Categorizing rice cultivars based on differences in chemical composition

Abstract

This research aimed to verify variations in chemical composition of rice cultivars after polishing and to evaluate the constancy between two cultivated years in order to categorize them into groups with distinct nutritional characteristics. The cultivation year only significantly affected the Ash values. Categorizing cultivars showed that some of them presented a standard pattern for some measures. The groups formed by cluster analysis from 2001/2002 samples were: 1A [PROCNT (crude protein)=7.80%; CHOAVL (digestible starch)=85.8%; FIBINS (insoluble fiber)=1.14%; FIBSOL (soluble fiber)=1.23%], 2A (PROCNT=9.90%; CHOAVL=84.8%; FIBINS=0.85%; FIBSOL=1.64%) and 3A (PROCNT=8.54%; CHOAVL=83.5%; FIBINS=1.64%; FIBSOL=1.48%); and by 2002/2003 samples were: 1B (PROCNT=7.63%; CHOAVL=86.1%; FIBINS=0.89%; FIBSOL=1.69%), 2B (PROCNT=10.3%; CHOAVL=82.9%; FIBINS=1.31%; FIBSOL=1.65%) and 3B (PROCNT=8.56%; CHOAVL=84.2%; FIBINS=0.66%; FIBSOL=3.09%). The groups formed in the two years were different, but some cultivars showed a standard pattern for some measures (i.e. BR-IRGA-409, IRGA-416 and FORMOSA for CHOAVL-high, PROCNT-low, and FIBINS-intermediate), which can serve as indicators of the persistence of these characteristics. These results are of great importance for use in genetic improvement, since if we have a common cereal with differentiated nutritional values, we can improve diet quality in poor populations that need special attention.