FIBRE SORGHUM: INFLUENCE OF HARVESTING PERIOD AND BIOLOGICAL CYCLE ON YIELD AND DRY MATTER IN SOME HYBRIDS

The EU energy policy requires a gradual in- crease of the energy quota obtained from sustainable sources, in response to concerns about the difficulties of energy supply and environmental pollution. In this situa- tion so careful to these environmental problems are open- ing up new prospects involving the use of biomass from wood and cellulose residue or from crops grown express- ly cultivated. In the development of agricultural biomass for energy use some interest has been reserved for the fi- bre sorghum, annual and photosynthetic efficiency plant (C4), with low inputs farming techniques and resistant to water stress. Field experiments were carried out in a five year period (2001-2005) at the Inviolatella Farm of the CRA-QCE at Rome. This paper compares three genotypes of fibre sorghum characterized by different maturity class- es: H128 (early maturing), H133 (early-medium maturing) and H132 (late-maturing), in order to establish the opti- mal harvesting period in the environmental condition of Central Italy and maximize the yield of dry matter (bio- mass) avoiding an excessive moisture content and risks of stem lodging. Were investigated the effect of four differ- ent harvest dates (0,7,14 and 21 days after flowering). The results of statistical analysis showed that the late-maturing hybrid H132 was more productive (28.9 t ha -1 ) but har- vested of autumnal season, runs the risk of an unsuitable field drying. Early and early-medium maturing hybrid (H128 and H133) harvesting 7 or 14 days after flowering were the best compromise between yield and a safer and shorter drying in the field in climatic conditions of the Mediterranean summer.