Smoke-Water Enhances Germination and Seedling Growth of Four Horticultural Crops

Abstract

The impact of plant-derived smoke as a promoter of seed germination in many crops is well documented. However, very little is known about (1) the appropriate plant species for smoke-water preparation, (2) the effect of smoke-water on the germination and the post-germination parameters in non-fire-prone environments, and (3) the relative importance of dark and light conditions and their possible effects. To fill these gaps in knowledge, we conducted field experiments to evaluate the effect of smoke-water produced from five plant species—white willow, sage, rice straw, rosemary, and lemon eucalyptus—on the germination and seedling growth of cucumber, tomato, scotch marigold, and gladiolus. The seeds and cormels were soaked in smoke-water under light or dark conditions. The results revealed that the smoke-water treatments derived from white willow and lemon eucalyptus enhanced germination, post-germination parameters, and macro element content whilst also contributing to dormancy-breaking. In addition, these smoke-water treatments significantly reduced abscisic acid content and increased α-amylase activity under light conditions; however, the stimulating effects were absent under dark conditions. In conclusion, we provide new evidence that germination and seedling growth in non-fire-prone environments can be enhanced by plant-derived smoke, and that stimulating impacts depend on the plant species used to prepare the smoke-water.

Plant-Derived Smoke Affects Biochemical Mechanism on Plant Growth and Seed Germination

“…Smoke-water-treated tomato seedlings exhibited a remarkable increase in growth and yield [ 34 ]. Seedling mass was reported to be enhanced by smoke treatment in lettuce and cucumber [ 17 , 35 ]. Plant-derived smoke showed a promoting effect on edible banana by increasing the number of shoots [ 36 ], while, in onion, number, length and mass of leaves, and bulb diameter and weight was also increased in response to smoke treatment [ 35 ].…”

“…Seedling mass was reported to be enhanced by smoke treatment in lettuce and cucumber [ 17 , 35 ]. Plant-derived smoke showed a promoting effect on edible banana by increasing the number of shoots [ 36 ], while, in onion, number, length and mass of leaves, and bulb diameter and weight was also increased in response to smoke treatment [ 35 ]. Growth enhancement in horticultural crops suggested the possible use of smoke technology for cultivation and improvement of these crops.…”

Multi-Omics Strategies for Decoding Smoke-Assisted Germination Pathways and Seed Vigour

“…Studies have shown the impact of smoke originating from wildfire to restore the vegetation of fire-prone native species in the Mediterranean region [ 31 ]; Australia [ 32 ]; South Africa [ 33 ]; California [ 34 ]; and, the Mediterranean basin [ 35 ]. Additionally, its positive impact on the germination of cereal crops [ 2 , 36 ]; weed species [ 1 ]; horticultural crops [ 14 ]; and medicinal plants [ 37 ] has also been confirmed. The smoke-dependent germination process improves germination success across phylogenetically diverse plant groups including gymnosperms; angiosperms [ 33 ]; annuals; bi-annuals; short-lived species; and, perennial herbs [ 38 ], in different weather regions around the globe from tropical to the fire-prone Mediterranean region, disturbed habitats, representing a broad array of fire-prone environments [ 30 , 32 ].…”

“…The smoke-dependent germination process improves germination success across phylogenetically diverse plant groups including gymnosperms; angiosperms [ 33 ]; annuals; bi-annuals; short-lived species; and, perennial herbs [ 38 ], in different weather regions around the globe from tropical to the fire-prone Mediterranean region, disturbed habitats, representing a broad array of fire-prone environments [ 30 , 32 ]. Smoke has been used as an effective mediator to release dormancy in the laboratory [ 39 ] and field conditions [ 14 ]. Altogether, the germination response to smoke is not just associated with plant traits such as habitat requirements, seed bank, type, life form, and seed morphology, but also the chemical stimuli that alleviate the dormancy state.…”

“…KARs have been shown to interact with plant phytohormones and currently unknown transcription factor (TF)-like proteins to process endogenous signals for dormancy breakdown and seedling vigour process [ 9 , 10 , 11 ]. To understand the smoke-assisted regulatory pathways in model and non-model species, large scale genomic screening studies along with targeted experiments have been conducted [ 12 , 13 , 14 , 15 ]. These studies were often designed to generate and analyse each dataset in isolation—ignoring the possible interactions between the underlying biomolecules—resulting in findings independent of one another.…”