A two-location experiment was carried out at five to six nitrogen levels to study the relationship etween chlorophyll-me-ter readings (SPAD values) and physiological or yield traits in short-season cotton. The results showed that there were highly significant (P<0.01) linear relationships between SPAD values and contents of both nitrogen and chlorophyll at each growth stage, and as well as with the daily increase in plant height during early flowering. The relationship between nitrogen concentration and SPAD was stronger when nitrogen was expressed on a leaf area (Na) rather than on a dry weight (Ndw) a dw basis. Significant curvilinear relationships were found between SPAD values at various stages and photosynthetic intensity, lint yield, and total boll number per hectare, respectively. Furthermore, the linear regressions between SPAD values and N. fertilizer levels were highly significant (P<0.01), and before the boll opening stage, the slopes of these regressions were similar (0.040-0.041) at the two locations. These data provided evidence that the chlorophyll meter could be used to determine sidedress N requirements of short-season cotton before boll opening stage. Critical SPAD levels for maximum lint yield were established as 32.4, 33.1, 35.0, 43.55, and 39.7 at early flowering, flowering peak, boll forming, the beginning of boll opening and boll opening stages, respectively. It was also established that 24.2-25.0kg hay1 increase in N application should be necessary for each unit decrease in SPAD value below the critical level.

A g reenhouse hyd roponic expe rimentwas conducedto studythe effects of cadmium (Cd; 0, 01, 10, 10 uMin nutrient solution) on yield and yield components as well as Cd concentration and accumulation in th ree cotton genopes (Simian 3, Zhongmian 16, Zhongmian 16-2). The results showed that Cd concent ration in diffe rent organs increased with increasing Cd levels in the nut rient solution in the ollowing order: root>petiole>xylem>f ruiting b ranch, leaf>phloem in vegetative organs and seed coat, seed nut>boll shell>fiber in reproductive organs There were significant genotypic differences in functional leaf and petiole Cd concent rations at 1 and 10μM Cd treatments, with the cultivar Simian 3 showing higher Cd concent rations and greater reductions in lint yield than the other two genotypes