Effect of Different Potassium Levels on Yield and Growth Indices of Potato in Mashad Climate Condition

To study the yield and growth indices of potato under different potassium levels an experiment was conducted in Agricultural and Natural Resource Research Center, Khorasan Razavi province, Iran during 2010. Potassium levels 0, 90, 180 and 270 kg K2O per hectare were included. In the experiment the tuber yields were 18.90, 21.59, 22.26 and 24.94 t/ha in 0, 90, 180 and 270 kg K2O per hectare, respectively. Potassium increased total dry matter (TuDM), root dry matter (RDM), stem dry matter (SDM), leaf dry matter (LDM), tuber dry matter (TDM), crop growth rate (CGR), leaf area index (LAI), leaf area duration (LAD), and net assimilation rate (NAR).The maximum TDM (835 g.m2) was obtained in 270 kg K2O per hectare and lowest TDM (778 g.m2) was taken in 0 kg K2O per hectare. The maximum RDM, SDM, LDM and TDM were in 1600 GDD, 1800 GDD, 1500 GDD and 2300 GDD, respectively. The maximum RDM, SDM, LDM and TDM obtained in 270 kg K2O per hectare and were 26.1, 324.86, 171 and 500 g.m2, respectively. The maximum LAD (309.37 m2.GDD-1) was obtained in 270 kg K2O per hectare in 1600 GDD. In the general potassium increased all of the growth indices in potato.