Mitigation of drought stress through plant growth regulators and vesicular arbuscular mychorrizae (vam) in cotton (gossypium hirsutum)
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Date
2007
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UAS, Dharwad
Abstract
The present investigation was carried out during kharif, 2006-07 with seed
priming through plant growth regulators (GA3, CK and CCC) and VAM (Vesicular
Arbuscular Mycorrhiza) tested under three levels of moisture stress i.e. 100 %, 70 %, 50 %
field capacity in Gossypium hirsutum cv. LRA 5166 to mitigate the drought stress.
Under severe moisture stress condition, germination decreased by
60 per cent while application of VAM enhanced germination by 25 per cent. Root and shoot
length and seedling vigour index reduced with increase in moisture stress. These parameters
enhanced considerably with VAM application to soil. While, root: shoot ratio was minimum
(19.5%) in VAM treatment compared to other treatments.
Total chlorophyll content and its fractions decreased with an increase in moisture stress.
In general, VAM treatment and seed priming with CCC showed lesser reduction in total
chlorophyll and its fractions followed by the kinetin and GA3 treatments. Free proline content
increased in all the treatments with an increase in moisture stress. The treatment VAM and
CCC further enhanced the accumulation of proline under increased moisture stress. The
reducing sugar increased in all the treatments with an increase in the moisture stress. The
treatment VAM and CCC accumulated more reducing sugar irrespective of moisture levels.
The peroxidase activity was maximum at 65 DAS and with increase in moisture stress
the peroxidase activity increased. Among the treatments, VAM and CCC showed higher
activity at both the stages followed by kinetin and GA3. Relative water content (RWC)
indicated significant differences due to plant growth regulators and VAM and it was higher in
the treatment VAM and CCC followed by kinetin and GA3.
Moisture stress reduced the seed cotton yield and yield components (number of bolls
and boll weight) and among the treatments, VAM recorded significantly higher seed cotton
yield, higher number of good opened bolls and higher boll weight at all the moisture stress
levels compared to other treatments.
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Crop Physiology