Pre‐Anthesis Defoliation Effects on Six Corn Inbreds1

Abstract

AbstractYield loss due to defoliation prediction charts have been developed for corn (Zea maysL.) hybrids, but not for inbreds. The latter is needed by the hail‐loss insurance industry. Field experiments were conducted at the University of Illinois on a Drummer silty clay loam (Typic Haplaquoll) in 1982 and a Flanagan silt loam (Aquic Argiudoll) in 1983 to evaluate the response of six corn (Zea mays L.) inbreds to 0, 50, and 100% defoliation at the 14‐leaf stage with respect to grain yields and yield components. One inbred, FRMo17rhm, produced yield responses quite different from the other five. Complete and 50% defoliation reduced grain yields of five inbreds by an average of 45.5 and 2.5%, respectively; and FRMol7rhmby 86.0 and 17.0%, respectively. With the exception of FRMo17rhm, yield, decreases were due more to a reduction in kernel number than kernel size. Yield reductions with 50% defoliation were due to a reduction in ear number as opposed to kernels per ear; whereas complete defoliation affected both yield components. Ear number was reduced both by decreasing the number of plants with double ears and increasing the number of barren plants. In general, genotypic differences in the yield response to complete defoliation coincide with genotypic differences in final leaf number and the effect of defoliation on increasing the interval between anthesis and silking.