Effects Of Nitrogen Application On C And N Metabolisms And Yield Of Relay Strip Intercropping Soybean

This experiment was conducted to study the effects of nitrogen fertilizer application on C and N metabolisms, indexes of population quality and yield of relay strip intercropping soybean (Rcsoybean), used limited-pod type soybeans, Gongxuan 1#, in raise/soybean relay strip intercropping system, establishing the relationship of each index and the laws of C and N metabolisms of soybean. The main results showed as follows:1. The N content (NC), N accumulation (NA) and Ureide content (UC), Ureide accumulation (UA) of vegetative organs declined as a single apex curve with the incensement of the Rcsoybean plant age. The peak value of NC occurred at the growth stage of R3, the peak value of NA occurred at R4, and it of UC, UA showed at R5. The NC in leaves and UA in stems lowered at the beginning and raised later with the increasing of nitrogen application level, but the NC in stems showed as "down-up-down", NC in pods, UC in stems and NA in vegetative organs declined as a single apex curve, the accumulation of B3 was the highest. At the growth stage of R5, the NC, NA in leaves and UA in stems of A2 were very significant higher than that of Al and A3, NC and UC in stems of A1 were very significant higher than that of A2 and A3. Under the effect of interaction between N treatment and N application level, the best combination with the highest NC in leaves and stems was A1B2, and it with the highest NC in pods and NA in vegetative organs was A2B2, and it with the highest UA in stems, which was 3.163 g/plant, was A1B1.2. The N application level has highly significant impacts on NER, NHI and NAE, and the impacts on TNA and NPE were under the significant level. The NER, NHI and NAE of Rcsoybean decreased gradually with the increasing of nitrogen application level. The N application patterns has significant impacts on Total N accumulation (TNA), N efficiency ratio (NER), N harvest index (NHI) and N agronomy efficiency (NAE), ordered as A2>A3>A1, and the impact on NPE was under the significant level. Under the effect of interaction between N treatment and N application level, the best combination for the highest TNA is A2B2, and for NER, NHI and NAE is A1B2.3. The Soluble sugar content (SSC) increased gradually while Starch content (SC), Soluble sugar accumulation (SSA) and Starch accumulation (SA) declined as single apex curves in leaves with the growth of soybean. The peak value of SC occurred at the growth stage of R5, and R3 was the time that the peak value of SSA and SA showed. SSC and SC lowered at first and raised later with the increasing of nitrogen application level, SSC of B3 and SC of B2 were the lowest, and SSA and SA in leaves increased gradually. At the growth stage of R5, SSC in leaves of Al and SC of A3 were the lowest, while SSA and SA in leaves of A2 were the highest. Under the effect of interaction between N treatment and N application level, SSC of A1B2 combination and SC of A2B3 combination were the lowest, while SSA and SA of A2B2 combination were the highest.4. The effects of nitrogen fertilizer planning and management on C/N of Rcsoybean mainly occurred after the growth stage of R4. As the increasing of nitrogen fertilizer, the C/N of soybean emerged to tendency of decreasing first and then increasing. Compared with the control group, the C/N of Al (40 N kg·ha-1), A2 (80 N kg·ha-1), A3 (120 N kg·ha-1), A4 (160 N kg·ha-1) respectively decreased by 29.89%,29.27%,31.19% and 22.26%, with B3's decreased the most. And B2 observably reduced the C/N, which is increased by 7.94% compared with B1 and 15.68% compared with B3, at the growth stage of R5.5. The composition of dry matter was different in different ages of Rcsoybean, at the growth stage of R1, dry matter of Rcsoybean was composed of stem (37.95%), leaf (47.76%) and leaf stalk (14.29%), while it was composed of stem (19.28%), leaf (24.54%), leaf stalk (7.40%) and pod (48.78%) at the growth stage of R7. It present as a single apex curve with the increasing of nitrogen application level, and compared with A3, which was with the best N level, higher than A1,A2 and A4 respectively by 25.02%,6.89% and 12.95%. The DW of A2B2 combination (145.17 g/plant) was the highest under the effect of interaction between N treatment and N application level. The Dry weight (DW) of B2 was higher than B1 and B3 by 11.34% and 14.59% at the growth stage of R5.6. Nitrogen application observably enhanced the number of the pods per plant, the number of seeds per plant, the seeds weight per plant, and 100-seeds weight, and compared with the control group, the combination of A2B2 was the highest, which was respectively higher by 81.03%,109.24%,77.92% and 11.30%. As well as the relation between the nitrogen fertilizer rate and yield was a quadratic equation (y=-0.074455x2 +13.1898x+ 866.9915, F=21.17**), and the yield reduced with the increasing of the nitrogen fertilizer rate, when the rate was over 88.52 N kg·ha-1. In the way of nitrogen application, B2, which has the highest yield, compared with Bl and B3, got the yield higher by 29.40% and 8.77%. Under the effect of interaction between N treatment and N application level, the yield of A2B2 combination (1467.84 kg·ha-1) was highest, second were A3B3 combination (1390.62 kg·ha-1).