ISHS Acta Horticulturae 401: International Symposium on Growing Media & Plant Nutrition in Horticulture
DIFFERENTIAL EFFECTS OF SALINITY AND HUMIDITY ON GROWTH AND CA STATUS OF TOMATO AND CUCUMBER GROWN IN HYDROPONIC CULTURE |
| Authors: | P. Adams, L.C. Ho |
| Abstract:
Tomatoes and cucumbers were grown at salinities of 3 to 9 mS cm-1 either in deep solution culture or NFT, and at four combinations of day and night humidities of 0.1 and 0.8 kPa (vpd) in rockwool. Increasing salinity had no effect on dry matter accumulation or partitioning in tomato, but reduced the dry weight of cucumber plants and increased the proportion of the total dry weight in the fruit, at the expense of the upper shoot. High salinity reduced Ca uptake mainly in cucumber and, at the same time, increased the proportion of the Ca in the leaves but reduced that in the fruit and upper shoot. In tomato, salinity only increased the proportion in the top but not in the fruit and leaves. High salinity decreased the volume and Ca content of the stem exudate in both crops, but the reduction was much greater in cucumber. High humidity decreased movement of Ca into the leaves of both crops but increased that into the fruit of tomato, particularly during the day. The concentration of Ca in cucumber fruit was about six times that in tomatoes. This difference was reflected in their stomatal densities, suggesting that fruit transpiration plays an important role in determining the Ca status of different plant organs and their susceptibility to Ca related disorders. | |
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