EFFECTS OF SOIL MOISTURE TENSIONS ON GROWTH OF WHEAT

Abstract

Greenhouse experiments in which wheat was grown on a limited amount of soil moisture showed that crops subjected to moisture stress at an early stage of growth yielded well on all soils tested, but that crops with moisture stress late in the season yielded poorly on loam soils. Late stress was less damaging on clay because high soil moisture tension in this soil resulted in better distribution of moisture use during the critical period.Crops grown under early stress used less moisture, but were equally as efficient in grain production as those grown under optimum conditions. Crops with moisture shortage during heading and filling were inefficient in moisture use.Similar variations in moisture efficiency caused by seasonal trends in available moisture supply have been observed under field conditions. For example, good yields of wheat were produced with a minimum of rainfall in Saskatchewan in 1958 when a shortage of moisture in May and June was followed by more favorable conditions in July.