To identify the most suitable rootstocks for bergamot production in Italy, vegetative growth, yield performance, and fruit quality were assed in “Femminello” bergamot trees grafted onto eight different rootstocks under the Mediterranean edaphoclimatic conditions of Reggio Calabria (Southern Italy). Rootstock selection significantly affected tree vigor, productivity, and fruit quality. Alemow induced the greatest vegetative growth, producing trees with canopy volumes up to 60% larger than those grafted onto Sour Orange, whereas Flying Dragon caused a strong dwarfing effect, reducing canopy volume by approximately 80%. Carrizo Citrange and Swingle Citrumelo exhibited the highest yield efficiency (9.7 and 9.5 kg m−3, respectively), about 30% higher than Sour Orange, while Alemow showed the lowest efficiency (1.8 kg m−3). Cumulative yield over seven cropping seasons was highest on Carrizo Citrange (196 kg tree−1), with comparable values recorded for Sour Orange, Swingle Citrumelo, and Trifoliate Orange. In contrast, Alemow and Flying Dragon yielded 55% and 85% less, respectively. Rootstock selection significantly influenced fruit size, peel characteristics, and juice quality. Rootstock selection had a marked effect on fruit size, peel characteristics, and juice quality. Fruit weight ranged from under 170 g on Sour Orange, Volkameriana, and Alemow to approximately 196 g on Trifoliate Orange, while at full maturation, most rootstocks produced fruits weighing between 213 and 223 g, except for Alemow (<200 g). Trifoliate Orange and its hybrids promoted thinner peel and higher juice content, whereas Alemow and Volkameriana produced fruits with thicker peel and up to 15% lower juice content than Carrizo Citrange. Juice titratable acidity decreased during maturation, ranging from over 50 g L−1 on Sour Orange and Alemow to around 39–41 g L−1 on Trifoliate Orange, Carrizo Citrange, Troyer Citrange, and Flying Dragon at harvest. Overall, Trifoliate Orange, Carrizo Citrange, and Swingle Citrumelo emerged as promising alternatives to Sour Orange, combining high yield efficiency, satisfactory fruit quality, and improved yield precocity.
Mafrica et al. (Tue,) studied this question.