Assessment of variability and genetic divergence of longan genotypes (Dimocarpus longan Lour.) based on qualitative and quantitative traits

Abstract

Longan (Dimocarpus longan Lour.) is an important underutilized fruit crop. There is currently limited information available on the genetic background of longans, which is a key bottleneck in longan improvement. Studies on the extent of genetic variability and genetic divergence are crucial and it can provide relevant information which can be very useful for crop improvement programmes. In the present study, a total of 54 qualitative and quantitative traits were investigated of 20 different longan genotypes to determine the morphological and physiochemical traits that. Results revealed that the significant variability existed in the studied traits except few. Among the qualitative traits petiole colour, leaflet curvature, young leaf colour, mature leaf colour, branching density, leaflet midrib colour, abundance of flower, trunk surface, fruit maturity group, and tree vigour were showed more than the average value of Shannon’s diversity index. Higher PCV and GCV recorded for several traits viz., tree volume followed by aril weight, number of fruits per branch, aril/seed weight ratio, trunk girth, TSS acid ratio, aril thickness, number of days from panicle initiation to flowering, titratable acidity, width of inflorescence, length of inflorescence, petiole length, fruit weight, plant height, crown diameter and rachis length. High heritability estimates coupled with high genetic advance as % of mean were recorded for the traits viz., plant height, trunk girth, crown diameter, tree volume, rachis and petiole length, number of days from panicle initiation to flowering, length and width of inflorescence, number of fruits per bunch, fruit, aril and seed weight, aril thickness, fruit colour-a, titratable acidity and TSS acid ratio which is indicative of additive gene action and selection based on these traits would be more reliable. According to the Mahalanobis D² statistic, twenty diverse genotypes were grouped into eight groups. The presence of genetic divergence was also tested in cluster means by the significant amount of variability for various variables. Therefore, this study’s findings imply that these genotypes have variability in terms of fruit quality traits, yield and traits that contribute to yield, and other agronomic traits that could be useful in future crop improvement initiatives.