Abstract
California water-seeded rice is challenged with the rapid growth of nuisance algae at the beginning of the season. Rice seedlings entangled in the algal mat may not be established, causing empty rice patches in the field. Two separate studies were conducted to (1) evaluate the effect of nutrients (nitrogen and phosphorous) on algae growth, and (2) test various chemical options to control algae. Both studies utilized 19 L buckets inoculated with algae collected from a rice field. In the nutrient evaluation study, 36 nutrient treatments obtained from a combination of nitrogen (0, 60, 120, 180, 240 and 300 kg ha−1) and phosphorous (0, 20, 40, 60, 80 and 100 kg ha−1) rates were applied into the buckets, while eight chemicals with potential for algae control (two Protox inhibitor herbicides, four copper-based compounds, hydrogen peroxide, Zinc sulfate) were tested in the second experiment. In addition, a yeast extract-based surfactant (AMP activator) was tested in combination with a chelated copper formulation (Algimycin) and hydrogen peroxide. The studies had a completely randomized design with three replicates and each study was repeated two times. The result from the nutrient evaluation study showed that nitrogen and phosphorus can independently cause change in algae growth as reflected in the fresh and dry biomass. Moreover, low rates of either nitrogen or phosphorus resulted in a rapid increase in algae biomass and water chlorophyll a content, whereas the growth of algae declined at higher rates of applied fertilizer. Among tested chemicals in the second experiment, the chelated formulation of copper (Algimycin PWF) controlled algae (85%) better than the ethanolamine formulations [Cutrine-Ultra (70%) and Cutrine-Plus (52%)] and elemental copper (crystalline copper sulfate) (75%). Protox herbicides (oxyfluorfen and oxadiazon) were able to control algae by up to 70%. Hydrogen peroxide controlled algae by 50% and its efficacy dropped dramatically five days after treatment (DAT). Zinc sulfate was only effective at 1 DAT and algae recovered rapidly after that. Combining fertilizer management practices with chemical options will enable us toward an integrative approach for early algal bloom in the rice cropping system.
Highlights
California is the second largest rice producer in the U.S, and almost 90% of mediumgrain rice and 98% of short-grain rice in the U.S are produced there [1]
The results of our study showed that algae growth in rice can be stimulated with either nitrogen or phosphorus, or the combination of both fertilizers
At low rates (1/3 of the field rate), algae growth could be limited or slowed, which may provide enough of a window of opportunity for rice establishment
Summary
California is the second largest rice producer in the U.S, and almost 90% of mediumgrain rice and 98% of short-grain rice in the U.S are produced there [1]. Rice is predominantly grown in more than 200,000 hectares [1]. A water-seeded system for growing rice is used in California, where imbibed rice seeds are spread aerially into pre-flooded fields. This specialized, unique rice growing system can lead to the production of up to 12 metric tons of rice per hectare [1]. Rice fields are leveled to zero or no slope with permanent wide levees, allowing maintenance of a uniform water depth in large basins [2]. Once the field is prepared, a corrugated roller is used to eliminate large clods, pack the soil and more importantly provide a uniform surface for even distribution of rice seeds. It may take approximately two days to a week for a whole field to be flooded and the water level is maintained (2.5–20 cm) for most of the season from this time to prior to harvest [3]
Sign-in/Register to view highlights & summary 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 callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
