Physiological and Biochemical Basis of Resistance to Purple Seed Stain of Soybean [Glycine max (L.) Merrill]
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Date
2012
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UAS, Dharwad
Abstract
Investigations comprised of laboratory, field and pot experiments to elucidate
physiological and biochemical basis of resistance to Purple Seed Stain (PSS) disease in
soybean conducted at UAS, Dharwad during kharif-2011.
Recording of purple seed stain incidence taluk wise in northern Karnataka revealed
that Chikkodi recorded maximum PSS severity with 7.24 per cent followed by Bailhongal
(6.29%). Badal Ankalagi village of Bailhongal taluk recorded highest incidence of 12.93%.
Thus the disease incidence varies with weather conditions and agronomic practice.
Glass house and in vitro studies on PGPR and ISR elicitors revealed that seed
treatment with Trichoderma harzianum @ 1000 ppm showed more resistance to PSS disease
and recorded highest peroxidase activity.
Field screening of 50 germplasm lines to PSS showed that 14 lines as highly resistant,
9 resistant, 9 moderately resistant, 8 susceptible and 10 lines as highly susceptible.
Correlation study between disease susceptibility and bio-physiological parameters indicated
that there was positive correlation between chlorophyll and RWC (r = 0.035), while
chlorophyll and RWC were negatively correlated (r=-0.117 and r=-0.035, respectively) with
disease severity.
Seed germination study of seed priming with bioagents and fungicides under lab
condition indicated significantly maximum germination per cent in seeds primed with
combifungicide carboxin 37.5% + thiram 37.5% @ 0.2% (99%) followed by carbendazim @
0.2% (94%). Whereas, field performance of the primed seeds indicated that Bacillus subtilis
@ 0.6% recorded significantly higher seed yield (3221 kg ha-1) followed by captan 70% WP
+ hexaconazole 5% EC @ 0.2% (3116 kg ha-1) and carbendazim 25% + mancozeb 50 WS @
0.2% (3083 kg ha-1).
Thus, it may be concluded that priming of soybean seeds with the combifungicides viz,
captan 70% WP + hexaconazole 5% EC @ 0.2%, carbendazim 25% + mancozeb 50% WS @
0.2% or with bioinoculant Bacillus subtilis @ 0.6% controlled PSS disease substantially.