| heal.abstract |
Melon (Cucumis melo L. Cv Parnon) grown in rockwool culture in the greenhouse was CO2 enriched at 400, 800 and 1200ppm and trickle-irrigated with nutrient solutions amended with 0, 25 and 50 mM NaCl. Carbon dioxide enrichment, applied for five hours every morning resulted in significant increases in fruit number and fruit size mainly of unsalinated plants. CO2 enrichment did increase significantly the vegetative growth of the salinated plants. No significant change in shoot fresh weight of the unsalinated plants was recorded. In general, CO2 enrichment up to 800 ppm increased the surface area and the chlorophyll density of the measured leaves. In concentration higher than 800ppm, CO2 increased the leaf surface area and chlorophyll density to a lesser degree. Addition of NaCl in the nutrient solution caused significant reduction in total yield and total fresh shoot weight of the plants, in all cases. At 25 mM concentration of NaCl the decrease in yield resulted mainly from the smaller fruit size, but at 50 mM yield reduction was due to smaller fruit size and fewer fruits number per plant. Addition of NaCl, also, reduced significantly leaf surface area. Measurements of gas exchange showed that exposure to 25 mM and 50 mM NaCl inhibited significantly net carbon exchange rates. Stomatal conductance was affected most by NaCl at 50 mM NaCl. Substomatal concentration of CO2 was affected most by NaCl at 1200 ppm CO2. |
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