engleski

New type of biofertilizers: microspheres/microcapsules loaded with chemical and biological agents

Trends of encapsulation in agriculture are focused on the preparation of microcapsule formulations involving two active agents. Despite numerous methods of chemical agent encapsulation, there are only a few data in the literature about simultaneous encapsulation and delivery of biological and chemical agents. The main problems that should be solved here are: (i) to choose microcapsules that can incorporate biological and chemically active agents and (ii) the presence of active agents in the same compartment should not diminish their activities. Due to benefits of crop protection and nutrition as well as high compatibility, Trichoderma viride (STP) spores and copper or calcium ions were taken as a suitable couple of the chemical and biological agent. We have developed and characterized alginate microspheres and microcapsules (with chitosan layer) prepared by the ionic gelation using copper or calcium cations as a crosslinking agent and loaded with T. viride spores. Simultaneous loading in microspheres/microcapsules revealed that presence in the same compartment does not inhibit activity either of T. viride spores nor gelling cations. Controlled release that is the successful delivery of active agents at the right place and the right time is necessary characteristic for all bioactive agents’ delivery systems. To obtain the well- designed delivery system efficient for simultaneous loading and releasing active agents to plants at the rate that closely approximates plant demand, it is important to optimize parameters during microsphere/microcapsule preparation. The concentration of gelling cation, microsphere/microcapsule size, and presence of chitosan layer was considered as variables with possible influence on the essential microsphere/microcapsule parameters. The gelation of a fixed amount of sodium alginate at different concentrations of gelling cation in solution resulted in distinct kinetics and release mechanisms. The increase in the concentration of gelling cation promoted, but the presence of the chitosan layer on microsphere/microcapsule surface and increase in their size reduced the rate of an active agent release. Fitting to simple Korsmeyer– Peppas empirical model revealed the underlying release mechanism depends on the concentration of gelling cation and presence of T. viride spores as well as chitosan layer. The investigation pointed out that proper selection of formulation variables helps in designing microspheres/microcapsules with the controlled release of gelling cations and T. viride for plant protection and nutrition.

microspheres/microcapsules, Trichoderma viride (STP), releasing, nutrition, protection

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