Abstract:

To explore the effect of N, P, K, S mixing fertilization on SPAD and chlorophyll content of ‘Yunyan87’ tobacco, a study was carried out on the SPAD and chlorophyll content as well as the relationship between them by currency four factors quadratic rotation design. The results showed that there was significant difference between the SPAD and chlorophyll content of different fertilizer treatments. The SPAD and chlorophyll a, b and total content under no-nitrogen treatment were the lowest and showed the significant difference among others. However, the treatment with the most nitrogen fertilization did not reach the maximum in the whole growth period. Except treatment 13 and 17, the leaf middle SPAD reading was not significantly different with the means with the tobacco growth and leaf expansion, therefore the leaf middle part was recommended to determine the SPAD value. It was feasible to diagnose the tobacco leave chlorophyll content by SPAD rapidly under different stages, but the correlation between SPAD and chlorophyll during different periods was different. They had better binomial relationship during the rosette period, the regression equation of total chlorophyll was y=-0.0085x2+0.6803x-10.911 (r=0.7483), and the two had better power relationship during the prosperous long-term period, the regression equation of total chlorophyll was y=0.004x1.7371 (r=0.8514).