Evapotranspiration and water sensitivity of Amazonian yellow ipe seedlings under different shading conditions

Evapotranspiração e sensibilidade hídrica de mudas de ipê-amarelo amazônico em diferentes condições de sombreamento

ABSTRACT

The scarcity of information on the agroclimatic and ecophysiological requirements of forest species, especially in the initial phase, limits the production of quality seedlings, the planning and optimization of nurseries. The potential evapotranspiration, crop coefficients (kc) and water sensitivity coefficients (ky) of Amazonian yellow ipe seedlings were determined under different shading conditions and levels of water replacement to the substrate, in the dry period (July to October 2016), in the Cerrado-Amazon Rainforest transition region of the Mato Grosso state, Brazil. The experiment evaluated the full sun and black polyester nets with 35, 50, 65 and 80% shading, and the levels of water replacement to the substrate of 25, 50, 75 and 100% ETc in a split-plot scheme, with irrigation fractions established according to the maximum water retention capacity of the substrate. The water consumption of Amazonian yellow ipe was 239.2, 228.6, 204.1, 185.7 and 136.3 mm for cultivation under full sun and shading levels of 35, 50, 65 and 80%, respectively. The daily means of ETc were 3.37, 3.22, 2.87, 2.61 and 1.92 mm d^-1, whereas the kc means ​​were 1.13, 1.15, 1.05, 0.90 and 0.60 for the above-mentioned shading levels. ky values ranged from 0.89 to 1.28, with reduction due to the increase of water replacement and increase for higher shading percentage.

Key words: Handroanthus serratifolius; crop coefficients; water deficit; irrigation management