There are few studies that demonstrate the influence of water stress in biometric variables and cotton growth. Thus, the objective of this study was to evaluate different levels of water supply in the BRS 2 cotton growth, in the field of Campus Rio Verde - GO, in 2015. Experimental design used was randomized blocks, with three replications in a split-plot scheme of 5 x 4 with five water replacements (WR) (25, 50, 75, 100 and 125%) of evapotranspiration, and four times of evaluation (ET) during the growth cycle (40-60, 61-80, 81-100 and 1-20 days after emergence). The variables analyzed were plant height (PH), leaf area (LA), dry phytomass stem (DPS), dry phytomass of leaves (DPL), dry phytomass of reproductive organ (DPRO), dry phytomass of aerial part (DPAP), absolute growth rate (AGR), relative growth rate (RGR), net assimilation rate (NAR) and leaf area ratio (LAR). The behavior of PH and LA under the influence of water levels revealed that for a better performance of studied variables, it is important to consider the irrigation management, besides the crop coefficient. Water replacement influenced the cotton growth. Low cotton growth rate was caused by the reduction of water supply until the end of growth cycle.
Key words: Gossypium hirsutum L., dry phytomass, drip irrigation, crop evapotranspiration.