Supplemental Irrigation at Reproductive Growth Stages to Improve Popcorn Grown at Different Populations

Abstract

When irrigation sources are limited, supplemental irrigation at selected growth stages may help avoid crop stress. The objective of this study was to determine the effect of limited, supplemental irrigation at two reproductive growth stages of popcorn (Zea mays L.) grown at different populations. The experiment was conducted from 1995 through 1998 on a Parsons silt loam (fine, mixed, thermic Mollic Albaqualf). The experimental design was a randomized complete block with a split‐plot arrangement of treatments. Six irrigation schemes of no irrigation, application of 2.5 or 5 cm at R1 (silk stage) or R3 (milk stage), and 2.5 cm at both R1 and R3 were main plots, and populations of 37000, 49000, and 62000 plants ha−1 were subplots. Popcorn yield was affected by irrigation in only 2 of 4 yr. In the driest growing season (1996), yields were low, but either 2.5 or 5 cm of irrigation applied at R1 increased yields by 60% or more compared with irrigations at R3 or no irrigation. In 1997, 2.5 cm of irrigation at R1 or 2.5 cm at both R1 and R3 resulted in 23 to 27% greater yield than with no irrigation. These responses were partially explained by 12 to 13% greater number of kernels per ear. The optimum plant population was 49000 plants ha−1; this treatment maximized yield, kernel weight, and produced one ear per plant. Responses to irrigation were not affected by plant populations for any measured parameters. Popping expansion ratio was unaffected by treatments. Supplemental irrigation at critical reproductive growth stages influences yield but is inadequate to provide consistent yield and quality improvements for popcorn grown in the eastern Great Plains.