Doses of phosphorus and nitrogen in the production of Brachiaria híbrida cv. Mulato II

ABSTRACT The nutritional deficiency of Brazilian soils is one of the main factors limiting the production of fodder, and nitrogen and phosphorus nutrients that influence more biomass production. The objective was to evaluate the vegetative growth of Brachiaria hibrida cv. Mulato II under different phosphorus levels with and without nitrogen in northern Mato Grosso. The experimental design was a randomized complete block in a factorial 5 x 2 x 3 with three replications. The treatments consisted of application of five doses of phosphorus (0, 45, 90, 135 and 180 kg ha-1 P2O5), presence and absence of nitrogen (0 and 100 kg ha-1 of N) and three times with 30 intervals days. Shoot cuts were made at a height of 20 cm from the ground to determine the dry mass of leaves, dry weight of stem and total dry mass. For dry mass production leaves significant difference for phosphorus levels in isolation and interaction of nitrogen and cuts. In total dry mass were no significant differences for the double interactions of nitrogen and cuts, phosphorus and nitrogen, and phosphorus and cuts. As for the production of dry mass of stems, significant triple interaction for levels of phosphorus, nitrogen and cuts. The dry mass of leaves, stem and all responded positively to the application of 180 kg ha-1 match with the presence of nitrogen.

摘要 巴西土壤的营养匮乏是制约饲料作物生产的核心因素之一，其中氮、磷养分对生物量积累的影响最为关键。本研究旨在评估巴西北马托格罗索州地区，在不同施磷水平且施加或不施加氮肥的条件下，杂交臂形草（Brachiaria hibrida）穆拉托II号品种的营养生长状况。试验采用5×2×3因子设计的完全随机区组试验，设置3次重复。试验处理涵盖5个磷素施用量梯度（0、45、90、135、180 kg·ha⁻¹ P₂O₅）、2个氮肥施用水平（施氮100 kg·ha⁻¹与不施氮），以及3个间隔30天的刈割时间节点。于距地面20 cm处刈割地上部分，用以测定叶片干质量、茎秆干质量及总干物质质量。叶片干物质产量方面，单因素磷素水平、氮肥与刈割次数的交互作用均存在显著差异。总干物质产量方面，氮肥与刈割次数、磷素与氮肥、磷素与刈割次数的两两交互作用均未表现出显著差异。茎秆干物质产量方面，磷素水平、氮肥施用与刈割次数三者间存在显著的三重交互效应。叶片、茎秆及总干物质产量均在配施氮肥并施加180 kg·ha⁻¹ P₂O₅时呈现正向响应。