Grain Sorghum Yield and Yield Component Response to Timing and Number of Irrigations1

Abstract

AbstractEfficient use of irrigation water becomes more essential as the availability of this resource declines. Research evaluating the effect of timing and number of irrigation water applications on yield and yield components of grain sorghum [Sorghum bicolor(L.) Moench] was initiated in 1976. The experiment was conducted on a Richfield silty clay loam (fine, montmorillonitic, mesic, Aridic Argiustoll). Irrigation water treatments were applied at preplant (PP), PP + growth differentiation (GD), PP + boot (B), PP + GD + B growth stages, and PP + initiation of irrigation at 50% available soil moisture. Maximum grain yields were consistently achieved when three or more irrigations were applied. Two irrigation water applications reduced grain yields, but the timing of the in‐season water application (GD or B) had no effect on yields. Yield components were evaluated in 1982 and 1983 to determine what effect timing of water application had on these parameters. Irrigation at GD resulted in a greater number of kernels per head and per unit area, whereas applications at B increased seed weight. Head weight showed no response to the timing of water applications, suggesting that the same amount of dry matter was accumulated in the head whether water was applied at GD or B. Therefore, producers of grain sorghum have a broader time period over which to apply limited quantities of irrigation water without reducing grain yield than is reported in most literature. However, if maximum yield potential is desired, it is necessary to have adequate water available to the plant at GD to set the maximum number of kernels.