Diallel Analysis of Ethanol Yield in Leaves Versus Stems of Lowland Switchgrass.

Switchgrass (Panicum virgatum L.) is an important forage crop and a potential biofuel crop. Breeding for certain traits is important to optimize ethanol production for use in biofuel. Examining the predicted ethanol yield from the leaves versus stems may help with breeding and selection. The objectives of this research are to i) obtain the average ethanol yields from leaves and stems in a 5 x 5 parent diallel and ii) determine correlations between leaf ethanol and stem ethanol with traits such as biomass yield, whole plant ethanol yield, and leaf to plant biomass ratio. Selections from the cultivars ‘Alamo’, ‘Kanlow’ and ‘Miami’ were crossed in a complete diallel. The F1 progeny of these crosses were clonally divided and planted (1m centers) in space planted nurseries in Knoxville and Crossville, TN. Nurseries were planted in randomized complete block design with twenty replications of each cross and eight clonal replications of each parent. During the spring of 2013 and 2014, data were recorded on plant height, stem diameter, leaf diameter, and tiller number. In fall, heights of individual plants were recorded and the plants were harvested for biomass yield. A subsample of plants from each plot were separated into leaves and stems, ground, and analyzed using the FOSS NIRSystem to predict ethanol yield from the leaves and stems. Results indicated there were significant differences among crosses (P<0.05) in predicted ethanol yield from leaves versus stems. However, there was no difference in the amount of predicted ethanol in the leaves and stems (P>0.05). The leaf to plant biomass ratio had a moderate positive correlation (0.32) with the predicted ethanol for the whole plant (P<0.05). Total yield (P<0.05) displayed a moderate negative correlation with leaf to plant biomass ratio (-0.51) and a weak negative correlation with predicated plant ethanol (-0.08).