The leaf is one of the important parts of plant's absorption and transformation of nutrients, and it is a place where the plant converts light energy into chemical energy. The area of â€‹â€‹the leaf has a great influence on the adaptation of the plant and the quality of the crop. Due to the different sizes of the leaves, the variety of shapes, and the varying degrees of edge complexity, there are many researches on leaf area measurement methods. However, little research has been done on the accuracy evaluation of measurement methods. The reason is that the actual area of â€‹â€‹the measured blade is difficult to know, and it is therefore impossible to detect the closeness or accuracy of a measurement method's measurement results with the actual area. Some researchers apparently have obvious flaws in measuring the accuracy of the measurement method by measuring the results of the leaf area meter (regarded as the actual area) or the consistency (correlation) of several measurement methods or multiple measurement results.
At present, the methods for measuring leaf area mainly include leaf area instrumentation, grid method, punching and weighing method, paper-cutting weighing method, image pixel method, correlation coefficient determination method and regression equation method. The leaf area metering method has high accuracy, small error, simplicity, and convenience, but it is difficult to get popular because of its high cost; the grid method is labor-consuming and time-consuming, and the error is large when the blade edge is complex; the punching measurement method is effective. The leaves of plants have a certain degree of destruction, and it is difficult to drill holes for small leaf blades and leaves with large veins. The scope of application is small in practice; correlation coefficient determination and regression equation methods require area measurement after more complex mathematical modeling. Accuracy is also relatively low, and can only be measured for a certain kind of plant, can not be common between varieties and types, and is rarely used in actual operations. Paper-cut weighing method is simple and convenient, and does not require special instruments; image pixels have the advantages of simple and rapid measurement, and can be measured in batches. The measurement is not affected by factors such as the size and thickness of the blade. Therefore, the paper-cut weighing method and the image pixel method have been widely used.
Leaf is the main organ for photosynthesis and transpiration of plants. Its size has a great influence on the growth, development, resistance and yield of crops. It is often considered in the research of genetic breeding, crop cultivation, etc. It is also an assessment of the effect of environmental factors. The important growth indicators. Therefore, the establishment of a convenient and accurate leaf area determination method is of great significance for the evaluation of crop genetics and breeding and for the guidance of crop cultivation density and fertilization levels.
The author uses geometric drawings to cut out various figures (approximate with leaves), and by counting the number of squares they occupy, they can accurately measure the actual area, and then compare the measurement results of different known measurement methods for this known figure. Accuracy solves this problem better. In addition, the complexity of the blade shape and different human operations may also have an impact on the results of the measurement. Therefore, the author repeated the measurement method by multiple people and single persons, using this known area pattern and combining various shapes and complexity. Different leaves, a detailed comparison of the accuracy and reproducibility of the commonly used two leaf area measurement methods, taking into account the influence of different leaf shapes (sizes) on the measurement results, also taking into account the differences in different human operations, Therefore, the results and conclusions of the comparison are relatively more reliable.
Other agricultural instruments: chlorophyll meter