Productivity and Dry Matter Accumulation of Sugarcane Crop under Irrigation and Nitrogen Application at Rio Verde GO, Brazil

摘要

Dry matter production and productivity of stem currently are being widely studied in sugarcane, reinforcing the study in question, which aims to assess the accumulation of dry matter of the aerial segment and the productivity of stems of sugarcane crops within the first cycle, at different levels of water replacement (WR) with and without nitrogen fertilization, through a subsurface drip irrigation system. The assay was conducted in the experimental area of the Federal Institut Goiano, Campus Rio Verde, GO, Brazil, in a dystroferric Rhodic Hapludox soil, cerrado phase (savannah), and comprised experimental splits of three furrows with an 8-meter long double row. Experimental design consisted of randomized blocks in a 5 × 2 factorial array, with four replications. Evaluated factors comprised five levels of WR (100%, 75%, 50%, 25% and 0% of field capacity), with and without the application of nitrogen (0 and 100 kg·ha-1 urea). Harvest occurred in May 2013 and stem productivity (SP), productivity of pointers (PP), productivity of straw (PS), harvest index (HI), dry matter of stem (DMS), dry matter of pointers (DMP), the relationship between dry matter of pointer and dry matter of stem (DMP/DMS) and total dry matter of the aerial segment (TDM) were determined. The variables SP, PP, DMS and DMP had a linear growth in proportion to WR increase, whereas HI and DMP/DMS adjusted to a quadratic model. Nitrogen fertilization affected positively the variables SP, HI, DMS and DMP/DMS and occurred interaction to TDM; also increasing the productivity stem and the harvest index.