Effect of transpiration on the distribution of Ca under Na and Mg saline conditions in sweet pepper (Capsicum annuum L.)

摘要

Calcium deficiency in plants has frequently been related with blossom end rot (BER) appearance in tomato and sweet pepper. Several observations suggest that stress factors such as salinity and BER are related. The aim of this work was to assess cation distribution in sweet pepper plants cultivated under different salinity and transpiration treatments, so as to improve our understanding of the relationships between Ca content and distribution among plant organs and BER appearance. Sweet pepper plants were grown hydroponically for three months in aerated plastic containers. Two climate-controlled chambers of a glasshouse were used. In the first chamber high transpiration was forced by allowing sunlight to penetrate and by maintaining a low relative humidity (50% to 70% RH). In the second chamber low transpiration was achieved by shading and raising RH with humidifiers (70% to 80% RH). Three different nutrient solutions were used in every chamber: a control nutrient solution, a Mg saline nutrient solution, and a Na saline nutrient solution. Both saline nutrient solutions had the same ionic strength and the same anion concentrations. Plants were sampled every three weeks, and divided into leaves, stems, roots and fruits. Fresh and dry weight was determined. Atomic Absorption Spectroscopy of the acid-combusted tissue determined macronutrient concentration in organs. BER at the end of the experiment was determined. There were significant differences in water uptake and biomass production between high- and low-transpiration treatments. Transpiration and salinity treatments produced differences in leaf and fruit Ca concentration. Differences were also found in BER incidence between salinity and control treatments and between different transpiration conditions.