Yield response to pm-planned water-deficit irrigation

Yield responses to pre-planned-deficit irrigation are reviewed for cotton, maize, potato, soybean, wheat, common bean,, groundnut, sunflower and sugar cane. Crops including cotton, potato, maize, wheat, groundnut, common bean, sunflower 9 soybean, sugar beat and sugar cane are well suited to deficit irrigation practices if reduced evapotranspiration is imposed only, during a certain growth stage or stages. Among these crops, cotton, groundnut and maize can withstand reduced evapotranspiration imposed through out the whole growing season without, significant yield reduction. Mechanisms contributing to crop tolerance, to temporal water stress, developed during deficit irrigation, differ depending on crop species. Maize develops an adaptive strategy of extending rooting depth and extracting water from deeper soil while simultaneously reducing leaf area to decrease transpiration. Soybean reduces shoot and root growth, decreases leaf chlorophyll and shoot soluble sugars, but increases soluble sugar content of roots for lowering osmotic potential. Adaptation of cotton to deficit irrigation practice may be attributed to uninterrupted biosynthesis of fatty acids that strengthen cell membranes. The osmotic adjustment ability of wheat cultivars, largely, controlled by leaf sugar and proline concentrations, is another complex mechanism of field-crops, which makes deficit irrigation a feasible option to increase water-use efficiency.