TRINEXAPAC-ETHYL AS CHEMICAL RIPENING AGENT ON SWEET SORGHUM CROP

Resumo

Literary references on the quality of juice of sweet sorghum crop following chemical ripening agents spraying are rarely found up, mostly concerning to the trinexapac-ethyl. Accordingly, this article shares an unpublished content about chemically-induced physiological ripening on the sweet sorghum cv. CMSXS-646 by spraying trinexapac-ethyl before the crop flowering. A CO2-pressurized backpack sprayer, with flat spray nozzles, was employed to exogenously spray the plant growth inhibitor at 0.4, 0.8 and 1.6 l ha-1 on 90-days-old plants. Early after the crop harvesting, juice and lignocellulose samples were technologically assessed to total soluble solids, sucrose, purity, reducing sugars, total reducing sugars, fibers and yield of sugar. Sweet sorghum plants exposured to the trinexapacethyl at 0.4 and 0.8 l ha-1 produced juices with approximately 20.2 and 20.3 °Brix, 15.1 and 13.2% sucrose, 74.6 and 64.9% purity, as well as 107.7 and 98.2 kg t-1 sugar, respectively. Unlike, plants cultivated as control, juices with 21.0 °Brix, 16.0% sucrose, 76.9% purity and 118.0 kg t-1 sugar. Therefore, trinexapac-ethyl had suppressive effect on the quality of juice, mostly regarding to the total soluble solids and yield of sugar. Plants sprayed with trinexapac-ethyl at 1.6 l ha-1 developed the most fibrous stalks, as host-defense system response to stress induced on plant physiology. The conclusion is, therefore, that although does prejudices the quality of juice, making it unsustainable to the production of first-generation ethanol, trinexapac-ethyl as chemical ripening agent could lead the sweet sorghum cv. CMSXS-646, while lignocellulose renewable source, to the industrialization of cellulosic ethanol and bioelectricity.