Gas exchange and millet phytomass under organic fertilization and graywater irrigation

José R I Silva,Aldo T Sales,Maurício L De M V Leite,Eduardo Souza,Antônio C D Antonino,Genival Barros Junior

doi:10.1590/1807-1929/agriambi.v26n2p111-118

Abstract

ABSTRACT Graywater is an alternative method to increase the water supply for agricultural production in semi-arid regions. The objective of this study was to evaluate the effects of different irrigation depths of graywater on the gas exchanges and phytomass of millet plants with and without organic fertilization. The research was conducted under greenhouse conditions in Serra Talhada municipality in semiarid region of Brazil, in a randomized complete block design with a factorial (4 × 2 + 1) plot and three replicates. The first factor corresponded to graywater irrigation depth equivalent to 25, 50, 75 and 100% of the available water content of the soil, and the second factor was the addition of bovine manure as fertilizer (0 and 34 Mg ha-1), and a control (irrigation with low-salinity water). Irrigation with graywater effluent did not promote adverse effects on gas exchanges and phytomass accumulation; however, it also did not provide enough nutrients to promote increase in these variables. The reduction in irrigation depth caused a decrease in gas exchange from 45 days after the application of the treatments. The basal tiller mass was the most favored plant component due to organic fertilization.

Highlights

The irregularity of rainfall is the main factor limiting agricultural and livestock production in semi-arid regions
Graywater effluent is useful for agriculture as it does not receive waste from latrines; it has a low content of organic matter and pathogenic organisms (Leong et al, 2017)
From evaluation of gas exchanges at 15, 30, 45, and 60 days after the application of treatments (DAT), there was no interaction between treatments for the simple effect of organic fertilization with or without bovine manure (Table 2)

Summary

Introduction

The irregularity of rainfall is the main factor limiting agricultural and livestock production in semi-arid regions. The use of wastewater for irrigation is a management strategy aimed to minimize the impact of water scarcity (Leonel & Tonetti, 2021). A decrease in the volume of water applied to crops can cause disturbances in physiology (stomatal closure) and metabolism (accumulation of compatible osmolytes and production of reactive oxygen species [ROS]) in plants (Zhang et al, 2013; Chaves et al, 2016). These alterations reduce CO2 uptake, slow down the Calvin cycle and interfere with plant growth (Liu et al, 2020)

Objectives

Methods

Results

Conclusion