Seed priming has been shown to improve seed performance under sub-optimal temperature conditions (Lin and Sung, 2001). Priming increases the environmental range suitable for germination, and provides faster and synchronous seedling emergence (McDonald, 1999). Common priming methods such as polyethylene glycol (PEG) treatment are not suitable for large scale cereal crop production because farmers in developing countries could not cover the costs.
The Multifunctional Role of Chitosan in Horticultural Crops: A Review
Chitosan is a naturally occurring compound and is commercially produced from seafood shells. It has been utilized in the induction of the defense system in both pre and post-harvest fruits and vegetables against fungi, bacteria, viruses, and other abiotic stresses. In addition to that, chitosan effectively improves the physiological properties of plants and also enhances the shelf life of post-harvest produces.
Fragments from chitin and chitosan are known to have eliciting activities leading to a variety of defense responses in host plants in response to microbial infections, including the accumulation of phytoalexins, pathogen-related (PR) proteins and proteinase inhibitors, lignin synthesis, and callose formation. Based on these and other proprieties that help strengthen host plant defenses, interest has been growing in using them in agricultural systems to reduce the negative impact of diseases on yield and quality of crops. This review recapitulates the properties and uses of chitin, chitosan, and their derivatives, and will focus on their applications and mechanisms of action during plant-pathogen interactions.
Chitosan Effects on Plant Systems
Chitosan (CHT) is a natural, safe, and cheap product of chitin deacetylation, widely used by several industries because of its interesting features. The availability of industrial quantities of CHT in the late 1980s enabled it to be tested in agriculture. CHT has been proven to stimulate plant growth, to protect the safety of edible products, and to induce abiotic and biotic stress tolerance in various horticultural commodities. The stimulating effect of different enzyme activities to detoxify reactive oxygen species suggests the involvement of hydrogen peroxide and nitric oxide in CHT signaling. CHT could also interact with chromatin and directly affect gene expression. Recent innovative uses of CHT include synthesis of CHT nanoparticles as a valuable delivery system for fertilizers, herbicides, pesticides, and micronutrients for crop growth promotion by a balanced and sustained nutrition. In addition, CHT nanoparticles can safely deliver genetic material for plant transformation. This review presents an overview on the status of the use of CHT in plant systems.
Chitosan Biopolymer Promotes Yield and Stimulates Accumulation of Antioxidants in Strawberry
Chitosan, a biopolymer chemically derived from crustaceans and soluble in organic acids is one of a range of natural compounds that has shown efficacy against diseases in strawberries and other crops. It is considered environment-friendly for agricultural uses as it is easily degraded in the environment, and nontoxic to humans.
Consumption of strawberries, blueberries and brambles as fresh fruit containing bioactive compounds has gone up substantially during last decades due to their proven health benefits. Recent findings from several studies suggest that dietary sources of these bioactive compounds are highly beneficial to the health of humans. Strawberries are among the best sources of bioactive compounds containing anthocyanins, carotenoids, vitamins, flavonoids and phenolics with remarkable capacity of antioxidant activities. Antioxidant capacity in strawberry fruit, however, directly or indirectly dependent on the level of flavonoid groups such as flavanols and anthocyanins. Better health benefits to the consumers of strawberry can be obtained from elevated levels of these secondary metabolites.
Excessive use of synthetic agrochemicals for enhancing fruit yield and contents of secondary metabolites led to serious environmental and health concerns especially in commodities like strawberries that are consumed fresh.