Effect Of Group Cotton Spacing On Root System Architecture Under Soil Partial Wetting

Root is the vital organ of plants to obtain water and nutrients in the process of plants growth and development. Due to the plant roots grow hydro tropically, the variety of soil moisture will lead to root systems distribution change and influences crop growth. This paper analyzes the cotton group root systems competitive growth characteristics and cotton root deformation features under soil moisture stress on the basis of absorbing group root systems researches at home and abroad, and uses cellular automata model to measure the cotton group root growth simulation.The conclusions are:(1)Group cotton root systems had competitive growth characteristics under soil partial wetting and the ability of root systems competitive growth was determined by the number of lateral roots. Larger cotton spacing resulted in the quite different soil moisture situation in which cottons were cultivated, subsequently the number of lateral roots of cotton had 31.7% different from each other and the abilities of root system for competitive growth were also larger different, consequently the group cotton plants grew irregularly. Although the soil moisture condition in which cottons were planted were relatively uniform when cotton spacing was small, the overlapping cross distribution density was larger and competitive growth performed fierce between roots, which also affected on cotton plants growth.(2)Soil moisture was distributed uniformly in the condition of localized irrigation and no groundwater impact or groundwater depth deeper then the root system architecture of the cotton cultivated presented a symmetrical “umbrella” pattern, the diameter difference between main and lateral roots was 5-6mm, and the average angle between them was 70°—80°which would decrease with growth of cotton. Soil moisture spatial stress would influence the cotton which was cultivated away from irrigation point that the root system architecture was asymmetry. The roots grew toward high soil moisture zone, and that 48.15% of lateral roots became thicker adventitious root system, which performed as bifurcated main root. The diameter difference between the bifurcated roots was 1-4mm, and the average angle between bifurcated roots along vertical direction was between 20°—37°, which would increase with the growth of cotton.(3)Result of the program by cellular automata model can obtain the distribution of root system architecture simulated cotton group root: the distribution of soil moisture and cotton group root density in testing holes were consistent; cotton group root system performan a significant phenomenon was grew hydrotropically. It was greater of the cotton root competitive ability nearby the irrigation point than soil wetting front in treatment 1, and there was a certain degree of root competitive growth and root system overlap and lateral will make root competition for water resources more fiercely.The simulation and experimental results were consistently. Proved the effectiveness of the group root simulation with cellular automaton model can also provide a valid basis for determining the soil moist area under partial irrigation.(4)Comprehensive analysis of plants and root growth, three cotton plants and root growth was evenly and cotton 3 has a distance of 50 cm from soil wetting front in treatment 2. Cotton 1 grow better and cotton 3 grow not good relatively, while cotton 2 grow stable and has a distance of 40 cm from soil wetting front in treatment 1, so the cotton 2 within the effective range of effective soil moist region. Therefore, this paper on the basis of experimental for designing partial irrigation, the effective soil moist area is 100 cm, or cotton spacing was seting about 20 cm and has a distance of 30-40 cm from soil wetting front, then can ensure the cotton group access to sufficient strain with water resources to grow evenly.