Effects Of Nitrogen Forms On The Growth, Root Morphology And Photosynthetic Characteristics Of Direct Sown Winter Oilseed Rape

Rapeseed is one of the most important oil-bearing crops, and reasonable application of nitrogen fertilizer is important for the yield of rape. The choice of suitable nitrogen forms is an important indicator of the reasonable application of N fertilizer. This study under the field experiment conditions was carried to study the effectss of nitrogen forms on the yield, nitrogen accumulation and nitrogen use efficiency, has been clear about the suitable choice of nitrogen forms of rapeseed production in direct seeding. Formsthis, we analysis the physiological mechanism of the effect of different nitrogen forms on rape growth formsthe root growth and architecture, and the light electron energy distribution of nitrogen, in order to provide the theoretical basis of the choice of nitrogen forms.The main results were as follows:1. The study found that the application of nitrogen forms affect the yield, yield components, dry matter, nutrient cumulative and distribution andnitrogen fertilizer utilization. The average yield reached the maximum by 2026 kg/hm2 when NO3-/NH4+ was 1:3. Applied ammonium nitrogen can also promote flowering, pod numbers per plant and number per pod. The dry matter in different treatments showed differences in periods, and the proportion of ammonium nitrogen application could increase the dry matter. From the nitrogen nutrient accumulation changes, nitrogen accumulation reached the maximum in the flowering period with the advancing of growth. The nitrogen accumulation and nitrogen utilization rate of NO3-/NH4+=1:3 got to 95.3 kg/hm2 and 46.5%, were increased by 13.4 kg/hm2 and 7.5% compared with urea treatment.2. The growth of roots increased with the advance of the growth period. The total root length, root surface area and root number increased gradually and reached the maximum value at the pod period, and the root volume was at flower period. Nitrogen forms can significantly affect the root morphology and composition. With the increase of ammonium nitrogen ratio, the total root length, root surface area, root volume and root tip number showed higher advantage when the ratio of NO3-/NH4+ was 1:3. This means that the appropriate ammonium nitrate mixed could promote root proliferation and increase the nutrient absorption ability of root. Meanwhile, the effect of different nitrogen forms on root configuration mainly concentrated in the stage of seedling, wintering and bolting, and the root configuration of 0-2.0 mm was influenced significantly.3. Nitrogen forms can affect the photosynthetic rate among the photosynthetic parameters, which the Pn of nitrate treatment was significantly lower than that of urea and ammonium. The proportion of nitrogen metabolism can reach 12.09%-29.27% in the distribution of photosynthetic electron flow, this means that nitrogen assimilation is an important part of energy consumption and photosynthetic electron consumption. The correlation analysis results shows that its an important causes for the decline of Pn by reducing the total electron flow and carbon assimilation, and its can save about 3% of energy consumption under the condition of ammonium nitrogen than that under nitrate nitrogen. Meanwhile, the correlation analysis results show that there is a significant positive correlation between NR activity and Je(N). This means that there must exists inevitable relation between the NR activity and Je(N).