Effect of drought stress on gas exchange, physiological parameters and yield of tomato (Solanum lycopersicum) genotypes was investigated under pot culture conditions in rainout shelter. The drought condition was created at 15 days after transplanting based on field capacity of soil. Experiment was laid out with 18 genotypes by adopting CRD with three replications and two treatments viz, 100 and 50 % field capacity. As the stress increased from 100 % field capacity to 50 % field capacity, reductions in photosynthetic rate, leaf water potential, chlorophyll stability index (CSI), relative water content (RWC) and nitrate reductase activity (NRA) were noticed at all the growth stages. The genotypes LE 114, LE 57, LE 118 and LE 27 which showed significantly less reduction in the above parameters during drought were considered as drought tolerant. Genotypes LE 1, LE 3 and LE 20 which recorded the lowest photosynthetic rate, CSI, RWC, proline and NRA and ultimately poor yield were considered as drought susceptible

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