Study On Nitrogen Uptake And Utilization Of Potato-Oat Intercropping System In Ningxia Semi-Arid Region

In order to investigate the effect of intercropping and nitrogen application on the nitrogen uptake,accumulation,and transport,yield and quality of potato and oat in semi-arid regions of Ningxia.The 'Qing shu No 9' and 'Yan ke No 1' were used as research materials.The effects of planting pattern and nitrogen application level on the growth and development of potato and oat,nitrogen uptake,accumulation and transport in plants,nitrogen content in different forms of soils,soil physical and chemical properties,activity of protective enzyme,yield and quality were studied.The research results are as follows:1.Intercropping,nitrogen application and interaction can promote the growth of potato and oat.Intercropping with 150 kg·hm-2 performe best two years.In the early growth period of potato and oat,the average plant height and stem thickness of intercropping increased by 46.52%?62.01%,8.13%?23.57%,56.90%.90.50%,28.40?43.31%.Intercropping and nitrogen application can effectively promote potato leaf area index and dry matter accumulation,the best dry matter accumulation parameter was 150 kg·hm·2 intercropping.The effect of nitrogen application was better than intercropping for potato growth.2.In the early stage,intercropping and nitrogen application can resist the external adversity by improving the protective enzyme activity of potato and oat,the activity of protective enzyme of intercropping was lower than monocropping.With the growth and development,the relative chlorophyll content,malondialdehyde content and proline content of potato increased first and then decreased and nitrogen application of 150 kg·hm-2 and 225 kg·hm-2 was the best.In the early stage of potato growth and the later stage of oats growth,planting pattern and interaction had significant effect on the protective enzyme.The content of malondialdehyde and proline of oats reached the maximum at maturity,and the activity of catalase increased first and then decreased,reached the maximum at filling stage.The activity of peroxidase of oats decreased first and then increased,the activity of peroxidase was the lowest at heading stage.Nitrogen application was helpful for improving the activity of peroxidase for oat.Compared with the control,the application of nitrogen significant increased 50.61%.3.Intercropping and nitrogen application able to improve the absorption,distribution and accumulation of nitrogen for potato and oat plants,and the interaction has a significant effect on the later growth stage of nitrogen accumulation.Nitrogen application of 150 kg·hm-2 and 225 kg·hm-2 has a significant effect two years.In the maturity stage,the average nitrogen accumulation of the whole plant increased by 10.38%?28.89%,10.76%?31.04%compared with the control,and in the flowering stage,the nitrogen content of the ear increased by 11.00%?53.74%,12.45%?39.38%.Intercropping and nitrogen application are more conducive to the improvement of potato nitrogen harvest index,nitrogen physiological utilization rate and nitrogen utilization rate,and significantly reduce the partial nitrogen production.The best effect of nitrogen application is 150 kg·hm-2,and the effect of planting pattern and nitrogen application level on nitrogen utilization rate reached significant.4.Intercropping and nitrogen application improved the total nitrogen,nitrate nitrogen,and ammonium nitrogen content in the soil of potato and oat ploughed layers,and improved soil physical and chemical properties,and could achieve nitrogen balance in soil and plants.Intercropping and nitrogen application have significant effect on the changes of soil nitrogen content in 0-40 cm cultivated layer.The total nitrogen,nitrate nitrogen,and ammonium nitrogen contents of the soil were higher in monocropping potato during tuber formation,and 150 kg·hm-2 was applied in the cultivated layer.Intercropping and nitrogen application have significant effect on the changes of soil nitrogen content in 0-40 cm cultivated layer,150 kg·hm-2 and 225 kg·hm-2 of applied were higher,the nitrate nitrogen content significantly increased in the intercropping mode,and the potato's ability to absorb fast-acting nitrogen was stronger than that of oat in the later period,and the soil nitrogen residue in potato was lower than that of oat.The soil pH,available potassium,available phosphorus,total nitrogen,and organic matter increased over past two years than before planting.Intercropping and nitrogen application had obvious effect on improving soil physical and chemical properties,and nitrogen application had a great effect on soil physical and chemical.5.Under the basal and topdressing fertilization,potato and oat organs of intercropping and nitrogen treatment have different 15N accumulation,Ndff,fertilizer nitrogen,and soil nitrogen absorption capacity.Fertilizer nitrogen had a significant contribute to the total nitrogen content of the reproductive organs of potato and oat under monocropping treatment,and nitrogen fertilizer had a higher contribute to the total nitrogen content of potato tuber under topdressing treatment.The contribution of oat topdressing to the reproductive organs was weaker than that of the vegetative organs.6.The intercropping advantage of potato and oat reached obvious,and the nutrition competition ability of oat is stronger than potato.Intercropping and nitrogen application can promote the yield and quality of potato and oats,boast obvious economic benefits.With the increase of nitrogen application,the yield of potato and oat increased first and then decreased under the monocropping and intercropping,and the yield(33635.10 kg·hm-2,36796.05 kg·hm-2)and benefit(23478.45 yuan/hm2,24546.75 yuan/hm2)were the best.Compared with the control,the yield of potato increased by 10.29%,31.23%,18.22%and 13.43%in 2018 and 2019,and the oat yield increased by 89.98%,66.84%,1.07%and 21.24%.Under the intercropping mode,the crude protein,starch,reducing sugar and soluble sugar of potato were slightly higher than monocropping,the crude protein and fat content of oat were opposite to that of potato,and the effect of nitrogen application was higher than planting pattern on the quality of potato and oat.