Biochemical characterization of maize ( Zea mays L.) hybrids under excessive soil moisture stress

A set of 32 maize hybrids were evaluated under excessive soil moisture (ESM) stress. The plants were subjected to waterlogging for 12 days at the flowering stage by maintaining 3–5 cm water level. Physiological and biochemical traits were examined to analyze plants’ response to waterlogging stress. The chlorophyll a, b and total chlorophyll content declined due to ESM stress, and the decrease was relatively higher in the case of susceptible hybrids. The decrease in chlorophyll content had shown a significant impact on total carbohydrate content, but the tolerant hybrids thrive better under stress with a capacity to maintain higher carbohydrate concentration. Proline accumulation was enhanced in all hybrids in response to the above stress, but it was tremendously increased in tolerant hybrids to offer osmotic protection compared to the sensitive genotypes. Total chlorophyll, chlorophyll-a, carbohydrate, proline as well as an increase in proline content in response to stress, revealed a significant positive association with seed yield, while percentage decline in chlorophyll, decrease in carbohydrate and senescence percentage maintained the reverse trend. Further, the chlorophyll ‘a' followed by an increase in proline content can be considered as important parameters for assessing tolerance to ESM stress owing to their high positive direct effects on seed yield.