Effects Of Nitrogen Fertilizer Management And Sowing Rate On Yield And Quality Of Regenerated Oat Under Grass-Grain Cropping Pattern

In view of the mountain foothill area in the production of oats solar-thermal resources"for more than one season"insufficient for both,and nitrogen use unreasonable situation,in the plains of Tu Mo Chuan oats harvest a crop of green hay and regeneration after mowing oats grain yield planting mode（hereinafter referred to as grass-grain planting patterns）,nitrogen fertilizer management and rate of oat green hay and regeneration after mowing oats grain yield and quality.Oat cultivars Tian Yan 2（V1）and Bai Yan 7（V2）were selected.In the nitrogen management model,the amount of pure nitrogen was 135 kg·hm-2,and the fertilization time and amount were set as follows:1/2 heading stage+1/2 booting stage of regenerated oat（N1）,1/2 heading stage+1/2 heading stage of regenerated oat（N2）,1/3heading stage+1/3 booting stage of regenerated oat+1/3 heading stage of regenerated oat（N3）.The seeding quantity is set to two,namely,180 kg·hm^-2（S1）and 225 kg·hm^-2（S2）.The effects of nitrogen fertilizer management and seeding rate on the growth and development of oat and soil nitrogen were investigated by using different treatments on the growth,physiology and nitrogen utilization characteristics,yield and quality of oat under grass-grain cropping mode,in order to recommend suitable nitrogen fertilizer management mode and suitable seeding rate in the southern foot of Yinshan Mountain.The results show that:1.The plant height,stem diameter and aboveground dry matter quality of regenerated oat were significantly improved.The plant height,stem diameter and shoot dry matter quality of oat were significantly improved by applying proper nitrogen fertilizer after cutting,and nitrogen fertilizer was significantly correlated with the growth and other indicators of oat.N1 was the best treatment for the growth index of regenerated oat at booting and heading stage,N2 was the best treatment for the growth index of regenerated oat at filling and maturity stage,and V1 variety grew better than V2 variety in each stage.2.Nitrogen fertilizer management and seeding rate can improve photosynthetic capacity of oat.Nitrogen management and seeding rate had different effects on net photosynthetic rate,intercellular CO₂ concentration,transpiration rate and SPAD value of oat,and improved photosynthetic capacity of regenerated oat.N2S2 treatment was the best,and the photosynthetic characteristics of V1 was better than V2.3.Nitrogen fertilizer management and seeding rate can improve the yield and quality of oat.Application of nitrogen fertilizer significantly increased the yield of oat,and nitrogen fertilizer operation mode and seeding rate had different effects on the yield of oat.N2S2treatment had the highest grass yield at heading stage and regenerated oat maturity stage,which was 42072.76 kg·hm^-2 and 30055.52 kg·hm^-2 respectively.The grass yield of V1 was high,and the grain yield of V2 was high.Nitrogen treatments had no significant effect on the quality of green hay at heading stage,and significantly increased the contents of crude protein,crude fat and soluble sugar of regenerated oat straw,but had no significant difference in neutral detergent fiber content.There were significant differences in n partial productivity,nitrogen nutrient accumulation and nitrogen harvest index among treatments of nitrogen management and seeding rate.4.Nitrogen fertilizer management soil nitrogen content is different in each treatment.The contents of nitrate nitrogen,ammonium nitrogen and total nitrogen in soil increased firstly and then decreased with crop growth.At heading stage,soil nitrate nitrogen content in regenerated oats reached the maximum and began to decrease,and nitrogen content was negatively correlated with soil depth.The contents of total nitrogen,nitrate nitrogen and ammonium nitrogen in N1S1 treatment were the highest in 0～20 cm soil depth,and the contents of total nitrogen,nitrate nitrogen and ammonium nitrogen in N2S2 treatment were the highest in 20～40 cm soil depth.5.Effects of nitrogen fertilizer management and seeding rate on oat yield from the perspective of economic benefit,N2S1V1 treatment was preferred.Considering the effects of nitrogen fertilizer management and seeding rate on growth characteristics,photosynthetic characteristics,yield,quality and nitrogen absorption of oat,it was found that nitrogen fertilizer management and seeding rate varied with different varieties and production purposes under grass-grain planting mode,the effect of nitrogen fertilizer was better in the growth period of oat.In forage production,Tianyan 2 cultivar was the best when the seeding rate was 180 kg·hm^-2,and nitrogen fertilizer was applied at the cutting stage and heading stage of regenerated oats respectively.In grain production,Baiyan7 cultivar should be the best when seeding amount is 180 kg·hm^-2 and nitrogen fertilizer is applied at booting stage and heading stage of regenerated oats respectively before cutting.