Changes in growth and photosynthetic capacity of rice with increased UV‐B radiation

Abstract

Sixteen rice ( Oryza sativa L.) cultivars from 7 different geographical regions were grown in greenhouses at the Univ. of Maryland with and without supplemental ultraviolet‐B (UV‐B) radiation to determine alterations in biomass, morphology and maximum photosynthesis that would be anticipated from potential reductions in the stratospheric ozone column. A wide range of UV‐B effects were observed, with the Philippines cultivar Carreon (5993) and the Sri Lankan cultivar Kurkaruppan (15449) showing the greatest decrease and increase, respectively, in total biomass with supplemental UV‐B radiation. Approximately one‐third of all cultivars tested showed a statistically significant decrease in total biomass with UV‐B radiation. For these sensitive cultivars, leaf area and tiller number were also significantly reduced. Photosynthetic capacity as determined by oxygen evolution declined for some cultivars, but the correlation between changes in photosynthesis and biomass with increasing UV‐B was equivocal. Results from this experiment indicate that: (1) a number of rice cultivars are sensitive to potential increases in UV‐B radiation: and (2) the diversity exhibited by rice in response to increased levels of UV‐B suggests that selective breeding might be successfully used to develop UV‐B‐tolerant rice cultivars.