Soil moisture associated with least limiting water range, leaf water potential, initial growth and yield of coffee as affected by soil management system

摘要

Water determines the success of coffee farming, since it influences the phenology of the plant and, consequently, its productivity, product quality and commercial viability. The Least Limiting Water Range (LLWR) associated with the monitoring of soil water content (theta) distinguishes management systems as to their effectiveness in supplying water to plants. The need for developing better management systems -in Brazilian rainfed farming that promote water uptake by coffee plant radicular systems at lower soil depths where water is more available, inspired this study. This work had as an objective to evaluate the availability of water in soil through LLWR limits in association with leaf water potential, as well as growth and yield of coffee plants, in the Cerrado region of Southeastern Brazil over 4 years. The management systems evaluated were: CV-0 (conventional management with coffee interrow maintained with bare soil); G-28 (conservation management, with maintenance of Brachiaria in interrow, ridging and additional application of 28 Mg ha(-1) gypsum applied in the rows) and G-7 (same as G-28, except for an additional application of 7 Mg ha(-1) of gypsum). theta was monitored every 15 days. Critical moisture for coffee crop in each phenological stage was added as the lowest limit of LLWR. In all evaluated management systems, theta was below the critical moisture as measured at the soil depths of 0.20 m and 0.60 m. At 1.00 m depth in the CV-0 management system, the greatest value of theta was found, which caused the assumption of smaller water uptake. Regardless of the management adopted, the leaf water potential reached -1.16 MPa in August 2010, but that did not cause water stress high enough to reduce productivity. At 0.60 m depth, the lowest value for theta between rows was observed for the G-28 management system. Plants showed a more accentuated initial growth in the CV-0 management system. Each management system showed distinct behavior regarding productivity of the evaluated crops: in 2011, CV-0 had the highest productivity, but, in 2012, productivity was greater for G-7 and G-28.