Yield and fruit quality traits of rambutan cultivars grafted onto three rootstocks and grown in a Mollisol soil in Puerto Rico

Abstract

With increasing ethnic diversity and demand for healthy and more varied foods, globalization has opened a window of opportunity for new tropical fruits, including rambutan (Nephelium lappaceum), to be offered to consumers in the Western Hemisphere. The lack of formal experimentation on rambutan performance using various scion/rootstock combinations prompted a study, conducted in Santa Isabel, Puerto Rico, using a randomized complete block design to assess the yield and fruit quality of three cultivars (‘Gula Batu’, ‘Jitlee’, ‘R-162’) when grafted onto three different rootstocks (‘Binjai’, ‘Gula Batu’, ‘R-134’) in an alkaline Mollisol soil. From 2011 to 2015, there was an increase in the number and yield of fruit for cultivar/rootstock treatments. Regardless of rootstock, ‘R-162’ and ‘Jitlee’ had a higher number of fruit and yield than ‘Gula Batu’. The cultivars produced significantly more fruit and had significantly higher yields when ‘Gula Batu’ was used as a rootstock. Cultivar/rootstock treatments did not have a significant effect on individual fruit weight which averaged 32 g. Cultivar ‘R-162’ grafted onto ‘Gula Batu’ had a higher concentration of soluble solids, but it was not significantly different than the rest of the treatments except for ‘Gula Batu’ grafted onto ‘Binjai’ and ‘Gula Batu’ grafted onto ‘R-134’, which had significantly lower soluble solids concentration. Individual fruit weight and rind weight did not vary among cultivar/rootstock treatments, and pulp weight varied very little. Seed weight differences were mainly associated with cultivar ‘Gula Batu’. This study confirms previous work by the author showing ‘R-162’ as a highly productive cultivar and, for the first time, shows that ‘Gula Batu’ is a superior rootstock, performing very well under alkaline soil conditions.