Effect of Planting Date and Depth on Agronomic Traits of Potato Cultivars (Solanum tuberosum L.) inAutumn and Spring Crops

In order to investigate the effect of effect of date and depth of tuber cultivation on some agronomic traits of potato cultivars in autumn and spring cultivations, a split factorial experiment was carried out based on randomized complete blocks design with three replications in Ardabil Agricultural and Natural Resources Research Station during the two cropping year 2017-2018. Planting date as the main-factor at three levels (10 Novomber, 10 December and 10 May) and a combination of four potato cultivars (Esprite, Marfona, Savalan and Agria) and four planting depths (10,15,20 and 25 centimeters) as a sub-factor was considered. The results of the investigated traits showed that the height of all four cultivars was significant on average 68 centimeters on the planting date of December and they were at the highest plant height. The highest average number of main stems (4 stems) during two years was observed in November planting date. Savalan cultivar with 9 tubers per plant had the highest number   in November cultivation at a depth of 10 and 15 centimeters. On 10 May planting date, Marfona cultivar had the highest tuber weight (on average with 675 grams) per plant in four planting depths. Single stem in plants is not a desirable trait. In Marfona cultivar, it was three in November and in single-stemmed plants in December, it was less than in November and May. The highest water use efficiency was observed in the cultivar of Sprite in 10, 15 and 25 depths in November and December planting dates. The highest tuber yield was in planting date May compared to two planting dates November and December. The Marfona cultivar at four sowing depths in May planting date 35.86, 32.39, 27.45 and 25.02 ton per hectare, respectively. Finally, it can be concluded that autumn cultivation of potato is suitable, especially in areas with water shortages. The highest water use efficiency in autumn cultivation at depths of 10, 15 and 25 centimeters was related to Esprit cultivar.