Loss of Kernel Set Due to Water Deficit and Shade in Maize

Abstract

To advance our understanding of the underlying processes by which kernel set is regulated in maize (Zea mays L.), leaf photosynthesis, sugars, starch, abscisic acid (ABA), and cytokinin were quantified in plants subjected to water deficit and shade, imposed for 5 d at the pre‐pollination and early post‐pollination stages. Both water and light deprivation, at both stages, decreased kernel set primarily in apical ear regions. Treatments decreased leaf photosynthesis similarly; however, sugar concentrations in reproductive tissues increased in water deficit while they decreased 20 to 50% in shade. During treatments, nonstructural carbohydrate accumulation was nearly halted in both apical and basal florets at the pre‐pollination stage, whereas it was decreased to a greater extent in apical than basal endosperm/nucellus at the post‐pollination stage. Both water deficit and shade increased ABA concentrations in reproductive tissues, but only at the post‐pollination stage was ABA greater in apical than basal ear zones, thus corresponding to effects on kernel set. Treatments did not consistently alter zeatin‐like cytokinin concentrations. We conclude that photosynthate flux and ABA are components of a regulatory system by which water and light deprivation affect kernel set at the post‐pollination stage, while additional factors may underlie effects at the pre‐pollination stage.

Corn Yield Response to Reduced Water Use at Different Growth Stages

“…The 50% FC treatment might have had significant moisture deficit stress on the plants starting at the V14 growth stage, as observed from the delay in tassel and silk emergence, and this has been reported in other studies in corn plants under moisture deficit stress [7] [8] [24]. Out of all the vegetative growth stages, the period V14 to V15 growth stage is the most critical period for seed yield determination [6] [28] [29].…”

“…In the present study, significant reduction in yield at 50% FC at the V14 stage could have been brought about by reduction in the number of ovules that develop silks. Moisture deficit stress that continues after pollination into the early stages of kernel development can abort developing kernels [6] [7]. In this study this could have occurred in the 50% FC treatments at the R1 growth stage resulting in significant yield reduction, and to some extent in the 75% FC treatment.…”

“…Therefore, the 75% FC treatment at the R1 stage may have retained sufficient moisture to maintain fertilization and development of kernels and produce yield comparable or close to that of the 100% FC treatment. Moreover, in the present study, the soil moisture treatments at the different growth stages were continued until maturity rather than a brief stress treatment only during a specific growth stage, as in other studies [7] [26].…”

“…Corn requires different amounts of water at different growth stages. It requires less water at the early and late growth stages, while the peak water requirement occurs during the period two weeks before and after silking [5]- [7]. In the Mississippi Delta, there is usually adequate precipitation during the vegetative growth stages of corn plants (April-May), but during the reproductive and the grain fill stages (June-August) there is frequent drought and irrigation is required to avoid yield loss.…”

Leaf Rolling Reduces Photosynthetic Loss in Maize Under Severe Drought

“…For instance, a fi ve-day drought stress during pollination has caused formation of aborted embryos and decrease in kernel numbers in maize (ZINSELMEIER et al 1999). Drought stress and shading during pre and post pollination stages have decreased kernel set in the apical regions of maize ears (SETTER et al 2001).…”