Genotypic diversity of bran weight of whole grain rice and its relationship with grain physical traits

Authors: Chen, Ming Hsuan; McClung, Anna

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/8/2018
Publication Date: 3/13/2019
Citation: Chen, M., McClung, A.M. 2019. Genotypic diversity of bran weight of whole grain rice and its relationship with grain physical traits. Cereal Chemistry. https://doi.org/10.1002/cche.10117.
DOI: https://doi.org/10.1002/cche.10117

Interpretive Summary: Rice bran, the outer most layer of the whole grain, is the primary site of deposition of most nutrients, minerals and bioactive compounds, however, rice bran accounts for a very small portion of the whole grain by weight. Increasing the weight proportion of the bran to whole grain will enhance whole grain rice nutritional value. Using 134 diverse rice genotypes, more than 2.3- and 2.5-fold variation in total bran weight and bran weight per surface area (BWS), respectively, of the whole grain were found. Mean of bran color classes showed that purple bran genotypes had the highest BWS, followed by red, white, light brown and brown. This report showed high bran weight genotypes can be selected for in a breeding program to improve whole grain nutritional quality.

Technical Abstract: Rice bran, the outer most layer of the whole grain, is where nutrients, minerals and bioactive compounds, except starch, are primarily deposited. Rice bran accounts for a small portion of the whole grain weight. Increasing the weight proportion of bran will enhance the health beneficial value of whole grain rice. We determined the physical and bran traits of 135 rice genotypes grown in two years. More than a 2.3- and 2.5-fold variation was found for bran weight per gram of whole grain and bran weight per surface area of the whole grain (BWS, representing bran thickness), respectively. Principle component analysis of the seven physical traits and two bran traits grouped the bran traits into PC3 and accounted for an average of 15.5% of the total variance, whereas kernel weight, width, thickness and grain surface area were in PC1, and kernel length and length/width ratio were in PC2. Mean comparison among bran color classes showed that purple bran genotypes had the highest BWS, followed by red, white, light brown and brown. BWS moderately correlated with kernel weight, width and thickness. This report demonstrates high bran weight genotypes can be selected to improve the nutritional value of whole grain rice.