Evaluation of the Salinity Tolerance of Russian Thistle to Determine its Potential for Forage Production Using Saline Irrigation Water
Utilization of New Mexico’s saline groundwater supplies for irrigated agriculture could reduce the demand on good quaLity water and conserve it for other purposes. The successfuL use of saline water will depend upon the identification of crops and potentiaL crop species specificalLy adapted to saline environments. Russian-thistle (Salsola species) is a plant species with economic potential as a forage crop. This species is known to be drought and heat tolerant, water use efficient, capable of high productivity on margin lands and suspected of being salt tolerant. Greenhouse and Laboratory studies were conducted to determine the salinity tolerance of Russian-thistle and evaluate the effect of salinity on some nutritional qualities.
The salinity tolerance of Russian-thistle was studied in three plant developmental stages: (1) germination, (2) juvenility and (3) reproduction. A variable response to salinity was observed among these stages of plant development. Russian-thistle is considerably less salt tolerant during germination than at later stages of growth. When initially exposed to a saline environment in the seedling stage in a sand solution culture, Russian-thistle plants developed a relatively high level of tolerance to salinity. This tolerance appeared to increase with time of exposure. An enhancement of biomass yield due to salinity was observed which resuLted in a 56 and 24 percent increase in biomass yield over that of the control at 64 days after planting at electrical conductivities of treatment solutions of 10.5 and 18.2 dS m-1 respectively. Russian-thistle plants were considerably less tolerant to salinity when initially exposed to salinity during the transition from the vegetative to the reproductive stage.
Salinity generally increased crude protein content of Russian-thistle plants but reduced the levels of acid detergent fiber and acid detergent lignin. Levels of potentially toxic components of Russian-thistle plants, nitrate and water soluble oxalates, were reduced by salinity. Ash content, however, increased with increased salinity.
A literature search revealed a number of chemical compounds of potential economic value that have been isolated from Salsola species. No attempt was made to isolate these chemicals from Russian-thistle. However, if these chemicals can be economically extracted from this species, it could increase the potential of Russian-thistle as an arid lands crop.