Study On Screening Methods And Threatening Pressure Of Maize Varieties To Low Nitrogen Tolerance

In this paper, screening methods and threatening pressure of maize varietyes were studied under low nitrogen levels using solution incubation pot experiment. Here the main results of this study are presented:1.According to critical period definition of plant nutrition, aftering three leaves stage, four leaves stage of maize genotype is likely to critical period of screening maize genotypes for resisting to low nitrogen levels.2. Under very low nitrogen level of 0. 05mol/L , there were significant differences in N-deficiency ,shoot dry weight .ratio of root weight to shoot weight and total nitrogen uptake among different maize genotypes ,with readily assessed low nitrogen nutrition characters of maize genotypes. So, nitrogen level of 0. 05mol/L is probably proper threatening pressure for screening low nitrogen maize genotypes.3. There were to some extent influence of different stage supplying nitrogen on N-deficiency, biological biomass, morphological characteristics and plant nitrogen nutrition status of different maize genotypes. Amang above some indices, biological biomadd .root bulk, totalnitrogen uptake and N-deficiency appeared notably variation, which abviously reflected stage characteristics of nitrogen nutrition of maize varieties.4. Xinghai201, Xinghuangdan892, Guibi303, jiaosandanjiao, yayu No.2 and Qianxing No. 4 has high capacity to uptake nitrogen under low nitrogen threatening situation, and existing higher nitrogen utilization efficiency.