Saltgrass, a Minimum Water and Nutrient Requirement Halophytic Plant Species for Sustainable Agriculture in Desert Regions

Abstract

Context: Desertification of arable lands due to global warming and water shortage mandates use of low-quality water for irrigation. Using low-quality water imposes more stress on plants which are already under stress. Thus, there is an urgent need for finding stress tolerant plant species to survive/sustain under such stressful conditions. Since the native plants are already growing under such conditions and are adapted to these stresses, they are the most suitable candidates to be manipulated under the minimum cultural practices and minimum inputs for use under stress. If stress tolerant species/genotypes of the native plants are identified, there would be a substantial savings in cultural practices and inputs in using them. Aim: This grass has multi usages, including animal feed, soil conservation, saline soils reclamation, use in desert landscaping, and combating desertification. The objectives of this study were to find the most salinity and drought tolerant of various saltgrass genotypes for use in arid regions, where limited water supplies coupled with saline soils result in drought and salinity stresses. Materials and Methods: Various genotypes of saltgrass were studied in a greenhouse either hydroponically in culture solution for salt tolerance or in large galvanized cans contained fritted clay for drought tolerance. For the salinity stress tolerance, twelve inland saltgrass clones were studied in a greenhouse, using hydroponics technique to evaluate their growth responses under salt stress. Four salt treatments (EC 6, 20, 34, and 48 dS/m salinity stress) were replicated 3 times in a randomized complete block design experiment. Grasses were grown under these conditions for 10 weeks. During this period, shoots were clipped bi-weekly, clippings were oven dried at 75°C and dry matter (DM) weights were recorded, shoot and root lengths were also measured. At the last harvest, roots were also harvested, oven dried, and DM weights were determined. Grass quality was weekly evaluated and recorded. Although all the grasses showed a high level of salinity tolerance, there was a wide range of variations observed in salt tolerance of these saltgrass clones. For the drought tolerance study, 21 saltgrass clones were studied to evaluate their growth responses under drought stress. Plants were grown under normal condition for 6 months for complete establishment. Then, they were deprived from water for 4 months. Plant shoots were harvested weekly and oven dried at 75°C for DM weight determination. At each harvest, percentages of plant green covers were also estimated and recorded. Both the shoot dry weights and the percent of plant visual green cover decreased as drought period progressed. Results: Although all the grasses exhibited a high level of drought tolerance, there was a wide range of variations observed in various clones' responses. The superior salinity and drought stress tolerant genotypes were identified to be used for biological salinity control or reclamation of desert saline soils and combating desertification. Conclusion: My investigations at the University of Arizona on saltgrass (Distichlis spicata L.), a halophytic plant species, have indicated that this plant has an excellent drought and salinity tolerance with a great potential to be used under harsh environmental conditions.