A study compared how different types of crop straw react to very weak acid. They tested 15 straw types from five plants and found that rice, corn from Heilongjiang, and wheat from Shandong made the most sugar when broken down. Cotton straw had lower sugar levels. A lot of sugar depended on how much lignin a plant had - more lignin meant less sugar. Only a bit of the straw's hemicellulose and very little cellulose turned into sugar. The idea was to see which straw could make the most sugar with weak acid.