Cotton Seedling Nitrogen Nutritional Physiology Under Different Nitrogen Forms Supply

Study the relation of nitrogen forms which absorbed and translated by cotton and respiration of cotton, and the influence to inner hormone and some metabolize enzymes. Investigate the impact of accumulation and distribution of substance by adding ammonium nutrition on cotton. Explore the contact between different nitrate and ammonium rations and cotton growth, make sure the best ration to cotton grow.Xin luzao 8 and Xin luzao 13 were used to study the influence of NO₃^- -N and NH₄⁺-N on plant growth. In hydroponical culture condition grown cotton, mineral nutrition metabolize, hormone of cotton shoot and cotton root and so on were determined.The results showed that:(1) when the level of total nitrogen was 5mmoL/L it could affect the exterior shape by using different ration of nitrogen and ammonium. From 30days to 60days after planted, the cotton grow more blooming than other treatments when the ration was 75/25, and every index get well.(2) Different nitrogen forms coexisted, the content of ammonium have different effect on cotton leaf.(a) while NO₃^--N / NH₄⁺-N ratio was 75:25 and 100:0, the number of SPAD of the cotton function leaf is larger than other treatment 35-60 days after plant.(b) As the increase of ammonium in total nitrogen the stoma of cotton leaf was influenced, the higher the content of ammonium the higher the number of stoma ratio reading 0-40 days after plant. And the two treatments which NO₃^--N / NH₄⁺-N ratio were 75:25 and 100:0 stoma ratio was higher than other treatments 40-60 days after plant.(c) Different breeds have different exhibition on cotton young body root activity: Xin luzao 8 breed, the treatment which NO₃^--N / NH₄⁺-N ratio was 75:25 was better than other. Xin luzao 13, when the nitrogen form was ammonium the cotton root growth well, and in nitrate forms the cotton root activity was poor.(d)The more ammonium in total nitrogen the cotton function leafs had the more stronger photosynthesis capability.(e) NO₃^--N / NH₄⁺-N ratio could also affected the total content of N,P&K in young cotton body, and the balance of them varied. (f) Furthermore, levels of kinds of inner hormone were different in cotton function leaf and root. The treatmentâ…¤, all ammonium form nitrogen namely, level of IAA is highest in leaf , but lowest in root. Breed 8 Leaf of cotton grew in nitrate the ABA level is highest, and it had no difference on breed 13. NO₃^--N / NH₄⁺-N 75:25 treatment the level of ABA was highest. Moreover, under all experimental conditions, stimulation of leaf growth by NO₃^- was consistently associated with increased concentration of the physiologically active forms of cytokinins, zeatin and zeatin riboside. The level of ZR in leaf is higher than other treatments when the ratio of nitrate and ammonium were 25:75 and 0:100, in root the level of ZR did not behave difference.