AUGMENTATION OF BIOCHEMICAL DEFENSE AGAINST ALTERNARIA BLIGHT OF MUSTARD BY INDUCTION OF DROUGHT STRESS
S.A. Mallick, P. Kumari, M. Gupta, S. Gupta, M.I. Jeelani
Effect of induced drought on plant defense response to Alternaria blight infection and subsequent impact on yield and oil quality was investigated in leading Indian mustard varieties viz. RSPR-69, Pusa Mahak and RH-30 with reference to variety PC-5 as control. Alternaria blight incidence in induced drought was found to be reduced significantly in all mustard varieties. Foliar levels of antioxidant ascorbic acid and total phenol, detoxifying/cell protecting enzymes viz. superoxide dismutase (SOD), peroxidase (POX), phenylalanine ammonia ayase (PAL) and polyphenol oxidase (PPO) and related biochemical parameters viz. proline, total amino acid and total soluble protein increased in infected leaves and their level further elevated under induced drought as well as Alternaria brassicae inoculation. However, remarkable rise in total sugar level and further loss in chlorophyll content and relative water content (RWC) were observed under induced drought conditions. Moreover, losses due to Alternaria blight infection i.e. seed/oil yield, decline in iodine number and rise in peroxide and saponification number were recovered when drought was artificially induced to the mustard varieties. The Alternaria blight sensitive but drought tolerant RSPR-69 variety got maximum recovery out of induced drought treatment.