EFFECT OF CALCIUM CARBIDE ON PHOTOSYNTHETIC CHARACTERISTICS, GROWTH AND YIELD OF TOMATO CULTIVARS

In order to ascertain the growth, yield and photosynthetic responses of tomato (Lycopersicon esculentum Mill.) cultivars to ethylene releasing compound calcium carbide (CaC2), a pot trial was conducted. Response of three tomato cultivars “Rio Grande” “Tenzila” and “F-1 3560-S” to different rates of CaC2 was observed. Polyethylene coated CaC2 was applied at different rates (0,100, 200 and 300 mg pot^-1) two weeks after transplantation of nursery plants into pots and data on photosynthetic characters; net photosynthetic rate (PN), carboxylation efficiency, photosynthetic water use efficiency, plant water use efficiency (WUE) and agronomic parameters; plant height, root and shoot dry weight, number of days to flower and fruit yield per plant were recorded. Results revealed that PN, carboxylation efficiency and photosynthetic water use efficiency were increased by 40, 33 and 10%, respectively in Rio Grande; 16, 36 and 42%, respectively in Tenzila and 37, 48 and 29%, respectively in F-1 3560-S cultivar compared with control by applying 200 mg pot-1 coated CaC2. Plants treated with 100 mg pot-1 CaC2 improved 13, 17 and 28 % WUE in all three cultivars, respectively. Application of CaC2 reduced plant height, number of days to flower while improved number of fruits set per plant. The rate of CaC2 @ 300 mg pot^–1 gave the best results in improving number of fruits and yield per plant.