Impact of environmental changes on the reproductive biology in Pyrostegia venusta Presl.

ABSTRACT

Local environment (temperature and relative humidity) affects reproductive biology in Pyrostegia venusta (Bignoniaceae) growing at Agra and Mysore. At Agra, the species flowers profusely during December to March, but fails to bear fruits. At Mysore, on the other hand it flowers during November to February and produces well developed fruits with winged seeds. This species, growing at two places, exhibited differences in their pollen fertility and in vivo pollen germination. Pollen fertility at Agra and Mysore was 27.55 and 80-90%, respectively. The in vivo pollen germination on stigmatic surface was only 3-4% at Agra, but 85-95% at Mysore. The flowers at Agra also exhibited heterostyly and increased number of stamens and stigmatic lobes. The significantly low and wide ranged temperature (4.5-33.8oC) and between 23-98% RH during the flowering period at Agra could be the cause for reduced in pollen fertility, floral polymorphism and inhibition of pollen germination on the stigmatic surface and fruitlessness. At Mysore, where temperature ranges between 20.2-33.5oC and RH varies from 33-75% profuse fruiting takes place. The study shows a direct control of environment over the process of reproduction.