The Use of Ecological Hydromulching Improves Growth in Escarole (Cichorium endivia L.) Plants Subjected to Drought Stress by Fine-Tuning Cytokinins and Abscisic Acid Balance

Miriam Romero-Muñoz,Alfonso Albacete,Josefa López-Marín,Francisco M Del Amor,María Carmen Piñero,Amparo Gálvez

doi:10.3390/agronomy12020459

Miriam Romero-Muñoz, Alfonso Albacete + Show 4 more

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https://doi.org/10.3390/agronomy12020459

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Abstract

Drought is considered as one of the major limiting factors to plant growth and productivity. Drought stress reduces stomatal conductance, affecting water relations and decreasing CO2 assimilation rate and photosynthesis. Several strategies have been developed to alleviate the negative effects of drought in the agricultural industry. One of these strategies is the use of the mulching technology, which retains water in the soil surface. Knowing that hormones play a key role in plant growth and drought stress responses, we hypothesized that the use of a new ecological mulching technology called hydromulching would improve growth over bare soil under drought stress through changes in the hormonal balance. To test this hypothesis, escarole plants (Cichorium endivia L.) were grown in pots filled with coco fiber, non-covered (bare soil) or covered with polyethylene film (PE) and three types of hydromulches made up with recycled additives: wheat straw (WS), rice hulls (RH), and substrate used for mushroom cultivation (MS). Half of the plants were subjected to drought by reducing the volume of irrigation water to 70% of crop evapotranspiration. Despite drought stress impaired escarole growth-related parameters in all treatments, plants mulched with MS maintained significantly superior growth, due to improved plant water relations and photosynthetic function. This can be explained by an efficient interaction hydromulch/soil/plant in regulating the hormonal balance under water depletion. Indeed, the concentrations of the active cytokinins (CKs), trans-zeatin and isopentenyladenine, were higher in plants grown with MS treatment, associated with shoot growth-enhancing and photosynthetic rate maintenance under stress conditions. The concentrations of the stress-related hormone, abscisic acid (ABA), varied antagonistically to those of the active CKs. In this regard, ABA increased with drought but to a lower extent in MS plants thus regulating stomata opening, which, in crosstalk with the ethylene precursor 1-aminocyclopropane-1-carboxylic acid and salicylic acid, improved plant water relations. The results obtained demonstrate that hydromulching is an efficient and sustainable management strategy to ameliorate the drought effects on escarole plants through fine regulation of the CKs/ABA balance, which will be of utmost interest and applicability in the actual climate change scenario.

Highlights

IntroductionThe reduction in freshwater resources and the imbalanced distribution of water are becoming critical problems that limit global agricultural production [1]
With global climate change, the reduction in freshwater resources and the imbalanced distribution of water are becoming critical problems that limit global agricultural production [1]
Leaf area, which is a developmental parameter related to the gas exchange capacity of the plant, significantly increased in plants grown with mushroom substrate-based hydromulch (MS) under both well-irrigated and drought-stressed conditions by 43% and

Summary

Introduction

The reduction in freshwater resources and the imbalanced distribution of water are becoming critical problems that limit global agricultural production [1]. Modern agriculture has to increase yields and product quality while reducing environmental impacts. It is urgent to improve crop productivity with concomitant conservation of water resources and environmental safety to justify the demand for more yield per drop of water [2]. There is a dire need to adopt appropriate technologies to conserve the water in the soil profile and its best possible utilization for plant growth [3,4]. Mulching technology in horticultural crops is a very common practice to cope with the scarcity of water, apart from other agronomic benefits, such as soil temperature maintenance, weed control, reduction of soil erosion, etc. Mulching technology in horticultural crops is a very common practice to cope with the scarcity of water, apart from other agronomic benefits, such as soil temperature maintenance, weed control, reduction of soil erosion, etc. [5,6]

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