Effects of different irrigation regims and amounts of potassium on qualitative characteristics of potato in Mashhad climatic conditions

In order to study of yield and qualitative characteristics of potato (Aola variety), an experiment was conducted in Mashhad conditions under irrigation regims and different levels of potassium fertilizer. This experiment was based on randomized copmpletely blocks with split plot design with three replications in Khorasan Razavi Agricultural and Natural Resource Research Center in 2010. Three levels of water regimes were including: irrigation after 70, 100 and 130 mm evaporation from class-A pan and potassium level had five levels: 0, 62.5, 125, 187.5 and 250 kg ha-1. Water regimes arranged as main plots and potassium placed in sub plots. Deficit irrigation decreased yield and sturch content of potato tubers and increased tuber protein. The smallest tuber size and tuber second growth were in 130 mm evaporation from class-A pan. In this research, application of potassium fertilizer was increased tubers yield, size and sturch and tubers phosphour and potassium concentrations and decreased number of marketable potato tubers. Uusing 250 kg ha-1 K2O increased tuber yield, sturch, phosphour and potassium about 31.5%, 14.26% 2.78% and 3.85% respectively. The highest sturch was in 70 mm evaporation from class-A pan with 250 kg ha-1 K2O and also the highest tuber protein was in 100 mm evaporation from class-A pan with 187.5 kg ha-1 potassium level.