Gas exchange characteristics of the flue-cured tobacco (Nicotiana tabacum L.) cultivars grown under two production systems

The net photosynthetic rate (P-N) intercellular CO2 concentration (C-i), st omatal conductance (g(s)), transpiration rate (E), water use efficiency (WU E), and leaf biomass production of four American flue-cured tobacco (Nicoti ana tabacum L.) cultivars K 326, K 358, and Speight G 28 were compared with three local Indian cultivars 16/103, Special FCV, and PCT-7, during 1994 a nd 1995 crop seasons under irrigated and rainfed production systems (Northe rn light soils, NLS, and Karnataka light soils, KLS) in India. By compariso n, the American tobacco cv. K 326 showed the highest P-N and g(s). A positi ve correlation was found between P-N and biomass production in all the vari eties tested (r = 0.55 in NLS and 0.73 in KLS). The American cultivars were superior than the local cultivars in their biomass production and P-N unde r Indian fanning conditions.