Yield Response Factor to Water (Ky) of FMX 993, FMT 701 and FMX 910 Cotton Varieties in Campo Verde, MT

Production of herbaceous cotton in rainfed is subject to water-deficit risks due to climatic variations, such as precipitation with non-homogeneous spatial-temporal distribution. In this sense, the objective of this study was to evaluate the yield response factor to water of FMX 993, FMT 701 and FMX 910 cotton varieties, in Campo Verde County, Mato Grosso State, Brazil. Real yield data of the 2009/10 and 2010/11 seasons of the three varieties were obtained. Meteorological data were used to estimate the maximum yield and to calculate the daily water balance for each variety and seasons. From these values the yield response factor to water (Ky) was obtained. Ky values ranged from 0 to 0.9, with the lowest and highest values for FMX 910 for the 2009/10 and 2010/11 seasons, respectively. These values obtained from Ky indicate that all varieties studied present increasing tolerance to water-deficit. The FMX 993 variety had a lower variation in Ky values between 0.3 and 0.5 for the 2009/10 and 2010/11 seasons, in that order. Therefore, among the cotton varieties evaluated in this study, recommend FMX 993 for the conditions of Campo Verde County, Mato Grosso State, due to its greater tolerance to the water-deficit.