Thesis (M.S.)--University of Wisconsin--Madison, 1964. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 88-93.

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Thesis (Ph. D.)--University of California, Berkeley, 2006. / Includes bibliographical references.

Salt glands are important structural adaptations in some plant and animal species that are involved in the excretion of excess salts. Zoysia matrella is a highly salt tolerant turf grass that has salt glands. Two cultivars of Z. matrella, ‘Diamond’ and ‘Cavalier’, were examined in this study to look for salt gland related factors responsible for the differences in their degree of salt tolerance. In addition to the adaxial salt gland density being higher in ‘Diamond’, the salt glands in salt treated (300 mM NaCl) plants of this cultivar were bigger than the ones in ‘Cavalier’. ‘Diamond’, as well as some of the ‘Diamond’ x ‘Cavalier’ hybrid lines, showed a significant induction in salt gland density in response to salt treatment. Examination of salt gland density in ‘Diamond’ x ‘Cavalier’ hybrid lines showed that salt gland density was a highly heritable trait in the salt-treated population. Ultrastructural modifications in the salt glands observed with Transmission Electron Microscopy (TEM), coupled with Cl- localization studies, suggested a preference for symplastic transport of saline ions in Z. matrella. Salt glands have been studied in several plant species; however, no studies have tried to associate the role of ion transporters with the functioning of salt glands in plants. RNA in situ studies with Na+ transporters showed localization of ZmatHKT1 transcripts in the adaxial salt glands, leaf mesophyll and bundle sheath cells for both cultivars. ZmatSOS1 expression was observed in the xylem parenchyma cells for leaves from both cultivars, but the expression was markedly different around the cells bordering the vascular tissue. The strongest expression of ZmatSOS1 for ‘Diamond’ was seen in the bundle sheath cells and the phloem, while for ‘Cavalier’ the signal was strongest in the mestome sheath cells and in cells surrounding the phloem. No expression of ZmatSOS1 was seen in the salt glands for either cultivars. ZmatNHX1 expression in both cultivars was very low, and observed in the salt glands and neighboring epidermal cells. Three alleles of ZmatNHX1 were identified in Z. matrella, along with three alternatively-spliced forms of ZmatNHX1, the expression of which were cultivar and treatment specific. Together, these results provide a model for salt transport in Z. matrella and signify potential roles of salt glands and select ion transporters in the salt tolerance of this species.

Thesis (M.S.)--University of Delaware, 2008. / Principal faculty advisor: W. G. Shriver, Dept. of Entomology & Wildlife Ecology. Includes bibliographical references.

Section 1: Introduction, Section 2: Physical Features, Section 3: Biological Resources, Section 4: Social/Economic Characteristics, Section 5: Important Resources, Section 6: Watershed Classification, Section 7: Watershed Management, Section 8: Local Watershed Planning, Section 9: Key Elements, Appendix A: Table 1, Appendix B: Suggested Readings, Appendix C: RUSLE, Appendix D: AGWA

Soil salinity is a serious problem for farmers in irrigated agriculture. Soil salts cause reduced stands and yields because of toxic ion and osmotic problems for surviving seedlings. The tolerance to sodium chloride during germination and emergence was studied in three commercial cultivars of short staple cotton (Gossypium hirsutum L.). It is this stage of the life cycle that cotton is most sensitive to salts in the soil solution. The objectives of this study were to increase the tolerance to sodium chloride during germination and emergence and to determine the narrow sense heritability of this factor. Parental cultivars initially demonstrated 15% emergence at -1.2 MPa NaCl. Surviving salt tolerant plants were planted in the field and seeds from these plants were used as the germplasm for the next cycle of salt tolerance selection. Experiments were conducted to determine the relative salt tolerance of all plants at -1.2, -1.4, -1.6, and -1.8 MPa NaCl. Emergence of salt tolerant accessions from the first cycle of selection ranged from 3.1 to 25.8% in the first relative salt tolerance experiment. The average emergence of all accessions taken over all four salinity levels was 8.9% for first cycle plants. After a second cycle of selection for salt tolerance, the average emergence percentage increased to 13.0% over the four salinity levels. Emergence ranged from 0.7 to 32.6% in the second relative salt tolerance experiment. Narrow sense heritability of sodium chloride tolerance during germination and emergence was estimated at 0.38 using data from the first and second relative salt tolerance experiments.

The application of fertilizers and saline irrigation water have resulted in increased soil salinity and the removal of large land areas from crop production. One method to overcome the effects of soil salinity is to increase the salt tolerance of crops. The objective of this research was to investigate the physiological, genetic, and agronomic differences between alfalfa (Medicago sativa, L.) bred for increased salt tolerance and salt sensitive alfalfa. The materials used in these studies were the result of five cycles of selection for germination NaCl tolerance, AZST 1978 to 1982, and the source population, 'Mesa-Sirsa'. All salt-tolerant cycles and Mesa-Sirsa were evaluated for ability to germinate in NaCl, NaNO₃, KCl, KNO₃, mannitol and polyethyleneglycol (PEG) solutions ranging from -1.0 to -1.6 MPa of osmotic potential and a control of distilled water. Germination in the lower osmotic potentials of all germination medias was significantly higher with each succeeding cycle of selection for germination NaCl tolerance. Selection for tolerance to NaCl during germination also resulted in increased tolerance to the other salts as well as mannitol and PEG. Germination in mannitol was higher than in any of the salt solutions. This suggests that ion toxicity also inhibits germination. There was no significant difference between Mesa-Sirsa and AZST 1982, the most salt-tolerant cycle, in seed respiration in NaCl solutions or in uptake of tritiated NaCl solution during germination. Broadsense heritability of germination NaCl tolerance was estimated at 49%. All the Arizona Salt Tolerant cycles and Mesa-Sirsa were evaluated for several mature plant characteristics under non-saline field conditions. There were no significant differences among germplasm sources in forage yield, apparent photosynthesis, transpiration, or diffusive resistance. Seedlings of Mesa-Sirsa and AZST 1982 were grown in NaCl solutions ranging from 0 to 18000 ppm NaCl in the greenhouse. The plants were evaluated for several plant growth characteristics to determine whether selection for germination NaCl tolerance resulted in increased salt tolerance at more mature plant growth stages. There was no evidence that germination salt tolerance is related to salt tolerance at later growth stages in alfalfa. Salt tolerance during germination and later growth stages may be controlled by different physiological and genetic mechanisms.

Seedlings were grown at five salinity levels in Hoagland's solution for 4 weeks. Transpiration, leaf diffusive resistance, leaf temperature and plant growth of the tomato (Lycopersicon esculentum Mill.) cultivars 'VF 145B' and 'VF 10' were examined at different levels of NaCl ranging from 0 to -12 bars. Salinity-reduced transpiration increased leaf diffusive resistance and increased leaf temperature for both cultivars. Shoot length, root length, shoot and root weight and leaf area were all lower for the two cultivars at increasing salinity levels. However, the two cultivars responded differently to salinity, with VF 10 showing better growth at the control and the -4 bar treatment than VF 145 B. At -9 and -12 bar treatment, the reverse was true. Selection of tomato for salt resistance should not be based on vigorous growth at non-saline conditions because different genes may control the salt tolerance ability of the plants at high salinity levels.