Effects of planting date on two cultivars of potato yield in Kermanshah climatic conditions

A factorial layout based on a randomized complete block design in three repetitions was carried out to evaluate and compare the effect of early and common planting on two potato cultivars in 2018-2019 in research farms at Razi University of Kermanshah. Experimental factors included 4 planting dates (November 16, 2018- March 16, 2019- April 9, 2019- May 10, 2019) and two cultivars (Sante and Marfona). Cultivar factor affected significantly on total yield, No. of small (less than 35 mm) and medium tubers, the weight of small and medium tubers (p< 0.01), marketable yield, and tuber dry matter (p<0.05). Also there were significantly different in total yield, marketable yield, the weight of medium and large tubers, number of large tubers, the weight of infected tubers, number and length of the main stem, dry matter percentage, and tuber starch percentage between various planting dates. The highest and the lowest mean marketable tuber yield were observed in November and May planting dates, respectively (53.1 and 36.6 tonnes per hectare, respectively). Also, planting date significantly affected on infected tuber weight (p<0.01), so November planting date resulted in no infected tuber compared to other planting dates. Water consumption (m3.h-1) was 5040, 7230, and 6962 in March, April, and May planting dates, respectively, that were more than the November planting date (4350). Then, net income increased 55% from the sale of tubers by shifting the planting date from common to autumn cultivation. In addition to producing higher quality tubers, potato cultivation in the autumn had a relatively higher price in the market.