Effects of Water Stress and Different Potassium Levels on Yield, Water Use Efficiency and Harvest Index in Potato

In order to investigate the effects of water stress and potassium fertilizer on yield, yield components, economic water use efficiency (EWUE), biologic water use efficiency (BWUE) and harvest index (HI) of potato var. Aola, used furrow irrigation with different irrigation intervals. This research was conducted in split plots experiment based on randomized complete block design with three replications. Main plots consisted of three treatments of water stress, after 100 mm (light deficit) and 130 mm (severe deficit) evaporation from class A pan along with control (without deficit) and sub plots to five levels of potassium fertilizer with five levels i.e. 0, 62.5, 125, 187.5, and 250 kg.ha-1 K2O were applied. Water stress with three levels i.e. irrigation after 70 mm (without deficit), 100 (light deficit) and 130 (severe deficit) evaporation from class-A pan and potassium with five levels i.e. 0, 62.5, 125, 187.5, and 250 kg.ha-1 K2O were investigated. Sever deficit decreased tuber yield, tuber number per plant, average tuber weight, tuber and total dry matter, HI and EWUE but increased BWUE of potato. The highest amount of BWUE and EWUE were 893 and 631.1 g.m-3 respectively that resulted from light deficit. The highest amount of other traits that resulted from without deficit. The amount of all traits increased in higher levels of potassium. The highest amounts of yield (23.62 t.ha-1), average tuber weight (39.89 g), tuber dry matter (6.38 t.ha-1), total dry matter (871.60 g.m-2), HI (%71.2), BWUE (871.1 g.m-3) and EWUE (617.4 g.m-3) resulted from 250 kg.ha-1 K2O.