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

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.

Water use in the growth of atlantic forest tree species seedlings under different shading levels

“…Regardless of the species and variable used in the calculation, the light attenuation of 37% ensured seedlings with better growth, higher DQI and promoted the best results of irrigation water productivity (WPi). Keffer et al (2019) obtained values of approximately 0.99, 1.83, 1.92, 1.28 and 1.11 g L -1 in seedlings of Amazonian yellow Ipe after 82 days of cultivation, respectively, under full sun and shading levels of 35, 50, 65 and 80%. For Dipteryx alata Vogel, a species native to the Cerrado biome, Borella et al (2020) found WPi values at 125 days after transplantation of 0.96, 1.12, 1.20, 1.06 and 1.43 g L -1 , respectively, for cultivation under full sun and black nets with 45.3, 54.1, 68.3 and 83.3% shading.…”

“…The production of seedlings of native tree species is necessary due to the increased demand for environmental restoration projects (Scalon et al, 2011), mainly in the Atlantic Forest, currently with 12.5% of its original coverage and is considered one of the most threatened biomes in the world (Santos et al, 2019). In addition, in reforestation process many species are cultivated for economic purposes (Delgado et al, 2017), and success in planting depends on seedling quality, which is influenced by water supply, local microclimate (Keffer et al, 2019), substrate used and management (Davide et al, 2015). In tree species nurseries there is usually no irrigation management and, therefore, losses of up to 70% of the applied water have already been observed (Dumroese et al, 2005).…”

Water requirement and growth indicators of forest tree species seedlings produced with automated irrigation management

“…We understand that the interpretation of the proposed index (Gpf) helps in the management of seedling production systems, however it cannot be compared numerically with other results in the literature as it is not normally used to evaluate the sensitivity of forest seedlings to water deficit. In any case, [ 6 ] state that the low sensitivity of forest tree species to water deficit in the seedling phase occurs because they have only one vegetative stage. It can be affirmed that the reductions in height and diameter are relatively small compared to the evaluated levels of water deficit, indicating that the species have high capacity for forming stands in initial processes of regeneration, even under conditions of low rainfall, provided that there is minimal water supply in the soil.…”

“…In the formation of stands aimed at forest restoration, it is essential to produce seedlings with high quality and rusticity, which are influenced by the availability of water, both over time and in terms of volume [ 6 ], and by the substrate used. Adequate supply of nutrients to seedlings can be performed by using sewage sludge biosolid as substrate [ 7 ], as it contains high organic matter content and has appreciable amounts of N and P [ 8 ].…”

“…Seedling quality is also related to the water supply in the nurseries, which should be carried out in response to the crop water requirement according to the interactions of the environment and water dynamics in the substrate [ 6 ]. About 49% to 72% of the water applied in reforestation nurseries is lost, varying according to the species [ 9 ].…”