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- Author or Editor: M. C. Shannon x
- HortScience x
Abstract
Rapid screening techniques for selecting salt-tolerant plants are heretofore untried, untested, or unproven. Theoretically, we know it is possible to screen plants for this trait. Halophytes and salt-tolerant ecotypes exist in nature and variability in tolerance has been demonstrated in a number of agronomic species (48). However, the complexities of salt tolerance and the multitude of ways in which plants adjust and adapt to it have caused much confusion. The effect of salinity on a plant may depend on ontogeny (3, 11), humidity (21, 22, 34), temperature (21, 35), light (14, 35), irrigation management (8, 9), cultural practices (6, 11), soil fertility (10, 32), air pollution (20, 26), and the particular growth or yield parameter measured (3, 49). If all environmental conditions are optimal it is possible to grow some agricultural crops at seawater salinity concentrations. Barley, wheat, millet, and various other crops have been grown on sandy beach areas using seawater for irrigation (4, 5, 16, 24). The use of sand facilitates leaching and minimizes salinity accumulation. Additionally, coastal areas may be cool and humid, and, if fogs are common, have low light intensities. These factors create a favorable environment and decrease salinity damage. Recently, Epstein and colleagues used such an environment to screen a barley composite for salt tolerance (16). Several lines were selected which seemed to produce higher yields than the test cultivars. It is possible that such research will result in the selection of traits that will enhance salt tolerance in barley cultivars adapted to other environments.
Abstract
Salt tolerance differences among 115 plant introductions of lettuce (Lactuca sativa L.) were screened in sand cultures under greenhouse conditions. Leaf and root fresh weights of plants grown for 4 to 5 weeks in salinized sand cultures were compared to a benchmark cultivar, ‘Buttercrunch’. Plant introductions showed a wider range of salt tolerance than standard cultivars of the United States and therefore have some potential in breeding programs designed to increase the salt tolerance of this crop.
Agroforestry plantations offer environmentally acceptable strategies for the reuse of saline drainage waters. Tree species suitable for use in such systems must be selected for survival and sustained growth under highly saline conditions. In this screening trial, four clones of Eucalyptus camaldulensis Dehn. (4543, 4544, 4573, and 4590) and one clone of E. rudis Endl. (4501) were grown in greenhouse sand cultures irrigated with sodium sulfate–dominated waters. Solution compositions were prepared to simulate saline drainage waters typically found in the San Joaquin Valley of California. Electrical conductivities of the solutions ranged from 2 to 28 dS·m–1. Treatments were replicated three times. All plants survived and were harvested after 7 weeks under saline treatment. Plant height was measured weekly and shoot biomass was determined at final harvest. The salinity levels that resulted in a 50% reduction in biomass production (C50) were 16.4 (4573), 17.1 (4543), 17.7 (4544), 29.0 (4590), and 30.0 dS·m–1 (4501). Over the range of salinities from 4 to 20 dS·m–1, clones 4501, 4590, and 4573 generally maintained higher relative growth rates (RGR) than did clones 4544 and 4543. However, at the highest salinity, RGRs of clones 4501, 4544, and 4573 were significantly greater than those of clones 4543 and 4590. Assessed on the basis of biomass production, clones 4501 (E. rudis) and 4590 (E. camaldulensis) showed exceptional potential for use in agroforestry systems where the saline drainage waters are sodium sulfate–dominated.
Abstract
Cultivated and wild accessions of Cucumis melo L. were evaluated for salt tolerance to identify germplasm useful in breeding programs. Entries were tested for seed germination and seedling emergence in a -6.0 bar osmotic solution of NaCl + CaCl2 (2:1 molar ratio) under laboratory conditions. Seedling growth was measured in the greenhouse as fresh weight of plants grown in sand cultures irrigated with saline nutrient solutions of -0.3, -1.7, and -3.3 bars osmotic potential. Salinity decreased emergence and growth, but quantitative responses varied with differences in environmental conditions between experiments. A wide range of variation in response to salt stress was found for both emergence and vegetative growth. Several plant introductions had better emergence rates and growth than the cultivar ‘Top Mark’ under saline conditions. Salt tolerance exhibited by these introductions may be useful in breeding programs to improve muskmelon performance under saline conditions.