REFERENCES
- Chaudhary , T. N. and Chopra , U. K. 1983 . Effect of soil covers on growth and yield of irrigated wheat planted at two dates. . Field Crops Research , 6 : 293 – 304 .
- Cheng , X. G. 1996 . Effects of various soil moisture on the growth and nutrients absorption of winter wheat. . Scientia Agricultura Sinica , 29 ( 4 ) : 67 – 74 .
- Gao , S. M. and Zhao , S. L. 1995 . Research on the compensatory effects to water deficits on dryland spring wheat in semi arid area. . Acta Botanica Boreali-Occidentalia Sinica , 15 ( 8 ) : 32 – 39 .
- Li , F. M. , Zhao , S. L. , Duan , S. H. and Gao , S. M. 1995 . A preliminary study on limited irrigation for spring wheat field in semi-arid region of Loess Plateau. . Chinese Journal of Applied Ecology , 6 ( 3 ) : 259 – 264 .
- Li , F. M. , Cao , J. and Wang , T. C. 1998 . The influence of phosphorus supply in different depth soil on yield formation of spring wheat. . Journal of Plant Nutrition , 21 : 1921 – 1931 .
- Li , F. M. , Guo , A. H. and Wei , H. 1999 . Effects of Plastic Film Mulch on the Yield of Spring Wheat. . Field Crops Research , 63 : 79 – 86 .
- Li , F. M. , Song , Q. H. , Liu , X. L. , Li , F. R. and Liu , H. S. 2001a . Effects of pre-sowing irrigation and phosphorus application on water use and yield of spring wheat under semi-arid conditions. . Agricultural Water Management , 49 : 173 – 183 .
- Li , F. M. , Yan , X. , Li , F. R. and Guo , A. H. 2001b . Effects of different water supply regimes on water use and yield performance of spring wheat in a simulated semi-arid environment. . Agricultural Water Management , 47 : 27 – 37 .
- Li , S. and Lan , N. J. 1995 . Research progress in plastic film covered wheat. . Gansu Agricultural Science and Technology , 5 : 1 – 3 .
- Liang , Y. L. and Chen , P. Y. 1994 . Effects of water and phosphorus nutrition in soil on root system growth physiologic character of wheat. . Acta Botanica Boreali-Occidentalia Sinica , 14 ( 5 ) : 56 – 60 .
- Niu , J. Y. , Gan , J. W. , Zhang , J. W. and Yang , Q. F. 1998 . Post anthesis dry matter accumulation and redistribution in spring wheat mulched with plastic film. . Crop Science , 38 : 1562 – 1568 .
- Unger , P. W. 1975 . “ Role of mulches in dryland agriculture. ” . In Crop physiology. , Edited by: Gupta , U. S. 237 – 260 . New Delhi. : Oxford & IBH Publishing Co. .
- Wang , X. B. 1995 . The factors influenced water use efficiency of dryland crops. . Progress in Soil Science , 23 ( 5 ) : 16 – 20 .
- Zhao , S. L. , Li , F. M. , Zhang , D. Y. and Duan , S. S. 1997 . Crop production is a population process. . Acta Ecologica Sinica , 17 ( 1 ) : 100 – 104 .