With the end of the test period and the release of new hybrids, sweet sorghum is close to become the responsible for increasing the time of operation of ethanol plants, reaching up to 60 days. However, farmers and mill owners do not have enough information about methods of crop management as tools for weed management. Because the request of studies about weeds in the context of the culture of sweet sorghum, this project has two objectives: * to determine the critical period of interference prevention (CPIP) and study the phytosociology of the weed community in two sweet sorghum hybrids, both grown in two seasons; * study the suppression of sweet sorghum on reinfestation of weeds in the following crop. In order to reach the first objective, will be carried out four field trials with weekly periods of coexistence and weed control for determining the CPIP, besides phytosociological studies of weeds present. In these trials, will be study two hybrids with different morphological characteristics and grown in two positioning times (sowing in July and November). In the study of suppression, will be assessed the reinfestation of weeds and the emergence fluxes of soil seed bank in production areas that have residues of sweet sorghum harvest on the soil surface in comparison with four other covers. In this case, it is expected that the sweet sorghum provides an area with reduced weed infestation for the following crop (sugarcane). Once noticed presence of allelopathic effects in sweet sorghum residues (roots, leaves and panicles), each one of the three materials will be milled and, at qualified laboratory, the extraction, fractionation and isolation of allelochemicals will be make to try to prove the allelopathy potential.
News published in Agência FAPESP Newsletter about the scholarship: