Abstract

Nitrogen (N) is the most applied nutrient in Coffea canephora crop. However, the absorption of N, especially in the form of nitrate, does not guarantee its effective use in the synthesis of biomolecules. The reduction of nitrate in the cytosol is often limited by the deficiency of molybdenum (Mo). This study, conducted during two coffee production cycles under field conditions, aimed to evaluate the effects of applying Mo on the nutrition of Conilon coffee subjected to doses of N. The experimental design used was in randomized blocks, in a 2 x 5 factorial scheme, the first factor being the absence and presence of molybdic fertilization and the second factor, N doses (300, 500, 700, 900 and 1,100 kg ha⁻¹year⁻¹). Increasing doses of N promoted a linear increase in S, and within certain limits, increased the concentrations of N-NH₄⁺, P, K and Ca in coffee leaves; while there was a decrease in the levels of Mg and Mo. The sodium molybdate fertilizer applied to the soil was efficient in supplying Mo to the coffee. Although the Conilon maintains basal levels of nitrate in the leaves, molybdic fertilization prevented the excessive accumulation of NO₃^- in plants submitted to N doses above 515 kg ha⁻¹. In the second year, the highest concentrations of N-NH₄⁺, P, K and Ca were achieved with doses of N between 698 and 967 kg ha⁻¹, which provided yield greater than 145 bags ha⁻¹.

摘要

氮 (N) 是咖啡豆作物中应用最多的营养元素。然而，氮的吸收，尤其是以硝酸盐的形式，并不能保证其在生物分子合成中的有效利用。细胞溶质中硝酸盐的减少通常受到钼 (Mo) 缺乏的限制。本研究在田间条件下的两个咖啡生产周期中进行，旨在评估施用 Mo 对施用 N 剂量的 Conilon 咖啡营养的影响。 使用的实验设计是随机区组，采用 2 x 5 因子方案，第一个因素是钼肥的存在和缺失，第二个因素是氮剂量（300、500、700、900 和 1,100 kg ha ^-1年^-1）。增加N剂量促进S线性增加，并在一定限度内增加咖啡叶中N-NH ₄ ⁺、P、K和Ca的浓度；Mg 和 Mo 的含量有所下降。施用到土壤中的钼酸钠肥料可以有效地为咖啡提供 Mo。尽管 Conilon 保持叶子中硝酸盐的基础水平，钼施肥阻止了植物中 NO ₃ ^-在超过 515 kg ha ^{-1 的}氮剂量下的过度积累。在第二年，N-NH ₄ ⁺、P、K 和 Ca的最高浓度在 698 至 967 kg ha ^-1的 N 剂量下实现，产量超过 145 袋 ha^-1。