Nutrient Uptake by High-Yielding Cotton Crop in Brazil

ABSTRACT: Determining nutrient uptake and accumulation rates by cotton crops is important to define management strategies, especially for transgenic varieties, which are cultivated using high-technology approaches that require substantial investment to maximize yield. Currently in Brazil, the states of Bahia and Mato Grosso are responsible for 84.4 % of the total cotton growing area. In the present study, two trials were conducted in 2013, one that involved planting FM 940 GLT, FM 980 GLT, and FM 913 GLT varieties in the state of Bahia and the other which involved FM 940 GLT and FM 980 GLT varieties in the state of Mato Grosso. The aim of the two trials was to represent the two regions that currently encompass the largest areas of cotton cultivation. Tissue samples, consisting of leaves, stems, and reproductive components, were collected eleven times during the crop cycle for determination of nutrient content and shoot dry matter. After weighing, plant tissue samples were dried and ground to determine nutrient contents. Because there were no overall differences in nutrient contents and biomass accumulation of the varieties during the crop cycle, we undertook joint analysis of the data from all varieties at each site. Favorable climatic conditions in Bahia promoted plant biomass production that was twice as much as plants grown in Mato Grosso, with cotton yields of 6.2 and 3.8 t ha−1 of lint and seed, respectively. The maximum nutrient accumulation occurred between 137-150 days after emergence (DAE) for N; 143-148 for P; 172-185 for K; 100 for Ca; 144-149 for Mg; and 153-158 for S. Maximum uptake ranged from 218-362 kg ha−1 N; 26-53 kg ha−1 P; 233-506 kg ha−1 K; 91-202 kg ha−1 Ca; 28-44 kg ha−1 Mg; and 19-61 kg ha−1 S. On average, the sites revealed nutrient export of 14, 2, 23, 3, 2, and 2 kg t−1 of lint and seed for N, P, K, Ca, Mg, and S, respectively, with little variation among sites. Extraction of nutrients per area by cotton vary among sites, but nutritional requirement of cotton per unit of lint and seeds is similar independently of yield potential.

摘要：明确棉花作物的养分吸收与累积速率，对于制定田间管理策略具有重要意义，这一点对于转基因品种尤为关键——这类品种需依托高技术栽培手段开展种植，且需投入大量成本以实现产量最大化。当前巴西的棉花种植总面积中，巴伊亚州与马托格罗索州占比达84.4%。本研究于2013年开展了两项田间试验：其一在巴伊亚州种植FM 940 GLT、FM 980 GLT与FM 913 GLT三个品种，其二在马托格罗索州种植FM 940 GLT与FM 980 GLT两个品种。两项试验的设置旨在覆盖当前巴西棉花种植面积最大的两个主产区。在作物全生育期内，共采集11次由叶片、茎秆及生殖器官组成的植株组织样品，用于测定养分含量与地上部干物质重量。称重后，将植株组织样品进行干燥与研磨处理，以测定其养分含量。鉴于各供试品种在生育期内的养分含量与生物量累积未出现显著整体差异，本研究对每个试验点所有品种的测定数据进行了合并分析。巴伊亚州的气候条件更为优越，其植株生物量产量是马托格罗索州的两倍，皮棉与籽棉产量分别达6.2 t·ha⁻¹与3.8 t·ha⁻¹。各养分的最大累积时段分别为：氮（N）在出苗后137~150天（DAE），磷（P）在143~148天（DAE），钾（K）在172~185天（DAE），钙（Ca）在100天（DAE），镁（Mg）在144~149天（DAE），硫（S）在153~158天（DAE）。最大养分吸收量区间分别为：氮（N）218~362 kg·ha⁻¹，磷（P）26~53 kg·ha⁻¹，钾（K）233~506 kg·ha⁻¹，钙（Ca）91~202 kg·ha⁻¹，镁（Mg）28~44 kg·ha⁻¹，硫（S）19~61 kg·ha⁻¹。两个试验点的平均养分携出量（以每生产一吨皮棉与籽棉计）分别为：氮14 kg、磷2 kg、钾23 kg、钙3 kg、镁2 kg、硫2 kg，且各试验点间的差异极小。尽管不同试验点的单位面积棉花养分提取量存在差异，但无论产量潜力如何，棉花生产单位质量皮棉与籽棉的养分需求量均较为一致。