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Texas Tech University (TTU) (2008)

Screening of alfalfa (Medicago sativa) cultivars for salt tolerance in West Texas

Scasta, John Derek

Titre : Screening of alfalfa (Medicago sativa) cultivars for salt tolerance in West Texas

Auteur : Scasta, John Derek

Université de soutenance : Texas Tech University (TTU)

Grade : Master of Science (MS) 2008

[[ Résumé partiel
Alfalfa (Medicago sativa) is a very important crop commodity in the Trans-Pecos region of Texas and New Mexico where salinity problems occur in the soil and irrigation water resources. There has been significant research in the area of salt tolerance of alfalfa but there is need for screening current and experimental alfalfa cultivars to assist growers with variety selection. Due to the complexity of salinity tolerance in plants, it is also necessary to compare laboratory and greenhouse screening methodologies and results to field conditions. These experiments were designed to evaluate commercial and experimental alfalfa cultivars at different growth stages and varying salinity concentrations and assess correlations between laboratory, greenhouse and field experiments. In addition to salinity tolerance, there is a need to evaluate alfalfa cultivars for potential quality differences between varying fall dormancy (FD) ratings to assist growers in cultivar selection. The first experiment evaluated plant germination under increasing levels of salt concentrations conducted in the laboratory. Statistical differences were observed for percentage germination among cultivars which could influence stand establishment of alfalfa in saline conditions. These differences in turn are exhibited in the IC(50) values which reflect osmotic potential required to inhibit 50% of seed from germination. The second experiment evaluated forage production under two levels of salt concentration conducted in the greenhouse. There were no significant differences in raw or transformed SCR values among the 32 cultivars at Cut 2, Cut 3 or Cut 4 when subject to analysis of variance. SCR values were then evaluated for statistical differences using the three harvests as replications over time. Significant differences in raw and transformed SCR values were found between cultivars with Cut 2, Cut 3 and Cut 4 serving as replications over time. The third experiment evaluated forage production under saline field conditions that exist at the Texas AgriLife Research Station west of Pecos, TX. Throughout the two-year project significant differences among cultivar yields were observed only 4 out of the 13 (31%) harvests at alpha = 0.05 (6 out 13 exhibited significant differences when using alpha = 0.1).

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