Objective:
Characterize a large collection of S. spontaneum clones as well as a representative sample of clones from related species of Saccharum (S. officinarum, S. barberi, S. robustum and S. sinense) for starch and other juice quality traits (e.g. purity, sucrose, fructose, and glucose) with the aim of enhancing their use for sugarcane improvement.

Approach:
The plant materials for this study will be obtained from the World Collection of Sugarcane and Related Grasses at the Subtropical Horticultural Research Station, Miami, Florida and sugarcane breeding programs. About 150 S. spontaneum clones and 25 clones each of S. officinarum, S. barberi, S. robustum and S.sinense and cultivars will be used in the study. About 4-5 stalks will be sampled from each clone and used for the analysis. The juice will be extracted by squeezing all the stalks in a roller mill. Each juice sample will be immediately divided into three sub-samples: one for starch analysis; the second for analysis of Brix, pol, and purity; and the third for analysis of sucrose, fructose and glucose. Starch Analysis: Juice samples will be boiled immediately for 15 minutes in a temperature controlled water bath, to denature the natural amylases in the juice. The juice will then be cooled and stored on ice. Juice for all other analyses will be frozen and stored until shipped on dry ice whereupon it will be stored again until analyzed. The juice will be used to run two sub sample determinations of starch on each clone. Starch will be measured using the rapid SPRI iodometric method with minor modifications. Juice (3 ml) will be transferred to two test tubes and placed in a boiling water bath for 10 minutes to completely solubilize the starch. After boiling, the juice will be cooled on ice. After cooling, 2N acetic acid (1.2 ml), 10 % KI (0.25 ml) and KIO3 (2.5 ml) will be added in that order. The contents of the test tubes will be mixed using a vortex. The mixing forms a blue/purple specific starch-iodine complex. The test tubes will be centrifuged for five minutes. The supernatant from the test tubes will be transferred to cuvettes and the absorbance read at 600 nm on a spectrophotometer. The starch will be determined from a pre-determined calibration curve. Brix, Pol, Purity Analyses: Analysis for Brix and pol will be carried out immediately after the cane is crushed. Brix will be measured using a temperature-controlled refractometer. Pol will be measured using a polarimeter. To measure pol, the juice will be clarified by first adding Octopol and mixing it thoroughly followed by filtration of the juice using filter paper. Purity (%) will be calculated as (Pol (apparent sucrose)/Brix) x 100. Sucrose, Fructose and Glucose Analyses: The juice samples for sucrose, fructose and glucose analyses will be collected and stored until it is shipped in dry ice whereupon it will be stored again until analyzed. Sucrose, glucose and fructose contents of juice samples will be determined by high-pressure ion chromatography with pulsed amperometric detection (HPIC-PAD) using a ion chromatograph. Quantification of the individual sugars will be by comparison with external standards.