A Preliminary Investigation on Possible Role of Allelopathy in Saffron

A <strong>Preliminary</strong> <strong>Investigation</strong> on Possible Role of Allelopathy in
Saffron (Crocus sativus L.)
M. Hosseini S.J.H. Rizvi
Khorasan Research Center for Technology Development Professor of Plant Physiology
P.O. Box 91735-139
Rajendra Agricultural Univ.
Mashhad
India.
Iran.
Keywords: autotoxicity, wheat germination
Abstract
A preliminary experiment was conducted on possible role of allelopathy
in saffron. Seven treatments composing of soil and corm extracts of saffron were
applied on seed germination of wheat (cv. Omid). The statistical method used for
data analysis was carried out on the basis of Completely Randomized Design.
The results showed that effect of substances present in saffron corms was evident
on percent and rate of germination, dry weight of radicle and plumule of wheat
seeds. Characters under investigation were adversely affected by extracts of old
(E) and new (F) corms of saffron farms. There was a considerable loss compared
to treatments: A, B, C, D, and G. It appeared that substances extracted from
saffron corms showed autotoxicity effects reducing saffron yield after several
years. More research is yet required to determine these substances and find
possible elimination ways from saffron farms with biological treatments instead
of displacing farms.
INTRODUCTION
Saffron (Crocus sativus L.) is one of the most important crops in southern and
central Khorasan. This crop has a considerable role in the socio-economic situation of
people living in this area. Currently, saffron is cultivated in more than 20000 ha and
in more than 15 cities of Khorasan province. Saffron cultivators experience yield
reduction in their farms and they displace the farms after eight years. The reasons are
not fully understood yet. Plants compete for moisture, light and nutrients. Part of this
competition is chemical interaction (allelopathy) that in many cases are resulted from
secondary substances. These chemicals are produced in different parts of plants.
Allelopathy affects plant population and has been studied extensively (Chase
et al., 1991; Rice, 1974; Waler, 1989). Allelopathy has an important role in growth,
development and evoluation of plants (Hedin, 1990; Sing et al., 1992). Conventional
method of allelopathy studies includes evaluation of extracts of embryos, roots and
stems of growing plants (Athanassova et al., 1981; Greca et al., 1990; Roussev, 1974).
Aqeous extract of Artemisia sp. has inhibitory effects on germination and elongation
of recipient plants (Kil and Yun, 1992). Acid ferulic prevents from growth of leaves
and reduces water consumption in tomato and cucumber (Hollapa and Blum, 1991).
Purpose of this experiment was to determine probable presence of allelopathic
chemicals in saffron corms.
MATERIALS AND METHODS
In order to study saffron allelopathy, samples were collected from saffron
corms and soils. Treatments were: soil of old farm (A), soil of old farm from where
saffrons were selfthinned (B), soil of new farm (C), soil of a farm that saffron had not

een cultivated in was used as control 1 (D), corm of old farm (E), corm of new farm
(F), distilled water as control 2 (G). Samples were collected in autumn 1998 from two
year old saffron farm (new one) and from eight year old saffron farm (old one)
located at the experimental station of saffron and medicinal plants in Khezri, Ghaen.
Samples of saffron corms and soils were collected from depth of 25 cm from
soil surface. They were sent immediately, frozen and kept at temperature -40 °C
before conducting the experiment.
Samples were kept in the lab. temperature at least for two hours. Soil samples
each one was mixed completely and 100 g soil was mixed into the beaker with 500 ml
distilled water. Two collected corm samples, at first, separately were washed with
water and then with distilled water. After this stage, each corm sample was kept in
80% ethyl alcohol for one minute. 100 g corms was transported into a grinder and
crushed with a little distilled water (Rizvi and Commun., 1997).
It was poured into a beaker with 500 ml distilled water. Since then, following
the experiments for soil and corm samples were similar. Samples were shook for at
least 18 hours with a shaker in 30 °C. Then, solutions were centrifuged with 4000
rpm. Solid phase was eliminated and the rest was passed from a membrane filter for
decontamination of the microbes and the samples were transferred into the
refrigerator with 5 °C. Samples were kept in the lab. temperature for a while before
operation. In this stage, bioassay test was conducted on wheat seeds cv. Omid. Plates
were sterilized in 150 °C and then the seeds were disinfected with 50 % Benomyl
fungicide. 15 cm plates were used with 50 seeds in each one. 18 ml solution was
added to each one. Each treatment with 4 replications was established. Wheat seed
germination was tested in the darkness in 15 °C in the germinator. Germination
(length of radicle as much as half the seed length) was measured for 5 days. Rate of
germination was calculated with the following equation (MaGuire, 1962).
M
R.G.= ∑
i D
In which M is number of germination till i th day, and D is number of days spent from
the beginning of the test.
Four wheat seeds were selected in each plate with four replications for
measurement of radicle and plumule dry weights. On the basis of growth, in the 5 th
day plumules and radicles of the four seeds were put in an envelope and were kept in
an oven with 65 °C for 48 hours. Thus, their dry weights were measured. Results were
analysed statistically as C.R.D. (P

Figure 2 (a) shows dry weight of wheat radicle affected by corm extract of old
farm (E) and showed significant difference compared with control 1 (D) and control 2
(G). Dry weight of radicle in four treatments related to soil and corm samples of new
farm was affected by allelopathy but this effect was less than treatment related to
corm of old farm. These chemicals also had negative effects on dry weight of wheat
plumule (figure2b). Corm extracts of old farm (E) and new farm (F) reduced
significantly dry weight of wheat plumule. Aqeous extract of leaves and roots of
Chenopodium murale also prevented from germination and growth of wheat and
barley seedlings under laboratory conditions (Qasem, 1993). Perez et al. (1991)
reported about effects of excreted chemicals from wild oat roots on spring wheat.
Ben-hammonda et al. (2001) have reported that aqeous extract of barley reduces
radicle and plumule growth of durum and bread wheat.
Results show that there are allelopathic chemicals in saffron corms. In order to
determine these chemicals and their adverse effects on different stages of saffron
growth and development as autotoxicity further researches are needed.
Literature Cited
Athanassova, D.P., Roussev, G. and Konstantinov, K. 1981. Isolation of specific
factors from embryos of Echinochola crusgalli L. Plant Physiology, Sofia 7:
78-85.
Ben-Hammouda, M., Ghoral, H., Kremer, R.J. and Oueslati, O. 2001. Allelopathic
effects of barely extracts on germination and seedlings growth of bread and durum
wheats. Agronomie 21:65-71.
Chase, W.R., Nair, M.G. and Putnam, A.R. 1991. 2, 2- Oxo- 1”azobenzene: Selective
toxicity of rye (Secale cereale L.) allelochemicals to weed and crop species. J.
Chemic. Ecol. 17:9-19.
Greca, M.D., Mangoni, I., Molonaro, A., Monaco, P. and Previtera, L. 1990. (20S)-4-
methylenecholes- 7- en- 3- ol an allelopathic sterol from Typha latifolia.
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potential allelopathic compound, on leaf growth, water utilization and endogenous
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a)
Percent of germination
60
50
40
30
20
10
a
a
a
a
b
b
a
0
A B C D E F G
b)
Treatments
Rate of germination
16
14
12
10
8
6
4
2
0
a
a
a
a
a
b
b
A B C D E F G
Treatments
Fig. 1. Effects of different treatments of soils and corms of saffron on percent of
germination (a) and rate of germination (b) in wheat seed. A: soil of old farm, B:
soil of old farm from where saffron was selfthinned, C: soil of new farm, D: soil
of no saffron cultivated (control 1), E: corm of old farm, F: corm of new farm, G:
distilled water (control 2).

Dry weight of plumule (gr) Dry weight of radicle (gr)
0.025
0.02
0.015
0.01
0.005
0
0.045
0.04
0.035
0.03
0.025
0.02
0.015
0.01
0.005
0
(a)
a
a
a
a
a
b
b
A B C D E F G
Treatments
(b)
a
a
a
a
a
b
b
A B C D E F G
Treatments
Fig. 2. Effects of different treatments of soils and corms of saffron on dry weight of
radicle (a) and dry weight of plumule (b) in wheat seed. A: soil of old farm, B: soil
of old farm from where saffron was selfthinned, C: soil of new farm, D: soil of no
saffron cultivated (control 1), E: corm of old farm, F: corm of new farm, G:
distilled water (control 2).