ARS | Publication request: INVESTIGATIONS INTO SEED CHEMISTRY CHARACTERISTICS OF RED RICE AND RED RICE-RICE CROSSES

Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: February 24, 2002
Publication Date: N/A

Technical Abstract: Red rice (Oryza sativa L.) is one of the most troublesome and costly rice weeds of the southern U.S. It can intercross with commercial rice cultivars, making it an even greater problem. Rice grain contaminated with red rice seeds has lower commercial value due to the undesirable color of red rice and the difficulty in separating the two types of seed. Chemical quality characteristics of red rice seed and their potential influence on the quality of red rice-contaminated rice seed are not well known. Accessions of red rice or red rice-cultivated rice crosses were obtained from the southern U.S. and grown under flood irrigation at Stuttgart, AR in 2000. Harvested seed were evaluated for chemical characteristics including levels of amylose, protein, and lipids, and alkalai spread. Presence of 2- AP, a volatile component of aromatic rice, was also determined. Amylose contents in red rice ranged from 19 to 27%, but generally were near the levels found in an indica standard. Amylose levels in red rice crosses ranged from 14 to 23% as compared to 13 and 20% for medium- and long-grain commercial standards, respectively. Alkalai spread values for red rice ranged from 3 to 7. Protein levels typically followed the order commercial rice standards > crosses > blackhull red rice > strawhull red rice. 2-AP was detected only in two crosses. A delayed planting resulted in higher alkalai spread and protein levels, and lower amylose levels in red rice. These results suggest that red rice in mixture with commercial rice seeds may negatively affect chemical quality of the rice depending on the identity and quantity of the red rice accession present.