Soybean field outlook: water use efficiency and Bradyrhizobium japonicum

Abstract

The efficient use of limited water resources is an urgent issue for the Republic of Moldova. In field experiments at the level of cenosis water-use efficiency (WUE) is defined as yield (Y) divided by applied water.1 As the measure of applied water or water consumption of the crop usually used the evapotranspiration (ET)-the mass of water evaporated in the cenosis during the growing season by the soil (evaporation, E) together with plants (transpiration, T). E is included in water requirement since Briggs and Shantz (1913),2 in view to practical difficulties to estimate separately beneficial (T) and nonbeneficial (E) consumption of water. In connection with the use of portable gas exchange analyzers (simultaneously CO2 and H2O), it was proposed to evaluate WUE at the leaf level as a ratio of carbon dioxide assimilation (A) to water consumed, expressed as transpiration (T); the time-scale for defining WUE can be instantaneous (i).3