Qj. Dai et al., INTRASPECIFIC RESPONSES OF 188 RICE CULTIVARS TO ENHANCED UVB RADIATION, Environmental and experimental botany, 34(4), 1994, pp. 433-442
Phytotron studies were conducted to determine the intraspecific variat
ion in sensitivity of rice (Oryza sativa L.) to enhanced UVB and to te
st the hypothesis that rice cultivars originating from regions with hi
gher ambient UVB radiation are more tolerant to enhanced UVB. Out of t
he 188 rice cultivars (from various rice growing regions and ecosystem
s) tested, 143 had significantly reduced plant height, 52 had smaller
leaf area, 61 had lower plant dry weight and 41 had less tiller number
under elevated UVB radiation (13.0 kJ m(-2) day(-1)) for 3 weeks. Six
cultivars showed significant positive growth response to enhanced UVB
radiation, although the mechanism is not clear at present. These six
cultivars were from the summer rice crop of Bangladesh and from high e
levation rice areas where prevailing UVB radiation is most likely to b
e greater. However, there was no correlation between the dry matter ch
anges under enhanced UVB and the ambient UVB level at the origin of th
e cultivar across the 188 cultivars tested. Therefore, cultivars origi
nating from regions with higher ambient UVB are not necessarily more t
olerant to enhanced UVB radiation.