Submitted to: Annals Of Botany
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/19/2004
Publication Date: 10/5/2004
Citation: Koti, S., Reddy, K.R., Kakani, V.G., Khao, D., Reddy, V. 2004. Soybean (glycine max) pollen germination characteristics, flower and pollen morphology in response to enhanced ultraviolet-b radiation. Annals Of Botany. 94:855-864. Interpretive Summary: The harmful ultraviolet-B radiation reaching the earth surface is rising rapidly due to changes in global climate. It is important to evaluate the effects of this harmful radiation on crop productivity. A study was conducted to evaluate the effects of ultraviolet-B radiation on soybean pollen production, and pollen germination. From this study, it was observed that increased harmful radiation will have detrimental effects on reproductive biology of soybean crops. It was also observed that there are cultivar differences in sensitivity to harmful radiation in soybean. These differences in sensitivity to harmful radiation can be used in breeding programs by identifying tolerant cultivars.
Technical Abstract: The influence of ultraviolet-B (UV-B) radiation on flower and pollen morphology, pollen production and in vitro pollen germination characteristics of soybean (Glycine max L.)was studied. Six genotypes of soybean were investigated by growing them in four levels of biologically effective UV-B radiation of 0 (control), 5, 10 and 15 kJ m-2 d-1 in sunlit controlled-environment chambers. Reductions in lengths of flower, standard petal, and staminal column along with reduced pollen production, germination and tube growth were observed in all the genotypes with increasing UV-B radiation. Combined response index (CRI), the sum of percentage relative responses in length of the flower, pollen production, pollen germination and tube growth due to UV-B radiation in comparison with control, varied with UV-B dosage; -67 to -152 at 5 kJ m-2 d-1, -90 to -212 at 10 kJ m-2 d-1, and -118 to -248 at 15 kJ m-2 d-1 of UV-B. Genotypes classified based on the UV-B sensitivity index (USI) showed that D 90-9216 as tolerant (USI < 5), Stalwart III and PI 471938 as susceptible (USI >10) and DP 4933RR, D 88-5320 and DG 5630RR as intermediate (USI 5-10). Pollen grains produced in plants grown at 15 kJ m-2 d-1 UV-B radiation were shriveled/collapsed and lacked apertures compared to control and other UV-B treatments in both sensitive and tolerant genotypes, and the differences were more conspicuous in the sensitive genotype (PI 471938) than in the tolerant genotype (D 90-9216). The number of columellae heads of the exine was reduced gradually with increasing UV-B radiation. The UV-B-tolerant genotypes identified in this study might be useful as possible donors in soybean breeding programs for UV-B tolerance.