| Red rice samples were obtained in 1992 from Arkansas, Louisiana, Mississippi, and Texas. Nineteen ecotypes including eleven strawhull, five blackhull, two goldhull, and one brownhull were hand-transplanted in the field for phenological studies in comparison to rice cultivars 'Lemont', 'Mars', and 'Maybelle'. Forty-two different plant and seed traits were evaluated. Most ecotypes were uniform and stable, but with considerable amount of genetic variability among ecotypes. Averaged, ecotypes flowered three to five days later than rice, but 12 reached 50% anthesis at the same time or earlier than 'Lemont'. Most ecotypes had high and early seed shattering and strong dormancy. Some ecotypes had plant characters closely related to rice cultivars, such as erect and glabrous leaves, resistance to shattering, and long, glabrous grains.;Seed longevity of non-dormant and dormant red rice ecotypes were evaluated in the soil at two locations. Flooding during the rice growing season did not affect longevity of non-dormant red rice. Five months after burial, only three ecotypes had viable seeds (;Red rice seed longevity evaluated using the accelerated aging technique did not correlate to the field results. There was no association between seed dormancy and longevity under laboratory conditions.;Greenhouse studies showed large variability in herbicide sensitivity among ecotypes. None of the 19 ecotypes were adequately controlled by all herbicide treatments applied at the recommended rate. Ecotype TX 4 showed tolerance to glufosinate at the normal use rate, while the 2X rate provided more than 90% control.;Field experiments showed that rice rotation to soybeans can be an effective system to control red rice. Soybeans treated with metolachlor alone or in mixture with imazaquin applied PPI consistently resulted in very good red rice control and the best soybean yields. |
