SCHEDULING IRRIGATION FOR PEANUTS WITH VARIABLE AMOUNTS OF AVAILABLE WATER

Field experiments were conducted on sandy loam soils for two summer se asons to formulate optimum water management practices for peanuts grow ing under variable water supplies. Scheduling irrigation to supply ade quate water during the moisture sensitive periods of flowering and yie ld formation stages, yet allowing moderate stress at vegetative and ma turity phases produced the optimum yield (2823 kg/ha) with maximum wat er-use efficiency (7.73 kg/ha/mm) and water economy. At times of defic it water supply, irrigations can be scheduled at 60% depletion of avai lable soil moisture all through the crop period without reducing the a rea under the crop for want of irrigation water. Yield response factor s (ky) which relate relative yield decrease to relative evapotranspira tion deficit were calculated. These curves measure crop sensitivity to degree of soil moisture stress. Lower ky values due to no soil moistu re stress at flowering and yield formation stages stress the need for an adequate water supply at these stages. For a relative ET attainment of 0.71 to 0.74, the relative yield levels varied between 0.5 and 0.6 only. On the other hand, for relative seasonal ET of 0.76 to 0.84, th e peanut yields varied from 0.74 to 0.86. These relationships at varyi ng irrigation schedules suggest that it is possible to recommend an op timum irrigation schedule that will ensure a high yield at different l evels of irrigation water availability.