Accurately grasping the root water absorption status of plants and understanding the distribution dynamics of soil moisture consumption are not only conducive to the rational establishment of irrigation systems, ensuring agricultural water-saving and high-yield, stable production, but also the study of soil-plant-atmosphere continuum (SPAC) water movement and regional The SVAT model and other aspects of the water conversion relationship are indispensable links. Studying root water absorption has important hydrological significance. Since the 1950s. Researchers in many fields such as plant physiology, irrigation and water conservancy, soil physics, hydrology and water resources have conducted extensive studies on the mechanisms and characteristics of water absorption in plant roots and water absorption models for roots in various aspects, such as agricultural irrigation, hydrology and water resources, etc. The fields all have very important practical application value.
Due to the above characteristics of apple trees, the following points should be taken into consideration when establishing the water absorption model of apple tree roots:
1. Rationally arrange soil moisture measurement points and scientifically perform root zone soil moisture observations. The correctness of soil moisture observation data is very important for establishing the root water absorption model. It is a measure of the correctness of root water absorption model, and is also an important data for establishing root water absorption model by means of root water absorption dynamic simulation. Therefore, soil moisture observation data should be ensured. Scientific rationality.
2. Pay attention to the effect of soil moisture observation on root water uptake and plant transpiration. Because the roots of the apple tree have more obvious changes in the horizontal direction, even if the soil moisture measurement points are properly arranged, the number of soil moisture measurement points is still larger. However, whether or not arranging so many soil moisture measurement points will have a significant impact on root water uptake and plant transpiration of apple trees, which is related to the importance of the correctness and validity of the model.
Therefore, the effect of soil moisture measurement on root water uptake and plant transpiration should be studied.
3. The dimension of the water absorption model of apple tree roots. The roots of apple trees not only change in the vertical direction, but also change in the horizontal direction, and even in different directions in the horizontal direction. If only for a certain apple tree, establishing a three-dimensional water absorption model can truly reflect the root water absorption. However, due to differences in actual conditions in the field, the roots of some apple trees are biased towards this side, while some apple trees have their root systems biased toward the other side. The differences between plant individuals are inevitable. In this way, the application of the root water absorption model established based on an apple tree to other apple trees will inevitably cause large deviations; while the one-dimensional model and two-dimensional model will be conducted in space due to root density or soil moisture. A certain degree of average, so this deviation may be smaller. Therefore, the problem of establishing a multidimensional water absorption model suitable for apple trees should be studied.
4. The rationality of the water absorption model of different types of apple trees. The water uptake model of the root system was established by distributing the transpiration of the plant in proportion to the root density, and the root density observation data were needed as basic data. Using this method to establish the root water absorption model, the calculation workload is small, and there is no problem in the establishment of the model that affects the root water absorption due to soil moisture observation; however, the quantitative relationship between root density and root water absorption is not yet clear. The measurement of root density is relatively large, the root density is difficult to determine accurately, and the damage to the root system is so great that after the model is established, it is no longer suitable for the original apple tree. The root water absorption model was established by dynamic simulation of root water absorption. The dynamic data of soil moisture was needed as basic data. Using this method to establish the root water uptake model, there is no model error caused by inaccurate root density measurement. The actual water uptake by the root system is inverted by the soil moisture dynamic data, the measurement workload is small, and the damage to the root system is small. , but the calculation workload is large. Moreover, using this method to establish a root absorption model should first ensure that soil moisture determination does not have a significant effect on the natural conditions of root water absorption. It is reasonable to determine which method to use to establish the root water absorption model.
5. Consider the soil layering problem. Due to soil layering, not only the soil parameters at different depths will be different, but also the water absorption characteristics of roots at different depth levels may differ. Therefore, when establishing a root absorption model, not only should soil parameters be considered differently with soil delamination, but also the differences in root water absorption characteristics at different depth levels should be considered: that is, within the same soil moisture content range, units at different depth levels are compared. Root length density of water absorption.
6, the model of time and space verification. Since the apple tree is a perennial plant, the root water absorption model established based on a certain period of time should be verified for its applicability to apple trees of different ages and different tree ages. In addition, because the purpose of establishing a water absorption model for apple tree roots is to apply it to other more apple trees, the applicability of the water absorption model of the root system to individual apple trees should be verified.
7. Using the theory of space random field to study the root water absorption model of apple trees. The growth of apple trees in orchards is generally relatively uniform, but due to differences in actual conditions, differences among plant individuals are still common. Although this difference is not great, it can not be ignored, and this difference has a greater randomness. Therefore, apple trees in the apple orchard can be regarded as spatially random variables with small disturbances. Then the spatial water field theory is used to study the water absorption model of apple trees in apple orchards. This requires further exploration.
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