عنوان مقاله [English]
Introduction: Tomato is a major source of the antioxidant, lycopene, which has been linked to many health benefits, including reduced risk of heart disease and cancer. It is also a great source of vitamin C, potassium, folate and vitamin K. Optimal planting dates and appropriate cultivars are farm management cases that are effective in increasing yield. The purpose of the planting date is to find the planting time of a cultivar or a group of similar varieties of a plant so that the set of environmental factors at that time would be appropriate for the emergence, establishment and survival of the seedlings. Because of off-season production, tomato has a high economic status in Bushehr Province. Some researchers reported that cultivars with larger fruits had the lowest number of fruits per plant. By investigating the response of tomatoes to time of transplantation, fruit yield and crop characteristics of the cultivars, a number of researchers reported that the date of transplantation had a significant effect on the number of days to flowering, the number of branches per plant, the diameter of the fruit, the number of fruits per Plant and fruit yield, early transfer of seedlings increased the harvest period, while late planting date was significantly effective on flowering, and the plants sooner went to flower.
Materials and Methods: The study was conducted in order to determine the best transplanting date and tomato cultivars. An experiment was carried out in Randomized Completely Block Design with four levels of transplanting dates (6 Sep, 27 Sep, 17 Oct and 6 Nov) in main plots and four cultivars (Petopride 2, Peto Early CH, Cal J-N3 and Kimia) in sub plots with four replications in Bushehr Agricultural and Natural research resource center during 2009-2011.The spacing between rows of planting was 140 cm and plant spacing was 50 cm. Each plot included 4 planting lines of 4 meters long. Before planting in the summer, land preparation was done between June and August. The amount of fertilizer was determined based on soil test results. Phosphorus fertilizers, potassium, micronutrient and one third of nitrogen fertilizers and iron sequestrons, along with decayed animal manure, were mixed prior to deployment of type tubes and mixed with soil. One third of nitrogen fertilizers and iron sequestrons were given during flowering and one-third remained at the time of fruit start. Irrigation was carried out on a regular basis, taking into account the weather conditions and plant requirements. After each harvest, fruit yield, fruit number per plant, fruit weight, yield per plant were measured. To determine the length and diameter of fruit, acidity and soluble solids from each plot, 10 fruits were selected randomly.
Results and Discussion: Interaction effect among the tomato cultivars and transplanting dates on fruit yield, yield per plant, number of fruits per plant, fruit weight and fruit diameter were significant at 1% probability level. In the first year, the highest total yield and fruit yield per plant were obtained from the transplanting date of 6 September and Potoperide 2 cultivar, and the lowest yield was produced with November 15 transplanting date and Kimia cultivar. In the second year, the highest total yield and fruit yield per plant were obtained from the transplanting date of 27 September and kimia cultivar, and the lowest amount was obtained from the transplanting date of 6 November and Peto Early CH cultivar. Planting date is one of the most important management practices which affects the crop growth through the effect on photoperiod, day and night temperature, light intensity and soil moisture. In most cases, earlier planting dates due to the longer vegetative and reproductive growth period of the plant may improve the allocation of photosynthetic materials to the plants.
Conclusions: This study showed that fruit yield and yield components were significantly affected by planting date and cultivars. Generally, delay in planting reduces fruit yield, plant yield, fruit weight and number of fruits per plant. Environmental factors such as light, temperature, CO2, moisture content can be changed from year to year. These factors affect the number of flowers formed in the plant, their pollination, the percentage of fruit formation. Also, the potential of cultivars had a significant effect on yield and its components and the cultivars producing the shorter fruit had the least number of fruits per plant.