Growth Characters of Sweet Sorghum Cultivation for Bio-Ethanol Production in the Southern Region of Ibaraki Prefecture, Japan.

In recent years, great attention is focused on bio-fuel production under concern affairs such as drying up of the fossil fuel and pollution problem in global and/or regional environment. As for renewable energy production, the bio-ethanol production using bio-energy crop is thought to be one of the most promising methods. In this study, we examine the growth characters of sweet sorghum cultivation as a bio-energy crop in southern region of Ibaraki prefecture Japan. Three cultivars were used in this experiment: FS501, FS902, and KCS105. Seeds were sown in the field of the Field Science Center, The College of Agriculture, Ibaraki University, Japan at June 10 (I) and 30 (II) , 2008. Slow release fertilizer was applied at the rate of 9.0 g m^-2 of N and K₂O, and 7.4 g m^-2 of P₂O₅. Quick acting fertilizers were also applied at the rate of 3.0 g m^-2 of N, P₂O₅ and K₂O as basal dressing (Treatment A), or supplemental dressing at 48 days after sowing (Treatment B) respectively. Above ground portions were harvested every 15 days after heading. Plant lengths, stem length, fresh and dry weigh of stem, leaf and panicle were measured. Brix value of juice taken from each elongated internodes was also measured. Regardless of fertilizer application, plant length, stem dry weight and water content were higher in I than in II in every cultivar. Brix value and stem sugar content were highest at 45 or 60 days after heading in all cultivars and fertilizer applications. Among three cultivars, stem sugar content was the highest in FS902 than other cultivars in almost of all treatments. The number of elongated internodes was relatively higher in I than II. In addition, the number of elongated internodes seems to have positive relation with the stem sugar content. From these result, it is important not only to choose the adequate cultivar with consideration of earliness but also to determine the optimum sowing date for gaining effective sugar yield in sweet sorghum cultivation.