EFFECT OF POLY-GREENHOUSE SHADING RATIOS ON GERMINATION AND YIELD OF TOMATO UNDER FAYOUM DEPRESSION CLIMATIC

Abstract

Four similar experimental poly-greenhouse models with different shading rations and ventilation gaps were used and compared with the open field condition. One of the four poly-greenhouse models was covered by a single layer of polyethylene (without shading), and the others three models were covered with an external black screen shade net sheets of 25%, 63% and 75% shading ratios, during the winter months. While, three poly-greenhouse models were covered only with black screen shade net sheets of 25%, 63% and 75% shading ratios during the summer months. The thermal performance of the greenhouse models and their effects on seedlings germination and yield of tomato (GSI Seed, Hybrid Tomato, Nora-765) were investigated under Fayoum depression climatic conditions during the winter and summer months of 2009. The obtained results indicated that the air temperature inside the un-shaded model was almost higher than in shaded models and ambient temperature during the winter months (January to May). The air temperature inside the greenhouse models covered only by black screen shade net sheets of 63% and 75% shading ratios were down the ambient temperature during the summer months (June to October) with ventilation rate during the night time. All shading ratios caused to increase the relative humidity inside the greenhouse models, especially with 63% and 75% shading ratios. As shading ratio increased the light intensity decreased, and thus, the light intensity was adequate when it decreased by 63% and 75%, which is satisfactory for seedlings germination, plant growth and yield of tomato at the summer months. Poly-greenhouse with single layer of polyethylene was found more suitable for seedlings germination, plant growth and yield of tomato than those with the other shading ratios and open field condition during the winter months. Poly-greenhouse covered only by black screen sheets (especially with 63% or 75% shading ratios) was found more suitable for better seedlings germination, plant growth and yield of tomato than this with 25% shading ratio and open field condition in the summer months.