Abstract
Extracting allelochemicals from rice (Oryza sativa) straw and use for weed management is more sustainable than burning and reduces herbicide dependence. Water soluble compounds were extracted from shoots and roots of OM 5930, generating both a crystallized by-product and liquid extract. Crystallized product was applied to soil with pre-germinated barnyardgrass (Echinochloa crus-galli L. Beauv), red sprangletop (Leptochloa chinensis L. Nees), and grass-like fimbry (Fimbristylis miliacea L. Vahl) seeds. As little as 9.4 g per pot (1 ton ha−1 biomass) reduced survival of all species, with the order of sensitivity barnyardgrass (BG) < red sprangletop (RS) < grasslike-fimbry (GF). Increased rates or time of exposure (3 to 42 days after treatment; DAT) resulted in a stepwise reduction in seed survival. Using liquid extract, 5.33 g pot−1 (3 tons ha−1 biomass) reduced BG survival by 49.8%, while 2.67 g pot−1 reduced survival of RS and GF by 49.7 and 54.3%, respectively at 42 DAT. A rate of 8 g pot−1 reduced survival of BG seedlings by 78.3% but was lethal to RS and GF seedlings. The most abundant allelochemicals present were ergosterol peroxide, p-coumaric acid, and salicylic acid. OM 5930 rice is a promising variety for extraction of allelopathic compounds and application for extended herbicidal activity.
Highlights
Weeds are one of the largest impediments to optimizing rice production [1]
For BG, red sprangletop (RS), and grass-like fimbry (GF) at 3 days after treatment (DAT), the inhibition level ranged from 6.7–40%, 30.0–63%, and 40.5–94%, respectively from the lowest (9.4 g pot−1) to the highest rate (28.26 g pot−1)
No rate was lethal to all BG seedlings by 42 DAT, while a minimum of 18.84 and 9.4 g pot−1 were lethal to all RS and GF seedlings, respectively
Summary
Weeds are one of the largest impediments to optimizing rice production [1] Banyardgrass has growth and morphological characteristics like rice, making timely removal difficult Another factor contributing to the competitiveness of BG is that plants can remove 60–80% of the available nitrogen in the soil [4]. According to Chin (2001), rice yield decreased 50% following season-long competition with as few as 15 BG m−2 [1]. The competitiveness of both BG and RS partially results because they are C4 plants; more efficient photosynthesis increases overall biomass. GF competition with rice reduced yields up to 10% [9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
