The Dynamic Distribution Of Preemergence Herbicide In Soil And Its Effect On The Growth Of Sugarcane Germination (SCBV)

Sugarcane (Saccharum officinarum) is one of the world’s major sugar crops, and weed is one of the main factors of sugarcane yield inhibition. In order to reduce the cost of weeding, chemical herbicides are widely applied in farmland, becoming one of the important symbol of modern agriculture development. Scientific application of herbicide can contral the weeds, save labor costs and promote the crop production, while improper use may result in effectiveness and input waste, herbicide injury target crop, the problems of residue and environment pollution, etc..This paper aimed at studying two kinds of herbicides, atrazine and acetochlor, which are widely used in production before crops germination. Through the bare land and planting sugarcane two different conditions, having a systematic study on the herbicides’dynamic distribution in the soil (0 to 10cm), sugarcane sprout emergence and the effect of sugarcane stemdirect contact stress by herbicide with different gradient concentration and different soil compaction. Providing a scientific and efficient application of the herbicides by having a knowledge of the dynamic distribution of the herbicide in the soil. To obtain an optimized preemergence herbicide concentration and scientific sugarcane sowing technology. Having a preliminary discussion on the effect of preemergence herbicide on the direct stress of sugarcane sprout growth, providing a reference for the study of sugarcane herbicide stress tolerance mechanism and develop selective herbicide. The results are as follows:1. Setting up a new pretreatment method, which can detect atrazine and acetochlor in the soil at the same time. Detecting the soil samples by using solid phase extraction to separate and purificate the samples, meanwhile combining the gas chromatography analysis method setting up by the predecessors. Compared with the methods reported by the existing literature, the method is more convenient, saving solvent, efficient, stable and higher recovery, more accuracy and sensitivity.2.Under the condition of bare land, study of different periods, spraying concentration and soil compaction, the results show that the total amount of atrazine in soil have a significant effect on spraying concentration and soil compaction, particularly 15 days after spraying. Moderate soil compaction have a major impact on the 15th day after the spraying of atrazine adsorption properties, forming an effective gradient distribution in the soil, relative compaction of soil and appropriately increase the spraying concentration can improve topsoil (0-2cm) initial adsorption capacity. Atrazine infiltration very quickly in loose soil, revealing the necessity of planting sugarcane covering repression from the angle of the herbicide efficacy. This study put forward 15 days after spraying, combined with the whole soil, especially 6-8cm soil layer can be used as the research object of atrazine adsorption, volatilization or leakage dynamic effects in suitable and appropiate soil location.Study also shows that acetochlor relatively steady at 0-3 cm soil layer, the degradation rate is relatively stable, and put forward that 15 days or 30 days after spraying, combined with 0-2cm soil layer analysis can be used as adsorption and degradation dynamic effects in suitable and appropiate soil location.3.Under conditions of planting sugarcane, study on the effect of different periods and spraying concentration, the results show that 15 days after spraying is also the suitable period to analysis the total content and layered content of atrazine in the soil of planting sugarcane. The rapid decline in the total amount of atrazine in soil mainly found in 0-6cm soilafter spraying for 15-30 days. It reveals that in the soil the efficacy is too short to contral the problems of winter and early spring weeds in planting sugarcane field. The gradient effect of acetochlor total concent is more significant than atrazine with the increase of spraying concentration.In this study, after herbicide treated, no significant adverse effect on the sugarcane overground growth can be seen, but significant adverse effect on the sugarcane root growth can be seen after spraying herbicide for 30 days. Since then it seems to appear the phenomenon of eliminating inhibition, recovering and stimulating the growth of the root. The biology and physicochemical response characterostics and internal mechanism of herbicide stress to sugarcane root need further research.4.The effect of four different herbicide gradient concentration on Sugarcane seedling emergence, in which sugarcane stem is direct immersion stress. Results show that whether high or low degree of stress, sugarcane buds inhibited significantly affected germination significantly and reduce the number of emergence, even after emergence, shoot and root growth are subject to significant inhibition, it is bound to have a significant adverse impact on the final yield. The study also shows that there are differences of sugarcane shoots in toleranting herbicides. Having a research on herbicide stress tolerance of different bud biology age shoots, and the effect of adsorbing and transmiting herbicide in each shoot tissue on biological activity, can provide important reference basis for using molecular improvement technology to obtain the seeds that can resist herbicide.