Screenning For N Efficiency Potato Varieties And Research On Its Physiologcal Mechanism

For selecting nitrogen efficiency of potato varieties and studying the physiological mechanism of nitrogen efficient, The sand culture and field experiments were conducted,by measuring the potato dry matter, nitrogenrate, nitrogen accumulation and yield, to studying the 27 genotypespotato varieties of different efficiency of nitrogen. Through sand culture method, under different nitrogen levels and different nitrogen (N) efficiency of potato genotypes, SPAD values, nitrate reductase activity, glutamine synthesis enzyme activity, root activity, root uptake kinetics of the ammonia nitrogen and root uptake kinetics of nitrate were measured, to revealing the mechanism on differences of genotypices in nitrogen efficiency and to provide the theoretical basis on cultivating nitrogen efficient varieties.The results are as follows:1 Under the three nitrogen levels, the different genotype potatos have significant genotype differences in nitrogenous rate, dry matter content, nitrogen accumulation both in seedling stage and expanding period of the tuber,besides output of maturation stage,so the four indexes would be for the selection index of N efficient genotypes of potatos.2 In the test,it has set up three nitrogen levels, include low,medium and high. With the output as the primary index,choose the best nitrogen level among the medium level and high leve.Combined with relative N uptake, relative N content and relative dry mat-ter accumulation or another index, evaluate the 24 different genotype potats by the method of weighted mean.Through the comprehensive evaluation value to performing clustering analysis, Feiwuruita, Bashu10, Gaoyuan7,Yunshu301 for high nitrogen efficiency cultivars;Chuanyu56 and Langshu97 for low nitrogen efficiency cultivars;Mila, Taiwanhong,Zhongshu5, Huiyi2, Hezuo88, Liangshu14, Daxiyang, Chuanyu10, Zhongshu3, Chuanyu39, Chuanyuzao, Chuanyu5, Zhongshu2, Baishu9, Eshu5, Chuanyu4, Yunshu201, Yunshu102 for in termediate species. From the quantity of the high nitrogen efficiency cultivars, Intermediate species and the low nitrogen efficiency cultivars can be seen, the different varieties of nitrogen efficiency into normal distribution, positively that this method can well reflect different varieties of nitrogen efficiency between the potato, screening for potato varieties with different N efficiency. 3 Field experiment indicated that different potato genotypes under the same nitrogen level showed significant differences,In the case of non-N, the lowest yield of Liangshu 97 and Chuanyu 56, the relatively high yield of Feiwuruita and Yunshu 301, Therefore, the filter results of field test and the sand culture experiment had a strong consistency.4 The nitrogen accumulation,nitrogen use of the high nitrogen efficient varieties Yunshu301 and Feiwuruita were higher than Liangshu 97 and Chuanyu 56; and the growth period of dry matter accumulation, nitrogen accumulation and yield to show a significant positive correlation.5 The same genotype varieties of chlorophyll content under the level in N1 was higher than in NO and under the level in N2 was lower than in N1. The SPAD value of the high nitrogen efficient varieties Yunshu301 and Feiwuruita were higher than Liangshu97 and Chuanyu56; Levels in the N0, the order of different genotypes of potato leaf photosynthetic rate was that:Feiwuruita> Yunshu301>Liangshu97>Chuanyu56.6 Levels in the N0, the order of different genotypes of potato nitrate reductase activity was:Yunshu301>Feiwuruita> Chuanyu56>Liangshu97; Levels in the N1 and N2, the order of different genotypes of potato nitrate reductase activity were:Feiwuruita> Yunshu301> Liangshu97> Chuanyu56; The nitrate reductase activity of the high nitrogen efficient varieties Yunshu301 and Feiwuruita were higher than Liangshu97 and Chuanyu56, so the ability of the high efficient genotype varieties assimilat NO3 --N was strengther than the low efficient genotype varieties; Nitrogen levels in all, the order of different genotypes of potato glutamine synthetase activity was:Feiwu-ruita>Yunshu301>Liangshu97> Chuanyu56. The glutamine synthetase activity of the high nitrogen efficient varieties Yunshu301 and Feiwuruita were higher than Liang shu 97 and Chuanyu56.7 The root activity and the affinityof the NO3--N,the high nitrogen efficient varieties Yunshu301 and Feiwuruita were higher than Liangshu97 and Chuanyu56; The maximum absorption rate of NO3--N and NH4+-N were not significantly different,but the apparent constant of NH4+-N was lower than the apparent constant of NO3--N. So the same genotype of potato on the affinity of NH4+-N was significantly higher than the affinity of NO3--N.