Effects Of The Product Of Thermal Effectiveness And Photosynthetically Active Radiation On Growth And Yield Of Cotton In Different Plant Densities

【Objective】The main objective of this study was to set different density, and measured plant height, leaf age, the bolls number and other agronomic parameter at different period of cotton.The photosynthetically active radiations were measured and the accumulations of aboveground cotton biomass were calculated at the boll period of cotton. The made clear understanding relationships between the product of thermal effectiveness and photosynthetically active radiation(TEP) at the development process of cotton. And the dynamic feature of TEP and the influence on development process of cotton under the condition of interactions. The method, which should be the reference through the accumulated TEP to predict yield, could provide a new theoretical basis and technical support for cotton growth and monitoring.【Methods】In this study, the experimental design included two cotton cultivars(Lumianyan24 and Xinluzao 50) grown with three density treatments(240×103, 176×103, and 82.5×103plants ha-1). The canopy photosynthetic active radiation, the temperature, the layered leaf area and the biomass of cotton were measured at 48 d 56d and 68 d days after emergence of the cotton. And the radiation and temperature data were recorded in the whole growth period of the cotton.【Results】1. The effect of the TEP on the growth anddevelopment of cotton.When the cotton’s plant height, leaf age, and the number of bolls and buds reached the maximum, the results show that D3>D2>D1 under two cotton cultivars with three density rates.2. The relationship between the dry matter accumulatin and the TEP in the whole growth period of the cotton.The dry matter accumulatin dynamic change feature with the accumulated TEP shows the “S” type surve. The accumulated of TEP with dry matter accumulation could be divided into three phases. The results show that D3>D2>D1 in the early growth stage and D1>D3>D2in Mid-growth stage.3. The dynamic change of PAR transmittance in different canopy of cotton.The vast majority of PAR in cotton canopy was intercepted by the upper canopy of cotton. The extinction coefficient(K) showed that obvious diurnal variation was higher at miday, and was lower at morning and evening in the different density rates.4. Relationships between the accumulated TEP and yield of the cotton.The results clearly indicated that the yield of cotton for the LMY 24 reached in the highest yield 4306.8 kg ha-1 at the plant density of 240 × 103 plants ha-1. And the yield of cotton for the XLZ 50 reached in the highest yield 4267.73 kg ha-1at the plant density of 240× 103 plants ha-1. In cotton harvest season, the yield of cotton was increased with the increase of the accumulated TEP. And the relationships between the accumulated TEP and yield of the cotton were best described by the liner function. The liner function was y = a + bx. The determination coefficient value was R2 > 0.88, the maximum value of R2 reached 0.96. The most important composing factors of cotton yield were the number of bolls. We concluded that the best dynamic growth model for the boll of cotton was222)(c xb ay??? ?. The best model for estimated cotton yield was determined by the criteria of high R2 values and low RMSE values. Verification models with data from in 2011 and 2012, and the RMSE=1.8 per plant, R2=0.92.【Conclusion】1. On the canopy of cotton PAR capture and distribution, density has been considered as an important effect parameter. In the three density rates, the extinction coefficient(K) of the D2 treatment(176×103plant ha-1) was superior to the other two density rates. The results clearly indicated that the D2 rate was better plant structure of cotton in Xinjiang province.2. Density decrease appropriately, the accumulated TEP will be increased in the early growth stage, and reduce in the late growth stage for the dry matter accumulation three phases of cotton.3. The yield of cotton was increased with the increase of the accumulated TEP. And the relationships between the accumulated TEP and yield of the cotton were best described by the liner function. With the density of cotton dynamic changed, the relationships between the accumulated TEP and yield not only related to density but also related to the variety of cotton.4. The bolls of cotton could be predicted by the growth function equation:79.327)36.1448(293.17 TEP y??? ?.