Evaluation of the Salinity Tolerance of Russian-Thistle, a Potential Forage Crop

Russian-thistle (Salsola spp.) has economic potential as a forage for arid-lands agriculture. It is drought and heat tolerant, uses water efficiently, and may be salt tolerant. Laboratory and greenhouse studies were conducted to determine the salinity tolerance of Russian-thistle in three developmental stages: (i) germination, (ii) juvenility, and (iii) reproductivity. Treatment solutions were prepared using NaCl and CaCI₂ in a 2:l molar ratio. The effect of salinity (electrical conductivities of 0.1, 10.1, 18.8, 26.7, and 33.8 dS m⁻¹) and temperature (5, 10, 15, 20, 25, and 30°C) on germination was determined under laboratory conditions. Salinity response during juvenility and reproductivity was studied under greenhouse conditions using sand culture irrigated with salinized nutrient solutions with electrical conductivities of approximately 1.3, 10.5, 18.2, 26.7, and 33.2 dS m⁻¹. Germination percentages, fresh and dry biomass yield (total aboveground production), water content, ash content, and mineral composition of the ash were measured. A variable response to salinity was observed among the stages of plant development. Russian-thistle was less salt tolerant during germination than at later growth stages. Germination generally declined linearly with increasing salinity at all temperatures. However, final germination was significantly reduced only at 30°C. Continuous exposure to salinity from the seedling stage through early flowering increased dry biomass yield by 56 and 24% over the control at treatment solution salinities of 10.5 and 18.2 dS m⁻¹, respectively, 64 d after planting. In contrast, when the initial exposure to salinity occurred during the transition from the vegetative to the flowering stage, yield decreased linearly as salinity increased, with no yield enhancement at any salinity level. The reason for this differential response to salinity in the two growth stages was not determined. Journal Article no. 1335, Agric. Exp. Stn., New Mexico State Univ., Las Cruces. The research on which this report is based was financed in part by the US. Dep. of the Interior, Geological Survey, through the New Mexico Water Resources Res. Inst., and in part by a grant from the New Mexico State Univ. Plant Genetic Engineering Lab.