Response of Thai rice varieties under elevated CO2 concentrations

Rice grain quality includes the processing quality of brown rice percentage, milled rice percentage and head rice percentage. Percent brown, milled and head rice percentage will be calculated from the weight of brown, milled and head rice per sample of rough rice multiplied by 100%. Grain length and width will be measured and ratio of grain length to width will also be determined. About 5 g of milled head rice from each variety and will be classified for chalkiness on the basis of the proportion of chalky area in an image of each grain taken with grain scanner. There will be four chalkiness classifications: Perfect (0% = P; no chalkiness), Small (S; 0–15%), Medium (M; 15–40%), and Large (L; over 40%).