Increased synthesisand bioaccumulation of such carboxylic acids have also been reported when C4 perennial grasses are subject to abiotic stress such as drought.This finding indicates opportunity for direct isolation of succinic acid as a coproduct from biomass feed stocks without typical lignocellulosic hydrolysis and upgrading from glucose in competition for use with primary biofuels .In order to investigate this potential, the objectives of this research were to: 1)evaluate succinic acid content and total yield across candidate lignocellulosic feed stocks under field conditions, and 2) characterize the impact of deficit irrigation upon succinic acid bioaccumulation across candidate lignocellulosic feeds tocks under greenhouse conditions. Pearl millet is an annual diploid . It originated in northern Africa in an area extending from western Sudan to Senegal . Pearl millet is mainly used as a grain crop in India, Pakistan, and Africa; however, its main use in the USA, Australia, and parts of South America is as forage. There is an increasing interest in planting this grass as a grain crop to feed livestock in the USA . Although grain production of pearl millethybrid is not comparable to sorghum and maize hybrids, as a forage crop its yield can exceed sorghum and maize. Pearl millet is also more drought tolerant and suited to marginal lands than maize .
One study comparing forage yield among sorghum, millet and corn cultivars found greater biomass yield in pearl millet than sorghum cultivars Jumbo, Speed feed, and Sugar graze . Sugarcane is a perennial grass cultured mainly for sucrose production.As a perennial bioenergy crop derived from sugarcane, energycane is derived from sugarcane but selected for greater fiber concentration, biomass yields, and cold tolerance . Improved cold tolerance allows energy cane to be grown in areas further north than sugarcane in the USA . More importantly, its improved adaptation to marginal land gives it more potential as a lignocellulosic biomass feedstock.Biomass yields of energy cane are comparable to other lignocellulose feedstocks . Sorghum is an important crop used mainly for grain and forage production, and it is now being evaluated as a bioenergy crop . Its diverse utilization, including bioenergy potential of grain sorghum, sweet sorghum and high biomass cellulosicsorghum , is significant . Among many traits of foragesorghum that may impact forage quality, one trait is controlled by brown midrib mutants and influences forage quality.Chemically induced BMR mutants in sorghum were first induced in 1978 and can reduce lignin concentration as much as 51% in stems and 25% in leaves. With reduced lignin concentration,BMR sorghum cultivars have greater forage digestibility .
More importantly from a bioenergy perspective, this attribute could improve overall cellulosic ethanol conversion efficiencies when recalcitrance caused by lignin is mitigated. Biomass and estimated ethanol yields among sweet sorghum, BMRsorghum cultivars, and several perennial grasses indicated that the greatest biomass yield and ethanol production can be achieved from sweet sorghum . In the greenhouse trial, succinic acid concentrations did not vary across irrigation treatments. However, feedstock entries differed in their response to irrigation levels. PMN and Merkeron had the highest succinic acid concentration underdeficit irrigation, while the non-BMR annual sorghum had the lowest succinicacid concentration. Under non-deficit irrigation, Merkeron,PEPU 09FL03, PEPU 09FL01 and switch grass had the highest succinic acid concentrations,and the BMR annual sorghum had the lowest concentration . Hemp sesbania, avigorous, nodulating, epigeal, leguminous weed in soybean , cotton and rice , can attain a height of 3 m and was deemed one of the 10 most troublesome weeds in the southern U.S..It can reduce crop yield through shading and competition and has high reproductive capacity. No pre or post-emergent herbicide can provide season-long control of hemp sesbania.This weed exhibits some tolerance to glyphosate, but glufosinate can provide effective control .
Glufosinate is the ammonium salt of phosphinothricin, which is the active ingredient of bialaphos derived from non-phytopathogenic species in the genusStreptomyces .Biological weed control using plant pathogens has received attention by academic and industrial researchers for quite some time.Colletotrichum truncatum is a plant pathogenic fungus with bioherbicidal activity for controlling hemp sesbania. However, as with most foliar pathogens, spores of this fungus require sustained free-moisture,or a dew period to promote spore germination, establish infection and cause disease . Hemp sesbania was effectively controlled in soybean by C.truncatum conidia formulated in an invert emulsion.Greenhouse experiments showed that oil-in-water emulsions of unrefined corn oil and C. truncatum spore suspensions could reduce the dew period requirements for maximum weed infection and mortality of hemp sesbania, and thus delay the requirement for free-moisture.