Dominantly Cyperus esculentus ,Cyperus iria and Echinochloa crusgalli germinated together with rice seedling.These weeds have rapid growth, and they are highly competitive and adapted to aquatic condition . Particularly weeds adapted to aquatic condition become more difficult to control by continuous flooding when they are established. However, Moody et al .reported that weed population density and total dry weight per unit area decrease as water depth increases. On the other hand, Sahidand Hossain reported that emergence and survival of some weeds remain unaffected by a flooding depth of 15 cm. Water management is crucial in successful weed control in water seeded rice because flood water affects the density,vigor, and uniformity of rice stands,and severity of weed competition . This research in following years will be focused on other alternative methods such as use of plastic mulch covering for weed management in organic rice production.The higher weed suppression potential of Jasmine 85 and Rondo observed in the experiment is largely due to higher plant stand and better seedling establishment than other rice varieties.
Main characteristics imparting weed competitiveness to rice include selection of cultivars, seeding vigor, early and faster seedling establishment, shoot-root characteristics and self-supportive allelopathy. Oluyemi, A.T.reported that Jasmine 85 grows rapidly, gives high yield,cannabis grow equipment carries good resistance to pests in Southern United States and also suppresses the growth of weeds in surrounding area. Likewise, Gealy and Yan reported that Rondo has high yield potential and ability to suppress or tolerate rice pests,including weeds. Soybean has been grown in Ontario, Canada since 1881and it is currently the largest and most valuable cash crop in the province. In 2015, soybean was seeded on 1.2 million hectares, and produced over 3.6 million tonnes, which was worth close to $1.6 billion . Weed control is an important component of soybean production, especially early in the growing season.Soybean is most susceptible to yield loss during the critical weed-free period that begins at V1 and ends at V4 , which is the reason why herbicide applications are typically made prior to soybean emergence and soybeans are maintained weed-free through the end of the vegetative growth period prior to flowering.Weed control was greatly simplified when glyphosate-resistant soybean was commercialized in Ontario in 1997.
Glyphosate is a Group 9, non-selective herbicide that controls over 300 weed species . It has a wide margin of crop safety, low toxicity, and a flexible application window ; these factors contributed to the high adoption rate of GR soybean. In 2015, 70% of Ontario soybean was produced from GR cultivars. While glyphosate applied alone maybe a simple and effective weed management strategy, its lack of residual control often requires glyphosate to be applied multiple times in a growing season to obtain full-season weed control. Furthermore, the sequential application of a single herbicide with one mode-of-action may select for herbicide-resistant weed biotypes; for this reason, the repeated use of a single mode-of-action is strongly discouraged . The growing concern of selecting HR weed biotypes has prompted research for weed management solutions that can fill the agronomic gaps left by using only glyphosate.Two-pass weed management strategies including a preplant or preemergence residual herbicide followed by a post emergence herbicide often result in full-season weed control using multiple modes-of-action. The addition of multiple modes-of-action and including multiple application timings can improve weed control, minimize soybean yield loss caused by weed interference, and reduce selection pressure for HR weed biotypes .Soybean resistant to both dicamba and glyphosate will be commercially available for the 2017 growing season. Dicamba is a Group 4, system icbroad leaf herbicide that controls over 40 broadleaf weed species and provides short-term residual weed control . Dicamba provides excellent control of many troublesome weeds such as common and giant ragweed , common lambs quarters , and redroot pigweed. In addition,dicamba controls several GR broadleaf weed species found in Canada and the United States.