Production Performance And Pests And Diseases Characteristics Of Red Clover Varieties

Red clover (Trifolium pratense L. )is one of the main legumes and widely grown in the world. Different cultivars have different performance in productivity, nutritive value, as well as disease and insects resistance. In this thesis, 4 cultivars including R-1, Rider, Dory and Minshan were used to compare their differences in production performance, nutritive value, isoflavone content, and resistance to powdery mildew, root rot, mite damage and aphid damage. The effects of growth years on productivity, nutritive value, and disease and insects resistance were also analyzed; Grey Correlation Analysis was applied for comprehensive evaluation. The main results are as follows:(1) Great differences were observed among different cultivars in terms of their productivity and nutritive value. Days to maturity, florets per inflorescence, plant type, leaf area, height, branch number, regrowth speed, and chlorophyll content contributed to the differences in producity. R-1 had the highest dry yield, followed by Dory, Rider was the last. At flowering stage, R-1 had higher protein and calcusium content, with the lowest acid ditergent fiber content, it was a superior cultivar with higher yield and nutritive value.(2) Growth years had significant influence on red clover productivity and nutritive value. With the increasing growth years, R-1 increased its plant height, branch numbers, annual hay yield, fresh/dry ratio, and seed yield per plant. four-year-old and five-year-old R-1 got significantly higher producitivity; however, their nutritive value decreased with the increasing growth years, mainly showed in the decrease in protein content and increase in ADF.(3) Grey correlation analysis was applied to comprehensively evaluate the production performance and nutritive value of R-1. The result indicated that the four-year-old red clover was the best with higher productivity and nutritive value. The best utilization time of red clover was the forth year after planting. (4) Different red clover varieties had significantly different isoflavones content. The descending order of isoflavone content of the four tested cultivars was: R-1>Rider >Minshan> Dorry. The monomer isoflavone content of red clover varieties were also significantly different.The daidzein had the biggest variation, followed by genistein, and formononetin thorn was the smallest.The accumulating ability of isoflavones in red clover showed the law as: formononetin thorn> biochanin A> genistein > daidzein.(5) The results of diseases and pests resistance showed that the R-1 had the least disease and pest index, with the highest resistance to powdery mildew, root rot, mite damage and aphid damage. Rider had lower powdery mildew resistance and Minshan was the poorest in comprehensive resiatance.(6) The significant difference in disease and pest resistance was onserved among R-1 plants with different growth years. With the increasing growth year, R-1 showed reducing tendence in root rot resistance and increasing trend in aphids and mites resistance. No obvious change was observed in terms of powdery mildew resistance.(7) Accroding to the gray correlation analysis, the four-year-old red clover had the strongest pest and disease resistance, while the one-year-old red clover was the weakest.