Under different water conditions,the chlorophyll contents,chlorophyll fluorescent parameters and photosynthetic rates of wheat leaves were studied,which indicated that the chlorophyll content decreased with intensified water stress and that the contents of chlorophyll a decreased more quickly than that of chlorophyll b.Under same water conditions,the chlorophyll conents and photosynthetic rates varied in similar seasonal patterns,i.e.quickly rising from the jointing to the heading and quickly decreasing at ...