Moisture and Salt Tolerance of A Forage and Grain Sorghum Hybrid During Germination and Establishment

Sorghum [Sorghum bicolor (L.) Moench] is being explored in California as a multi-utility, water-use efficient crop, but water and salt stresses are common in the state's San Joaquin Valley (SJV). Experiments were conducted to study the effect of water and salt stress on seed germination and the effect of salt stress on the early growth of a forage (SS405) and a grain (NK5418) sorghum hybrid. Solutions ranging from 0 to-5.56 MPa and 0 to 25 ds m(-1) were prepared using polyethylene glycol and sodium chloride, respectively, and germination was evaluated in these solutions. Salinity tolerance at early growth stage was tested on plants irrigated with solutions ranging from 0 to 20 ds m(-1). Plants were harvested 6 weeks after planting and their aboveground biomass was recorded. Chlorophyll content and stomatal conductance were also measured. Germination was reduced by 50% in SS405 and NK5418 at -2.5 MPa and-1.5 MPa, respectively, and by 50% in SS405 at 19.3 dS m(-1), but NK5418 had 70% germination even at 25 dS m(-1). Biomass of both hybrids was reduced by 50% at 16.8 dS m(-1). Chlorophyll content and stomatal conductance of both hybrids was reduced by 50% at 10 dS m(-1). Such studies may help in varietal selection of sorghum for cultivation in the SJV.