Grain Weight and Grain Quality of Wheat in Response to Enhanced Ultra-Violet (UV-B) Radiation at Latter Stages of Crop Development.

The increase of UV-B radiation may be a challenge for wheat production systems in Southern Chile. Previous reports had shown that increased UV-B radiation decreased wheat yield by affecting both grain number and grain weight. The objective of the present study was to evaluate the response of grain yield, yield components and grain quality to higher UV-B radiation during key periods for yield component determination. The experiment was carried out at field conditions in the Universidad Austral de Chile (40 ˆ South latitude). Treatments consisted on 2 spring wheat cultivars exposed to 2 periods of supplemented UV-B radiation (280-320 nm): between (i) booting and anthesis and (ii) anthesis and physiological maturity. Ultra-violet radiation was enhanced 3.5 kJ m-2 during 5 hours per day by UV-B lamps (Q panel UV-313, Philips). At harvest, plants were sampled to quantify above-gound biomass, grain yield, grain number and thousand grain weight. In addition, protein and gluten concentration of grains were measured. Grain yield was not affected (p>0.05) by UV-B increase either at pre- nor at post-anthesis treatments. Similar results were found for each yield component. In addition, grain protein and gluten concentration showed similar values between enhanced UV-B and control treatments. Therefore, these results do not support that expected increases of UV-B radiation in Southern Chile could compromise wheat production systems, at least if increases of UV-B radiation take place at latter stages of the crop cycle [ABSTRACT FROM AUTHOR]