6Beard BJ. Turfgrass science and culture[M]. Prentice Hall Inc. England Cliffs, NJ. 1973. 209-260.
7Razmjoo K, Kaneko-S. Effect of potassium rate on growth, quality, chemical composition, and winter hardiness of perennial ryegrass[J]. Journal of Plant Nutrition, 1993,16 : (1) ,195-201.
8Gilbert WB,Davis DL. Influence of fertility ratios on winter hardiness of bermudagrass [J]. Agron.J. 1971,63:591-593.
9Reeves SA,George. Effct of N,P and K tissue levels and late fall fertilization on the cold hardiness of Tifgreen Bermudagrass ( Cynodon dactylon ×C. ytsndbsslrndid) [J]. Agron. J. 1970,62 : 659-662.
10Barrios HP,Jones LG, Leger LP. Influence of certain nitrogen fertilizers on quality and growth of lawngrasses in Louisiana[J]. Bulletin Agricultural Experiment Station, Louisiana State University. 1982,73(9) :21.
