Effect Of Plant Density On Cotton Growth And Natural Resources Utilization

The number of cotton plants grown per unit of ground area has gained attention due to the high prices of inputs and lower production.Yield consistency across a series of plant populations is an attractive cost-saving option.Plant density,soil water consumption and light interception has great impact on yield of cotton.The objectives of this study were to investigate soil water consumption,light interception,cotton growth,yield and biomass accumulation by using different plant densities at treatment and to find out the optimal plant density.A 2-year field experiment was conducted in a randomized complete block design under six plant densities(D1,15,000;D2,33,000;D3,51,000;D4,69,000;D5,87,000 and D6,105,000 ha^-1).Soil moisture data and light interception were collected and analyzed through spatial grid method.The average daily water consumption of high-density cotton was significantly higher than that of low-density cotton during any reproductive period.The average water daily consumption after the bud period gradually increases up to reaching the peak in the flowering period and D6 treatment were highest and reached the maximum 4.59 mm and 5.12 mm while D1 treatment was the lowest with 2.96 mm and 4 mm during both years respectively.The maximum total water consumption was 340.27 mm and 355.64 mm in highest plant density D6 and minimum total water consumption was 242.79 mm and 256.02 mm in lowest plant density D1 during both years respectively.During both growing season the total water consumption followed the trend D6>D5>D4>D3>D2>D1.Highest daily water consumption was concentrated between 8 am to 20 pm and lowest was concentrated between 20 pm to 8am.The Plant density D5 had more water use efficiency while lowest WUE was of D6 and followed the trend D5>D4>D3>D2>D1>D6.During bud and flowering-boll stage,the soil moisture variation was concentrated at the soil layer of 0-60 cm and during the boll-opening period,the soil water content did not change significantly at various locations and there was no significant difference between densities.The light interception decreased with increasing plant height.Light interception was higher at high cotton plant densities than lower.The greater light interception was observed at bottom of the canopy at horizontal direction while in vertical direction greater light interception was observed near cotton rows.Cotton at high plant density produced high LAI while number of bolls per unit of ground area along with net photosynthetic rate increased up to D5 while decreased with further increase in plant density.High planting density（D5）produced 33%and 30%more lint yield as compared to low planting density（D1）during both years,respectively.The highest seed cotton yield(4446 kg ha^-1)and lint yield(1697 kg ha^-1)were produced by high plant density（D5）while the further increase in the plant population（D6）decreased the yield.The increase in yield of D5 was due to more biomass accumulation in reproductive organs as compared to other treatments.The highest average(VA=110.3 kg ha^-1 d^-1)and maximum(VM=125.8kg ha^-1 d^-1)rates of biomass were accumulated in reproductive structures.High leaf area index was observed in high planting density as compared to low treatments.Plants with high density had greater fiber length as compared to the low plant density,while the fiber strength and micronaire value decreased with increasing plant density.It is concluded from the research that D5 plant density produced high seed cotton and lint yield with maximum water use efficiency.Conclusively,plant density of 87,000 plants ha^-1is a promising option for enhanced yield,biomass,and uniform fiber quality of cotton in term of natural resources utilization.