Effect of rootstock on the fruit quality of mandarins ‘Clemenules’ and ‘Tango’, and blood oranges ‘Tarocco Rosso’ and ‘Moro’

Abstract

Citriculture constantly faces changing environmental scenarios that cause different biotic and abiotic stress that can make production difficult or might affect fruit quality. The rootstock onto which a specific variety is grafted is an important tool to help to improve its agronomic adaptability to each crop area. The present Thesis was carried out to study the effect of rootstock on physicochemical and nutritional fruit quality in some varieties of much commercial interest today: ‘Clemenules’ and ‘Tango’ mandarins, and ‘Tarocco Rosso’ and ‘Moro’ blood oranges. In ‘Clemenules’, the most representative mandarin variety in the Mediterranean Region, the fruit of the trees grafted into eight rootstocks at three harvest times was evaluated by performing studies during two seasons. Of the evaluated rootstocks, Forner-Alcaide 13 and C-35 Citrange stood out for their earlier color change, which is very interesting for this variety, in which early harvesting is a relevant aspect from the commercial point of view. Forner-Alcaide V17 also stood out for maintaining optimum acidity levels until the season ended, and also presented the highest contents in vitamin C, flavonoids, glucose and fructose. Carrizo Citrange brought about high concentrations of sucrose and vitamin C in fruit. ‘Tango’ is a mandarin variety that has been recently introduced into the Mediterranean Region. Its harvest time is very interesting because it starts when that of clementines ends. The present Thesis studies changes in the physico-chemical, nutritional and sensorial quality of the ‘Tango’ mandarin grafted onto two rootstocks (Carrizo Citrange and Forner-Alcaide 5) during the harvest period in the two main production areas in Andalusia (S Spain). The results revealed that fruit quality during harvest was influenced by the location of orchards, which was particularly related to soil texture composition. However, in both areas, Forner-Alcaide 5 was the rootstock that induced higher acidity content, and more total soluble solids, sucrose, vitamin C and citric acid in fruit. The physico-chemical determinations, along with the sensorial evaluation, allowed the optimum harvest time to be established depending on the different studied conditions.