Study On The Productive Performance, Photosynthetic Characteristics And Quality Of Multifolilate Alfalfa Cultivars

Alfalfa is a main forage palnting in many areas. It is important to plant the alfalfa which has the high hay yield and rich protein content. The purpose of this study was to provide the academic reference for the variety improvement and production application of alfalfa by measuring growth characters, photosynthetic physiology characters and quality characters of three multifolilate alfalfa and three trifoliolate alfalfa from 2008 to 2009.1. There was no obvious difference of multifolilate expressiont from three multifolilate alfalfa. With the growth of plant, the average number leaflet per compound leaf and the multifoliate expression on leaf amount both have a gradual decline in the each growth period of the first cutting; Incidence four leaflets were more than the others, which was over 45% of the multifoliate expression on leaf amount. The amount of the rate of the four leaflets and five leaflets were more than 83% of the multifoliate expression on leaf amount. The average multifoliate expression on leaf amount of the three multifolilate alfalfa was between 13.5%~15%, and the average number leaflet per compound leaf was 3.13~3.51.2. The hay yield in the first cutting was highest than which in the other cuttings. And the hay yield was declined in the order of the first cutting> second cutting>third cutting> forth cutting. The results of significance test of difference between two different kinds of alfalfa showed that the hay yield of multifolilate alfalfa, except in the first cutting, was significantly higher than which of trifoliolate alfalfa(P<0.01).3. The results of significance test of difference in the sixteen growth characters between two different kinds of alfalfa showed that the hay yield of multifolilate alfalfa had significant correlation with density of branches, specific leaf weight, dry weight of branches, plant height, number of compound leaves, photosynthesis rate, stem/leaf ratio and fresh/dry ratio(P<0.05). What significantly correlated with the hay yield of trifoliolate alfalfa includes plant height, density of branches, specific leaf weight, internodal number, fresh/dry ratio and stem/leaf ratio (P<0.05). It had difference in the characters which had effect on hay yield between multifolilate alfalfa and trifoliolate alfalfa. The results of significance test of difference in the common characters between two different kinds of alfalfa showed that it can increase the hay yield by enhancing the specific leaf weight and reducing the stem/leaf ratio and fresh/dry ratio, even though the density of branches of multifolilate alfalfa was lower than trifoliolate alfalfa. Therefore, It could enhance the hay yield of multifolilate alfalfa by increasing the number of branches number and applying rational close planting.4. The results showed that the Pn of multifolilate alfalfa and trifoliolate alfalfa, expect Zhen Yuan alfalfa and Shaan Bei Alfalfa in the squaring period of the first cutting and Zhen Yuan alfalfa in the initial blooming period of the second cutting, presented"double peaks"or"single peak"curves, respectively. The second peak of the multifolilate alfalfa was because of the stomatal limitation and the decline was because of the non-stomatal limitation, while the decline of the trifoliolate alfalfa was the stomatal limitation translate into non-stomatal limitation.Although there were different influence factors which led to"noon break"of the same multifolilate alfalfa in 2008 and 2009, they had the same trend. The trend is that the Pn rise is because of stomatal limitation at the beginning. Significance test of difference for the characteristic index of photosynthesis and transpiration between two kinds of alfalfa in each cutting showed that the hay yield of multifolilate alfalfa was influenced by many factors, such as photosynthetic pigments, net photosynthesis rate(Pn), transpiration rate(Tr), internal CO2 concentration(Ci), stomatal limatation(Ls), Light use efficiency(LUE) and Water use efficiency(WUE). The multifolilate alfalfa had high Pn, high LUE, high Tr and low WUE. The Pn in the first cutting. The Pn values were declined in the order of the first cutting> third cutting> second cutting.5. The results of significance test of difference in the chlorophyll fluorescence between two kinds of alfalfa showed that the multifolilate alfalfa had the high use and transformation efficiency of light and especially the high use efficiency of weak light than the trifoliolate alfalfa in the initial blooming period of the fist cutting and the second cutting, which product the ample energy for carbon assimilation. There were no differences in the other periods.6. The content of chlorophyll a , chlorophyll b, total chlorophyll and carotenoid in multifolilate alfalfa very significant higher than which in the trifoliolate alfalfa(P<0.01), except the chlorophyll a in the branching period of 2009. The chlorophyll a/b of the multifolilate alfalfa was lower than trifoliolate alfalfa in the branching period of 2008 and each period in the first cutting of 2009, Therefore, the photosynthetic activity of multifolilate alfalfa was better than the trifoliolate alfalfa in these period..7. The research of the quality between multifolilate and trifoliolate alfalfa showed that the crude protein(CP) and Crude ash(CA) in the multifolilate alfalfa was higher than which in the trifoliolate alfalfa in the first cutting(P<0.05), while the Ether extract(EE) and Crude fiber (CF) in the multifolilate alfalfa were lower than which in the trifoliolate alfalfa(P<0.01). The structure proportion of the totle hay yield showed that the CP yield in the multifolilate alfalfa was higher than the trifoliolate alfalfa, which decide the quality of the multifolilate alfalfa is better than the trifoliolate alfalfa.