PLANTING MATERIALS OF HEVEA
T.A. Soman, M. Suryakumar, Kavitha K. Mydin* and James Jacob* Rubber
Research Institute of India, Hevea Breeding Sub-station, Kanyakumari- 629581,
Tamilnadu, India
*Rubber Research Institute of India, Kottayam- 686009, Kerala, India
Received: 7 February 2011 Accepted: 16 May 2011
Soman, T.A., Suryakumar, M., Mydin, K.K. and Jacob, J. (2011). Comparison of root trainer and polybag
grown planting materials of Hevea. Natural Rubber Research, 24(1): 84-90.
A propagation technique which will promote deep growth of taproot and well-developed lateral roots, is
very important under a warmer and drier agro-climate influenced by global warming. Polybag plants with
improper root system may not be able to withstand the various stresses characteristic of dry agro-climate.
Vigorous seedlings of polycross origin propagated by means of seed-at-stake planting seem to be the best
planting technique for the future. Advanced planting materials produced by the new propagation technique
of in situ budding of stocks raised in root trainers may also perform well under an agro-climate influenced
by global warming.
Keywords: Global warming, Plant propagation, Polybag plant, Root trainer, Seed-at-stake planting, Young
budding.

Natural Rubber Research, 24(1): 91-96, 2011
SOME GOOD AGRICULTURAL PRACTICES
FOR ADAPTING RUBBER CULTIVATION TO
CLIMATE CHANGE
Sherin George ,V.K. Syamala , Sabu P. Idicula and N. Usha Nair
Rubber Research Institute of India, Kottayam - 686 009, Kerala, India
Received: 12 January 2011 Accepted: 22 May 2011
George, S., Syamala, V.K., Idicula, S.P. and Nair, N.U. (2011). Some good agricultural practices for adapting
rubber cultivation to climate change. Natural Rubber Research, 24(1): 91-96.
Drought is one of the most important manifestations of climate change as far as the rubber growing regions
in India are concerned. The effect of type of planting material and water conservation techniques like
tillage, mulching and in situ water harvesting on growth of immature rubber and storage of soil moisture in
two ongoing experiments are discussed. In the nursery experiments, growth parameters of planting materials
raised through direct-seeding in polybags followed by in situ budding and planting budded stumps in
polybags were compared. The results indicated significant difference in the growth performance depending
up on the type of planting material. It was observed that the planting material produced through direct-
seeding with an intact root system was significantly superior in stem diameter, plant height, number of
whorls, fibrous root and dry matter compared to plants raised through budded stumps. In the field
experiment, direct-seeded green budded plants were integrated with moisture conservation practices like
tillage, mulching, silt pits and enhanced fertilizer application along with the use of organic manures. It was
observed that the soil moisture storage during summer was significantly increased compared to the plots
where plants were raised from budded stumps following the current package of practices. A significantly
higher leaf area index (LAI) and root length density (RLD) were maintained by the direct-seeded green
budded plants under integrated management. The growth of the direct-seeded green budded plants under
integrated management was significantly superior to other treatments. Therefore introduction of planting
materials with a good root system and adoption of good agricultural practices (GAPs) could play an
important role in adapting plants to future extremes of climate change.
Keywords: Climate change, GAPs, Growth, Immature rubber, Soil moisture.

Natural Rubber Research, 24(1): 106-116, 2011
EXCHANGE PROPERTIES OF SOILS IN
THE TRADITIONAL RUBBER GROWING TRACT
IN SOUTH INDIA
Mercykutty Joseph
Rubber Research Institute of India, Kottayam-686 009, Kerala, India
Received: 28 January 2011 Accepted: 25 May 2011
Joseph, M. (2011). Exchange properties of soils in the traditional rubber growing tract in south India.
Natural Rubber Research, 24(1): 97-105.
Exchange properties of the soils from five locations in the traditional rubber growing tract in South India
with distinct variation in average annual rainfall were compared. The base saturation per cent and
exchangeable bases showed wide variation between soils with variation in average annual rainfall. Soils of
the high rainfall areas were showing very low base saturation with extremely low status of potassium,
calcium and magnesium. Extractable acidity values were also high in two locations experiencing high rainfall.
Though natural rubber is adapted to acidic, low base environment, studies are required to assess the growth
and yield performance in soils with extremely low base status.
Keywords: Base saturation, Cation exchange capacity, Exchangeable bases, Extractable acidity, Hevea
brasiliensis.

Natural Rubber Research, 24(1): 106-116, 2011
PERFORMANCE OF SOME HEVEA CLONES
UNDER THE CHANGING CLIMATE OF
SUB-HIMALAYAN WEST BENGAL
Gitali Das, R. S. Singh 1 , S. Meti 2 and D. Chaudhuri 3
Rubber Research Institute of India, Rubber Board, RES, Jalpaiguri, West Bengal, India
1. Rajendra Prasad Agriculture University, Pusa, Samastipur, Bihar, India
2. Rubber Research Institute of India, Rubber Board, Kottayam, Kerala, India
3. Rubber Research Institute of India, Rubber Board, RRS, Guwahati, India
Received: 26 January 2011 Accepted: 24 April 2011
Das, G., Singh, R. S., Meti, S. and Chaudhuri, D. (2011). Performance of some Hevea clones under the changing
climate of sub-Himalayan West Bengal. Natural Rubber Research, 24 (1): 106-116.
Twenty years weather data taken at RES, Nagrakata was analyzed to estimate whether there was any change
in weather attributes in this part of India. Successive averages of ten years data (moving average) over a
stretch of twenty years meteorological attributes indicated an increasing trend in minimum (Tmin) and
maximum (Tmax) temperature and relative humidity (RH) in the morning. This may make this region more
suitable for rubber cultivation. A clone trial was initiated in 1991 in this region with ten clones along with a
check clone RRIM 600. The girth increment (GI) and weather data were grouped into non-winter (NW -
April to September) and winter (W - October to March) periods in order to understand the effect of two
contrasting weather on growth or rubber. In general, the Tmax during NW period was higher than the W
period. Similarly, Tmin during NW was almost double the temperature during W period indicating a cooler
weather during W period than that of the NW period. The girth increment (GI) during NW was significantly
higher than the W period at immature (3-5 yr), juvenile (6-8 yr) and early mature stage (9-11 yr) stage
indicating effect of weather on growth ofrubber. Data on the dry rubber yield showed that none of the
clones was superior to the check clone RRIM 600. In terms of yield, coefficient of variance over years,
incidence of tapping panel dryness and wind damage, only one clone i.e. RRII 208 was found to be suitable
for the region along with RRIM 600. Study on correlation between yield and weather parameters showed
that in post-W (May to September) and pre-W (October to December) periods, there was a positive correlation
between yield and Tmax. During post-W period when Tmax was high, Tmin showed negative correlation; during
pre-W period, when environment dominated with cool weather, increasing trend of Tmin would be appreciable
which reflected on correlation study with yield showing positive trend. Therefore, with changing climate
in the sub-Himalayan West Bengal, rubber production responded positively.
Keywords: Change in weather, Growth, Performance, Yield.

Natural Rubber Research, 24(1): 117-123, 2011
SEASONAL VARIATIONS IN YIELD AND
ASSOCIATED BIOCHEMICAL CHANGES IN
RRII 400 SERIES CLONES OF HEVEA BRASILIENSIS
S. Sreelatha, Kavitha K. Mydin, Sheela P. Simon, R. Krishnakumar,
James Jacob and K. Annamalainathan
Rubber Research Institute of India, Kottayam – 686 009, Kerala, India
Received: 12 February 2011 Accepted: 27 April 2011
Sreelatha, S., Mydin, K.K., Simon, S.P., Krishnakumar, R., Jacob, J. and Annamalainathan, K. (2011). Seasonal
variations in yield and associated biochemical changes in RRII 400 series clones of Hevea brasiliensis. Natural
Rubber Research, 24(1): 117-123.
Variation in yield and associated biochemical changes were studied in five newly evolved RRII 400 series
clones during peak yielding and low yielding stress (summer) seasons and compared with the popular
check clone RRII 105. A significant reduction in dry rubber yield was observed in all the clones during the
stress period compared to peak yielding season. Metabolism of carbohydrates and activities of antioxidant
enzymes showed significant variation between seasons. Significant clonal variations were also observed in
the case of latex ATP, C-serum thiols and SOD during the stress season. Clones RRII 422, RRII 430 and RRII
414 showed higher ATP concentration in latex, C-serum thiols, invertase and SOD during stress season.
RRII 429, RRII 417 and RRII 105 showed very low SOD, thiols and invertase activity in C-serum during this
period. The present study indicates that among the clones studied for yield attributes, RRII 422 followed by
RRII 430 and RRII 414 may be more tolerant to stress situation than other clones. The significance of these
biochemical parameters are discussed in relation to yield obtained during the peak yielding and stress
seasons.
Keywords: Antioxidant enzymes, Invertase, Rubber yield, Yield depression.

124
Natural Rubber Research, 24(1): 124-131, 2011
CRITICAL WEATHER FACTORS INFLUENCING
THE INCIDENCE AND SEVERITY OF CORYNESPORA
LEAF FALL DISEASE IN HEVEA
Shammi Raj and Annakutty Joseph
Rubber Research Institute of India, Rubber Board, Kottayam-686009, Kerala, India
Received: 11 February 2011 Accepted: 30 April 2011
Raj, S. and Joseph, A. (2011). Critical weather factors influencing the incidence and severity of Corynespora
leaf fall disease in Hevea. Natural Rubber Research, 24(1): 124-131.
Recent incidences of attack of the pathogen, Corynespora cassiicola on rubber trees in North Kerala and
South Karnataka necessitated the study of critical weather conditions which trigger the onset of the disease.
Daily leaf fall due to Corynespora infection during the January-February period was studied in relation to
the prevailing weather parameters at five different locations. A new index, termed the Humid Minimum
Temperature Index (HTnI) was found to be related to disease incidence and severity of leaf fall in all the
locations in the traditional rubber growing belt. A value of HTnI > 5.5 for seven consecutive days was found
to be the critical limit for severe leaf fall and HTnI > 4.0 for consecutive 3 to 4 days for the onset of the
disease. Similar results were obtained when leaf fall was studied in relation to spore count per unit area
within the canopy. Forecasts during the refoliation period based on the critical values of HTnI could be
utilised to wisely adopt prophylactic measures to combat this disease, a major biotic constraint of rubber
productivity.
Keywords: Corynespora Leaf Fall Disease, Humidity Thermal Index, Leaf baskets, Leaf fall.

Natural Rubber Research, 24(1): 132-139, 2011
IS CLIMATE INIMICAL TO THE DEVELOPMENT
OF ABNORMAL LEAF FALL DISEASE IN NATURAL
RUBBER PLANTATIONS IN NORTH EAST INDIA?
C. Bindu Roy, Sailajadevi * , Shammi Raj, Nripen Kr. Gogoi * and Jacob Mathew
Rubber Research Institute of India, Kottayam 686 009, Kerala, India
* Regional Research Station, Agartala, India
Received: 2 February 2011 Accepted: 23 May 2011
Roy, C.B., Devi, S., Raj, S., Gogoi, N.K. and Mathew, J. (2011). Is climate inimical to the development of
abnormal leaf fall disease in natural rubber plantations in North East India? Natural Rubber Research,
24(1): 132-139.
Abnormal leaf fall (ALF) disease caused by Phytophthora spp. is one of the most destructive diseases of
rubber (Hevea brasiliensis) in South India. High incidence of pod rot and ALF disease caused by P. botryosa
was observed in Tripura (North East India) during 1988 and 1989 but not during the subsequent years
although a Phytophthora-susceptible rubber clone RRIM 600 is widely cultivated in this area. Therefore, a
possible threat of Phytophthora exists in the rubber plantations of North East India. In this study Phytophthora
was isolated from soil and litter collected from rubber plantations in Agartala, Tripura and Kottayam in
India. It was found that Phytophthora inoculum density was low in Tripura and they were less virulent. As
weather plays an important role in development and spread of Phytophthora disease, a comparison of weather
parameters between Tripura and Kottayam during May to August 1988 to 2009 was made. A hot weather
with low relative humidity coupled with less number of continuous rain spells may be some of the important
factors preventing inoculum build up for initiating Phytophthora infection in rubber plantations of Tripura.
Low virulence of Phytophthora would also have contributed to near complete absence of ALF in NE India.
Keywords: Abnormal leaf fall, Climate, Hevea brasiliensis, North East India, Phytophthora.

Natural Rubber Research, 24(1): 140-144, 2011
REDUCTION IN CARBON DIOXIDE EMISSION
IN BLOCK RUBBER PRODUCTION
BY BIOMASS GASIFICATION
N. Rajagopal and Thomas Sebastian
Department of Processing & Product Development, Rubber Board, Kottayam – 686 009, Kerala, India
Received: 25 January 2011 Accepted: 16 April 2011
Rajagopal, N. and Sebastian, T. (2011). Reduction in carbon dioxide emission in block rubber production by
biomass gasification. Natural Rubber Research, 24(1): 140-144.
During the processing of block rubber, a major share of energy is required in drying. The power and fuel
used together constitute around half of the direct cost of production of block rubber. This forced the processor
to explore alternate and cost effective sources of heat energy which led to the introduction of biomass
gasifiers in the block rubber sector. The utilization of biomass gasification technology is found to reduce
the drying cost of block rubber by 50 per cent when compared to diesel fired driers. It would also result in
considerable reduction in the emission of CO 2 in addition to avoiding the use of fossil fuels. This technology
has further scope for contributing towards CO 2 emission reduction in natural rubber processing as very
little quantity of block rubber is now being dried with this technology.
Keywords: Biomass, Block rubber, CO 2 emission, Field coagulum, Gasifier technology, TSR.

Natural Rubber Research, 24(1): 159-164, 2011 SHORT SCIENTIFIC COMMUNICATION
CLIMATE UNCERTAINTIES AND EARLY
ESTABLISHMENT OF YOUNG RUBBER PLANTS
IN TRADITIONAL RUBBER GROWING
REGIONS OF INDIA
M. D. Jessy, R. Krishnakumar, K. Annamalainathan and James Jacob
Rubber Research Institute of India, Kottayam – 686 009, Kerala, India
Received: 3 February 2011 Accepted: 27 April 2011
Jessy, M.D., Krishnakumar, R., Annamalainathan, K. and Jacob, J. (2011). Climate uncertainties and early
establishment of young rubber plants in traditional rubber growing regions of India. Natural Rubber Research,
24(1): 145-147.
Observations indicated that climate uncertainties are increasing the number of casualty of young plants
immediately after field planting. Symptoms of drought are manifested on young plants during summer
and life saving irrigation is increasingly being practiced in very young holdings even in the traditional
rubber growing regions to tide over drought. In addition to the already recommended summer management
practices, tilling of the plant basin at the end of the rainy season increased soil moisture storage, reduced
casualty during summer and enhanced growth of young plants. This may be a good practise to manage
drought in young plantations.
Keywords: Casualty, Climate uncertainty, Drought, Hevea brasiliensis, Life saving irrigation, Soil moisture,
Tillage.

Natural Rubber Research, 24(1): 159-164, 2011 SHORT SCIENTIFIC COMMUNICATION
POTASSIUM AND SILICON HELP
YOUNG RUBBER PLANTS TIDE OVER
TRANSIENT DROUGHT
P. Prasannakumari, M.D. Jessy and K. Annamalainathan
Rubber Research Institute of India, Kottayam-686 009 Kerala, India
Received: 21 January 2011 Accepted: 19 May 2011
Prasannakumari, P., Jessy, M.D. and Annamalainathan, K. (2011). Potassium and silicon help young rubber
plants tide over transient drought. Natural Rubber Research, 24(1): 150-154.
A glass house experiment was conducted with polybag plants of clone RRII 105 to study the effect of
potassium and silicon in alleviating the adverse effects of soil moisture stress in young rubber plants. The
experiment consisted of two treatments, viz, irrigated and unirrigated. Under each treatment, there were
four sub-treatments viz, control (standard practice), silicon (Si), potassium (K) and silicon + potassium
(Si+K). Silicon was supplied as rice husk ash, and incorporated into the soil, two weeks after planting. In
treatments with potassium, 2.5 times the recommended dose of K was added so that N:K was maintained
as 1:1. Observations on leaf water potential and chlorophyll content index indicated positive effect of silicon
and higher dose of potassium in overcoming soil moisture stress.
Keywords: Hevea brasiliensis, Moisture stress, Potassium, Silicon.

Natural Rubber Research, 24(1): 159-164, 2011 SHORT SCIENTIFIC COMMUNICATION
VARIATIONS IN LEAF FATTY ACID COMPOSITION
OF DIFFERENT CLONES OF HEVEA BRASILIENSIS
Molly Thomas and Jayasree Gopalakrishnan
Rubber Research Institute of India, Kottayam-686 009, Kerala, India
Received: 29 January 2011 Accepted: 18 April 2011
Thomas, M. and Gopalakrishnan, J. (2011). Variations in leaf fatty acid composition of different clones of
Hevea brasiliensis. Natural Rubber Research, 24(1): 155-158.
The increased unsaturation of lipids in plant cell membranes is considered as a necessary adaptation to
cold stress. Fatty acid composition of leaf polar lipids in different Hevea brasiliensis clones was analyzed
and the double bond indices computed. The main unsaturated fatty acids in the leaf polar lipids of H.
brasiliensis were palmitoleic acid, oleic acid, linoleic acid and linolenic acid. Palmitic acid and stearic acid
were the main saturated fatty acids. The double bond indices of leaf polar lipids in different Hevea clones
varied significantly. Among the clones, the highest double bond index was noticed in RRIM 703, suggesting
that it would be the most cold tolerant clone.
Keywords: Cold tolerance, Double bond index, Hevea clones, Leaf fatty acid.

Natural Rubber Research, 24(1): 159-164, 2011 SHORT SCIENTIFIC COMMUNICATION
STUDIES ON THE PERFORMANCE OF
HEVEA IN THE CHANGING CLIMATE OF
GARO HILLS (MEGHALAYA)
A.P. Thapliyal, R.P. Singh, M.J. Reju, D. Chaudhuri 1 ,
R. Krishnakumar 2 and James Jacob 2
Rubber Research Institute of India, Regional Research Station, Tura-794 001, Meghalaya, India
1. Rubber Research Institute of India, Regional Research Station, Guwahati-781006, Assam, India
2. Rubber Research Institute of India, Rubber Board, Kottayam-686009, Kerala, India
Received: 12 February 2011 Accepted: 9 May 2011
Thapliyal, A.P., Singh, R.P., Reju, M.J., Chaudhuri, D., Krishnakumar, R. and Jacob J. (2011). Studies on the
performance of Hevea in the changing climate of Garo hills (Meghalaya). Natural Rubber Research, 24(1):
159-164.
Meghalaya is one of the potential areas in North East India where natural rubber can be successfully
cultivated. However, the sub-Himalayan conditions prevailing in this part of the country, particularly low
temperature conditions during winter can be inhibitory to growth in the initial stages while summer
temperatures are congenial. It has been observed that low air temperature plays a very important role in
defoliation, refoliation and seed production in the region. Warmer winter conditions may increase survival
rate and shorten gestation period. Early leaf fall and refoliation lead to early production of extra-floral
nectar and helps seed production. This also helps in escaping from Oidium incidence. Thus a small shift in
the climate can have significant impact on rubber cultivation in North East India. Gradual warming may
make winter less severe and more areas in the North East may become suitable for rubber cultivation in the
years ahead.
Keywords: Climate Change, Garo hills, Refoliation, Temperature.

Natural Rubber Research, 24 (1): 165-169, 2011 SHORT SCIENTIFIC COMMUNICATION
DROUGHT TOLERANCE OF MODERN HEVEA
CLONES GROWN IN THE NORTH KONKAN
REGION OF MAHARASHTRA
Ravichandran, S. Meena Singh, James Jacob*, Krishnakumar, R*
and Annamalainathan, K*
Regional Research Station, RRII, Dapchari, Maharashtra-401 610, India
*Rubber Research Institute of India, Kottayam-686 009, Kerala, India
Received: 18 January 2011 Accepted: 18 May 2011
Ravichandran, S., Singh, M., Jacob, J., Krishnakumar, R. and Annamalainathan, K. (2011). Drought tolerance
of modern Hevea clones grown in the north Konkan region of Maharashtra. Natural Rubber Research, 24 (1):
165-169.
An experiment was conducted at Regional Research Station, RRII, Dapchari, Maharashtra to find out the
tolerance of modern Hevea clones to drought stress at the early stages of growth. Six months old young
plants of Hevea clones (RRII 105, RRII 208, RRII 414, RRII 429, RRII 430 and RRIM 600) were used in this
study. The maximum temperature during the study period ranged between 35.5 to 43.0 0 C. Visual
observations on drought injury indices viz., scorching, leaf yellowing, drying and leaf fall were taken at
frequent intervals (once in 4 days) after imposition of drought both in the polybag and field grown plants.
Clone RRII 429 showed relatively higher scorching than the other clones. In the polybag plants, leaf yellowing
was minimum in clones RRII 429 and RRIM 600, while other clones showed more leaf yellowing after 26
days of drought imposition. Clones RRII 429 and RRII 208 showed higher percentage of drying and leaf fall
in the polybag plants while clone RRII 430 had the least. Similar observations have been made under field
condition for these clones. Results from the field observations showed that clone RRII 430 was more tolerant
to drought stress than RRII 414 under field conditions.
Keywords: Drought, Drying, Hevea brasiliensis, Leaf fall, Yellowing.

INFLUENCE OF CLIMATE CHANGE
ON RUBBER HONEY PRODUCTION
S. Devanesan, K.S. Premila and K.K. Shailaja
AICRP on Honey Bees and Pollinators, Department of Agrl. Entomology, College of Agriculture,
Vellayani, Kerala Agricultural University- 695 522, Kerala, India
Received: 20 February 2011 Accepted: 11 May 2011
Devanesan, S., Premila, K.S. and Shailaja, K.K. (2011). Influence of climate change on rubber honey
production, Natural Rubber Research, 24 (1): 170-173.
Apiculture and commercial honey production in Kerala mainly depend on the rubber plantations. Rubber, Hevea
brasiliensis Muell Arg. yields both latex and honey (nectar). The latex is produced by the laticeferous cells in the
bark and nectar exuded from the extra-floral nectaries at the junction of the trifoliate leaf petiole. The leaves
of rubber tree shed during December-January. Generally the shedding of older leaves commences in the
Northern parts of Kerala during December and extends up to January in Southern parts. After this,
refoliation starts almost within one or two weeks depending on the weather conditions. The occurrence of
rainfall during these period results in the infection of tender leaves Oidium causing leaf shedding, affecting
seriously the nectar secretion. The young leaves at half maturity (light green colour) secrete nectar through
extra-floral nectaries situated at the junction of the petiole. The honey flow begins in Northern districts of Kerala
during January- February months and it extends up to February- March in Southern districts. A study was
conducted by AICRP on Honey bees and Pollinators at Vellayani centre to correlate the influence of untimely
rainfall and honey yield in rubber. Weather conditions influenced the secretion of nectar from the extra floral
nectaries. Rain washes away or diluted the nectar from the leaves resulting in severe economic loss to the
beekeepers. The increased relative humidity during the refoliation period due to untimely rainfall paved way
for the incidence of powdery mildew (Oidium heveae Steinm) on tender leaves. The leaves showed powdery/ashy
coating, curling, crinkling and edges of leaves rolled inwards resulting in leaf fall within a week. The average
honey yield and data on summer rain for the last five years showed that the untimely rainfall in 2008 honey flow
season negatively affected honey yield. The secretion of extra floral nectaries and in turn the production of honey
from the rubber plant are related to the prevailing weather and climate change especially too much rains during
the nectar secreting season will be harmful for honey production.
Keywords: Climate, Honey production, Nectar, Powdery mildew, Refoliation.

IMPACT OF CLIMATE CHANGE ON INSECT PESTS,
PATHOGENS AND THEIR NATURAL ENEMIES
Suseelendra Desai and M. Srinivasa Rao Central Research
Institute for Dryland Agriculture, Santoshnagar, Hyderabad
500059, Andhra Pradesh, India
Received: 28 January 2011 Accepted: 27 May 2011
Desai, S. and Rao, M.S. (2011). Impact of climate change on insect pests, pathogens and their natural
enemies. Natural Rubber Research, 24(1): 174-186.
Climate variability and climate change are exerting additional load on developing countries of tropics and
subtropics which are already burdened with the increasing demand for food owing to increasing population
pressure. Even a small rise in temperature in these areas will cause significant yield decline in major food
grain crops. The changing climate not only influences the crop growth and development but is also expected
to alter stages and rates of development of the pathogen, modify host resistance, and change in the physiology
of host-pathogen interactions. It is expected that the range of many insects, diseases and weeds will expand
or change, and new combinations of pests and diseases may emerge when natural ecosystems respond to
altered temperature and precipitation profiles. Although, the research in establishing the climate change
impacts on pathogens and their natural enemies is at its infancy, independent studies conducted across
laboratories world wide could be used to draw inferences. Elevated CO 2 levels are known to increase foliar
density which in turn will influence the microclimate of the pathogen, altered host morphology which
affects host-pathogen interaction, enhanced sporulation of pathogen, and increased dry-root rot under
moisture stress conditions. For instance, an increase in temperature may lead to increased host
susceptibility, a new/rapid development of the pathogen, more rapid vector development leading to faster
spread of the vector transmitted viral diseases, a variable
overwintering/over-summering of the pathogen/vector and shift in spread pattern of the pathogens. Initial
studies show an increased sporulation and altered bio-control traits in Trichoderma, a known bio-control agent.
Efforts are underway at CRIDA and other research organizations to assess climate change impact on important
pathogens and their natural enemies. The present paper reviews the interaction of weather variables with
different insects, diseases and weeds and the probable threats to food grain production, availability and
quality.
Keywords: Climate change, Climate variability, Insect-pests, Natural enemies, Plant pathogens.

NATURAL RUBBER RESEARCH
RESEARCH PAPERS
The manuscripts of research papers (about 8000
words) shall be divided into different sections.
1. Title page shall contain
f The full title, brief but appropriate and
informative,
f a short running title, not more than six words,
f name(s) of author(s) with surnames in bold
f affiliation and address(es) of the author(s)
f the name and email address of the principal
author or the author to whom correspondence
shall be made
2. Abstract shall include a brief statement of the
work and major findings, shall not exceed 200
words.
3. Keywords shall not exceed eight words.
4. Introduction shall include a clear statement of
the scope indicating the essential background.
5. Materials and methods/Experimental shall
contain sufficient details of the materials used and
techniques followed.
6. Results and discussion shall include all the
results, highlighting the significance of each.
Theoretical explanations for the major
observations may also be provided. The last
paragraph shall contain major conclusions and
recommendations, if any.
7. Acknowledgement shall be brief.
8. References shall be arranged in alphabetical order
of the author’s surnames and typed on a separate
page. This list shall include the name(s) of author(s),
year of publication, title of the paper, name of the
journal in full, volume, number and pages.
Examples:
Krishnakumar, A. K. and Dhanakumar, V. G. (2000).
An assessment of rubber producer’s societies (self
187
The Natural Rubber Research (formerly Indian Journal of Natural Rubber Research)
is published since 1988 by the Rubber Research Institute of India. The Journal
in English language has two issues, published half-yearly during June and
December, to each volume. Original research papers, short scientific
communications, invited review articles and theoretical papers are published.
INSTRUCTIONS TO AUTHORS
Two hard copies of the manuscript shall be sent to the Editor-in-Chief along
with one copy in electronic format either as email or on a CD. The manuscript
in English, shall be typed in double-space on one side, on white bond paper
of size 20x22cm. A margin of 4 cm shall be left on the left hand side. All
pages shall be numbered serially. Spelling conforming to the Concise Oxford
Dictionary of Current English is preferred.
help group of small growers), in the rubber
plantation sector in India. Proceeding of the
International Planters’ Conference, 17-20 May 2000,
Kuala Lumpur, Malaysia, pp. 491-502.
Mathew, N. M., Thomas, K. T. and Philipose, E. (1988).
Studies on ozone resistance of natural rubber-
ethylene/propylene rubber blends. Indian Journal
of Natural Rubber Research, 1 (1):8-17.
Mercykutty, V. C., Marattukalam, J. G., Saraswathyamma,
C. K. and Meenakumari, T. (2002). Identification of
Hevea clones: A manual. Rubber Research Institute
of India, Kottayam, 103 p.
Nair, N. U. (2000). Biochemistry and physiology of
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Agromanagement and Crop Processing (Eds. P. J.
George and C. Kuruvilla Jacob). Rubber Research
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Reghu, C. P. (1983). Structural studies on tension wood
of some broad-leaved trees. Ph.D Thesis, Sardar Patel
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References in the text shall be indicated by the
surname(s) of author(s) and year of publication. For
reference with more than two authors, the surname
of the first author followed by et al. and the year of
publication shall be used. References to the same
author or group of authors in the same year shall be
distinguished with small letters (Stanford, 1984a, b).
Tables, drawings and photographs
Each table shall be typed on separate page,
consecutively numbered with arabic numerals and
shall have an appropriate title. Data illustrated in
figures shall not be repeated in tables.
Line drawings shall be printed bold in black ink.
Each figure shall be drawn on a separate sheet and
consecutively numbered in arabic numerals.
Inscriptions and legends shall be relevant and legible.
Structures and schematic representations may be
printed in black on separate page.

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Photographs shall be glossy colour or black and
white prints of high contrast. Photographs will be
included only if essential. Magnifications must be
clearly indicated in the case of photo-micrographs.
Each photograph shall be consecutively numbered
in arabic numerals. Colour photographs related to
articles are welcome for printing on the cover page
window.
Captions to figures and photographs shall be
typed on a separate page. Explanatory material shall
be placed in the caption and not in the figure.
Scientific names
The full scientific name (genus, species, authority
and cultivar, if appropriate) shall be used for every
organism when first mentioned. Subsequently, the
genetic name may be abbreviated except where
intervening references to other genera would cause
confusion. Common names, if used, must be
accompanied by the correct scientific names on first
mention. Latin names shall be printed in italics. Chemical
names shall conform to the IUPAC system.
Units
International system of units shall be used for
exact measures of physical quantities. Standard
abbreviations are preferred.
Abbreviations, formulae and schemes
Widely accepted abbreviations may be used, but
the expansion shall be given on first mention.
Mathematical formulae must be carefully
printed with symbols properly aligned and correctly
spaced. When a manuscript contains several
mathematical equations, each major equation shall
be identified by a number in parenthesis.
Schemes shall be prepared on separate sheets,
camera ready for direct reproduction. Captions and
explanations shall be typed on a separate page and
not in the scheme.
SHORT COMMUNICATIONS AND REVIEWS
The manuscript of short scientific communica-
tions (up to 2000 words) shall also follow the style of
research papers. However, subheadings shall not be
given.
Review articles shall be comprehensive and shall
cover all relevant literature.
PROOFS
Proofs will be sent to the corresponding author
by email unless otherwise specified. The corrected
proof shall be returned to the Editor-in-Chief within
one week of receipt.
CORRESPONDENCE The
Editor-in-Chief Natural
Rubber Research
Rubber Research Institute of India
Kottayam – 686 009, Kerala, India
Phone : 91 481 2353311-20
91 481 2352770-71
91 481 2352773-79 (20 lines)
Fax : 91 481 2353327
Website : www.rubberboard.org.in
Email : rrii@rubberboard.org.in