Physiological and agronomic responses of sudangrass to water stress.

A study was conducted in Plant Physiology Section, Agronomic Research Institute, AARI, Faisalabad, Pakistan during 2007 to evaluate ten accessions of Sudangrass (Sorghum sudanense) (337, 8614, HOK, 9580, TV-3368, 958, 39501, Succro, 4158 and Line 7) for drought tolerance on the basis of physiological and agronomic attributes. Data were recorded for stomatal conductance (gs), water potential (Ψw), osmotic potential (Ψת), turgor pressure (Ψp), shoot length (SL) and root length (RL) under control as well as water stress conditions. Analysis of variance indicated significant differences among all accessions for all characters. Average reduction in gs, Ψw, Ψת, Ψp, SL and RL was 32.30, 3.32, 1.53, 13.02, 7.28 and 3.47 percent, respectively. Accession HOK comparatively maintained its leaf water relations under water stress conditions. Based upon principle component analysis, proportional contribution of osmotic potential, water potential, turgor pressure, root length, shoot length and stomatal conductance was 38.3, 24.3, 14.7, 7.4, 5.3 and 10 percent for drought tolerance. So proportional contribution of osmotic potential was the highest towards drought tolerance. Osmotic potential could be used as selection trait for drought tolerance as it contributed maximum to all drought parameters. Line 7, 337 and 958 had the highest multivariate scores under water stress, whereas, 9580, 39501 and 8614 had the lowest scores. The most promising and drought tolerant accessions (three accessions with highest scores and three with lowest scores) were screened through multivariate scoring index.