English

Abstract

Although sugarcane crop has moderate tolerance to water stress, it shows high response to irrigation. Thus, the improvement of irrigation techniques becomes necessary to achieve maximum water use efficiency. Several studies in Brazil and worldwide on different sugarcane varieties have shown the effect of irrigation on productivity. Moreover, nitrogen fertilization stands out as one of the cultural practices of higher research demand, since studies on nitrogen show very variable results and sometimes even contradictory. The aim of this study was to evaluate the biometric indices of sugarcane in different growing stages, stalk productivity, and water use efficiency at different levels of water replacement by subsurface drip system with and without nitrogen application during cultivation. The experiment was carried out in the experimental field of the Federal Institute of Goias - Campus Rio Verde, GO. The experimental design was randomized blocks, with 5 × 2 factorial design and four replications. Treatments consisted of five levels of water replacement (100, 75, 50, 25, and 0% soil moisture at field capacity) combined or not with nitrogen fertilization (0 and 100 kg urea ha-1). Plant height, stalk diameter, and leaf area of three plants were determined in the floor space of each plot in nine steps each month, from 90 days after planting (DAP), corresponding to the following periods: 90, 120, 150, 180, 210, 240, 270, 300, and 330 DAP. The results were subjected to analysis of variance by F test at 5% probability, and in cases of significance, linear and quadratic polynomial regression analysis was performed to the levels of water replacement. For nitrogen fertilization, means were compared by Tukey’s test at 5% probability. The subsurface drip irrigation provided suitable conditions for accelerating sugarcane growth. The levels of water replacement contributed linearly on the development parameters and stalk yield. The nitrogen fertilizer contributed to the development of biometric variables in the latter stages of crop development.   Key words: Subsurface drip irrigation, water deficit, growth, sugarcane.