Study On Nitrogen Distribution In Pepper Organs And Migration Of Substrate Nitrogen Under Different Irrigation Limits By ¹⁵N Tracer Method

Substrate cultivation of vegetables in solar greenhouse plays an important role in the development and utilization of non cultivated land,to clear nitrogen in the matrix of migration and accumulation in plant organs and the absorption and distribution characteristics,contribute to the development of scientific and rational management of water and fertilizer system of vegetables cultivation.Terefore,the pepper?Longjiao 10?was used as test material.The K¹⁵NO₃ was labeled at substrate 5¹0 cm?F5?and 15²0 cm?F15?respectively by isotope tracing method,and two irrigation limits 60%?W60?and 80%?W80?were set up.To explore the different irrigation lower limit on pepper growth,photosynthetic characteristics,yield and quality,regular of nutrient uptake and distribution and accumulation of nitrogen in different organs of pepper plants were also studied.The main results are as follows:1.After treatment with 90 d,the height of W80F5 treated pepper plant is 152 cm,significantly higher than that of W60F5.The stem diameter of the plant under W60F15treatment is 13.5 mm,significantly higher than that of the treatment W80F15,and the dry weight of the plants treated with W60F5 pepper is 95 g/plant and the fresh weight was 719.3g/plant,which is significantly higher than that of other treatments.2.After treatment with 90 d,the content of chlorophyll a,chlorophyll b and chlorophyll a+b in W80F5 treatment is significantly higher than that of W60F15 treatment,but there is no significant difference in carotenoid content among the treatments.The transpiration rate,stomatal conductance,net photosynthetic rate,intercellular CO₂ concentration,and actual photochemical efficiency of pepper leaves under 80%irrigation treatment are significantly higher than that of 60%irrigation treatment.3.The accumulation of total N and total P in pepper plants is significantly different among treatments,and the accumulation of total N and total P in peppers treated with W60F5was significantly higher than other treatments.The uptake of N>P>K in peppers is in order of potassium>nitrogen>phosphorus;the contents of total potassium in leaves of each plant were leaf>stem>fruit;total nitrogen content is leaf>fruit>stem;total phosphorus content was fruit>Stem>leaf;There is no significant difference in total potassium content among treatments.4.The utilization rate of ¹⁵N in pepper and the accumulation of total nitrogen in the substrate of W60F5 are significantly higher than other treatments,and the accumulation of nitrogen in the fourth layer is lower than that of other layers.In spatial distribution,with the depth of the marker,the accumulation of ¹⁵N in the matrix decreased significantly,the loss rate increased significantly,and the leaching effect of W80F5 treatment ¹⁵N is stronger than that of W60F5,which increased the ¹⁵N downward migration at 15²0 cm at the matrix layer,and increased the absorption and utilization of total nitrogen in the W60F5 treatment.5.There is no significant difference in soluble protein content among W60F5,W60F15and W80F5 treatments,but it is significantly higher than W80F15 treatment.W60F15treatment is beneficial to increase the soluble sugar content of pepper fruits;W80F5 treatment is beneficial to increase pepper yield and fruit Vc content and reduce fruit nitrate content.