Germination, Growth, and Ion Uptake of 15 Guar Accessions under Elevated Salinity

Core IdeasSalinity and drought are the major issues confronting agriculture in arid regions of the world.Guar is a multipurpose drought- and salt-tolerant crop that has the potential to improve farm revenue in arid regions.Guar accessions vary in their salt tolerance and there is a strong need for developing information on accessions appropriate for elevated salinity.Results of this study provide information on accessions appropriate for saline arid regions. Growers in the arid regions of the world constantly face freshwater scarcity and salinity. It is essential to develop information on crops that can tolerate water and salinity stress for ensuring long-term viability of agriculture in these extreme environments. Guar (Cyamopsis tetragonoloba L.) is a multipurpose crop mainly grown in arid regions of south Asia and the United States is a major importer of this crop. If guar can be produced on saline soils in the arid west, it can improve farm income of local growers. This controlled environment study evaluated germination, physiological response, seedling growth parameters, and ions uptake of 15 guar accessions under different salinity (0.9-control, 4.5 and 9.0 dS m(-1)). Results indicated that while one accession (PI 268229) recorded 100% germination at 9.0 dS m(-1), two accessions (PI164476 and PI 43359) showed 100% germination at 4.5 dS m(-1). Across all accessions the chlorophyll content and assimilation of CO2 decreased as salinity level of irrigation water increased, but the chlorophyll fluorescence (Chl F) remained higher at all three salinity levels. Accession PI 549164 had maximum leaf area and shoot biomass (OD weight) at 9.0 dS m(-1). Although the Na and Cl contents increased, K content and K/Na ratio decreased in all accessions with increasing salinity. This could indicate that selective ion uptake to be the dominant salinity tolerance mechanisms in early stages of guar.