Responses to Solar Radiation by Two Varieties of Pepper (Capsicum annuum L.)

Two hundred and fourty plants, half of them of the “Corno di bue giallo” cultivar and half of the “Piccante di Caienna”, were grown in Turin (45˚N) in the field, from June to November, in different conditions of solar radiation. There were four treatments being compared:natural radiation and radiation reduced of 30 or 50 or 70% by shading with plastic nets. It was found that the height of the shaded plants(30-50-70) is much above that of the plants grown in natural conditions (0); the difference is due not to an increase in the number of nodes but to the greater length of the internodes. The area of leaf blades of the shaded plants is also noticeably more extended than that of the o plants while the percentage of dry matter in the leaves is lower. The 0 plants were found to produce a greater number of flowers; however the 30 treatment gave the highest yield per plant, the maximum number of berries and the maximum average weight per berry. Considerable differences were also found in the average time of ripening of the berries. Although they are very different in growth habit and productive behaviour, the two genotypes considered responded to the treatments in much the same way.