灌浆期高温胁迫下褪黑素对玉米产量及淀粉粒分布的调控作用OA

In order to clarify the regulatory effects of melatonin on maize yield and starch granule distribution under high-temperature stress during the grain filling stage,the maize hybrid AK985 was used in a field experiment conducted from June to September 2022.Under natural high-temperature stress during the grain filling stage,different concentrations of melatonin were applied.The effects of melatonin on maize yield,starch particle size distribution,starch viscosity parameters,and related enzyme activities under high-temperature stress during the grain the filling stage were studied.The results showed that melatonin significantly increased grain weight and grain yield of maize under natural high-temperature stress during the filling stage.With increasing melatonin concentration,both grain weight and yield increased first and then decreased.Compared with the control,melatonin treatment reduced corn kernel protein content while significantly increased grain starch and fat content.Additionally,melatonin significantly decreased the volume and surface area proportions of medium-sized starch granules,increased those of large-sized starch granules,with no significant effect on the number proportions of medium-sized and large-sized starch granules.Among the treatments,peak viscosity,trough viscosity,final viscosity,breakdown value,and setback value of maize starch first increased and then decreased with increasing melatonin concentration.Melatonin significantly enhanced grain AGPase and SS enzyme activity,with the MT200 treatment showing the highest values.Under natural high-temperature stress during the grain filling stage,melatonin treatment elevated the volume and surface area proportions of large starch granules,and subsequently increased kernel starch content,contributing to higher kernel weight and yield.The optimal effect was observed at a melatonin concentration of 200 μmol/L.