Planting Date and Harvest Maturity Impact on Biofuel Feedstock Productivity and Quality of Sweet Sorghum Grown under Temperate Louisiana Conditions

Abstract

Sweet sorghum [Sorghum bicolor (L.) Moench] is recognized as a promising biomass energy crop for meeting the increasing demand for bioenergy feedstocks. Field experiments were conducted at sites in northern and southern Louisiana for 2 yr to assess planting date and harvest maturity effects on yield from primary plantings and ratoon crops. The cultivar M81‐E was evaluated using a split plot arrangement of treatments in randomized complete block designs. Planting date from mid‐March to early July was the primary plot treatment. Harvest maturity at the early heading (EH) or hard dough (HD) stage was assigned as the subplot treatment. A range of planting dates from mid‐March to early June produced substantial yields of biomass and fermentable sugar with appropriate harvest maturity and could support sugar mill operation for up to three additional months. However, sweet sorghum planted in early May and harvested at the HD stage produced 30 to 210% more fermentable sugar than other tested planting dates and maturity combinations. Ratoon crop production was not dependable showing inconsistent tiller growth with resultant low biomass yields. Correlation coefficients of sugar yield with biomass or other quantitative agronomic characteristics were higher than 0.79, while that with brix was only 0.32 (P < 0.0001). Production management in Louisiana from long season cultivars such as M81‐E based on a single harvest 150 to 160 d from planting at the HD stage can provide more biomass and fermentable sugar than can production management targeting a ratoon crop.

Dedicated Energy Crops and Crop Residues for Bioenergy Feedstocks in the Central and Eastern USA

“…Conservation tillage increased biomass by 11 % during the dry year, but no difference was observed between tillage systems for the wet year [36]. In the Southeast, sweet and photoperiod sensitive sorghums have been examined as potential energy crops due to high biomass production, low N requirements, and drought tolerance relative to corn [34,[36][37][38]. Sweet sorghum has additional benefits of a typically shorter growing season and production of fermentable sugars, although biomass production is reduced compared to photoperiod sensitive sorghum [34,38].…”

“…In the Southeast, sweet and photoperiod sensitive sorghums have been examined as potential energy crops due to high biomass production, low N requirements, and drought tolerance relative to corn [34,[36][37][38]. Sweet sorghum has additional benefits of a typically shorter growing season and production of fermentable sugars, although biomass production is reduced compared to photoperiod sensitive sorghum [34,38]. In addition to the bmr gene, low amylose or waxy endosperm genes and sweet genes are being incorporated and evaluated in current breeding programs that would improve sorghum as a bioenergy feedstock [39].…”

Effect of sowing dates and nitrogen levels for ethanol production from sweet sorghum stalks and grains

“…Both photoperiod and temperature interact, thus further influencing yield especially for very late plantings (Rao et al, 2013). Much information on the impact of planting date on stalk and sugar yields are available on sweet sorghum genotypes grown in temperate climatic conditions (Han et al, 2012;Burks et al, 2013), but information is very limited on mid-summer planting on ethanol production. The present experiment was conducted to identify optimum time of sowing and N level for achieving higher biomass and grain yield for ethanol production.…”

Offsetting high water demands with high productivity: Sorghum as a biofuel crop in a high irradiance arid ecosystem

“…Lower productivity in ratoon crops has been previously shown to be caused by unavoidable damage during harvest (e.g. in sugarcane (Bull, 2000;Cabral et al, 2012) and in sorghum (Han et al, 2012;Rao et al, 2013). It has also been reported that certain sorghum genotypes exhibit lower biomass production in the second and third ratoon crop of the growing season compared to the crop grown from seed (Rooney et al, 2007;Rao et al, 2013), however, these genetic drivers are not well resolved.…”