Study On Effects Of Different Nitrogen Use Efficiency On Characteristics Of Roots And Rhizosphere Soil Of Potato

Through the test of two different nitrogen use efficiency of potato cultivars as materials, through the different nitrogen levels, using randomized block experiment design, studied under different nitrogen levels, with different nitrogen use efficiency potato varieties in physiological characteristics of root, the components of root exudates, the rhizosphere soil properties, Initially reveals the mechanism of potato nitrogen efficient utilization.The results are as follows:1. In three determination period, the root vigor of the high nitrogen efficient varieties bashulO is higher than low nitrogen effieieney cultivars liangshu97. In seedling stage and rhizome expanding period, two varieties root active absorption area have no significantly difference. In mature period, in Level N2, root active uptake area of bashu10were significantly lower than that of liangshu97In three determination period, root cationic exchange capacity of bashu10in NO and N1levels were higher than liangshu97, in level N2root cationic exchange capacity were significantly lower than liangshu97. With the increase of nitrogen,in seedling stage, root exchange capacity of bashulO increased and then decreased, liangshu97decreased and then increased. In rhizome expanding period, root cationic exchange capacity of two varieties decreased and then increased. In mature period, root cationic exchange capacity of bashulO continue to increase, liangshu97decreased and then increased.2. Under the three nitrogen levels,the compounds in the root exudates of the different N efficiency potatoes were roughly the same, but the chemical composition and relative content were different.22,25and21kinds of compounds were detected in the high nitrogen efficient varieties bashu10root exudates respectively using GC-MS;24,31and28kinds of compounds were detected in the low nitrogen efficient va-rieties langshu97.The compounds in the root exudates were mainly acids and hydr- ocarbons.Levels in the N1and N2, the content of acids of the low nitrogen efficient varieties langshu97has a1.31%and9.58%higher than bashu10respectively, but in Level N0, has a6.33%lower;the content of hydrocarbons of the high nitrogen effici-ent varieties bashu10has a3.33%and15.49%higher than langshu97respectively, but in Level N0, has a30.57%lower. With the increasing of nitrogen, the acid contents of the root exudates decreased and the hydrocarbon contents increased in the two varieties.3. The root exudates of different N efficiency potatoes both increased available nitrogen, phosphorus and potassium content. Under different nitrogen application amount, the mobilization of nitrogen, phosphorus and potassium in soils with root exudates collected from bashu10was better than langshu97. With the increase of nitrogen application, the mobilization of nitrogen, phosphorus and potassium in soils with root exudates collected from bashu10and langshu97both continuously increased.4. At the three determination stages, the amount of bacterium, fungus and actinomycete in soil of bashu10were higher than langshu97. During the seedling period and the growing period, with the increase of nitrogen application, the amount of bacterium decreased and then increased, but increased and then decreased in mature period. In three period,the amount of fungus decreased and then increased. The amount of actinomycete is decreased in the seedling period.5. At the three determination stages, soil urease activity,catalase activity and urease activity in rhizosphere of bashu10were higher than langshu97. During the seedling period and the growing period, with the increase of nitrogen application, urease activity in rhizosphere increased,catalase activity and invertase activity increased and then decreased. In mature period, with the increasing N fertilizer, urease activity in rhizosphere and catalase activity increased and then decreased,and invertase activity decreased and then increased.