عنوان مقاله [English]
Background and Objectives: Determination of the most suitable time for crop planting is one of the basic requirements to gain the highest yield and income. Planting date is one of the most important factors in growth, development and yield production in potato planting effects of temperature fluctuations on growth and tuber abnormality and inappropriate quality comes from the special features of the that region being uncontrolled by farmers.
Materials and Methods: This study was conducted in 2015-2016 in research station of Faculty of Agriculture, Ferdowsi University of Mashhad as split-plot based on Complete Randomized Block Design with three replications. Treatments were combination of four planting dates (March 5th, March 19th, April 3th and May 4th) as main plot and three potato cultivars (Agria, Fontane and Sante) as sub-plots. Harvesting was done 90 days after 50% of emergence.
Results and Discussion: Number of stem per plant as one of the effective potato yield components was not affected by planting date. Results indicated that as planting date was delayed from March 5th to May 4th, leaf area index was increased by 64 and 85% in two cultivars of Agria and Fontane while a decreasing trend of this parameter was observed in Sante. Number of tubers per plant was decreased by delaying planting date from March 5th to May 4th except in Fontane in which number of tubers per plant was increased in April 3th and was reduced thereafter. The highest and lowest tuber yield with a difference of 12391kg.ha-1was found in April 3th and March 19th, respectively and was observed in Fontane cultivar. Tuber dry matter percentage of Agria was increased as planting date delayed while it was increased till April 3th and reduced in Fontane. The highest (22.13) and lowest (18.50) tuber dry matter percentage of Sante was found in March 5th and 19th, respectively. An increasing trend of potato tuber specific weight was observed with delaying planting date in a way that the highest and lowest mean of this parameter was found in March 19th and May 4th, respectively. No significant difference was observed between Agria and Fontane in different planting dates according to reduced sugars content of tubers. Total antioxidant and starch of potato tubers was increased in all three cultivars as planting date was delayed and reduction sugar decreased by delayed in planting date.
Conclusion: Late planting dates were better than early plantings. Sante showed a better performance in early planting dates compared to the two other cultivars, producing more marketable tubers with higher quality and dry matter percentage. Generally, it could be concluded that in Mashhad weather conditions, Sante is more appropriate for early planting compared to Agria and Fontane but its superiority is lost when planting date is delayed.