Study on Root Growth and Vitality of Wheat Root Analyzer

Under the current cultivation conditions, a key factor limiting the increase of wheat yield and the breakthrough of high yield is the restriction of wheat root function. Therefore, accurate determination of the development characteristics of crop roots using a root analyzer is critical to scientifically estimating crop yield and crop yield.

In recent years, root research has been used as a fundamental research topic for further increasing crop productivity in the world, and many researches have been carried out on the morphology and physiology of wheat roots, and preliminary studies have confirmed the occurrence of wheat root morphogenesis. Its relationship with above-ground parts studied the effects of soil water and fertilizers and some agronomic practices on the growth and development of roots and their vitality. In particular, the study of root signals has brought root research to a new stage.

Root growth analyzers are now used to summarize the growth and vigor of wheat roots.

1 Dynamic changes of wheat root length

The length and thickness of the crop's root system are crucial to the crop's absorption of nutrients and moisture. Studies have shown that the absorption of nutrients by crops does not depend entirely on the weight of roots, but on root length and root surface area. The root length of single wheat is highly influenced by the water and fertilizer conditions in the soil and other environmental conditions, especially on soils. The response to moisture is more sensitive. When the soil is severely drought (40% of soil relative water content), the elongation of roots is seriously impeded. When the soil moisture is good, the root length is significantly increased. When the relative soil moisture content is about 55%, the root system is the longest.

Many experiments show that fertilization can promote the growth of crop roots, and thus promote the absorption and utilization of deep soil moisture by crops. The effect of P nutrition on root length varies with soil moisture status. Under severe water shortage conditions, P application has an extremely significant effect on the promotion of root growth. Subsequently, soil fertility decreases with increasing soil moisture content; Fertilizer can not only increase the number of roots in the upper layer, but also can promote root barbulation, increase root length and root number, enhance crop water absorption and improve drought resistance, and P fertilizer has greater influence on root length than N fertilizer. Studies have shown that the length of wheat roots is not sensitive to the response of N fertilizer. With the increase of soil moisture, the effect of N fertilizer on root length is gradually weakened.

Cultivation measures also have a significant impact on the growth and vigor of wheat roots. Deep ploughing and breaking the bottom of the plough will help improve the permeability of the soil, increase the ability to store water and conserve soil moisture, and promote root barrows; moderate drought at the seedling stage also promotes root barbism; the number of secondary roots per plant decreases with the increase in density. The number of rooting increases with the density. Plastic film mulching helps to promote early root growth, increase root length, root number and root weight, improve the distribution of roots in the soil, and is conducive to prolonging the absorption function of part of the root system during the late growth period. Film mulching improved the soil environment in wheat fields and significantly promoted root growth. According to reports, the roots covered with wheat were (5.08±0.64), and the open field wheat was (3.79±0.43); the number of secondary roots of plastic film wheat was 10.6, and the exposed wheat was 7.2, and the difference was extremely significant.

2 Dynamic changes of wheat root weight

The number and weight of wheat roots are generally believed to increase with the occurrence of tillers. The highest number of wheat roots occurs in the highest tiller period, and the total weight of roots before and after heading is the largest. Roots gradually die after heading, root volume decreases, but root systems The activity has remained until the end. The distribution of root system in the soil is consistent with the distribution area of ​​available phosphorus in the soil. 80% of the root system is distributed in the soil tillage layer. The effect of soil moisture on the dry weight of wheat roots is obvious. When the soil relative water content was 40%, the roots of wheat were seriously obstructed and the root dry weight was significantly reduced. The relative dryness of roots was the highest when the soil relative water content was between 55% and 61%. The greater the relative soil moisture content, the lower the root dry weight. It shows that the relationship between root weight and water use efficiency is very close.

The effects of N and P fertilizers on root dry weight have a great relationship with soil moisture. The results showed that the appropriate amount of N (276 kg/hm2) could increase the total root weight and root weight in deep soil and help increase the drought resistance of wheat. Excess N application (690 kg/hm2) can increase the root weight of the upper layer. However, when soil moisture is seriously deficient, the application of N fertilizer is unfavorable for improving the dry weight of wheat roots. Increasing P fertilizer can significantly increase the root dry weight, but under different water conditions, the appropriate amount needed for P to promote root weight growth is different. The effect of P fertilizer on root dry weight was also related to the location of its application, and the effect of P was most significant when the soil was severely droughty (the soil relative water content was 40%). N and P interactions have a significant effect on root dry weight. When one of the N and P elements in the soil is maintained at a higher level, lowering the other element will increase the root to shoot ratio, that is, when the soil is unbalanced with N and P. Root-to-crown ratios will be affected, and root growth will increase relatively. The combined use of organic and inorganic fertilizers can increase the dry weight of winter wheat, especially the root dry weight of 40-100 cm soil layer. The covering of winter wheat is conducive to the increase of root weight and the lower roots, absorption of the lower layer of water, to achieve the root water transfer. The root weight of the mulched wheat under the same moisture treatment was increased by 30.3%-48.6% compared with the control, and the distribution was deeper.

3 Wheat Root Surface Area and Root Activity

Under field conditions, the strength of root absorption activity not only depends on the spatial distribution of root absorption activity, but more importantly, it depends on the level of root activity in the unit soil, and the increase and decrease of the root absorption activity of field winter wheat in the horizontal direction. The changes in the order from near to far and from top to bottom in the vertical direction and from inside to outside in the entire soil space finally show the complete decline of the vitality of the entire root system. The spatial expansion of root absorption activity is consistent with the scope of morphogenesis of the root system. After the annual deep roots of winter wheat increase after flowering, there are some aging roots in the upper layer of soil. Secondly, the water deficit during the flowering period will cause the decline of root activity and premature aging, which will directly affect the grain yield. The lack of water in the early period will affect the size of the vegetative body and have little effect on the yield. The lack of water during the grain filling stage will result in the dry matter stored in the stem, reducing the Grain to stem ratio and harvest index. When the soil relative water content is above 70%, with the increase of P level, the root respiration increases; when the soil relative water content is below 55%, with the increase of P level, the root respiration is weakened. The effect of N on root respiration was related to the fact that when the soil relative water content was 40% to 70%, the respiratory intensity of the high N level root system was always higher than that of the low N level, and regardless of the N level, the respiration intensity under the soil water deficit condition It is always higher than the breathing intensity under high water conditions.

The vitality of wheat root system is greatly affected by cultivation measures. Sparse planting can increase root activity and promote deeper distribution. In autumn, 1 to 2 years old tillage is used to promote root growth and improve root activity in deep soil. Increase wheat production. Soil moisture conditions have a dramatic effect on the surface area of ​​the root system and are parabolically distributed. At different levels of P nutrition, soil water had different effects on root surface area: under the condition of no application of P, the root surface area peaked when the soil relative water content was 57%; when the P level was 90 kg/hm2, the soil was relatively When the water content was 54%, the root surface area was the largest; when the P level reached 180 kg/hm2, the root surface area reached its maximum value when the soil relative water content was 51%. This shows that P fertilizer can significantly increase the active absorption area of ​​the root system.

Therefore, adjusting the application amount of N and P fertilizer based on soil moisture can promote the expansion of wheat root surface area. Organic fertilizer can stimulate the activity of wheat roots, thus changing the absorption characteristics of phosphorus in the root system and increasing the absorption of phosphorus. However, the effect of using organic fertilizer is short, and the application of organic and inorganic fertilizers can maintain this effect for a long time. , Can effectively reduce the root membrane lipid peroxidation, enhance root activity; different periods of fertilization of water has a short-term effect on root activity, jointing fertilizer and water and booting stage fertilizer can improve root activity in the late, delay leaf senescence, and promote grain weight increase.

4 Changes of Spatial Distribution of Wheat Root System

Reports on the dynamic changes of the spatial distribution of wheat roots vary according to the object of study. The vertical distribution of maximum root biomass at the heading stage of winter wheat in dryland is about 85% of the 0-20 cm topsoil layer, the root weight is reduced to 7.7% in the 20 to 100 cm soil layer, 2.9% is from 100 to 200 cm, and below 200 cm to the edge The total root system accounts for about 4.4%. In winter soils, both the root length and the root weight, 80% of the winter wheat is distributed in the 0-50 cm soil layer, and the root system below 100 cm is less than 6% of the total root coefficient. The results of vertical root distribution of different drought-resistant winter wheat cultivars at heading date showed that the root dry weight decreased with the increase of subterranean soil layer, ie, 0-15 cm>15-30 cm>30 cm; the root dry weight of the drought-resistant varieties Increase in proportion.

The vertical distribution of wheat root system regardless of quantity or biomass (root weight, root length, root surface area, root volume) shows a decreasing exponential function (y=A・e-BX, where -B is the decreasing rate, which determines the root distribution Important parameters; A is the maximum value; the percentage of cumulative root weight, root length in each layer of soil with the relative depth is in accordance with the hyperbolic function form; the total root length and total dry weight changes with time as a Logsitic curve. The optimum growth curve of the number of wheat is a cubic polynomial.

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