Central Rice Research Institute Annual report...2011-12

Natural Resource Management and Input Use Efficiency for Improved Crop
Standardization of management practices for
System of Rice Intensification
A field experiment was conducted during the dry
season of 2010-11 with the objective to estimate the
nutrient requirement through organic and inorganic
sources for realizing higher yield under System of Rice
Intensification (SRI). Twelve days old seedling of
Naveen rice variety was transplanted with a spacing
of 25 cm x 25 cm under different treatments i.e., SRI
with organic source of nutrient (FYM @ 5t ha -1 ), SRI
with 50% RDF + 50% organic source, SRI with chemical
fertilizer (RDF: 80: 40: 40 NPK kg ha -1 ), SRI with
chemical fertilizer (120 % of RDF), 25% of RDF + 75%
organic source, T6- SRI with 75% of RDF + 25% organic
source, Conventional method (15 x 15 cm with
recommended management practice). Results revealed
that application of chemical fertilizer @ 120% of RDF
produced significantly higher grain yield (6.18 t ha -1 )
which was 38.3% and 26.1% more than treatment with
nutrients supplied through 100% organic sources and
traditional method of cultivation, respectively. This was
evident by significantly higher panicle weight (3.32 g),
grains per panicle (146.4), leaf area index (5.02) and
harvest index (0.49).
In another experiment, conducted during the dry
season of 2010-11, different weed management options
were evaluated under SRI method of rice cultivation.
Twelve days old seedling of rice variety Naveen was
transplanted with a spacing of 25 cm x 25 cm under
different treatments i.e., Azimsulfuron 35 g a.i. ha -1 (Low
dose high efficacy), weed free check (weeding at 20, 40,
60 DAT)/(15, 30, 45, 60 DAT), two hand weedings (15
and 30 DAT), weeding by cono-weeder,weeding by finger-weeder
and no weeding. Results showed that among
the different weed control practices, weed free check
produced maximum grain yield of 5.21 t ha -1 . The herbicide
Azimsulfuron 35 g a.i. ha -1 (Low dose high efficacy)
was found to be effective for controlling the pre
dominant weeds viz., Cyperus difformis, Sphenoclea
zeylanica, Fimbristylis miliacea, Marsilea quadrifolia,
Ludwigia parviflora etc. and produced comparable yield
with cono weeder (twice at 12 and 25 DAT) and hand
weeding (twice at 15 and 30 DAT). Yield reduction due
to weed competition in weedy plots was 48%.
Standardization of management practices for
organic rice production
In a field study, the efficacy of different nutrient
management options involving combinations of FYM
(at 5 t ha -1 , dry weight basis), Sesbania (5 t ha -1 , fresh
weight basis) and rice straw (5 t ha -1 ) was evaluated for
organic rice production. The combination of rice straw
and Sesbania produced highest yield. In another study,
efficacy of botanical i.e. neem oil @ 5ml lit -1 of water
with 2 ml labolene against major insect pests in two
promising quality rice variety, ‘Katrani’ and
‘Chinikamini’ was evaluated against control (No protection).
The experiment was laid out in a split-plot
design with 4 replications. The neem oil application
resulted in 8-10% higher grain yield and higher yield
was observed in ‘Chinikamini’ (4.20 t ha -1 ) compared
with ‘Katrani’ (3.34 t ha -1 ).
Evaluation of new herbicide molecule on wet
direct seeded rice
A field trial was conducted to evaluate the efficacy
of Penoxsulam + Cyhalofop-butyl at two different doses
along with Bispyribac sodium and was compared with
recommended practice of hand weeding twice at 20 and
40 days after sowing and weedy check. The rice cv. ‘Moti’
was established by sowing under puddled condition
in four replications. Significantly higher yield (5.08 t
ha -1 ) was recorded in recommended practice of hand
weeding twice. Among the tested herbicide, Penoxsulam
+ Cyhalofop-butyl at 135 g ha -1 controlled the weeds
effectively but recorded comparable yield with
Penoxsulam + Cyhalofop-butyl at 120 g ha -1 . The yield
reduction due to weed competition in weedy plot was
43%.
Rhizosphere effect on soil chemical
environment and nutrient use efficiency for
sustainable rice production
Exudation of organic acids by the roots of two rice
cultivars grown in three different soils with different P-
status, and their impact on the rhizospheric P-dynamics
and P-uptake by the rice plants was investigated.
Root exudates from all the rice cultivars were significantly
greater at 21 days after transplanting than at
maximum tillering, panicle initiation, flowering and
grain filling stages. Malic acid was the most predominant
organic acid present in the rice root exudates (9.1
to 103.2 mol plant -1 d -1 ), followed by tartaric, citric and
acetic acids. Greater exudation of organic acids from
rice grown in P-deficient soil by all the rice cultivars
suggested response of rice plant to P-stress. The differential
response on individual genotypes to nutrient
deficiency based on the type and quantity of organic
acids exuded suggests a genotype and nutrient-spe-
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