Fertilizer Rate And Plant Density Interaction Effects On Cotton Growth, Yield, Yield Components, Biomass And Nutrient Accumulation

The objective of this study was to understand the effects of one time fertilizer application under different plant densities on cotton growth, biomass partitioning, and lint yield response. Field studies were conducted in the 2013 and 2014 growing seasons at the Huazhong Agricultural University, using one variety Huazamian H318 (G. hirsutum L.) under two fertilizer rates (112.5,225.0 kg/ha) with one application at the first flower stage and three plant densities (6.0,7.5,9.0 plants/m2). The results showed that:1. Cotton growth period was affected by fertilizer rate, plant density, and their interaction significantly. Higher fertilizer rate delayed the squaring stage for 1-4 days, while higher plant density elongated the vegetative growth for 2-3 days but decreased the reproductive growth for 1-3 days.2. SPAD values were increased with the advance of plant growth and development. SPAD values were increased at the fertilizer rate increased while it was not affected significantly by plant densities.3. Growth parameters were not affected by fertilizer rate, plant density, and their interaction, except the boll number which was significantly affected by plant density, as treatments with high plant density had the highest boll number in both years.4. Biomass accumulation (total, vegetative and reproductive) increased with the advance of plant growth and development. Biomass accumulation was not significantly affected by either fertilizer rate or plant density. However, combinations of high fertilizer rate with medium or high plant density had the highest average and maximum speed.5. Cotton yield and yield components were not significantly affected by fertilizer rate in both years, and the highest seed cotton yield and lint yield were obtained from high plant density with low or high fertilizer rate.6. Nutrient accumulation was altered by fertilization rate, plant density and their interaction, where combinations of high fertilizer rate with low or medium plant density had the shortest FAP with the highest FAP speed both average and maximum.7. Fresh leaves sugar content was not significantly affected by fertilizer rates, plant density, and their interaction. Fresh leaves protein content increased with fertilizer rates increased and decreased with plant density increased. The interaction was significant only at the peak bloom where combinations of low and high fertilizer rate with high plant density were the highest. The C/N ratio was significantly affected by the interaction only at the peak bloom stage, where combinations of low fertilizer rate with low or high plant density had the highest ratio.On the basis of these observations, we recommend low fertilizer rate with high plant density or high fertilizer rate with moderate or high plant density as management combinations that could maximize yield, lint yield, and its component.