EFFECT OF SHADING AND GRAFTING TECHNIQUE ON GROWTH AND FRUIT PRODUCTION OF SWEET PEPPER PLANTS

Horticultural cultivation in Mediterranean greenhouses requires the implementation of refrigeration systems to avoid stress situations, particularly under spring-summer conditions. The effect of the temperature and high solar radiation in the greenhouse can be decreased by shade screen. The use of grafting onto adequate rootstocks could be an interesting alternative to maintain commercial fruit yield and quality under stress conditions. The effects of using aluminised screens offering different degrees of shading combined with two transplant types (grafted or ungrafted) were analyzed in sweet pepper plants. Simultaneous comparisons were made among greenhouse that were either non-shaded (control) or covered with reflective aluminized shadecloth that attenuated 40% (T40) and 60% (T60) of direct sunlight. The shadecloth was applied at the start of warm weather in May. The greenhouses were shaded for the rest of the summer, and fruit being picked until August. The use of shadecloth proved to be efficient in improving vegetative growth and reducing the unmarketable yield, compared to non-shaded conditions. The results showed that fruit yield was highest in the T40 treatment, presented significantly different, and the T60 treatment had a lower production. On the other hand the use of the grafting promoted vegetative growth. Grafting increased the marketable yield compared to the ungrafted plants under shade and non-shade conditions.