Abstract

Out of 28 genotypes (inbred lines) of maize (Zea mays L.) one waterlogging resistant (HUZM-265) and a susceptible (HUZM-55) were identified on the basis of waterlogging tolerant coefficient (WTC) by imposing waterlogging stress during early growth phase. Selected genotypes were further grown in pots and after 20 days subjected to root zone waterlogging with or without 50, 500 and 2000 µmol L^-1 sodium nitroprusside (SNP) as a donor of NO in the flooding water. Waterlogging caused reduction in leaf number, leaf area and dry weights of plants in both genotypes. Flooding root zone with 50 µmol L^-1 SNP, alleviated the stress effects or sensitivity (not tolerance), but to a greater magnitude in susceptible genotype.  Stomatal conductance, transpiration rate, chlorophyll decreased as the waterlogging duration increased. Nitrogen content in roots and shoot of waterlogged plants also declined significantly. 500 µmol L^-1SNP treatment tend to alleviate the deleterious effect of waterlogging. Cell membrane injury in roots of waterlogged plant was higher in genotype HUZM-55 than in HUZM-265 and 500 µmol L^-1SNP were found to have mitigating role in combating it. 500 µmol L^-1SNP was found effective for alleviating transpiration rate, chlorophyll content and nitrogen content in both genotypes while 50 and 2000 µmol L^-1SNP increased stomatal conductance in HUZM-265 and HUZM-55, respectively. It is concluded that SNP mitigates the deleterious effect of waterlogging in maize. However, the effective concentration varies for different parameters and the different genotypes.

Key words: Zea mays L., waterlogging, nitric oxide, sodium nitroprusside, waterlogging tolerance coefficient.