The chlorophyll meter readings (SPAD values) of the functional leaves (the penultimate 3-4 main stem leaves) were measured in the fields at the time of birth at 8 to 9 am in different growth periods such as Chuhua, Shenghua, Shengling, and Xicai using the chlorophyll meter. 35 tablets. Then take the above leaf sample analysis to determine the intensity of photosynthesis (modified half-leaf method), chlorophyll content (acetone:ethanol:water-4.5:4.5:1), specific leaf weight (dry weight per leaf area), total dry weight of the leaf Nitrogen content Ndw (Kjeldahl distillation method) combined with specific leaf weight to calculate total nitrogen content per leaf area.
By chlorophyll meter determination, the SPAD value of functional leaves and the total nitrogen content per unit leaf dry weight Nd, and the total nitrogen content per leaf area at different growth stages of short-season cotton. All showed significant positive correlations, and at the same time, each growth period was strongly correlated with N:. This shows the prediction of chlorophyll meter readings for total nitrogen content, in N. Better. In addition, SPAD values ​​and N during each growth period. The slope of the linear regression equation is between 0.080 and 0.097, which means that the total nitrogen content (N:) of the functional leaf increases by 0.080% to 0.097 intestine per +1 increment in chlorophyll meter readings. It shows that the chlorophyll meter reading is the external performance of nitrogen nutrition status in the short-season cotton, and can be used as a diagnostic indicator of nitrogen nutrition.
Chlorophyll meter can quickly, easily and non-destructively detect crop chlorophyll content in the field, and diagnose plant nitrogen nutrition status by measuring chlorophyll content. In the process of crop cultivation, this method has become a common technology, and its application prospects are very broad. However, the chlorophyll meter has not been studied for the correlation between the chlorophyll content and nutrition of cotton. At present, domestic research work on the chlorophyll meter for the diagnosis of crop nitrogen nutrition is still underway. There is no report on the research on the diagnosis technology of short-season cotton diagnostic fertilization. The correlation between chlorophyll meter readings of functional leaves at different growth stages of short-season cotton and nitrogen nutrition, yield, and related physiological characteristics was studied to provide scientific basis for scientific application of short-season cotton.