بررسي تحمل برخي از نمونه هاي گوجه فرنگي مدارات شمالي نسبت به سرماي زمستانه استان خوزستان

The tolerance of some tomato ecotypes of northern altitudes to winter hardiness at Khouzestan Province - Iran

Temperature play fundamental role in all biological processes of tomato plant. High temperature is an obstacle to germination seed and emergence of the seedling. Furthermore, low temperature affects fruit setting and its growth and development. In south west of Iran early autumn sown crops due to high temperature exhibited poor emergence along with epidemy of diseases and plants death. At the final stages of growth, low temperature in the area decreases plant growth by leaf development, branching and fruit setting. Therefore, identifying lines tolerant to high temperature for early growth stage and tolerant to low temperature at final growth stage was the main objective in this research. In order to obtain such lines during 1998 to 2000, 11 seed samples from north latitudes used in several experiments at south west of Iran were employed. The sample "M40" exhibited relativity high tolerance to high temperature at emergence stage by 100% of the seed were emerged and until transplanting without any mortality. However the mortality in other cultivars was up to 65%. Some early maturing cultivars started flowering and fruit setting, some others exhibited tolerance tolow temperature and no damages to leaves and branches were observed. This was specially true in the case of plants that did not set any fruit. The sample "M21" exhibited higher cold tolerance in this plants with stand below zero temperature. "M40" and "M64" showed relatively high tolerance to low temperature, produced fruit without any extra operations such as pruning. "Kl", "Stormy", "H1" and "L2" were found to be sensitive to low temperatures, but yeilded seedless fruits after removal of the low temperature. Only the tolerant samples set seed during the low temperature period.