The Interplay between Light Quality and Biostimulant Application Affects the Antioxidant Capacity and Photosynthetic Traits of Soybean (Glycine max L. Merrill).

Ermenegilda Vitale,Teresa Capriello,Carmen Arena,Violeta Velikova,Ida Ferrandino,Tsonko Tsonev

doi:10.3390/plants10050861

Abstract

This paper evaluates the combined effect of biostimulant and light quality on bioactive compound production and seedling growth of soybean (Glycine max L. Merrill) plants. Germinated seeds pre-treated with different concentrations (0.01%, 0.05%, 0.5%) of an amino acid-based biostimulant were grown for 4 days at the dark (D), white fluorescent light (FL), full-spectrum LED (FS), and red-blue (RB) light. Potential changes in the antioxidant content of sprouts were evaluated. Part of the sprouts was left to grow at FL, FS, and RB light regimes for 24 days to assess modifications in plants’ anatomical and physiological traits during the early developmental plant stage. The seed pre-treatment with all biostimulant concentrations significantly increased sprout antioxidant compounds, sugar, and protein content compared to the control (seeds treated with H2O). The positive effect on bioactive compounds was improved under FS and RB compared to D and FL light regimes. At the seedling stage, 0.05% was the only concentration of biostimulant effective in increasing the specific leaf area (SLA) and photosynthetic efficiency. Compared to FL, the growth under FS and RB light regimes significantly enhanced the beneficial effect of 0.05% on SLA and photosynthesis. This concentration led to leaf thickness increase and shoot/root ratio reduction. Our findings demonstrated that seed pre-treatment with proper biostimulant concentration in combination with specific light regimes during plant development may represent a useful means to modify the bioactive compound amount and leaf structural and photosynthetic traits.

Highlights

In the last decades, agricultural practices are changing to meet the increasing market demand in response to the nutritional requirements of a growing population
The light modulation approach allows an in-depth understanding of the photosynthetic responses to different light wavelengths [4,5] as well as the plant potentiality to produce bioactive compounds induced by diverse light quality treatments [6]
Kaishi and the light quality regimes (LQ) regime during plant growth, as single factors or in interaction, strongly influenced the bioactive compound synthesis in sprouts producing an enrichment of antioxidant capacity, protein, and carbohydrate amount compared to the controls

Summary

Introduction

Agricultural practices are changing to meet the increasing market demand in response to the nutritional requirements of a growing population. This high production of food is leading to an overexploitation of the resources, especially of the soil, exacerbated by climate changes [1]. The primary outcomes agree that red and blue wavelengths are absorbed in the top of the leaves/canopy and are the most used regions of the light spectrum driving the photosynthetic process, biomass accumulation, shoot elongation, root development, stomata opening/closing regulation mechanism, pigment and polyphenol synthesis [7,12,13,14,15]. The choice of specific wavelengths matching plant photoreceptors can determine plant morphology, physiology, and metabolism, allowing us to define suitable light fertilization protocols [17]

Objectives

Methods

Discussion

Conclusion