SWEET PEPPER CROP RESPONSES TO GREENHOUSE CLIMATE MANIPULATION UNDER SALINE CONDITIONS

Soil and/or water salinity adversely affects growth and production of many crops. Salinity has a negative effect on plant water uptake which eventually affects growth and yield. However, improving shoot conditions by manipulating greenhouse climate (potential transpiration ETo) may improve plant water status and mitigate this negative effect. To test this hypothesis, climate in two identical greenhouse compartments was controlled normally in one (HET, high evapotranspiration) and with 25% less ventilation opening in the other to have lower vapor pressure deficit while preserving the same assimilation level. During summer, additional humidification was applied when necessary in the second compartment (LET, low evapotranspiration) so that ETo was not to exceed 0.15 l/pl.h. In each compartment, half of the rows of sweet pepper crop cv. Mazurka were fed, four weeks after transplanting, with 2 dS/m nutrient solution (LEC, low EC) while the other half was fed with 6.5 dS/m (HEC, high EC). Under high salinity, vegetative growth (number of leaves and total leaf area/plant) were enhanced by LET. HEC increased fruits infected with blossom end rot (BER) in the two greenhouses, while LET increased this fraction more by increasing the total number of fruits/plant. Salinity conditions also reduced significantly the number of marketable fruits. Plant total fresh and dry weights were significantly improved under saline conditions by greenhouse climate manipulation (LET). Mineral contents (%) of N, P, K, Ca and Mg were not significantly affected by the treatments. In conclusion, greenhouse climate manipulation can mitigate the effect of high EC in the root zone.