Fertility variation among individuals in natural stands of Acacia leucophloea

Abstract

Growth characteristics and fertility variations were evaluated at four natural stands of tropical arid zone species,A. leucophloeain southern India. Three stands (TNL 1, TNL 2 and PDM) were situated in dry upland regions while one stand (RKP) was at waterlogged site. The tree height and girth at breast height did not vary between stands in two years. Fertility variation (sibling coefficient, ψ) was estimated based on flowering abundance and fruit set collected for two consecutive years. Fruit production per tree was generally lower in the RKP stand than the other three stands. No year-to-year variation was observed on fruit set in all stands. Growth and flower production showed a weak-positive correlation in both years (R2= 0.39 to 0.1). The correlation to check if the larger inflorescence size, the higher number of fruit production was also failed. Male fertility variation did not vary much among stands (ψm= 1.28 ~ 1.62). Female fertility variation was low (ψf= 1.71 ~ 2.02) in the three stands situated in dry upland regions than the RKP stand (ψf= 4.09 ~ 4.16). The cumulative contribution of trees to the overall fertility was deviated from the ideal situation (equal contribution) in all stands, especially the RKP stand showed a skewed distribution (R2≤ 6.5). The effective population size was low in the RKP predicting a high genetic drift when compared with other sites. Similarly high group coancestry and low gene diversity were observed in the stand RKP. The implications of fertility variation on gene diversity of the species and future management of the natural stands were also discussed.