Preparation and Standardisation of Smoke-Water for Seed Germination and Plant Growth Stimulation

Abstract

Smoke-water (SW) has a positive effect on seed germination in many plant species and its application in various fields of plant science has become popular. The method of preparing SW is relatively easy and inexpensive. However, many researchers working in the field of smoke biology are still unfamiliar with preparing SW and testing it for bioactivity. Thus, the aim of this study was to develop a low-cost efficient apparatus to produce SW using grasses, its standardisation and quantification of major active biomolecules. The prepared crude SW was diluted with distilled water (SW:DW) to 75:25, 50:50 and 25:75 (v/v) and these sub-dilutions were further diluted to 1:500; 1:1000; 1:1500; 1:2000; 1:2500; 1:3000 and 1:3500 (v/v). For the standardisation of SW, lettuce seeds (Lactuca sativa L. cv. Grand Rapids) were tested to determine the best working concentration. The ratio 1:2500 (v/v) from the sub-dilution 25:75 (v/v) of SW was the best for germination of lettuce seeds in the dark, achieving 91% germination against the water control that had only 7–10% germination. This is the first study which reports the levels of stimulatory (karrikinolide 1, KAR1 and karrikinolide 2, KAR2) and inhibitory (trimethylbutenolide, TMB) compounds present in SW using ultrahigh-performance liquid chromatography–electrospray positive ionisation tandem mass spectrometry (UHPLC-ESI(+)-MS/MS).