Differential growth, yield and biochemical responses of maize to the exogenous application of Kappaphycus alvarezii seaweed extract, at grain-filling stage under normal and drought conditions

Abstract Maize is sensitive to water stress at flowering and grain-filling stages and thus strategies for the mitigation of stress and improving the yield sustainably would be beneficial. Two factorial pot experiments were carried out to assess the efficacy of a biostimulant product obtained from Kappaphycus alvarezii in conjunction with recommended rate of fertilizers (RRF), in mitigating moderate and severe stress in maize. The plants were subjected to normal as well as water deficit conditions following which Kappaphycus alvarezii seaweed extract (KSWE) was applied foliarly only once at the grain-filling stage along with a suitable control (water spray + RRF). Growth and yield parameters along with antioxidant enzymes, metabolites and reactive oxygen species content in leaves were studied. The results revealed that water deficit conditions (moderate and severe) significantly (p  O 2 − and H 2 O 2 levels, both under normal and stressed conditions, resulted in a lesser degree of oxidative stress in KSWE treated plants. Thus, the results revealed that a single application of KSWE, even at a late crop stage can be beneficial under normal irrigated condition.