Evaluation of Sorghum (Sorghum bicolor L.) as a bio-energy crop in Pakistan

Abstract

Bio-energy is a sustainable and promising energy source owing to less greenhouse gas emissions. In Pakistan, there is no information available regarding the bio-energy production from plant biomass. In this framework, four experiments were conducted for the two-years at Post Graduate Agricultural Research Station (PARS), University of Agriculture, Faisalabad, Pakistan to determine the effect of different management considerations on the dry matter yield (DMY), composition, and, methane production from Sorghum bicolor. In the first experiment, ten different sorghum cultivars (JS-263, Jawar-2011, Hagari, JS-2002 and YS-2016) and lines (5025, 6024, 5018, 113 and 1914) were compared to sort out best genotype and lines regarding the DMY, composition and methane yield (MY). The second experiment was comprised of different sowing methods i.e., broadcasting, drill sowing, ridge sowing and bed sowing and sorghum cultivars, i.e., JS-263, Jawar-2011, Hagari, JS-2002 and YS-2016. The third experiment was comprised of three sowing dates, i.e. SD1= 1st May, SD2= 20th May, SD3= 10th June and sorghum cultivars, i.e., JS-263, Jawar-2011, Hagari, JS-2002 and YS-2016. The fourth experiment was composed of five harvesting times (HT); 60, 75, 90, 105, 120 days after sowing (DAS) and five sorghum cultivars, i.e., JS-263, Jawar-2011, Hagari, JS-2002 and YS-2016. The first experiment was executed in a RCBD and remaining three experiments were performed in RCBD with split plot arrangements and replicated three times. In the first experiment cultivars and lines featured significant differences for the DMY, quality and MY. Jawar-2011 and YS-2016 were the top performers with respect to methane production owing to higher DMY although they had minimum specific methane yield (SMY). Amongst lines L-5018 produced the higher DMY and MY as compared to other lines. In the second experiment planting methods and cultivars had a substantial impact on the growth, DMY and MY ha-1 basis. However, ridge sowing performed remarkably well and produced more DMY (+31%, +33%) and MY (+26%, +29%) as compared to broadcasting during both years. Although planting methods had no impact on the compositional attributes i.e., protein, sugars, fiber fractions, lignin, and ash contents and SMY. Amid cultivars, Jawar-2011 produced maximum MY (4193 m3N ha-1, 3874 m3N ha-1) afterward YS-2016 (3877 m3N ha-1, 3746 m3N ha-1) and JS-2002 produced minimum MY (3590 m3N ha-1, 3451 m3N ha-1) during 2016 and 2017. In the third study, early sowing had better growth and produced more DMY and therefore, the higher MY. Moreover, maximum protein (11.03%, 10.71%) and sugar contents (10.28%, 9.86%) were recorded in early sowing as compared to later sowing, however, later sowing had more NDF (54.96%, 56.06%) and lignin (5.02%, 5.15%) possibly due to more stem proportion. In early, sowing cultivar Jawar-2011 produced more DMY and MY and in later sowing YS-2016 performed appreciably well due to quick growth life cycle and produced maximum DMY and MY during both years. In fourth experiment Jawar-2011 and YS-2016 produced highest DMY than the other cultivars, and consequently the higher MY. Delaying in harvesting (120DAS vs 60DAS) resulted in significant differences in all the traits; increase in the DMY (+47%, +51%), ADF (+47%, +43%), NDF (+52%, +44%) and lignin (+52%, +49%), and reduction in protein (-29%, -27%) and ash (-28%, -29%) and SMY (-20%, -19%) during both years. Therefore, the outcomes of these studies would set premise for the countries like Pakistan who have recently focused on the bio-energy production from plant biomass.