Improvement of frost tolerance in tomato by foliar application of potassium sulphate

• LT 50 values of tomatoes were determined for the first time by DTA. • A single exotherm per sample determined when tomatoes was subjected to subzero temperatures. • VT-1770 was found the most tolerant variety while Safir F1 was the least tolerant. • 1% K 2 SO 4 fertilizer dose offered considerable frost resistance after 24 and 72 h. The study aimed to determine the mean low-temperature exotherms (LTE) of the shoot tip of the Ömür F 1 , Cuma F 1 , Safir F 1 , VT-1770, Elibol F 1 , and Adelya F 1 tomato cultivars and Yerli-14 and Yerli-24 local tomato genotypes. Moreover, this investigation intended to specify the most effective dose of potassium sulfate with its efficacy time by applying four different doses of potassium sulfate (K 2 SO 4 ) foliar fertilizer on the most and least tolerant cultivar. The mean LTE of the shoot tip of seedlings was determined by using differential thermal analysis (DTA). In the second part of the study, 0%, 0.5%, 1%, 1.5%, and 2% dosage of K 2 SO 4 foliar fertilizer were applied on the least and most tolerant cultivars with the intent of identifying the most effective dose increasing frost tolerance. It was also stated how long the ideal fertilizer dosage would be effective. DTA method may be effectively used in the determination of frost tolerance in tomatoes. VT-1770 was found the most tolerant cultivar while Safir F 1 was the least tolerant. In the study, 1% fertilizer dose was found the most effective dose among the 0%, 0.5%, 1%, 1.5%, and 2% studied doses of K 2 SO 4 foliar fertilizer after applying on Safir F 1 and VT-1770 tomato seedlings. The dose of 1% K 2 SO 4 fertilizer offered considerable frost resistance after 24 and 72 h later while slightly losing its efficacy after 120 h later as compared to each other after 1% application of fertilizer dose applied on Safir F 1 and VT-1770 tomato seedlings. Present study revealed that the foliar application of K could be applied to enhancing frost tolerance in tomatoes.