Abstract
The lack of information regarding the water requirement of tree species results in water waste in the seedlings production in nurseries. Water requirement, the growth plant factors and water efficiencies for height and diameter were determined for Schizolobium parahyba (Vell.) Blake, Cytharexylum myrianthum Cham. and Ceiba speciosa Ravenna seedlings, under automated irrigation management and greenhouse conditions, located at 22o45’53” S and 43o41’50” W. We used sewage sludge biosolids as substrate in the seedling phase (280 cm-3 tube), and sandy soil material in the initial pot growth phase (18 dm-3 pot). In the seedlings phase, four water replacement levels were applied to the substrate, by drip irrigation, corresponding to average replacement ranging from 40 (V1) to 100% (V4) of the species water requirement. Seedlings developed properly and 80 days after emergence, S. parahyba, C. myrianthum and C. speciosa seedlings received, respectively, 2.40, 1.08 and 0.85 L per plant, for V4. After growth phase (230 DAE), the total water volumes were, respectively, 70.0, 50.3 and 52.7 L per plant. Under adequate water supply, there were rapid recovery and growth of the species, even for the seedlings which showed different height and diameter in the tube phase. The growth plant factors values found were below 0.5 for all species indicating low sensitivity to growth, both in height and in diameter, in response to water deficit. Water efficiency indicators point to distinct trends between the two phases, and C. speciosa has higher values of water efficiencies for height (80.7 and 17.0 cm L-1) and diameter (2.1 and 0.5 mm L-1) in both phases.
Highlights
Areas requiring some sort of recovery in different degraded ecosystems of Brazil reach about 21 million hectares and are characterized as with legal deficit of native vegetation [1]
In order to represent the impact of the use of water resources in the tree seedlings production, we present news growth and water efficiency indicators respectively related to water deficit and water volume applied, for the development of seedlings in height and diameter
At 60 days after the start of irrigation monitoring, from 20 to 80 days after emergence, the species reached on average the minimum standard for field planting in all treatments, which corresponds to the range from 20 to 40 cm for height and diameter greater than 3 mm [24], for quality seedlings produced in 280 cm3 tubes
Summary
Areas requiring some sort of recovery in different degraded ecosystems of Brazil reach about 21 million hectares and are characterized as with legal deficit of native vegetation [1] Much of this area is located in the Atlantic Forest biome, considered the most altered in Brazil, with an estimate of only 12.5% of its original cover [2], and one of the most important for conservation. With the degradation defined in the context of a resilience-based approach, when core interactions and feedbacks are broken, human intervention is required to initiate a trajectory of recovery [4]. In this context, the planting of seedling has been one of the most used techniques for the Atlantic Forest restoration [5]. 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]
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