EFFECT OF DEFOLIATION ON KERNEL DEVELOPMENT IN MAIZE

Abstract

A study was conducted to evaluate the effect of leaf removal on kernel dry matter accumulation, kernel moisture content, and rate of black layer formation in kernels, in relation to changes in soluble-solid content of the stem of maize (Zea mays L.). In 1970, defoliation was begun at mid-silking and continued at 2-wk intervals until 6 wk after mid-silking. The treatments consisted of (1) no leaf removal, (2) 50% of leaf blades removed, and (3) all leaf blades removed. In 1971, a treatment with complete leaf removal at 1 wk after mid-silking was added. Kernel number was greatly affected by the treatments during the first 2 wk after mid-silking, whereas later defoliation affected mainly kernel weight. Soluble-solid content in the stem declined rapidly after leaf removal, indicating an accelerated utilization of soluble carbohydrates from the stem for grain growth. Maturity, expressed as both kernel-moisture content and rate of black layer formation, was affected significantly by the defoliation treatments. The data presented indicate that a decrease in the source–sink ratio during grain-filling advances date of maturity.