Irrigation-yield response factor of processing potato for different phonological growth stages

The yield response factor of processing potato (variety: BARI Alu-25 and BARI Alu-28) was determined from field experimental data conducted during two consecutive years (2013 and 2014) at Bangladesh Agricultural Research Institute, Gazipur. There were six irrigation treatments including full irrigation at three growth stages (stolonization, tuberization and bulking stages), single irrigation at each growth stage, irrigations at stolonization and bulking stage, and irrigation at tuberization and bulking stage. Results reveal that the crop yield response factor (ky) and sensitivity index (λi) increased with the increase of intensity of water deficit at different phonological growth stages. Non-significant difference was found in paired t-test at 5% level of significant. On an average, the ky for tuberization + bulking, stolonization + bulking, stolonization + tuberization, tuberization and stolonization was 0.23, 0.24, 0.28, 0.03, and 0.006 for BARI Alu- 25, while 0.23, 0.24, 0.27, 0.04, and 0.007 for BARI Alu-28, respectively. According to the value of yield response factor, the most critical growth stages were in the order: stolonization + tuberization>stolonization + bulking>tuberization + bulking>tuberization>stolonization. For the entire growing season, the ky values were 0.76, 0.86, 1.07, 0.71 and 0.07 for tuberization + bulking, stolonization + bulking, stolonization + tuberization, tuberization and stolonization for BARI Alu-25, while 0.98, 1.13, 1.86, 0.77 and 0.08 for BARI Alu-28, respectively. The λifortuberization + bulking, stolonization + bulking, stolonization + tuberization, tuberization and stolonization stage was 0.12, 0.13, 0.19, 0.01, and 0.002 for BARI Alu-25, while 0.13, 0.15, 0.17, 0.01 and 0.003 for BARI Alu-28, respectively. A more sensitive growth stage has a higher value of lamda i, and therefore water supply is more important at stolonization + tuberization stage.