Encapsulation of seeds with biopolymers for increased efficiency of direct sowing in forest restoration projects

Abstract

In order to fulfill the international restoration commitments assumed by the Brazilian Government and to recover the 12.5 Mha provided for in the Decree No. 8,972 / 2017, it will be necessary to reduce costs and improve the efficiency of revegetation processes. Direct sowing has been considered as a technology applicable to rural producers that can contribute to reducing the deficit of restoration. However, the techniques employed require a great quantity of seeds due to the low establishment of the species. The encapsulation of seeds with the use of polymers can contribute to the success in the establishment of the forest species by direct sowing. The objective of this project is to develop technologies that generate greater efficiency and utilization of forest seeds in direct sowing in order to reduce the costs of restoration. For this, the development of biodegradable polymers by the technique of hierarchical crosslinking will be developed as a way of preventing adverse environmental conditions to the germination and establishment of native forest seeds. The alginic acid (sodium alginate) is an excellent alternative for seed coatings, since they are natural polysaccharides extracted from marine algae, which make it possible to obtain hollow pearls capable of encapsulating seeds in water or in a nutrient medium that favors the germination of the seed encapsulated. These pearls can be designed to withstand dry soil in environments with low relative humidity and to absorb water when irrigated (artificially) or by rain (naturally) releasing the seed. For the purposes of this project, it is intended to improve the mechanical and functional performance of alginate beads using waste from the wine industry and grape juice (bark and / or seeds). In the Sorocaba macroregion, the municipality of São Roque is known for the production of this fruit. Most of the grape processing industries in Brazil are wineries that consider grape marc as a byproduct. These agroindustrial wastes may be an important source of polymers for such seed treatments. This residue after drying under controlled conditions can be pulverized and mixed to the polysaccharide forming a blend that improves the mechanical strength and chemical properties of the beads that will be used in the restoration via direct sowing. For this purpose, polysaccharides mixed with grape marc powder (bark and / or seeds) will be tested to encapsulate seeds destined to the recovery of degraded areas by means of direct seeding. This innovative and environmentally friendly process will be compared with the use of semi-synthetic polymers derived from cellulose associated or not with vinyl polymers as well as with alginate beads without the use of grape marc. Such treatments will be tested in the laboratory and in prospecting in the field. In this way, it is also intended to contribute to loss reduction, value adding, diversification of processing to obtain new products and establishment of partnerships. (AU)