The effect of grafting on the fruit and seed production of the Sicilian long light green zucchini landrace (Cucurbita pepo L.)

The traditional Sicilian long light green landrace of zucchini (Cucurbita pepo L.) is known for their long fruit size, high sugar content and light green colour, is mainly widespread in Catania province (Sicily, Italy) and for that is also called the “Zucchino Catanese”. This old zucchini landrace is till now grown in the peri-urban vegetable farms where they are propagated and conserved on farm. From some decades some seeds are conserved at the GeneBank of the Di3A of the University of Catania. This landrace shows well-developed and deep root system, adaptation to soil-borne pathogens agents of plant fungal disease and good performance under high thermal conditions. In this study we assess the effect of the grafting, by the F1 hybrid rootstock RS841 (Bayer) on the growing, fruiting and seed production of the traditional zucchini landrace compared to a commercial short dark green cultivar ‘Sibilla F1’ during the summer 2022. Plant characterization showed significant differences between the grafted and non-grafted traditional cultivar. Furthermore, the use of hybrid F1 as rootstock induced a faster vegetative growth and first female flower anthesis, in addition to a reduction in male flower dominance of 10% and a better response for the organic plant nutrition protocol adopted. The highest soluble solid content (°Brix) was observed in the fruit of the grafted plants but with a faster fruit development with smaller fruits (yield decrease) compared to the non-grafted plant from the same cultivar. A better response for self-pollination was noted for the non-grafted plants and the seed production was also reduced by 30% in the grafted plants, from 120 to around 85 seed per fruit. The Sicilian zucchini landrace showed highest yield and elongated growing cycle, probably as consequence of the root size and structure permitted a good adaptation to the harsh thermal summer conditions compared to the hybrid F1 rootstock one.