Control of Substrate Water Availability Using Soil Sensors and Effects of Water Deficit on the Morphology and Physiology of Potted Hebe andersonii

Daniel Bañón,María Jesús Sánchez-Blanco,María Fernanda Ortuño,Sebastián Bañón,Beatriz Lorente,Juan José Alarcón

doi:10.3390/agronomy12010206

Abstract

Many plant producers tend to overwater crops to prevent water stress and salt-induced damage. These practices waste irrigation water and cause leaching that harms the environment and increases production costs. In order to optimize water consumption and minimize the environmental impact of plant production, this study aimed to determine the physiological and morphological responses of Hebe andersonii to three substrate volumetric water contents (49%, 39%, and 32%). The experiment was conducted in a greenhouse with an irrigation protocol that consisted of adding small volumes of water to avoid leaching while monitoring substrate moisture with dielectric soil sensors. The results showed that moderately low substrate moisture improved the water-use efficiency, while growth was significantly reduced under more severe water deficit conditions (but without leaf chlorosis or abscission). The photosynthetic activity of Hebe was primarily controlled by the stomatal aperture, which was co-determined by the substrate moisture and seasonal temperature. Hebe leaves promoted non-photochemical quenching when carbon assimilation was limited by a water deficit, and accumulated solutes through an osmotic adjustment process (especially Cl−, Na+, and K+) to maintain their water status. Overall, Hebe andersoni cv. Variegata could successfully grow and improve its water-use efficiency in low substrate moisture and under a non-draining irrigation regime.

Highlights

IntroductionManaging the irrigation of potted crops is a complex task because substrates can dry out due to their low water retention capacity and the small volume of the containers [1]
Managing the irrigation of potted crops is a complex task because substrates can dry out due to their low water retention capacity and the small volume of the containers [1].These conditions lead many ornamental plant producers to overwater their crops in order to avoid drought, while others irrigate the potting substrate to full container capacity to maximize growth, regardless of the plant’s water requirements
Evapotranspiration equaled the water consumption per day and per plant since no leaching was produced during irrigation and, water consumption was entirely due to evapotranspiration

Summary

Introduction

Managing the irrigation of potted crops is a complex task because substrates can dry out due to their low water retention capacity and the small volume of the containers [1] These conditions lead many ornamental plant producers to overwater their crops in order to avoid drought, while others irrigate the potting substrate to full container capacity to maximize growth, regardless of the plant’s water requirements. Salt flushing presents the disadvantage of draining away fertilizers, leaving them unavailable to the plant and diminishing vegetative development [3,5] Another drawback is that the discharge of pesticides and other chemical pollutants commonly found in agricultural drainage is likely to violate environmental policies [6]. Such arguments, added to increasing consumer demands, are promoting plant production based on environmentally friendly practices

Objectives

Methods

Results

Conclusion