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- Author or Editor: Samuel Mendlinger x
Twenty melon (Cucumis melo L.) cultigens (cultivars and breeding lines) were tested for salt tolerance. All cultigens were grown in the field using drip irrigation at three salt salinity levels: electrical conductivity (ECw = 1.2, 7.5, or 14.0 dS·m-1. Nineteen of the 20 cultigens proved to be salt-sensitive, as measured by reduction in fruit weight, but not necessarily to the same degree (i.e., some cultigens were tolerant at ECw = 7.5, whereas others were not). One line, `Evan Key', was salt-tolerant at ECw= 14.0. Increasing salinity levels did not affect the number of fruits produced in most cultigens. Overall, increasing salinity reduced netting quality but increased the total soluble solids content and shortened mean time to harvest in seven cultigens.
The increasing salinity of both irrigated lands as well as irrigation water in many parts of the world have emphasized the importance of having appropriate breeding strategies for developing salt tolerant cultivars. In a program to breed for salt tolerance (high yield and good quality at 5,000 ppm salinity) in melons, several breeding strategies were tried. The only systems that succeeded was using combining abilities in a hybrid program. We found that salinity did not effect the number of fruit or fruit quality but only fruit weight. Fruit weight of hybrids grown in fresh water was controlled by dominant genes (h2=0.09) whereas the same hybrids grown under salinity had fruit weight control by additive genes (h2=0.54) Therefore, we were capable of breeding tolerant hybrids from non-tolerant parents.
The increasing salinity of both irrigated lands as well as irrigation water in many parts of the world have emphasized the importance of having appropriate breeding strategies for developing salt tolerant cultivars. In a program to breed for salt tolerance (high yield and good quality at 5,000 ppm salinity) in melons, several breeding strategies were tried. The only systems that succeeded was using combining abilities in a hybrid program. We found that salinity did not effect the number of fruit or fruit quality but only fruit weight. Fruit weight of hybrids grown in fresh water was controlled by dominant genes (h2=0.09) whereas the same hybrids grown under salinity had fruit weight control by additive genes (h2=0.54) Therefore, we were capable of breeding tolerant hybrids from non-tolerant parents.
The muskmelon (Cucumis melo L.) cultivars Topmark, Galia, No. 1, and BG-84-3 (BG) were examined in a field test for the influence of increased salt concentration (700, 2500, 5000, 7500, and 10,000 ppm) on flower production, vegetative growth, yield, and fruit quality. Increased salinity did not affect the number or timing of staminate and pistillate flowers produced. Increased salinity significantly and to the same extent reduced vegetative growth in the four cultivars. Increased salinity did not affect the number of fruit produced in the four cultivars but reduced mean fruit weight in three. Mean fruit weight and yield of `BG' were not reduced; i.e., `BG' was salt tolerant. Increased salinity increased the soluble solids concentration and slightly improved fruit appearance of all cultivars.
Within a program determining the response of melon plants when grown at suboptimal cold temperatures, fruit quality was examined in 20 cultigens grown under two temperature regimes. The cultigens included open pollinated and hybrid cantaloupes and honey dews. The two temperature regimes were: (i) heated greenhouse, at minimum and maximum temperatures close to commercial cultivation requirements, and (ii) unheated greenhouse, at a temperature 7-8°C lower than the former, representing a major cold stress. The parameters examined included fruit appearance and marketability (weight, size, netting) as well as fruit constituents (sucrose, glucose, reducing sugars, TSS, pH, EC, titratable acidity). Cold stress was found to improve some parameters, but impair others. The low temperatures significantly reduced fruit weight and size, but increased fruit number per plant, sucrose and TSS in most but not all cultigens. Significant interaction was found between the temperature regimes and cultigens in these parameters. The results strongly indicate that genetic variation exists in melons for response to low temperature, and therefore that potential for breeding melons for cold stress is present.