Plant-derived smoke: Old technology with possibilities for economic applications in agriculture and horticulture

Fire and smoke have been used in traditional agricultural systems for centuries. In recent years, biologically active compounds have been isolated from smoke with potential uses in agriculture and horticulture. This article highlights the possibilities of using smoke-water or smoke-derived butenolide (3-methyl- 2H-furo[2,3- c]pyran-2-one, termed karrikinolide, KAR 1) for the cultivation of agricultural and horticultural crops. Treatments with smoke-water show promising results for improving seed germination, seedling growth and crop productivity. In certain cases, even under adverse conditions, such as low or high temperatures and low osmotic potentials, smoke-water or a KAR 1 solution can promote seed germination and seedling growth. This phenomenon is of great significance when seeds are sown under drought conditions. Smoke-technology, therefore, has potential for use in arid and semi-arid regions. Possibilities may also exist for controlling some plant diseases and managing weeds with the use of smoke or KAR 1 solutions. In addition, smoke-technology can possibly economize the use of commercial chemical fertilizers, pesticides and herbicides, making it a feasible technology for organic farming and for resource-poor farmers in developing nations. The positive role of smoke-water in flowering and fruiting of crops cannot be overlooked as the karrikins found in smoke are now recognized as potential new plant growth regulators. Very low concentrations of smoke-water or a KAR 1 solution are effective in promoting germination and post-germination growth. Thus, early harvesting and increasing the productivity of crops using smoke-technology may be possible. Here we review some of the effects of smoke and KAR 1 on various crop species and discuss the potential uses of smoke technology in agriculture and horticulture. ► Smoke has the potential to become an important tool in agriculture and horticulture. ► Smoke improves seed germination and seedling growth of many plant species. ► Smoke solutions may be useful under adverse environmental conditions. ► Smoke-technology may economize input of fertilizers, pesticides and herbicides.