Physiological responses to drought of Cnidoscolus quercifolius Pohl in semi-arid conditions

Fabio Rodrigues Ramos,Antonio Lucineudo Oliveira Freire

doi:10.34062/afs.v6i1.5735

Fabio Rodrigues Ramos, Antonio Lucineudo Oliveira Freire

Open Access

https://doi.org/10.34062/afs.v6i1.5735

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Abstract

This study aimed to evaluate the physiological behavior of faveleira (Cnidoscolus quercifolius Pohl) plants grown in the field, in Caatinga, during wet and dry seasons. Adult plants were selected for evaluation in March and April (wet season) and May and June (dry season), during 2016. We evaluated the soil water content, water potential (Ψw), osmotic potential (Ψπ), relative water content (RWC), stomatal conductance (gs), transpiration rate (E), photosynthetic rate (A), intercellular CO2 concentration (Ci), instantaneous water use efficiency (A/E) and carboxylation efficiency (A/Ci). The reduction in water availability in the soil promoted a marked decrease in soil water potential, which was more affected than the relative water content. The opening of the stomata was affected by the decrease in soil moisture content, reducing the stomatal conductance, transpiration rate, photosynthesis rate, instantaneous water use efficiency and carboxylation efficiency. The photosynthesis was more affected than transpiration by the reduction in soil moisture content.

Highlights

Water availability is the main factor limiting plant growth and survival in semi-arid region of Brazil
The water deficit, combined with the intensive use of soil and disorderly exploitation of forest resources has led to an advanced soil degradation and desertification, because these factors cause changes in water balance patterns
The main vegetation component of the semi-arid is the Caatinga, that occurs only in Brazil, which covers 844,453 km2, corresponding to 9.92% of Brazilian territory (IBGE 2010). Added to these climatic factors, the soils of the semi-arid region are generally shallow and stony, with low capacity of water retention, making adverse conditions for survival of the vegetal species (Alves et al 2009). In spite of these factors, the Caatinga has a diversity of environments, with generally deciduous, xerophytic and sometimes prickly vegetation (Veloso et al 2002)

Summary

Introduction

Water availability is the main factor limiting plant growth and survival in semi-arid region of Brazil. The main vegetation component of the semi-arid is the Caatinga, that occurs only in Brazil, which covers 844,453 km, corresponding to 9.92% of Brazilian territory (IBGE 2010) Added to these climatic factors, the soils of the semi-arid region are generally shallow and stony, with low capacity of water retention, making adverse conditions for survival of the vegetal species (Alves et al 2009). In spite of these factors, the Caatinga has a diversity of environments, with generally deciduous, xerophytic and sometimes prickly vegetation (Veloso et al 2002) These plants, subject to these environmental conditions that few would support, developed different survival strategies, enabling them to compete for scarce water resources (Dombroski et al 2011). It is the richest dry forest in biodiversity of the world (Holzman 2008), is the Brazilian ecosystem less studied and protected

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