Response Of Organic Acids Secreted By Roots Of Tartary Buckwheat Under Low Nitrogen Stress From Pot Experiment

Nitrogen is one of the many elements needed for plant growth and development,but nitrogen is a limiting factor in many arable soils in China.Selecting crops with high nitrogen tolerance can not only ensure the normal growth of crops,but also control the amount of nitrogen fertilizer and improve nitrogen use efficiency,which is of great significance for improving soil ecological environment.Tartary Buckwheat is an important cereal crop in barren areas,it has extremely high edible value and medicinal value.It has short fertility cycle and strong adaptability to drought and barrenness,but the resistance between different varieties and different genotypes of the same variety are difference.Therefore,in order to explore the response of different tartary buckwheat varieties to adapt to low nitrogen stress,three kinds of nitrogen treatments were set up in the pot experiment of two varieties of tartary buckwheat(HF and DQ),which were CK(no nitrogen treatment),N1(low nitrogen treatment)and N2(normal nitrogen treatment),respectively.Soil samples were collected in three periods(seedling,flowering and maturity stage),and their organic acid concentrations and soil physical and chemical properties were analyzed.The main results are as follows:(1)Nitrogen treatment and tartary buckwheat varieties have different effects on soil organic acid concentration.1)The concentrations of malonic acid,malic acid,tartaric acid,acetic acid and formic acid of soils in two tartary buckwheat under N2 were higher than those under N1.The concentrations of these organic acids of soil in DQ were higher than those in HF under N1.2)The concentrations of propionic acid,oxalic acid and lactic acid of soils in two tartary buckwheat showed that N1 was higher than N2 at seedling and flowering stage,and N2 was higher than N1 at maturity stage.The concentrations of propionic acid,oxalic acid and lactic acid of soils in DQ were significantly higher than those in HF under N1 in each growth period.(2)Nitrogen treatment and tartary buckwheat varieties have different effects on soil moisture and soil pH.1)The soil moisture of two tartary buckwheat in N1 were significantly lower than in N2 at seedling stage.The soil moisture of DQ is significantly lower than that of HF under N1 at seedling stage.2)The soil pH values of two tartary buckwheat under N2 are roughly higher than under N1.The soil pH of DQ under N1 is lower than that of HF,which is more significant at seedling and flowering stage.(3)Nitrogen treatment and tartary buckwheat varieties have different effects on the total nutrient content of the soil.1)Nitrogen application rate increased the total nitrogen content of soils in two tartary buckwheat at seedling stage,and the increase of DQ is more obvious;the total nitrogen content of soils in two tartary buckwheat under N2 was lower than N1 at flowering stage.The total nitrogen content of the soil in HF was significantly higher than that in DQ under N1 at seedling and flowering stage.2)The total phosphorus content of soils in two tartary buckwheat did not produce significant differences between N1 and N2.The total phosphorus content of the soil in DQ was higher than that in HF under N1,which is more significant at flowering and maturity stage.3)The total potassium content of soil in DQ did not differ significantly between N1 and N2.The total potassium content of soil in HF showed that N1 was higher than N2 only at maturity.The total potassium content of soil in HF was significantly higher than that in DQ under N1 at maturity stage,and there was no significant difference between seedling and flowering stage.(4)Nitrogen treatment and tartary buckwheat varieties have different effects on soil available nutrients.1)Nitrogen application will increase the ammonium content of soil at seedling and flowering stage.The ammonium nitrogen content of soil in HF under N2 was slightly higher than N1,but there was no significant difference.The ammonium nitrogen content of soil in DQ increased with the increase of nitrogen application rate and reached the highest value at N2.The ammonium nitrogen content of soil in HF was slightly higher than that in DQ under N1,but there was no significant difference between seedling and flowering stage.2)The nitrate nitrogen content of soil in HF showed that N1 was lower than N2 at seedling stage,but N1 was higher than N2 at flowering stage.The nitrate nitrogen content of soil in DQ showed that N1 was higher than N2 at flowering and seedling stage.The nitratenitrogen content of soil in DQ was significantly higher than that in HF under N1 at various growth stages.3)The available phosphorus content of soils in two tartary buckwheat are roughly expressed as N1 higher than N2 in each growth period.4)The available potassium content of soils did not produce significant differences between nitrogen treatments.The available potassium content of soil in DQ was significantly higher than that in HF under N1.In summary,tartary buckwheat may regulate soil nutrient availability by the secretion of organic acids such as oxalic acid and propionic acid to adapt to low nitrogen stress,while the concentration of organic acids secreted by DQ is significantly higher than that by HF.Therefore,for the cultivation of tartary buckwheat on poor soil,the difference in tolerance to nitrogen should be consider,the nitrogen-tolerant varieties have better nitrogen use efficiency and strong adaptability.