The transpiration response of 14 transgenic groundnut genotypes to water deficit was studied under greenhouse conditions and compared with that of JL 24 (control). Plants were grown under well-watered conditions until 19 days after sowing, after which the plants were saturated with water then subjected to drought stress (absence of irrigation). JL 24 started to show wilting symptoms (loss of turgor) after 21 days of stress, after which severe symptoms were evident in this line. JL 24 reached the stage III (normalized transpiration rate or NTR <0.1) after 27 days. Wilting symptoms were not observed in the transgenic lines even after 21 days. Thereafter, these lines exhibited various levels of wilting symptoms, with a few transgenic lines showing no symptoms, and lines RD 14, RD 22 and RD 25 showing reduced levels of symptoms compared to JL 24. The transgenic lines varied largely in the number of days to reach the end point. RD 14 reached the end point in 29 days, whereas RD 4 reached the endpoint in 52 days. Data on NTR, fraction of transpirable soil water, and number of days to end point were subjected to average linkage cluster analysis for the development of a dendrogram. This dendrogram showed that the lines could be classified into 4 groups, which clearly distinguished the water use pattern among these lines, suggesting that the transgenic lines varied in their stomatal response to water deficit
