Corrective phosphate application as a practice for reducing oxidative stress and increasing productivity in sugarcane

Emídio Cantídio Almeida De Oliveira,Fernando José Freire,Ariane Márcia De Sousa Silva,Lilia Gomes Willadino,Alexandre Tavares Da Rocha

doi:10.5935/1806-6690.20190022

Emídio Cantídio Almeida De Oliveira, Fernando José Freire + Show 3 more

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https://doi.org/10.5935/1806-6690.20190022

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Abstract

Corrective phosphate application increases the levels of phosphorus (P) in the surface layer of the soil, stimulates plant root growth and increases the volume of soil exploited for water and nutrient uptake, which may reduce abiotic oxidative stress in sugarcane. The aim of this study was to evaluate the productivity and the response of the antioxidant enzyme system in sugarcane when grown in soil that received corrective phosphate application, using doses and sources of P of varying solubility. The experiment was conducted under field conditions in the southern Forest Zone of the State of Pernambuco, Brazil. The treatments were arranged in a randomised block design, in a (4 × 3) +1 factorial scheme with four replications. The factors consisted of a control (with no phosphate application) and the doses (50, 100, 200 and 300 kg P2O5 ha-1 ) and sources (reactive natural phosphate, triple superphosphate and sugarcane press mud) of P applied during the pre-planting stage of the plant cane cycle. The P content of the leaf tissue was considered adequate, and was not influenced by the phosphate application. Phosphate application at an estimated dose of 150 kg P2O5 ha-1 reduced antioxidant enzyme activity and increased shoot dry matter (SDM) by 25.0% and stalk productivity by 8.5%. Superoxide dismutase (SOD) showed the highest positive correlation coefficient with the other antioxidant enzymes, and a negative correlation with SDM, and can be used to evaluate abiotic stress that promotes reductions in sugarcane productivity.

Highlights

Plants under natural conditions may often be subjected to multiple stress, such as water deficit, salinity, high temperatures, brightness and a deficiency or excess of nutrients
The toxic effect promoted by reactive oxygen species (ROS) in plant cells is suppressed or reduced by the defence mechanism that acts by activating the antioxidant enzyme system (WILLADINO et al, 2011), which includes activation of the enzymes superoxide dismutase (SOD), responsible for converting the superoxide radical into hydrogen peroxide; ascorbate peroxidase (APX), which eliminates hydrogen peroxide using ascorbic acid as a reducing agent; and catalase (CAT), which converts two molecules of hydrogen peroxide into water and molecular oxygen (NOCTOR; FOYER, 1998)
The P content of the leaves varied between 3.3 and 4.1 g kg-1 for the two periods under evaluation, and can be considered adequate for the cycle of the plant cane, since they were superior to those obtained by Santos et al (2013), who determined as optimal a content of from 2.5 to 2.8 g kg-1

Summary

Introduction

Plants under natural conditions may often be subjected to multiple stress, such as water deficit, salinity, high temperatures, brightness and a deficiency or excess of nutrients. Plant exposure to abiotic stress can lead to disturbances in physiological processes caused by the extreme generation of reactive oxygen species (ROS) (LAWLOR, 2013; MITTLER et al, 2011). The production and accumulation of ROS, such as the superoxide radicals (O2-), hydrogen peroxide (H2O2) and the hydroxyl radical (OH-), modifies organic molecules and results in damage to cells and tissue, leading to cell death (GUNES et al, 2007). The toxic effect promoted by ROS in plant cells is suppressed or reduced by the defence mechanism that acts by activating the antioxidant enzyme system (WILLADINO et al, 2011), which includes activation of the enzymes superoxide dismutase (SOD), responsible for converting the superoxide radical into hydrogen peroxide; ascorbate peroxidase (APX), which eliminates hydrogen peroxide using ascorbic acid as a reducing agent; and catalase (CAT), which converts two molecules of hydrogen peroxide into water and molecular oxygen (NOCTOR; FOYER, 1998). Yao et al (2011), working with canola genotypes, found that higher concentrations of phosphorus (P) in the tissue promoted the formation of less ROS, and that P deficiency resulted in more of the toxic oxygen species being formed

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