Identification for nitrogen stress of main maize cultivars in Guangxi

ObjectiveThe low-nitrogen tolerance of main maize cultivars in Guangxi were identified , and the low-ni-trogen tolerant maize cultivars suitable for local cultivation were screened out , in order to provide reference for maize cul-tivation in mountain area of Guangxi. MethodSplit plot design was used in the field experiment , nitrogen stress test was carried out, with nitrogen application rate as main treatment and variety as the secondary treatment. Main treatment included normal nitrogen application (N 180 kg/ha, CK) and nitrogen stress (N 0 kg/ha). The plant height and ear height were determined at filling stage, and yield and ear characters were investigated at maturation stage. Effects of nitrogen stress on main agronomic characters and yield of 10 maize cultivars were studied , so as to analyze low-nitrogen tolerance indexes and correlations of main agronomic characters of different maize cultivars. Then the barren tolerance of different maize varieties was comprehensively evaluated by method of subordinate function five-level system partition standard.ResultThe plant height, ear height, ear length, ear length, row number per ear, grain number per ear, hundred-grain weight and yield of maize under nitrogen stress were all lower than those of CK , and the barren tip length of ear was also longer than that of CK. In addition, there were differences in low-nitrogen tolerance indexes for main characters between different maize cultivars under nitrogen stress. The low-nitrogen tolerance index of yield was the least , it suggested that the nitrogen stress had the greatest influence on yield. And there existed little differences in low-nitrogen tolerance index of plant height, ear length, row number per ear, hundred-grain weight and other characters. The most drastic changes were found in low-nitrogen tolerance index of ear barren tip length. Correlation analysis showed that , the yield was extremely significantly positively correlated with number of grain number per ear(P<0.01, the same below), and significantly positively correlated with hundred-grain weight(P<0.05), but significantly negatively correlated with barren tip length; under ni-trogen stress, the effects of different characters on yield of maize was in order, as follows:grain number per ear>hundred-grain weight>barren tip length>rows number per ear>ear length>plant height>ear height. using fuzzy membership function method to evaluate low-nitrogen tolerance of different maize cultivars, the results showed that, Guidan 0810, Dika 008, Huayou 168 and Guidan 162 had strong low-nitrogen tolerance; Xianda 901, Yahang 0919, Zhaofeng 788, Guidan 901 and Zhengda 808 had medium low-nitrogen tolerance, Ruite 237 had weak low-nitrogen tolerance. ConclusionYield, grain number per ear, hundred-grain weight, and barren tip length can be used as fast and easy screening indexes of low-nitrogen tolerant varieties. And Guidan 0810, Dika 008, Huayou 168, Guidan 162 are identified as low-nitrogen tol-erant cultivars based on preliminary screening.