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Research Project: Using Genetic Approaches to Reduce Crop Losses in Rice Due to Biotic and Abiotic Stress

Location: Dale Bumpers National Rice Research Center

Title: Weed control in organic rice using plastic mulch and water seeding methods in addition to cover crops

Author
item Mahato, Gena - University Of Arkansas At Pine Bluff
item Huang, Bihu - University Of Arkansas At Pine Bluff
item Mcclung, Anna
item Mcclung, Anna
item Zhou, Xin-gen - Texas Agrilife
item Dou, Fugen - Texas Agrilife
item Watkins, Kenton - University Of Arkansas
item Bagavathiannan, Muthu - Texas Agrilife
item Way, Michael - Texas Agrilife
item Ntamatungiro, Sixte - University Of Arkansas At Pine Bluff

Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 1/19/2018
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Weeds are a major yield limiting factor in organic rice farming and are more problematic than in conventional production systems. Water seeding is a common method of reducing weed pressure in rice fields as many weeds connot tolerate flooded field conditions. The use of cover crops is another method of reducing the weed seed population in a field by competing with the weeds and preventing seeds from forming. The use of plastic mulch as a weed barrier is effectively used in some organic crops, like vegetables and fruits, that have high economic value. This research was conducted to evaluate the effectiveness of plastic mulch and water seeding methods as means to control weeds in organic rice. For the plastic mulch weed control study, in fall 2016 a mixture of annual ryegrass and crimson clover was planted and, in the spring, terminated and incorporated. The field was covered with Black Plastic Mulch 4ft. x 100ft. 1.0 Mil Embossed 3 weeks after cover crop termination. Six rice varieties including conventional and weed suppressive cultivars were tested using CRD experimental design with four replications. Twelve experimental hybrids were also tested using three replications and the same experimental design. The plots were hand seeded into the soil by making holes into the plastic mulch. Each plot consisted of single row with 14 plants spaced on a 15 cm x 30 cm grid. Plots were irrigated to achieve plants stand and continuous flooding was maintained after rice plants attained height of 12-15 cm. Another separate water seeded experiment was conducted in an area of the field previously planted to a fall cover crop mixture of oats and crimson clover. After termination of the cover crop in the spring, ten rice varieties were water seeded using RCBD design with two different seeding rates of 224 kg/ha and 448 kg/ha and four replications. After four weeks, a section of the plot was thinned to be the equivalent of six hill plots as a means of having similar comparison to the plastic mulch study. Data collected included days to heading, grain yield, and incidence of straighthead using a scale of 0 (none) -to 9 (100%) for both experiments. Weeds were effectively controlled in both the plastic mulch and water seeded trials. Weed pressure in the plastic mulch study was lower than the water seeded study during the whole growing season. However, weeds present in the water seed trial were primarily within the open areas of the field, not within the plots per se. Prevalent weeds included red stem and duck salad. Severe straighthead and panicle blanking were observed in the water seeded trial. Straighthead was found higher in the high seeding rate versus the lower. Rice varieties Rondo, Jasmine 85 and Cocodrie showed high straighthead scores whereas PI312777 and Presidio were moderate. Moreover, straighthead in thinned plot area was significantly lower than the high density area of the plots in both seeding rates. Conversely, rice varieties planted under plastic mulch had only moderate straighthead except for the highly susceptible Cocodrie. Some hybrid lines showed low straighthead scores with high yield. The results suggest that plastic mulch and water seeding can be effective means of weed control in organic rice systems. However, water seeded plots were more susceptible to straighthead than when plastic mulch is used as a weed barrier.