Characteristics on uptake and distribution of nitrogen, phosphorus and potassium in different genotypes of Bt cotton

Objectives The uptake and distribution characteristics of NPK nutrient of different genotypes of Bt cotton were investigated to provide a theoretical foundation for high yield cotton cultivation.

Methods A field experiment was conducted to study the accumulations characteristics of dry matter, N, P and K in different genotypes of Bt cottons and their relationship in 2015 and 2017.

Results The yield of Jimian169 was the highest, which was 27.9% and 25.5% higher than Lumianyan21, 65.9% and 41.1% higher than Daizimian99B in 2015 and 2017, respectively. The differences of boll weight among the three genotypes were consistent with the lint yield, while the number of bolls and lint percentage were not. The accumulation of dry matter, N, P and K in various organs of Jimian169 was higher than that of Lumianyan21, especially in the medium-late stages. And the highest content of N, P and K in vegetative organs of Jimian169 promoted a higher amount of dry matter, which provided sufficient material basis for boll development. In addition, the boll/leaf ratio was higher, thereby the boll number and the boll weight were the highest, which resulted in the highest lint yield and the efficiency of nutrient utilization. The accumulation of dry matter, N, P and K in every organ of Lumianyan21 was the lowest, and the highest transfer proportion of biomass to bolls, which restricted the growth of vegetative organs and the development of bolls in middle-late growth-stages. As a result, the number of bolls was the lowest, the boll weight was lower, and the lint yield was lower in Lumianyan21. Although Daizimian99B exhibited the highest accumulation of dry matter and N, P and K in various organs, its rapid accumulation period appeared after the full-flowering stage. The cotton plant was over-green, boll weight was the smallest, lint yields was the lowest, and the efficiency of nutrient utilization was also the lowest.

Conclusions The increase in lint yield of Bt cotton in different eras is attributed to the enlargement of boll weight, followed by the increase in boll number, which are induced by the synergistic increase in total biomass of cotton plant and the transfer proportion to reproductive organs, particularly in the medium-late stages. And the greater biomass of cotton plant and reproductive organs depend on the rising nutrient accumulation and utilization efficiency.