Study On Nodule Nitrogenous Activities And Amount Of Nitrogen Fixation Of Soybean

Soybean is a main crop as both food and oil. Studies on the nodule nitrogenous activities and amount of nitrogen fixation of soybean are implication of nitrogen fertilizer application, reduction of production cost, increase in yield for soybean, and reducing environmental pollution with fertilizer.This work, combined with the frame tests and sand culture, conducted in 2008-2009.In 2008, labeled 15N was used in the frame test, studied the difference of nitrogen-fixation amount and the ability of change in nodule nitrogenous of different varieties. The experiment design was as follow: testing varieties were HH41(the fifth, sixth accumulated temperature zone),SN14(the second, third accumulated temperature zone),HN40(the first accumulated temperature zone),MSD(feed soybean) and NON-NOD(comparison).In 2009,five N rates of N0,N100,N200,N300,N400 was set up and studied the effects of nodules nitrogenous activities in nitrogen levels; In sand culture, labeled 15N ammonium sulfate was used as nitrogen source and four N rates was set up. Nodules nitrogenous activities, nitrogen-fixation amount, the light and the temperature, and the effect of nodules nitrogenous activities in the source condition was measured. The result were shown as following:The ability of nodule nitrogenous was different as the soybean grew of different varieties.(1) Dry weight of all nodule showed a trend of a single-peak curve, dry weight of all nodule has little difference in seeding stage, but in the reproductive stage, if the growth period was longer, dry weight of nodule was heavier. (2)The trend of per unit of nodules nitrogenous activities was basically the same. The maximum showed between the early flowering stage(Ri) and the first pod(R3). The activities of early maturing one increased earlier and greater than other varieties. Per unit of nodules nitrogenous activities of feed soybean(MSD) in the whole growth period was lower than cultivated soybean.(3) Each plant of nodules nitrogenous activities in the whole growth period had very difference. In seeding stage, nodules nitrogenous activities is low. And increased after V4, but if the longer growth period,the longer keeping a high level of of nodules nitrogenous activities. The longer growth period of soybean plants and the higher nitrogen-fixation amount in grain, the greater ratio of nodule nitrogen account for total nitrogen in one plant. In different growth stage, the maximum of soybean nodule and nitrogen-fixation amount was significant positive correlation, correlation coefficient is r=0.9685**.The early drum grain (R5) and the cumulating of nodules nitrogenous activities in each period correlate with nitrogen-fixation amount greatly, correlation coefficient is r=0.9841**,r=0.9730**. The maximum of each plant of nodules nitrogenous activities showed between the first pod (R3) and the early drum grain (R5). The ability of nodule nitrogenous in different nitrogen level had a great influence.(1) In each nitrogen level, dry weight of nodule in the whole growth period showed a trend of the single-peak curve. N inhibit the growth of nodules and the higher level of nitrogen, the smaller dry weight of nodule.(2)The conditions of sand culture showed:in the early growth, nitrogen fertilizer promoted per unit of nodules nitrogenous activities, and showed N50>N100>N150 during the nitrogen treatment, but showed N0> N50>N100>N150 in the late (in the mult-pod stage R4); In the condition of frame tests, both the seeding stage(V4) and the mult-pod stage(R4) showed N100>N200>N300> N0>N400. Fixed nitrogen fertilizer promoted the increasing of per unit of nodules nitrogenous activities, but higher nitrogen fertilizer inhabit nodules nitrogenous activities.(3) In each nitrogen level, the difference among each plant of nodules nitrogenous activities was greater. In the seeding stage (V4), not to treat with nitrogen and higher nitrogen treatment were low. After the early flowering stage(R1),with the improving of exerting nitrogen, each plant of nodules nitrogenous activities gradually reduced. In different nitrogen level,nitrogen-fixation amount of nodules had differences. With the increasing of the nitrogen level,the proportion of nitrogen in plant and nitrogen-fixation amount of nodules was gradually reducing, the nitrogen level and nitrogen-fixation amount of nodules was significant negative correlation y=-102.2x+519.8 (r=0.983**). In different nitrogen level, the dry weight of nodule of early drum grain (R5) and nitrogen-fixation amount of nodules was positive correlation, correlation coefficient is r=0.9926**. The early drum grain (R5) and the cumulating of nodules nitrogenous activities in each period positive correlate with nitrogen-fixation amount greatly, correlation coefficient is r=0.9863**, r=0.9730**.Lighting had a great influence for per unit of nodules nitrogenous activities. Do dark treatment for soybean plants,activities decreased to 60% after 6 hours, activities did not change after 24 hours. After 96 hours, plants restored 24-hours light,then per unit of nodules nitrogenous activities recovered markedly. In dark treatment, nodules nitrogenous activities increased significantly with spraying sugar solution. With the increasing of the temperature, nodules nitrogenous activities showed a other shore flower trend of single-peak. The temperature fitted with nodules nitrogenous activities, we found that nodules nitrogenous activities was the highest in about 21℃.Nodules nitrogenous was not sensitive to low temperature, but more sensitive to high temperature.In both the frame tests and sand culture conditions, nodules nitrogenous activities and source contain in root had no correlation. But under dark treatment condition,per unit of nodules nitrogenous activities was significantly correlation with source contain of stems and roots in the different temperature.