Correlation and Path Coefficient Analyses in Sugarcane Genotypes of Ethiopia

To study the relations of certain morphological and sugar quality characters with sugarcane yield, an experiment was conducted at Wonji and Metehara Sugar Estates, Ethiopia between March 2012 and October 2013. The experiment, comprising of 400 sugarcane genotypes of which 174 were local that were collected from different regional states of Ethiopia and 226 introduced, was laid out in partial balanced lattice design with two replications. Data was collected on cane yield and its components, sugar yield and sugar quality traits. ANOVA, correlation and path coefficient analysis were done. Analysis of variance revealed significant differences (P < 0.01) for all the characters studied. Cane yield showed strong positive and highly significant (P < 0.01) correlation with millable cane number (r = 0.832), single cane weight (r = 0.528), stalk height (r = 0.517) and sugar yield (r = 0.987). There was also positive significant (P = 0.05) correlation of tiller count and cane diameter with cane yield. Path analysis revealed the highest positive direct effect of millable cane number (0.812) on cane yield followed by single cane weight (0.682) and pol percent (0.550). However, stalk diameter and brix percent had considerable negative direct effects and indirect positive effects through single cane weight on cane yield. Therefore, in view of their significant positive association with cane yield, indirect effects of stalk diameter and brix percent via single cane weight should be considered during selection. Genotypes should be selected on the basis of millable cane number, single cane weight and pol percent for getting higher cane and sugar yield.

Optimizing extrusion pretreatment and big bluestem parameters for enzymatic hydrolysis to produce biofuel using response surface methodology

Biomass has been identified as alternative renewable energy resource to replace 30%transportation fossil fuel through biofuels by 2.025.Big bluestem is a warm season native perennial grass warrants attention and studies revealed its potential as energy feedstock.Extrusion pretreatments employed on big bluestem showed a significant improvement on sugar recovery.The current study was undertaken to understand and optimize pretreatment conditions such as barrel temperature(45-225℃),screw speed(20-200 r/min),moisture content(10%-50%w.b.),and particle size(2-10 mm)for maximum sugar recovery from big bluestem;and to propose a model to predict the glucose,xylose,and combined sugar recovery.Statistical analyses confirmed that all the independent variables included in this study had a strong influence on sugar recovery.A quadratic polynomial model was proposed to predict the glucose,xylose,and combined sugar recoveries from big bluestem,which had high F and R2 values with low p values.The optimum pretreatment conditions such as barrel temperature 180℃,screw speed 150 r/min,moisture content 20%w.b.,and particle size 8 mm resulted in maximum glucose,xylose,and combined sugar recoveries of 71.3%,78.5%,and 56.9%,respectively.Surface area of the optimum pretreated big bluestem increased 68.5%than that of control sample,which is the main cause for increase in sugar recovery.