TROPICAL GRASS MANAGED UNDER INTERMITTENT LOTATION, SUBMITTED TO PHOSPHORUS SOURCES WITH DIFFERENT SOLUBILITIES, ASSOCIATED OR NOT TO NITROGEN FERTILIZER

Abstract The objective of this study was to evaluate the morphogenic and structural characteristics of piatã grass submitted to intermittent stocking and fertilized with phosphorus sources of different solubilities and nitrogen fertilization. The treatments were: control (without phosphate fertilizer application); slow solubility phosphorus source (FNR); fast solubility phosphorus source (FSS) and mixed solubility phosphorus source (FSM), whether or not associated with nitrogen fertilization. Measurements of pre-demarcated tillers were performed to evaluate the structural and morphogenic characteristics of the plants. Data were analyzed according to a randomized block design in a 4 x 2 factorial arrangement within each season. The minimum squared means of phosphate fertilizer treatments were compared with the control treatment by Dunnet test, and among themselves by the “t” test and the means of use or not of nitrogen fertilization were compared to each other by the “t” test at 5 % of significance. Sources containing readily available phosphorus, as in the FSS and FSM treatments, promoted greater leaf and stem elongation, as well as greater number and appearance of leaves, which highlights the importance of phosphorus and nitrogen availability in plant growth and development. confirmed by the increase in leaf elongation rate, leaf appearance and stem elongation. Thus, nitrogen and phosphate fertilizers are alternatives for the persistence and competitiveness of pasture livestock production. Regarding the source, the use of phosphorus sources with mixed solubility provides this nutrient in the short, medium and long term.

摘要：本研究旨在评估采用间歇放牧制度、施用不同溶解度磷源与氮肥的皮亚坦草的形态发生与结构特征。试验处理设置如下：对照组（不施用磷肥）、慢溶磷源（FNR）、快溶磷源（FSS）以及混溶磷源（FSM），各磷源均分别搭配是否施用氮肥的处理组合。通过对预先标记的分蘖进行测定，以评估植株的结构与形态发生特征。试验数据采用各季内4×2因子设计的随机区组设计进行统计分析。采用Dunnet检验将磷肥处理组的最小二乘均值与对照组进行比较，采用t检验对各磷肥处理组间的均值进行比较；同时采用显著性水平为5%的t检验，对施用与不施用氮肥的处理组均值进行两两比较。含有速效磷的FSS与FSM处理，可显著促进叶片与茎秆伸长，同时提升叶片数量与出叶速率，这凸显了磷与氮的有效供给对植株生长发育的重要性。该结论通过叶片伸长速率、出叶速率与茎秆伸长速率的提升得到了验证。因此，氮肥与磷肥可作为提升牧场畜牧生产持久性与竞争力的可选方案。就磷源类型而言，施用混溶型磷源可在短期、中期与长期为植株持续提供磷素营养。