Research with grain sorghum often involves sampling several times during the growth cycle. Samplings often are designated by calendar date, days after planting or emergence, or plant height. Often these bear little or no actual relationship to the morphological or physiological age or status of the plant. Although certain stages of sorghum growth are fairly well established, the growth cycle of sorghum has not been fully described. Therefore, a standard set of growth stages needs to be defined. Based on detailed studies of grain sorghum hybrids of different maturities, the following ten stages of development have been defined and illustrated: emergence, three‐leaf, five‐leaf, growing‐point, differentiation, final leaf visible in whorl, boot, half‐bloom, soft dough, hard dough, and physiological maturity. These stages are suggested as standards to describe the timing of sampling or treating sorghum.
Furrow irrigation studies comparing water applications to narrow and wide‐spaced furrows were conducted on three crops at thee locations in Oklahoma over eight growing seasons. Wide‐spaced‐furrow irrigation usually required about half the water of narrow spacing. In 9 of 11 studies, no yield reductions were noted. In the seasons where yield reductions were noted, the atmospheric evaporative demand was high. A simple test was devised to indicate if a season in progress shows high atmospheric demand. The evaporative demand test involves measurement of rainfall and daily wind movement. Using standard National Weather Service instruments, daily average of rain > 1.6 mm between 15 July and 31 Aug. combined with daily wind movement < 155 km in August caused no yield reduction in wide‐spaced‐furrow irrigation. Wind was measured at the standard height of a “Class A” evaporation pan (51 cm). Conservation of water from wide‐spaced‐furrow irrigation should be possible on medium to fine textured soils in many semiarid regions of the world.
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