Reliance Infrastructure Ltd.

Agricultural production of energy crops such as sugarcane (Saccharum spp. L) will be necessary to ensure a reliable supply of cellulosic feedstock to manufacture future renewable products such as biofuels.Complete enzymic saccharification of this cellulosic material is challenging.Targeted breeding of sugarcane to attain specific cell wall characteristics could improve cell wall digestibility (CWD).With the goal of devising criteria for choosing suitable sugarcane candidates, we measured the CWD and cell wall composition (lignin, structural polysaccharides, hydroxycinnamic acids (HCA), and lignin monomers) of stalk tissue from 34 sugarcane genotypes (Saccharum hybrids).CWD and acid insoluble lignin (AIL) were neg. correlated.The relative amount of syringyl and guaiacyl lignin monomers did not affect CWD.Individual HCA's, p-coumaric acid (CA) and ferulic acid (FA), also influenced CWD but to a lesser extent than AIL.CWD was neg. correlated to etherified CA and FA but pos. correlated to esterified FA.A CWD model was constructed using AIL and the esterified to etherified FA ratio as predictors.This empirical model explained 63% of the observed CWD variance.The model supported the notion that CWD could be improved by increasing the esterified to etherified FA ratio in conjunction with a moderate attenuation to lignification.This may be a promising tactic to avoid problems associated with low lignification.

Breeding energy cane for cellulosic biofuel production involves manipulating various traits. An important trait to optimize is cell wall degradability as defined by enzymatic hydrolysis. We investigated the feasibility of using near-infrared spectroscopy (NIRS) combined with multivariate calibration to predict energy cane cell wall digestibility based upon fiber samples from a range of sugarcane genotypes and related species. These samples produced digestibility values ranging between 6 and 31%. To preserve the practicality of the technique, spectra obtained from crudely prepared samples were used. Various spectral preprocessing methods were tested, with the best NIRS calibration obtained from second derivative, orthogonal signal–corrected spectra. Model performance was evaluated by cross-validation and independent validation. Large differences between the performance results from the two validation approaches indicated that the model was sensitive to the choice of test data. This may be remedied by using a larger calibration training set containing diverse sample types. The best result was obtained through independent validation which produced a R 2 value of 0.86, a root mean squared error of prediction (RMSEP) of 1.59, and a ratio of prediction to deviation (RPD) of 2.7. This study has demonstrated that it is feasible and practical to use NIRS to predict energy cane cell wall digestibility.

Sugarcane smut caused by Sporisorium scitamineum is one of the most devastating diseases of sugarcane.Two trialzole fungicides, propiconazole and triadimefon, have been used to protect seedcane from infection with sugarcane smut elsewhere, particularly after hot water treatment.These fungicides were registered under an emergency permit in Australia when smut was found for the first time in Queensland in 2006.A research program was initiated to screen and evaluate a range of fungicides against sugarcane smut.Nine fungicides were tested in vitro at various concentrations for their efficacy on smut spore germination.Azoxystrobin (Amistar), quintozene (Quintozene 750) and didecyl di-Me ammonium chloride (Steri-max) completely stopped germination of teliospores at 2.5 mg a.i./L.Propiconazole (Tilt), triadimefon (Bayleton), cyproconazole (Alto) and acibenzolar-s-Me (Bion) significantly (P < 0.05) reduced spore germination at 50, 100 and 200 mg a.i./L.Two field trials were planted in spring 2008 and autumn 2009, where cane setts that had been inoculated with smut were dipped in a range of fungicide suspensions for five or 10 min, prior to planting.Cyproconazole, propiconazole, triadimefon and azoxystrobin significantly (P < 0.05) suppressed disease expression for up to 6 mo in a summer experiment and 9 mo in an autumn experimentThese results have important implication for selecting new fungicides for the control of sugarcane smut in seedcane that is provided to Australian sugarcane growers as a disease-free propagation source.