The rainfall(100.0 mm)at soil water storage stage in l992

which was the least val-ue during 39 years

was considered to be the main reason that the growth of wintet wheatwasstrongly stressed and yield decreased.Higher daily averaged temperature

lower air relativehumidity and less soil water application intensified the degree of drought

and the lower waterproductivity increased the degree of yield reducation.The rainfall(116.2mm)at soil water stor-age stage in 1995

which was the same level to 1992’s

caused its soil moisture before sowing tobe the lowest value during 39 years.The second lowest level rainfall at growing period during 39years had been menacing the growth of winter wheat in the whole course.The air dry for clearhigher temperature and variotis lower air relative humidity and the long-term soil dry ap-proching wither soil moisture within deep soil effected the normal physiological action of winterwheat

at last

leading to the gravest dry year during 39 years