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Wheat Information
Service
Number 71: 16-18 (1990)
Effect
of wheat straw extract on the germination and seedlings growth of
wheat (cv. Pavon)
S. M. Alam
Atomic Energy Agricultural Research Centre, Tandojam,
Pakistan
Abstract
Wheat straw water extract at concentrations of 0.0, 0.2, 0.4 and
0.6% were evaluated to see their effects on the germination and
seedling growth of wheat (cv. Pavon) under laboratory condition. With
increasing concentrations of residue extract, the germination, shoot
and root growth of wheat crop were significnatly decreased. Root
growth was affected more than shoot. This may be due to the
inhibitory effect of water-soluble substances released from wheat
straw.
Introduction
Crop residues on the surface of the soil are very effective in
controlling soil erosion by wind and water. However, when crop
residues are left on the soil surface, crop yields are occasionally
reduced as compared to the incorporation of residues into the soil.
Substantial evidence has been accumulated to show that phytotoxic
substances are present in most crop plants and may be responsible for
reduced crop growth (Borner 1960; Garb 1961). Guenzi and McCalla
(1962) showed that the water extracts of a number of crop residues
inhibited the germination and growth of sorghum, corn and wheat in a
laboratory experiment. LeTourneau et al (1956) found that water
extracts from 23 common weed and crop species inhibited germination
and growth of wheat seedlings.
Researchers elsewhere have generally shown that allelopathy from
wheat residue reduces the subsequent wheat yield (McCalla 1971;
McCalla and Haskins 1964; McCalla and Norstadt 1974). They showed
that water-soluble substances in crop residues reduced the
germination and growth of wheat seedlings and other crops.
Allelopathic chemicals from soils, crop residues and weeds are known
to reduce the growth of several crops and there are numerous examples
of allelopathy among crop plants. Allelopathy is often more evident
in disturbed plant communities, such as agricultural ones.
The objective of this investigation is to study the effect of aqueous
extract of straw from wheat crop to germination and growth of wheat
seedlings (cv. Pavon).
Materials and Methods
i) Preparation of residues: Mature straw of wheat plant was
collected from the experimental wheat field at AEARC, farm, Tandojam
in April 1989. The samples were first dried in the sun for 12 hr.
then transferred to a forced-draft oven for thorough drying at 75 +
or - 5C for 24 hr. Dried samples were then ground in a Wiley mill to
pass a 1.18 mm2
screen. Ground
samples were kept in plastic bags at room temperature.
ii) Laboratory trials: Three levels of wheat straw extracts 0, 0.2,
0.4 and 0.6% (w/v), were prepared for use in petri-dishs germination
study with wheat seeds. The extracts were prepared by soaking the
dried ground residues in distilled water for 24 hr. at room
temperature in 250 ml Erlenmyer flasks. The extracts were then
filtered into 100 ml beakers using NO.41 Whatman filter paper.
Wheat seeds were disinfected in 1% sodium hypochlorite solution for 2
minutes and them rinsed with distilled water. Ten healthy wheat seeds
were placed in a petri-dish lined with filter paper and 5 ml of
extract added from each treatment. The treatment at extract level was
replicated three times in a randomized complete block design. All the
petri-dishs were kept in an incubator at 28 + or - 2C for 120 hrs.
The experiment was terminated after 120 hrs. The number of seed.
germinated were counted. Their shoot and root length were also
measured. The experiment, was conducted twice and the results were
expressed in terms of the averages of the two trials. The data were
analyzed to evaluate the treatment effect.
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