Abstract
This Research was conducted in Hamadan province for evaluation of potato cultivars reaction to cultivation date. This experiment was performed in split plot design based on randomized complete block in thee replication with two factors, containing, I. main plots are planting date including: 9 April, 25 April, 10May, 26May, 10 June, 26 June 2. And subplots are Cultivar with three Levels, Agria, Marfona and Sante. In developing period of growing time and harvesting date we measured 1l traits, including, days after planting to fifty percent germination 2. overlaping time 3. plant height 4. tuberization time s. main stem No 6. ripening time 7. total yield 8. marketable yield 9. Nonmarketable yield, 10. dry matter of tuber 11. long of tuber dormancy. Conclusion of multiple analysis variance demonstrated that year effect was significantly different at 1% level in tuberization also, was significantly different at 5% level in total yield and marketable yield. but hadn`t any significant difference with other traits. Cultivation date with cultivar reaction had significant difference in all traits. Cultivation date and cultivar had significant difference at 1% level with all traits other than main stem and plant height. Comparison of means showed that two dates of cultivation containing 10 May and 26 May with three cultivars had better marketable yield. Cultivation in 9 April produced highest total yield but was low quality in tuber production with marketability range. In totally, Marfona produced higher marketable yield In all cultivation date with comparison of two other cultivars.

Keywords: Potato, Planting date, Cultivar, Marketable yield, Dry matter of tuber