Effects of grafting combinations on the nutritional composition of pepper fruit

[EN] Introduction. Interest in grafting onto rootstocks resistant to soil-borne pathogens has risen since the phasing-out of methyl bromide, an efficient soil disinfectant. In this study, we have evaluated the putative effect of rootstock¿scion combinations on pepper fruit nutritional quality in relation to grafting, an effect that is sometimes overlooked. Materials and methods. As the scions, we used two representative sweet pepper cultivars, `Almuden¿ and `Coyote¿, and as rootstocks `Foc¿ and `Charlot¿, both resistant to Phytophthora capsici and Meloidogyne incognita. Dry matter, soluble solids, proteins, phenolics, and vitamin C content, as well as eight minerals (P, K, Ca, Mg, Na, Fe, Cu, and Zn) were measured in fruits from non-grafted, self-grafted, and grafted plants. Results and discussion. Differences in the fruit composition were found, depending on the genotype, rootstock, or rootstock¿scion combination. The main effects were as follows. Higher values of ¿Brix, phenolics, P, Mg, and Na were found in the fruit of `Coyote¿ whereas the vitamin C and Fe levels were higher in `Almuden¿ fruit. The dry matter, protein, and K concentrations were higher in the fruit from grafted plants with respect to the values from non-grafted plants, especially in the fruit from plants grafted onto `Charlot¿ and `Foc¿ rootstocks (increases of 11.8%, 17.6%, and 9.6%, respectively; when average values of the four combinations of these rootstocks). Fruit from `Almuden¿ and `Coyote¿ plants grafted onto the rootstock `Foc¿ had lower ¿Brix values (about one degree less than the control) and lower values of phenolics were also obtained when used this rootstock (14.4% less than for the control). On the other hand, the P concentration was higher in the fruit of `Coyote¿ grafted onto `Charlot¿ (17.2% higher than for the control). This combination also exhibited the highest fruit K concentration (226.70 mg 100 g¿1 fresh weight). Conclusion. From a nutritional point of view it is important to evaluate and select the best rootstock¿scion combinations: in our assay, this was `Charlot¿¿`Coyote¿ the fruit of which showed the highest ¿Brix and K, P, and protein concentrations.
This work was funded by the Fundacion Agroalimed (supported by the Valencian regional government - the Comunidad Valenciana). We thank Dr. David Walker for the revision of the written English in the manuscript