Reproductive biology of East Indian satinwood (Chloroxylon swietenia DC., Rutaceae: Sapindales), a threatened timber-yielding tree

Abstract

Chloroxylon swietenia DC. (Rutaceae) is widely used in folk medicine and provides a commercial timber. In the present study, phenological events such as flowering and fruiting phenology, pollinator visitation, anthesis, pollen viability, and pollen tube germination tests were analyzed in 11 populations, in Tamil Nadu, India. The number of flowers was recorded as 82.6 ± 1.4 to 162.2 ± 4.2 during flower bud formation and reduced to 25.4 ± 0.5 to 61.8 ± 1.0 at maturity. The number of fruits per twig was 21.0 ± 0.8 to 47.2 ± 0.7 in initial stages and slightly reduced to 16.2 ± 1.8 to 34.6 ± 1.4 at maturation. Sixty-two species of insects were visiting the flowers with bees/ants as effective pollinators. The 2,5-diphenyltetrazolium bromide assay revealed more viable pollen grains in five populations, and fluorescence dye assay revealed maximum viable pollen grains in six populations. In the pollen tube germination test, the 60% sucrose concentration provides significant results, with a high number of germinated pollen grains. Principal component analysis of flowering and fruiting phenology, floral visitors, and pollen viability showed 79.5%, 79.3%, 56.7%, and 41.7% for the first factor, respectively. Our results indicated that C. swietenia depends heavily on pollinators for its reproduction. Hence, there is a need to expand this study to related species which are having agronomic, pharmacological, and economic potential.

Keywords

• Chloroxylon swietenia
• Floral visitors
• Phenology
• Pollination
• Pollen viability