Progress 06/01/14 to 01/31/15
Outputs
Target Audience: The target audience during this project was corn growers and related professionals in drought prone regions of the United States, with a particular focus on market segments in California and the US corn belt. Growers in these regions have been greatly affected by drought, with corn especially susceptible to yield losses. Efforts to reach the target audience included contacting growers, extension agents and university personnel concerning regional needs and advanced product requirements. Based on these efforts, we have secured collaborations with university faculty and midwestern US growers (corn, soy and wheat) to perform field evaluations of our technology during the 2015 growing season. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest? These results have been disseminated via personal communication with farm owners, farm managers and academic researchers. This is allowing us to form collaborations for future research activities, including increasing the size and scope of field trials, and to further explore the mechanism of action of the drought control agent. Additionally, patent applications have been submitted and pursued, which will lead to publication of the research performed. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Drought is one of the most significant risks for farmers, rural economies, and the food supply chain; limited precipitation and irrigation acts as a major constraint on crop productivity. Climate change threatens to further exacerbate crop losses across America's most productive agricultural regions. There is a need for tools and strategies to enable farmers to adapt to climate change by reducing the water footprint of major commercial crops. While there have been promising advances in field management and in the development of drought tolerant crops, there is currently no crop protection product that enhances the robustness of field crops to periods of prolonged drought. Asilomar Bio identified a novel drought protective agent and validated its utility on grain corn. We developed two prototype crop protection products from the drought protection agent; a foliar spray and a seed treatment. Both of these prototypes conferred long term stress protection during greenhouse assays. Additionally, the foliar spray prototype was tested in three field trials and produced greater than 20% grain yield increases. A product that can be applied to crops as a foliar spray to boost the health and productivity of plants during drought stress would allow farmers to reduce the risk of crop loss and maintain productivity throughout variable weather. The overall goal of this project was to evaluate a new plant growth regulator (PGR) for use as a drought protective product for corn. This was achieved through three primary objectives: (1) Determining the effect of the PGR on vegetative growth of unstressed plants In addition to having the desired outcome when applied under drought conditions, it was important that the new drought protection agent did not produce phytotoxicity when applied to healthy, unstressed plants. Phytotoxicity symptoms include poor germination, death of seedlings, stunted growth, developmental abnormalities and brown spots on foliage. None of these symptoms were observed during the course of work on this project. This increased knowledge of the drought protection agent and confirmed our hypothesis that the agent would show no developmental defects or other phytotoxicity. (2) Measuring the onset of water stress symptoms in PGR-treated and untreated plants To establish a baseline for efficacy and investigate the dose-response function of the chemistry, we performed controlled drydown experiments with corn seedlings in a greenhouse. Seeds were planted and grown to the V2 stage with regular irrigation. At this point, plants were treated with the drought protection agent as a plant and soil drench or mock treated. Irrigation was stopped after treatment. Plants were monitored for symptoms of drought stress, which are manifest as leaf rolling. We scored plants in three categories: unstressed, moderate stress (incomplete leaf rolling), and severe stress (complete leaf rolling). We scored plant stress at 6 days post-treatment. Mock treated plants (control) were stressed, with over 60% of seedlings experiencing severe stress and less than 5% displaying no symptoms of stress. Treated plants showed lower amounts of stress as a population, with the distribution skewing towards the unstressed category as treatment concentration is increased (less than 40% of low dose treated and less than 15% of moderate dose treated showed severe stress). This data established that treatment is able to provide a drought protective effect on plants experiencing water limited conditions. A second method of delivering the drought protection agent, coating the seeds with active ingredient, was tested. At the V4 growth stage, a high dose seed treatment and a soil drench treatment plant routinely resisted stress better during the dry down period than the lower dose seed treatments. The control plant (untreated) performed worst. The difference between treated and untreated plants was evident by the time spent in stressed state in which leaves were completely rolled. Treated plants entered this state after the control plant and recovered before the control plant. By day 5, the control plant no longer had any periods without stress. The treated plants did not reach this state for another 24 hours. These results increased knowledge of the drought protection agent and confirmed our hypothesis that the treatment would prevent corn from showing symptoms of drought stress compared to untreated corn. (3) Measuring the impact of PGR application on grain yield in water stressed and unstressed plants. The reduction of drought stress in field crops can have beneficial effects in terms of harvest yield. To test the effect of treatment in this context, we performed a small-scale research field trial. The field was not irrigated. Treated plots were sprayed with a 2 g / ac dose at the tasseling (VT) stage. We arrived at our initial timing (at VT stage) and dose (2 g / ac) of application by considering the biological determinants of grain yield, plausible economic constraints for maximum dose and the outcomes of previous lab and greenhouse experiments. Corn is known to be especially sensitive to water stress during tasselling and silking (VT and the first reproductive stage of corn growth). Stress during this period is known to directly affect grain yield and quality. It follows that protection from water stress would be most valuable during this period and we timed application for the beginning of this stage. In choosing the initial trial dose, we sought to apply a moderately high amount. We monitored the health and vigor of plants as they progressed through the reproductive stages. Drought stress is known to affect the pollination efficiency of corn during VT and R1 stages. We found that treatment decreased the fraction of unfertilized ears while increasing the fraction of fertilized ears. The differences in kernel set (non-pollinated kernels do not develop, and drought stressed kernels often abort) could be visualized qualitatively at harvest by comparing ears from treated and untreated plots. Control ears showed incomplete kernel set and kernel abortion, symptoms of severe drought stress. Treated ears showed more complete kernel set and few signs of kernel abortion. One of the outcomes of drought stress during the reproductive stages is impaired kernel fill, where the average kernel mass is lower than in unstressed plants. We found that treated plots had 33% greater thousand kernel weight (225 g control versus 300 g treated). This data indicates that grain filling was better in treated plots, which is consistent with the hypothesis that treatment reduces the symptoms and deleterious effects of drought stress. The primary determinant of value for our technology (and any crop protection product) is its effect on yield. Control plots averaged 120 bushels per acre, while treated plots averaged 143 bushels per acre, a 19% increase. We performed two additional field trials. Treated plots were again sprayed with a 2 g / ac dose at the tasseling (VT) stage. Two trials were performed, one imposing 'moderate' stress via reduction of irrigation, and another imposing 'severe' stress. In the 'moderate stress' trial, the control plots averaged 70 bu/ac and treated plots averaged 93 bu/ac, a 21% increase. In the 'severe stress' trial, the control plots averaged 19 bu/ac and treated plots averaged 37 bu/ac, a 91% increase in yield upon treatment. These results increased knowledge of the drought protection agent and confirmed our hypothesis that treating corn can prolong the unstressed state when faced with drought stresses and enhances grain yield. A major achievement of this project was the production of product prototypes and the development of an application protocol that protected corn from drought stress in field trials. The results of this project provide a foundation for further scale up and field trials of this new technology.
Publications
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