Abstract
ABSTRACT This study aimed to evaluate the gas exchanges and photosynthetic pigments of soursop seedlings cv. ‘Morada Nova’ irrigated with saline waters and subjected to exogenous application of hydrogen peroxide by seed soaking and foliar spraying. The study was carried out using plastic bags under greenhouse conditions at the Center of Technology and Natural Resources of the Federal University of Campina Grande, PB, Brazil, using a eutrophic Regolithic Neosol of sandy loam texture. Treatments were arranged in a randomized block design, in 5 x 5 factorial scheme, which consisted of five levels of electrical conductivity – ECw (0.7; 1.4; 2.1; 2.8 and 3.5 dS m-1) of irrigation water and five concentrations of hydrogen peroxide - H2O2 (0, 25, 50, 75 and 100 µM), with four replicates and three plants per plot. As the salt stress increased, there were reductions in internal CO2 concentration, instantaneous carboxylation efficiency and water use efficiency, and instantaneous carboxylation efficiency was the most sensitive variable. Hydrogen peroxide at concentrations of 25 and 50 µM attenuated the deleterious effects of water salinity on stomatal conductance, CO2 assimilation rate and chlorophyll a content, and the concentration of 25 µM was the most efficient. The content of chlorophyll b and carotenoids of soursop cv. ‘Morada Nova’ had the deleterious effects caused by the salinity of irrigation water mitigated by the exogenous application of hydrogen peroxide in the concentration of 25 μM.
Highlights
Soursop is a fruit crop that has stood out for having potential of commercialization in the domestic market, with relevant economic importance and prospects for export, and the northeast region of Brazil is the largest producer (Braga Sobrinho, 2010; Cavalcante et al, 2017)
In the semi-arid region of Northeast Brazil, where the low rainfall levels unevenly distributed along the year are limiting factors for agricultural production, the practice of irrigation is the only way to guarantee a cultivation with water security (Lacerda et al, 2016)
This study aimed to evaluate the gas exchanges and photosynthetic pigments of soursop seedlings cv
Summary
Soursop is a fruit crop that has stood out for having potential of commercialization in the domestic market, with relevant economic importance and prospects for export, and the northeast region of Brazil is the largest producer (Braga Sobrinho, 2010; Cavalcante et al, 2017). Studies have been conducted using saline waters for cultivation in the Northeast region, for instance of sugar apple (Sá et al, 2015), citrus (Barbosa et al, 2017) and guava (Bezerra et al, 2018). It is extremely important to conduct research aiming to assess other fruit crops such as soursop, because studies involving the use of saline water in its cultivation are scarce
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