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

Abstract

The increase in the demand for seedlings of native tree species makes it important to determine their water and light requirements, which are important factors in their production, in terms of costs and time. Water use and productivity in the growth of seedlings of Dalbergia nigra (Vell.) Allemão ex Benth., Apuleia leiocarpa (Vogel) J.F. Macbr and Hymenaea courbaril L. were determined under four light levels (three shading levels and control), using a randomized block design with four replicates. Height, stem diameter, leaf area and biomass, as well as Dickson quality index (DQI) were evaluated. The seedlings were transplanted into 280-cm3 plugs, filled with substrate composed of pure biosolids, and irrigated by a drip system with automatic management. The highest total volumes applied were 3.1 L per D. nigra seedling (in 37 and 58% shading), 2.5 L per A. leiocarpa seedling (in 37% shading) and 3.8 L per H. courbaril seedling (in full sun). Growth indices, confirmed by the DQI, indicate that shading levels of 37 and 58% for D. nigra, 37% for A. leiocarpa, and full sun for H. courbaril are the most recommended. The highest volumes of irrigation promoted the greatest development of the species, in general for intermediate shading, which provided the highest values of DQI and irrigation water productivity.

Production of forest seedlings using sewage sludge and automated irrigation with ozonated cattle wastewater

“…Under shading levels ranging from 0% to 92% and using the same water as the T 1 treatment, evaluated the growth of D . nigra , for 115 days (July to October) in the same experimental area [ 24 ]. For an accumulated ETo of 436.5 mm, the irrigation system was activated 49 times on average, with an average activation time of 2.8 min.…”

“…This was achieved by using the simplified irrigation controller (SIC), proposed by [ 36 ], which operates in response to soil/substrate water tension and is regulated by the level difference between a ceramic micro-cup (sensor) and a pressure switch. This device has been used in irrigation management of different crops [ 37 , 38 ] and in the production of seedlings of forest species [ 23 , 24 ].…”

“…In each treatment, irrigation events were monitored, and SIC activation times were automatically recorded in a data collection and storage system composed of an Arduino Mega board and an SD card. Adapted from [ 24 ], to each irrigation event the system was programmed to interrupt the water supply for one minute every 30 seconds, preventing percolation in the plugs. If the power supply to the pressure switch remained active, the irrigation system was activated again.…”

“…In addition to treated wastewater, the application of sewage sludge has been carried out in forest areas aiming to enhance both tree growth and wood production and to improve several soil characteristics [ 21 ]. Called biosolid, after stabilization process, this solid waste comes from sewage treatment plants has become popular in Brazil [ 22 – 24 ], and used in the composition of organic substrates for seedling production [ 22 – 26 ]. This is a promising initiative for the forestry sector in the country [ 27 ], which has a nursery capacity of around 150 million seedlings of native forest species [ 28 ].…”

“…Associated with the use of biosolid as substrate, wastewater should be evaluated in systems for production of seedlings of forest species, which are characterized as a determining step in the regeneration of degraded areas, especially in Brazil, which has millions of hectares under this condition. However, regardless of the quality, the water supply must be done with discretion, especially in forest nurseries, which traditionally do not use irrigation management, compromising the efficiency of the system and the quality of the seedlings [ 24 ].…”