Effects on microclimate, crop production and quality of a tomato crop grown under shade nets

SummaryThe effects of four shade nets with different colour transmission properties and shading intensities (two black nets with shading intensities of 40% and 49%, a green net with a shading intensity of 34%, and a mixed green and black shade net with a shading intensity of 40%) on the screenhouse microclimate, and on the growth and development of a tomato crop, were investigated. Experiments were carried out during Spring and Summer 2003 in New Anchialos, a coastal area of Eastern Central Greece. Tomato seedlings were planted in soil and the following environmental variables were recorded at regular intervals: solar radiation, air temperature and relative humidity, leaf temperature, and several variables related to crop growth and development. Air temperature and vapour pressure deficit (VPD) values were similar under all four shade nets and without shading. However, canopy temperature and, accordingly, the canopy-to-air VPD were significantly lower under shading than without shading. Shading did not reduce the total plant dry matter content, but increased the leaf area index, the number of fruit per plant, and the total fresh tomato yield. Shading reduced losses caused by tomato cracking by 50%, and thus increased the marketable tomato fruit yield by approx. 50% compared to growth under non-shaded conditions.