The Response Of Maize With Different Genotypes To Enhanced UV-B Radiation

Ozone layer depletion, leading to the radiation intensity of UV-B on the earthsurface increased, has become a great environmental problem worldwide. UltravioletB (UVB,280-315nm) affects both the development of crops and the yield and qualityof harvested products reported by researches. Breeding new cultivars with enhancedresistance to UV-B stress and high yield must be an important way to guarantee thefood security and achieve agricultural sustainable development. Thus, finding genesand genotypes with strong tolerance or resistance to UV-B radiation would become animportant branch of molecular biology, genetics and crop breeding.In this study, Nongda108and Zhengdan958as well as their parent, X178/HuangC and Zheng58/Chang7-2, were used to evaluate the response differences to UV-Bradiation under enhanced UV-B radiation condition with normal light as control,artificially. During seedling and filling stage, treatments of increasing UV-B radiationboth in culture room with artificial light and net house with natural light environmentswere set to detect the response differences among234maize inbred lines in terms tophotosynthesis and antioxidant. We also investigated the yield and quality traits ofdifferent lines tested under the two light treatment conditions in net house. The mainresults are as follows:1For the same agronomic trait, there was a significant response difference acrossmaterials tested with different genotypes to increased UV-B radiation. For differentagronomic traits, the performances of the same genotype were inconsistent afterUV-B radiation stress treatment.2Hybrid showed superiority to their parental lines on the response to increased UV-Bradiation with regard to fresh and dry weight, net photosynthetic rate and PSⅡphotochemical efficiency, and no significant difference was found in terms tophotosynthetic pigment, Intercellular CO2concentration and average root diameter.While, for superoxide dismutase, total root surface area and root vigor hybridexhibited inferiority to their parental lines.3Significant differences occurred across different experimental conditions, differentgrowth stages and different genotypic lines. There was a slight correlation betweenthe screening results derived from seedling stage and grain filling stage, indicatingthat the screening result obtained under only one experimental condition or only one growth period was unreliable, consequently according to research objectives todetermine the test conditions and growth stages.4The impacts of enhanced UV-B radiation on yield and it related traits acrossdifferent inbred lines with heterogeneous genotypes were different, generally,enhanced UV-B radiation significantly reduced the yield and it assisted traits ofdifferent genotypic lines tested. According to the method of group classificationstep by step, different genotypic lines were classified into5types, that is highresistance to UV-B, resistance to UV-B, moderate resistance to UV-B, susceptibleto UV-B and high susceptible to UV-B.5The impacts of enhanced UV-B radiation on kernel quality traits across differentinbred lines with heterogeneous genotypes were different. The sensibility of fourkinds of quality traits to increased UV-B radiation was fat> lysine> protein>starch. The relative change of grain protein content, fat content and lysine contentincreased more than10%in16.3%,19.9%and13.3%inbred lines, respectively.