Germinative metabolism of Caatinga forest species in biosaline agriculture

Abstract

-The production of seeds and seedlings by these species is of utmost importance to prevent a loss of biodiversity of the Caatinga, a unique and exclusively Brazilian biome. Biosaline agriculture is conducted over a range of salinity levels in groundwater and/or in soils. The current study evaluated the application of biosaline agriculture to Anadenanthera macrocarpa, Myracrodruon urundeuva, Aspidosperma pyrifolium and Erythrina velutina by examining the germinative metabolism of seeds subjected to different electrical conductivities (ECs) of NaCl solutions and biosaline water. The seeds were germinated in biosaline water (4.94 dS.m -1) and in NaCl solutions with ECs of 0, 2, 4, 6, 8, 10, 12, 14, 16 and 18 dS.m -1 at 25 °C, 12-h photoperiod. The kinetic variables of germination were assessed, and the seeds and seedlings were assayed for reserve biomolecules, proline content and antioxidant enzyme activity. The seeds were highly tolerant to salinity, with germination-limiting ECs above 12 dS.m -1. Although high EC promoted alterations in seed metabolism that enabled salinity tolerance, seedling production was indicated with ECs no higher than 6 dS.m . These results demonstrated that Caatinga seedling production is viable through biosaline agriculture beucause the groundwater salinity of this region is within the tolerance levels of the seeds. . Embora, alta CE promova alterações no metabolismo sementes, permitindo tolerância à salinidade, a produção de mudas é indicada em CE inferior a 6 dS.m -1 . Assim, a produção de mudas da Caatinga é viável através da agricultura biossalina, pois as águas subterrâneas da região apresentam-se dentro deste nível.Termos de indexação: enzimas antioxidantes, germinação, mobilização de reserva, estresse salino.

Biosaline production of seedlings of native species from the Caatinga dry forest

“…This is especially true for desert or semiarid species, such as the species studied in this work. Studies investigating the effect of biosaline water on the germination (in lab trials) of these three dryland specialist species, showed that the seeds are tolerant (ie germination around 100%) to BGW with salinity levels of up to EC = 5 dS.m -1 and that seedling growth under biosaline agriculture is viable (DANTAS et al, 2014). In nursery conditions, these information were confirmed by this work (Figures 3-7), in which seedlings emerged and developed even when irrigated with high electric conductivity BGW (EC= 6.8 dS.m -1 ), even though in a slower rate.…”

“…The ability of protoplasm to tolerate high concentrations of salt depends on the osmotic balance between the cytoplasm and the different cellular compartments, such as the vacuole. This balance is maintained by the synthesis of organic compounds with osmotic activity, which results in the accumulation of amino acids, such as proline in seedlings (DANTAS et al, 2014). Maintaining appropriate water content in seedlings ( Figure 10) can also be an important feature of tolerance to salt stress.…”

“…and Aspidosperma pyrifolium (Mart.) (DANTAS et al, 2014). These native species can be used for a variety of purposes, such as urban landscaping, pharmaceutical and medicinal applications (AGRA et al, 2007) and mainly the recovery ad restoration of the Caatinga vegetation (RIBEIRO-FILHO;FUNCH;RODAL, 2009).…”

“…In line with this approach, various studies have attempted to evaluate the efficiency and safety of water reuse, mainly in countries or regions where potable water is limited and available groundwater is brackish. This is the case in the Caatinga ecosystem, where BGW can be used for irrigation in non-saline soils, or in sodic soils in tolerant crops or native vegetation (DANTAS et al, 2014;SOUSA et al, 2009).…”

Germinação de sementes de Vernonanthura discolor (Spreng.) H.Rob. (Asteraceae) procedentes de diferentes árvores matrizes

“…Tais conhecimentos são necessários para o aprimoramento das técnicas utilizadas nas áreas a serem recompostas por vegetação florestal (BUSATO et al, 2012). Ainda hoje, a propagação de espécies florestais é feita basicamente por meio de sementes, que apresentam diversidade quanto à morfologia e à fisiologia, incluindo mecanismos de dormência (DANTAS et al, 2014).…”