Doctor of Philosophy (PhD)


Plant, Environmental Management and Soil Sciences

Document Type



Field research was conducted from 2006 to 2009 to study Texasweed [Caperonia palustris (L.) St. Hil.] interference and management in Cocodrie rice. Texasweed interference at 10 plants/m2 caused 24 to 31% rice yield reduction. The maximum possible yield loss was estimated to be 81%. Rice yield reduction was primarily due to a reduction in culms/m2 and filled grains per panicle. For maximum yield, Texasweed must be removed by two weeks after emergence and managed until permanent flood establishment. Shade had no effect on Texasweed emergence but significantly reduced growth and reproduction. At 100 days after emergence, 50, 70, and 90% shade reduced dry matter per plant by 31, 47, and 90%, respectively. Texasweed height increased with increasing shade up to 70% and then decreased. After 28 DAI, Texasweed height in 70% shade increased 15 to 21% compared with 0% shade. Texasweed seemed to mitigate the adverse effect of shade on growth by increasing specific leaf area and leaf biomass. In a flood depth study, Texasweed plants were able to survive and produce seeds in flood depths up to 30 cm; however, growth and fruit production were reduced. A 76 and 41% reduction in total dry matter per plant was recorded for Texasweed flooded at two- to three-leaf and four- to five-leaf stage, respectively. Increasing flood depths resulted in an increase in plant height and greater biomass allocation to the stem. Texasweed plants produced adventitious roots and a thick spongy tissue, secondary aerenchyma, in the submerged roots and stem, which may play a role in its survival under flooded conditions. For Texasweed control, bensulfuron-methyl interacted synergistically with both penoxsulam and bispyribac-sodium. Bensulfuron-methyl, therefore, can be mixed with either penoxsulam or bispyribac-sodium to improve Texasweed control. V-10142 provided excellent PRE and EPOST activity on Texasweed. V-10142 at 224 g ai/ha by itself, applied to four- to five- leaf Texasweed, was not effective but improved Texasweed control when mixed with bispyribac-sodium at 29 g ai/ha or penoxsulam at 40 g ai/ha.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Williams, Billy J.