Impacts of LEDs in the Red Spectrum on the Germination, Early Seedling Growth and Antioxidant Metabolism of Pea (Pisum sativum L.) and Melon (Cucumis melo L.)

Cristobal Javier Solano,Gregorio Barba-Espín,Juan Suardíaz,José A Hernández

doi:10.3390/agriculture10060204

Cristobal Javier Solano, Gregorio Barba-Espín + Show 2 more

Open Access

https://doi.org/10.3390/agriculture10060204

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Abstract

(1) Background: In recent years, the use of light emitting diodes (LEDs) for plant production purposes has expanded. However, LEDs’ effect on seed germination and early seedling growth has been scarcely documented. (2) Methods: In this work, the effect of monochromatic red light (RL, 100 µmol m−2 s−1) for up to 60 min applied to seeds of pea and melon was analyzed in terms of seedling growth and antioxidant enzymes levels. An experimental LED chamber coupled to an electronic control system was developed for this purpose. (3) Results: RL did not alter the germination rate, but significantly improved the early seedling growth. Pea and melon seedlings showed the highest increase in fresh weight and length upon 15 min RL treatment of the seeds, whereas longer exposure times decreased seedling growth. Interestingly, RL favored the development of secondary roots in both species, which could favor the nutrition and water uptake by the seedling. The ability of the seedlings to respond to a hypothetical LED irradiance-induced oxidative stress was reflected differently on the antioxidant system of pea and melon. (4) Conclusions: These findings can be relevant for designing seed priming treatments to improve plant vigor, thus enhancing the productivity of important crop plants.

Highlights

Seed germination is a complex biological process determined by genetic, endogenous and environmental factors [1,2]
Light induction of germination is exclusively mediated by phytochrome B and other phytochromes that perceive the red (600–700 nm) to far-red (700–800 nm) ratio [4], being maximally induced by a saturating pulse of monochromatic red light (RL) [5], in which the photoreceptor pigment is activated as a switch between 640 nm and 670 nm
Was developed for testing the effect of specific doses on the germination and early growth was developed for testing the effect of specific RL doses on the germination and early growth of of melon melon and and pea pea seeds

Summary

Introduction

Seed germination is a complex biological process determined by genetic, endogenous and environmental factors [1,2]. Light induction of germination is exclusively mediated by phytochrome B and other phytochromes that perceive the red (600–700 nm) to far-red (700–800 nm) ratio [4], being maximally induced by a saturating pulse of monochromatic red light (RL) [5], in which the photoreceptor pigment is activated as a switch between 640 nm and 670 nm. The photoreversible nature of the phytochrome molecule explains its molecular switch behavior, as demonstrated in different studies conducted in different plants species, including lettuce, Paulownia and Arabidopsis [6,7,8]. The inactive, red-adsorbing phytochrome form becomes active by RL irradiation, which turns again into the inactive form by far-red light [9]. This was first shown on lettuce seeds, where pulses of RL

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