Abstract

The effects of artificial biologically effective UV-B radiation on a range of growth and physiological parameters in two cotton (Gossypium hirsutum L.) cultivars (Romanos and Allegria) were recorded. Three levels of biologically effective UV-B were used: (1) zero (2) ambient and (3) elevated (determined as that associated with a notional 15% depletion of stratospheric ozone). Plants were grown under artificial light in growth chambers and subjected to the biologically effective UV-B radiation treatments. Compared to the zero level, the ambient and elevated biologically effective UV-B radiation significantly reduced plant height, leaf chlorophyll content, net photosynthetic rate, stomatal conductance, bract length, petal length, anthers number, pollen germination, seed cotton weight, fibre strength, fibre elongation, fibre micronaire, fibre maturity index, fibre spinning consistency index, mean fibre length, fibre yellowness and fibre uniformity index. Both the ambient and the elevated UV-B radiation also significantly increased stomatal density, short fibre index and fibre reflectance.

Key words: UV-B radiation, cotton, photosynthesis, stomatal density, flower characteristics, pollen germination, seed cotton weight, fibre quality.