Variations in growth responses of 23 wild sugarcane ( Saccharum spontaneum L.) clones to enhanced ultraviolet-B radiation under field conditions in Kunming, China

Field studies were conducted at Kunming (China) to determine the sensitivity of 23 wild sugarcane ( Saccharum spontaneum L.) clones to enhanced ultraviolet-B radiation (UV-B, 280 to 315 nm). The clones sourced from different sites (altitude 0 to 1860 m and latitude 18 to 37oN) were evaluated in the field during 2003 and 2004, both with and without supplemental UV-B radiation of 5.0 kJ m–2. Significant effects of UV-B radiation on plant height, leaf area index, number of tillers, and shoot biomass were observed, besides their significant inter-correlations. Based on the response index, it was deduced that intraspecific sensitivities of wild sugarcane clones to UV-B radiation are profound. Six most sensitive wild sugarcane clones had negative response index lower than –165 in 2003 and –110 in 2004, and six other most tolerant clones had positive response index higher than 150 in 2003 and 110 in 2004. Clones originating from regions with high ambient UV-B were not necessarily more tolerant to enhanced UV-B levels, implying the need to introduce tolerant strains from elsewhere to such locations. UV-B tolerant wild sugarcane clones identified and evaluated in this study might as well be useful as donors in sugarcane breeding programme.