INFLUENCE OF GRAFTING ON YIELD AND FRUIT QUALITY OF PEPPER (CAPSICUM ANNUUM L.) GROWN UNDER GREENHOUSE CONDITIONS

Abstract

With the aim of determining whether grafting could improve the agronomic behaviour of pepper (Capsicum annuum L.), a greenhouse experiment was carried out to determine growth, yield and fruit quality of two bell pepper hybrid cultivars (Edo and Lux), either ungrafted or grafted onto five commercial rootstocks ‘Snooker’, ‘Tresor’, ‘RX360’, ‘DRO8801’ and ’97.9001’. Grafted plants were 29 and 28% taller than control for ‘Edo’ and ‘Lux’ cultivars, respectively. Total yield, marketable yield and fruit number were significantly influenced by rootstock, whereas no significant difference was observed on unmarketable yield, marketable fruit mean weight and fruit shape index for both cultivars. Grafted plants produced 22-46% more marketable yield than control plants for ‘Edo’. A similar trend was also observed on ‘Lux’, where the grafted plants had 25% more marketable yield in comparison to ungrafted plants. The lowest marketable yield recorded on ungrafted plants for ‘Edo’ and ‘Lux’ was related to a reduction in fruit number and not to the fruit mean weight. Nutritional qualities of grafted peppers such as fruit dry matter, total soluble solids contents, titratable acidity were similar in comparison to those of ungrafted plants. Since grafting increased the crop vigour and yield, and following the abandonment of methyl bromide, grafting technique should be useful for lowinput sustainable horticulture of the future. INTRODUCTION Pepper (Capsicum annuum L.) is a crop of high economic importance in the Mediterranean region. The area of protected pepper grown in Italy is 2,794 ha (20.3% of the total pepper cultivation area; ISTAT 2005). In the last three decades, pepper cultivation in greenhouses has become increasingly dependent on methyl bromide fumigation. This is due to continuous cropping and, consequently, to increasing crop damage due to the specific pathogens, Phytophthora capsici, Verticillium dahliae and Meloidogyne spp. (Morra and Bilotto, 2006). Because methyl bromide is highly toxic to humans and the environment (Ristaino and Thomas, 1997), 168 countries including Italy, have agreed to gradually reduce the use of methyl bromide. Research and technology transfer will therefore be necessary to fully implement an alternative to methyl bromide pest management systems for greenhouse vegetable crops (Batchelor, 2001). One way of avoiding or reducing losses in production caused by pathogens in high-yielding genotypes would be to graft them onto rootstocks capable of reducing soil-borne diseases and increasing yield (Lee, 1994). The aim of this study was to investigate and evaluate the agronomic performance of two popular Italian commercial hybrid peppers under greenhouse conditions following grafting on five newly resistant pepper rootstocks, in comparison with ungrafted plants. MATERIALS AND METHODS The F1 hybrids ‘Edo’ (red type; SAIS, Italy) and ‘Lux’ (yellow type, SAIS, Italy), were grafted on five commercial rootstocks, ‘Snooker’ (Syngenta, USA), ‘Tresor’ (Nuhmens, Holland), ‘RX360’ (Royal Sluis, Holland), ‘DRO8801’(De Ruiter, Holland) and ‘97.9001’ (SAIS, Italy) coming from the hybridization of Capsicum annuum L. using Proc. IV IS on Seed, Transplant and Stand Establishment