Effect of irrigation scheduling on potato crop parameters under water stressed conditions

Field experiments were conducted on a local cultivar, Kufri-Jyoti, of potato crop during the four winter seasons of 1995–1996 through 1998–1999. Five irrigation treatments were maintained based on the maximum allowable depletion (MAD) of available soil water (ASW). The treatments were 10% (T1), 30% (T2), 45% (T3), 60% (T4) and 75% (T5) MAD of ASW during non-critical stages of crop growth. Measurements of fresh tuber yield, dry tuber yield, plant dry matter (including roots but not tubers), total dry matter and leaf area index were made at various stages of crop growth during all four crop experiments. Fresh tuber yield of potato was significantly higher under high frequency than low frequency irrigation. With delayed irrigation, the yield reduced significantly under T4 and T5, which resulted in minimum fresh tuber yield and total dry matter yield during all four experiments. With increase in MAD from 45 to 75%, the fresh tuber yield reduced considerably due to reduction in the availability of water. A similar trend was observed for other crop parameters. Crop production functions with respect to crop water use were developed for five measures of plant growth; they were found to be linear. Though the results of the study are applicable for sub-humid sub-tropical climatic conditions with sandy loam soils as that of the study area, the objective methodology developed has universal applicability.