Research on the Propagation of Some Sweet Chestnut Cultivars Through Different Grafting Methods

Sweet chestnut was propagated till now in Romania mainly through seeds, and the trees obtained show a highly variable biological and economic behavior. Under current conditions of development and modernization of fruit growing, chestnut planting material for modern orchards should be obtained through clonal propagation. In the present study we aimed to propagate two Romanian sweet chestnut cultivars (‘Casval’ and ‘Romval’) and two French ones (‘Bouche de Bétizac’ and ‘Marsol’) using different grafting methods inside and in the field. As rootstock, local Castanea sativa seedlings were used. The bench grafting methods performed were: whip and tongue, cleft and side grafting followed by callus stimulation into a hot callusing device which provides temperatures of 26-27°C at the grafting point. In the nursery field same methods were used and also chip budding. Higher success rates were obtained for all cultivars when bench grafting was carried out inside (79.86%) compared with grafting in the field (69.94%). The highest success percentages were achieved inside when whip and tongue method was performed (85.33%), followed by cleft grafting (81.9%). The success rates obtained were: ‘Bouche de Bétizac’ (86.2%), ‘Marsol’ (85.27%), ‘Casval’ (75.0%) and ‘Romval’ (73.0%). In order to highlight the propagation capacity, the "Grafting Success Index" was determined, using three elements: callus formation, grafting success rate after callusing and grafting success rate at the end of the growing season. The scion/rootstock/grafting point ratio, as well as the scion growth in the first and second year after grafting, proved that the cultivars were compatible with the rootstock used. The results obtained in the given conditions allows us to recommend the adequate grafting methods in order to propagate the four sweet chestnut cultivars.