Eco-organic system and silicon-based biostimulant as a strategy for vegetable production under multistress conditions in South Africa: A review

Abstract: Plants get exposed to multiple stresses throughout their phenological growth stages. At most, these stresses are attributed to single or combined stresses like salinity, water deficits, wounding, mineral deficiencies, potting bag size, soil/root media density and type, soil pH, and the type of production system employed. Multistress factors have been widely reported to reduce the plant growth and development, strength, yield, and quality of horticultural crops globally. In the literature, reports extensively recommended the use of silicon-based biostimulants to improve the growth and development of commercial horticultural plants; however, little has been reported in South Africa on the recovery response mechanisms of beetroot (Beta vulgaris L.), lettuce (Lactuca sativa L.), tomato (Solanum lycopersicum L.), and kale (Brassica oleracea L.) grown under multi-stress conditions treated with silicon-based biostimulants, and using the cheaper eco-friendly production systems. In South Africa, most silicon-based biostimulant production companies reserve their novel concoctions as their company secrets; thus, many of the products are never tested in public to ascertain and monitor compliance with the Fertilizers, Farm Feeds, Agricultural Remedies, and Stock Remedies Act 36 of 1947 in South Africa. On the other hand, emerging farmers and smallholder growers are failing to afford existing agricultural insurance options, thereby affecting their yields against the commercially developed farmers. Although the government aids farmers, the assistance does not cover all costs associated with the multistress losses. Some farmers and growers adopted advanced production systems; however, at most, these systems are costly and rely primarily on electricity as a source of power, which is a challenge in South Africa. This paper explains various production systems used by commercial and emerging farmers, and the smallholder growers in South Africa to reduce costs related to multistress losses. Moreover, an alternative eco-organic production system that applies silicon-based biostimulant as a novel idea for commercial vegetables grown under extreme multi-stress conditions is recommended for emerging farmers and smallholder growers in South Africa. Future studies should be based on eco-friendly production systems in vegetable production in line with Sustainable Development Goals, to combat poverty and improve the livelihood of the African countries.