| Alfalfa is the highest quality leguminous herbage cultivated in china,the selection of varieties with high grass yield,high protein content,and strong adaptability is of great significance in promoting high quality,high yield of pasture and development of animal husbandry.The leaves of alfalfa reflect its nutritional value,which is the highest protein content,the lowest fiber content and the best palatability.It is the main place for photosynthesis,and leaf function is closely related to its yield performance and quality characteristics.Based on the previous research group's research on the establishment of the nitrogen efficiency evaluation system for alfalfa,this experiment adopted a split-zone test design to conduct a community test with two nitrogen treatments(0 and 103.5 kg·hm-2),four different nitrogen-efficient alfalfa varieties,comparative study on leaf characteristics,yield performance and quality traits of alfalfa cultivars with different nitrogen efficiency.By studying the characteristics and physiological characteristics of different nitrogen efficiency leaves of alfalfa?leaf characteristics,leaf photosynthetic gas parameters,and nitrogen metabolism key enzymes?,explored the effects of these factors on yield and quality and their relationships between the various elements.The aim is to achieve high quality and high yield by improving the factors that have positive effects on production and quality,or by restraining factors that have negative effects on yield and quality.The main results as follows:1.There were significant differences in leaf characteristics such as leaf weight,specific leaf weight,leaf increment and leaf-stem ratio among different nitrogen efficiency types of alfalfa.Under the treatment of N103.5 and N0,the efficiency of each stubble was higher than that of inefficiency,and the performance of the nomal efficiency and anti-efficiency were opposite,The photosynthetic parameters of different nitrogen efficiency alfalfa of each stubble were significantly different,under N103.5 and N0 treatments,the efficiency type was higher than the inefficient type;there were differences in nitrogen efficiency types between different nitrogen efficiency types of alfalfa of the nitrate reductase?NR?and glutamine synthase?GS?,the performance of each stubble is efficiency is higher than inefficiency.Comprehensive comparison,the leaf characteristics of different nitrogen efficiency types have different responses to nitrogen,efficiency alfalfa has stronger leaf functional characteristics.2.Anatomical structures of stems and leaves of alfalfa differ significantly in different nitrogen efficiency types.The vascular bundle area,phloem area,xylem area and the number of ducts in stem and leaf under N103.5 treatment were significantly higher than those in N0 treatment;The vascular bundle area,phloem area and xylem area of efficiency 6010 were larger,and the number of ducts was higher than that of inefficiency LD;Under N103.5 and N0 treatments,the performance between the normal efficiency and anti-efficiency is the opposite;Comprehensive comparison,efficiency alfalfa has larger vascular bundles,phloem and xylem areas,and number of catheters under N0 and N103.5 treatments,its growth and development is better,and it has higher transportation capacity.3.There were significant differences in yield and quality of alfalfa with different nitrogen efficiency types.Under N103.5 and N0 treatments,the yield of efficiency alfalfa was significantly higher than that of inefficiency,and the performance of nomal efficiency and anti-efficiency was opposite.Of the four types,the inefficiency accumulation of protein was the lowest,its quality was the worst,and its performance was significantly lower than that of efficiency.It can be seen that the yield of efficiency varieties has higher yield under different nitrogen treatments,and its yields were positively regulated by exogenous nitrogen,but there are differences in the response of nitrogen efficiency types to nitrogen.4.There are differences in the contribution rate of alfalfa leaf characteristics and physiological characteristics to yield of different nitrogen efficiency types.Path analysis shows,the yield of efficiency type 6010 was significantly or significantly positively correlated with leaf area,leaf number,leaf increment,leaf stem ratio,leaf weight,photosynthesis rate,transpiration rate and GS,among which the direct effect on yield,that directly affect the larger effect are leaf-stem ratio and leaf increment,and the direct path coefficients were 0.9068 and 0.7680;There was a significant or very significant positive correlation between the yield of nomal efficiency G3 and leaf weight,leaf increment,leaf-stem ratio,transpiration rate,photosynthetic rate,and stomatal conductance,among which the direct effect on yield,that directly affect the larger effect is leaf increment,the direct path coefficient is 0.8745,the direct effect of leaf-stem ratio on yield is anegative effect,and its indirect effect is relatively large and the indirect path coefficient is 1.6927;There was a significant positive correlation between yield of anti-eficiency G7 and leaf increment,leaf-stalk ratio,transpiration rate,photosynthetic rate,stomatal conductance,and GS,among which the direct effect on yield,that directly affect the larger effect is leaf-stem ratio,the direct path coefficient is 0.7671,leaf area and specific leaf weight had negative direct effects on yield,indirect effects were positive,the number of leaves is more indirect,the indirect menstruation coefficient is 0.8283,the indirect path coefficient is 0.8283,the indirect effects of transpiration rate,photosynthetic rate,stomatal conductance and GS on yield were larger,the indirect path coefficients were 1.5398,1.7834,1.4093,1.5202respectively;The yield of inefficiency LD has significant or extremely significant correlation with leaf weight,leaf number,leaf increment,leaf-stem ratio,stomatal conductance and photosynthetic rate,among them,the leaf weight was the most direct effect of its yield,its direct path coefficient is 0.7690,other indicators have a greater indirect effects on yield.So,the contribution rate of the leaf index to the yield of alfalfa with different nitrogen efficiency is different,and the difference is great,in actual production,the yield can be raised by increasing the positive factors of the yield of different nitrogen efficiency types of alfalfa,or restraining factors that have negative effects on yields.5.There is a significant difference in the correlation between the characteristics and physiological characteristics of different nitrogen efficiency types of alfalfa leaves and their quality.Correlation analysis shows,the leaf weight,leaf number,leaf increase and leaf-stem ratio of efficiency 6010 were significantly or significantly positively correlated with total protein and protein accumulation,and positive correlation with crude fat,in which crude protein and crude fat were positively correlated or positively correlated with total protein accumulation;The leaf weight,leaf area,leaf number,leaf increment and leaf-stem ratio of the normal efficiency G3were significantly or extremely significantly positively correlated with the crude protein,crude fat,and total protein accumulation;The leaf weight,leaf increment and leaf-stem ratio of the anti-efficiency G7 were highly significantly positively correlated with the crude protein and total protein accumulation,and the leaf area and the specific leaf weight were significantly positively correlated with the crude fat,and the crude protein and crude fat were positively correlated with the total protein accumulation;The leaf weight,leaf number,leaf increment and leaf-stem ratio of inefficient LD showed significant or extremely significant positive correlation with the crude protein and total protein accumulation,the total protein accumulation is significantly positively correlated with the crude protein and negatively correlated with crude fat. |
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