Abstract
To explore the high biomass producing accessions of guar [Cyamopsis tetragonoloba (L.) Taub.], under hot and dry conditions, an experiment was conducted under natural field conditions located at Research Station, University College of Agriculture, Sargodha, Pakistan using 36 different accessions. Twenty-day old plants grown under normal irrigation were subjected to control and drought (withholding of irrigation for 20 and 40 days) conditions. It was observed that plant fresh and dry biomass, plant height, net CO2 assimilation rate (P-n), transpiration rate (E) and inter CO2 conc. (C-i) of all guar accessions under study decreased considerably on withholding of irrigation for both 20 and 40 days. Of all guar accessions, Acc. BR99, 5597, BWP 5595, BWP 5596, BWP 5609, BWP 5611, 24323, Chiniot Black, Khushab Black were relatively higher in plant height and plant biomass (fresh and dry) under water stress conditions. However, a significant increase particularly in BR99, BWP 5595, BWP 5599, BWP 5609, 41671 followed by Sialkot White was observed in the relative membrane permeability of all guar accessions under water limited conditions. All accessions varied significantly in terms of P-n, E and C-i. Accessions BR90, BR99, BWP 5596, 24323, 24332, Chiniot Black, Khushab Black, 41671, 24323, BWP 5611, Khushab White, Mardan, Khanewal Local 2 and Sialkot White were better in P-n, C-i and E. No significant change was observed in the water-use efficiency of guar accessions under water-limited conditions. Overall, BR99, 5597, BWP 5595, BWP 5596, BWP 5609, BWP 5611, 24323, Chiniot Black and Khushab Black were higher, whereas accessions BWP 5595, 24321, Khushab White, Silanwali White, Sialkot Black and Khanewal Local lower in plant biomass and different gas exchange characteristics under water limited conditions, so the earlier mentioned accessions can be recommended as high biomass producing guar accessions for their cultivation on hot drought-prone areas.