Potassium humate foliar application effects on yield and yield components of different potato cultivars at spring cultivation in Ardabil region

The effect of different concentrations of potassium humate organic matter was investigated on yield and yield components of five potato varieties in spring planting date of 5th May in Ardabil region, northwest Iran. Experiment was carried out as factorial based on a randomized complete block design with three replications during 2010 and 2011 growing seasons. Potassium humate was applied at three levels (0, 250 and 300 mL.ha-1 in 300 liter water) and the studied potato varieties included Agria, Savalan, Kaizer, Markiz and Lota. Traits including number of stems, number and weight of tubers per plant, and tuber yield were measured during growing season and after harvesting. Results revealed significant effect of potassium humate, variety and interaction of potassium humate and variety on the studied traits. Savalan and Agria had the highest number of main stems per plant and the lowest number of that was observed in Lota. Number of tubers per plant was higher for Savalan than other studied cultivars. The highest number of tubers per plant was obtained with 250 mL.ha-1 potassium humate application. Savalan also produced the highest tuber weight per plant. The highest tuber weight per plant was obtained when 250 mL.ha-1 potassium humate was applied. Savalan produced the highest total tuber yield when 250 mL.ha-1 potassium humate was applied. Based on the results, Savalan, Kaizer and Markiz were recognized as high product and stable varieties, whereas Agria and Lota were unstable ones with lower yield.