Phytophthora capsici resistance evaluation in pepper hybrids. Agronomic performance and fruit quality of pepper grafted plants

Abstract

[EN] Phytophthora capsici has caused a major disease of pepper worldwide and only some partially resistant pepper cultivars are commercially available. In this work P. capsici resistance has been evaluated in the pepper hybrids Chariot and Foe, derived from pepper SCM 334, the most promising P. capsici resistance source. Inoculations with a highly virulent R capsici isolate Pc-8 and the isolates Pc-448 and Pc-450 show that both hybrids have a level of tolerance that is similar to SCM 334. The measurement of the agronomic performance of both hybrids when used as rootstocks was made by comparing growth, yield, and the fruit quality of two commercial peppers (Coyote and Almuden) that were grafted onto Foe and Chariot. Comparisons were made with non-grafted and self-grafted plants. No differences were observed for growth since earliness in fruit maturity has been observed in Coyote grafted onto both Chariot and Foe rootstocks. Grafted plants produced a higher number of fruits per plant. However, higher commercial yields were only obtained in Coyote-grafted plants. Almuden-grafted and self-grafted plants showed a greater variability in fruit shape. Differences among Coyote- and Almuden-grafted plants are indicative of the importance of rootstock-scion interaction. Some fruit modifications such as changes in shape were observed in grafted and in self-grafted plants. Therefore, these modifications may be partially the consequence of the grafting process. Grafting onto both Foe and Chariot rootstocks did not modify the pericarp thickness and the mean number of lobes per fruit in Coyote and Almuden fruit. A slight increase in minerals and similar vitamin C content, a very important nutritional quality trait of peppers, were also obtained in the analysed fruit from grafted, self-grafted, and ungrafted plants.