Study On The Method Of Drip Irrigation Cotton Root Architecture Simulation Based On Soil Water Distribution

Root is the organ of crops to absorb water and nutrients from the soil, and soil moisture is the mainfactor affecting the development of the root architecture. But the invisible feature of the soil which is thegrowing medium of root has brought great difficulties for researches, so the quantification and simulationstudy of root architecture have been necessary to root system researches. This paper is on the basis of thereview about root system researches at home and abroad and its visualization, and the root architecturefractal characteristics of barrels planted cotton were analyzed by fractal theories. The dynamicprogramming model for cotton root growth has been established which based on the principle of waterbalance. And the visualization reproduce of barrel planted cotton root architecture was conducted on thebasis of iterated function systems. The conclusions are:(1) The box-counting dimensions of whole root architecture and lateral root architecture of cotton bothincrease with advancing of growth period, but the former is always greater than the latter. However, theperiod after flowering stage, both substantially closely. It shows that the main root growth is dominant inseeding stage, but lateral growth is dominant in and after bud stage, and even during later period, the lateraldevelopment is primary. Moreover, with the development of lateral root, roots distribution become morecontinuous.(2) The variation principle of root abundance of whole root architecture and lateral root architecture issimilar to that of root architecture box-counting dimension. They both increase with advancing growthperiod, and the former is always greater than the latter. However, the abundance of lateral root architecturehas a greater increase, until after entering the flowering stage, the root abundance of lateral rootarchitecture(4.1113) is close to the root of the whole root architecture(4.189). This reflects that thedevelopment rate and spatial scalability of second-order and third-order lateral roots increased rapidly. Inaddition, with the increase of root length, the root abundance of lateral root architecture also increased,indicating that although the distribution pattern of root architecture will stabilize, but its possession of thesoil moist space will continue to strengthen, and root density increases.(3) Under the condition of without water stress and all the roots are absorbing in the major growthperiod of cotton,based on the principle of water balance and the dynamic programming theory,a dynamicmodel for simulating total root length change during crop root growth was established, and verified bybarrel-cultivated cotton experiment. The growth behavior of cotton root length simulated by the dynamicmodel was substantially consistent with that measured in experiment. The relative error between simulatedand measured change as first increases and then decreases final increases with the simulation process andoverall error in 15.41%, which proved the validity of the model as the soil moist area design method.(4) The change rate of cotton leaf area always greater than that of root length in each growth period,which shows that under water balance condition, the growth of cotton leaf area played a dominant role,canopy transpiration pull is the main driving force of cotton root water uptake, the root growing is to meetcanopy water consumption. When canopy transpiration increase, the root length have to increase so thatmeet water consumption and keep water balance; cotton in the late growth period, canopy transpirationdecrease, so the fine roots needed reduce and root attenuation, so as to some useless toots will senescenceand perish.(5) Iterated function systems was used to realize root architecture visualization of A and B treatedbarrel-cultivated cotton, simulated results shows that, the root shape of simulated accordance withmeasured; for the key period of water requirement of cotton, the similarity of root system density 2-Ddistribution contour map of simulated and measured not less than 75%, which helpful to cotton soil moistarea of drip irrigation design, so all these proved the effectiveness of iterated function systems. θ and φcontrolled the angle between first-order lateral roots and main root, which performance the characteristic init decrease with soil depth increase; the position of lateral root meristem changes along the soil depth; theaffine transformation call probability of each fractal element is positive correlation with cotton root lengthdensity of the corresponding area.