The use of soil detectors can directly detect soil nutrients. In recent years, chlorophyll detector has achieved good results in indirect rapid measurement of crop leaf nutrient. The SPAD value measured by chlorophyll meter can indirectly reflect the chlorophyll content of crop leaves. And the nitrogen content of crops can also be used to further predict crop yields and be used as a guide for topdressing.
The following conclusions have been drawn from experiments using the Chlorophyll Content Analyzer to determine nitrogen in soil:
1. SPAD values ​​in different parts of leaves and leaf nitrogen content and SPAD values ​​in different leaf positions are significantly different. Therefore, the use of SPAD for the diagnosis of cotton N nutrition must be carried out at a fixed leaf position. Studies have shown that the top four leaves of the plant are The best test site.
2. The effect of cultivar on chlorophyll meter is relatively large, and the chlorophyll content of different cultivars has a certain difference. Therefore, when converting, attention should be paid to changing the critical value to ensure the accuracy of the measurement results.
3. The chlorophyll content meter reading showed a highly significant linear correlation with the chlorophyll content, leaf total nitrogen content, total nitrogen content, and nitrogen uptake measured by conventional methods. There was a highly significant linear correlation between SPAD values ​​and nitrogen application rates. There was also a significant correlation between SPAD values ​​and yield during each growth period.
4. The use of SPAD for nitrogen fertilizers recommended that nitrogen fertilizers use more than 10% less nitrogen than conventional nitrogen fertilizers, so that the crops did not show a lack of nitrogen during the growth process and yielded the same or higher yields as conventional nitrogen fertilizer treatments.
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