Research Project: Integrated Water and Nutrient Management Systems for Sustainable and High-Quality Production of Temperate Fruit and Nursery Crops

Location: Horticultural Crops Research Unit

2020 Annual Report

Objectives
Objective 1. Determine the water and nutrient requirements needed to produce highquality temperate fruit and nursery crops in the Pacific Northwest. • Sub-objective 1.1. Develop water and nutrient guidelines to improve fruit and wine quality in Pinot noir. • Sub-objective 1.2. Characterize the interactions between water and nutrient use efficiency and plant quality in container-grown nursery plants. • Sub-objective 1.3. Identify salinity thresholds associated with compost and fertilizer use in highbush blueberry and basil. • Sub-objective 1.4. Determine temperature thresholds for sprinkler frost protection in cranberry. Objective 2. Evaluate the impact of soil microbes on crop water and nutrient use in grape and other specialty crop production systems. • Sub-objective 2.1. Characterize taxonomic and functional diversity of indigenous arbuscular mycorrhizal fungi (AMF) in vineyards. • Sub-objective 2.2. Determine the effects of AMF on interactions among plant development, resource allocation, and product quality in specialty crops. Objective 3. Develop irrigation and nutrient management practices and strategies that enhance crop productivity and quality with efficient use of water and fertilizers in berry and woody nursery crop production systems. • Sub-objective 3.1. Identify cover crop practices that enhance vineyard establishment and improve fruit quality in cool-climate wine grapes. • Sub-objective 3.2. Evaluate the potential benefits of using organic mulches under weed mat and identify the right source(s), time (fall vs. spring), and place (surface vs. incorporation) for organic compost application in highbush blueberry. • Sub-objective 3.3. Develop irrigation practices to reduce heat-related fruit damage in highbush blueberry. • Sub-objective 3.4. Develop nutrient management methods to increase cold tolerance in container-grown nursery crops.

Approach
Experiments will be conducted in the greenhouse and field on small fruit and nursery crops, including Pinot noir wine grape, highbush blueberry, cranberry, and container-grown Rhododendron, Vaccinium, Salix, Euonymous, floral geophytes (e.g., lily), and basil. For objective 1, relationships among soil N, P, and K availability, vine growth, and fruit quality will be determined in wine grape and used to develop leaf and petiole nutrient standards for production of Pinot noir and cool-climate cultivars in the Pacific Northwest. The extent to which berry quality of Pinot noir is altered by soil water deficits will also be investigated to provide benchmarks that relate specific indicators of vine water status such as leaf water potential and stomatal conductance to fruit quality. Greenhouse studies will be designed to test whether excess N availability reduces plant quality and water use efficiency in container-grown nursery plants and to identify salinity levels that limit shoot and root growth and function and lead to leaf necrosis in blueberry and basil. Critical temperatures for freeze damage in the region will be likewise determined for cranberry using combination of laboratory measurements on excised plant tissues and temperature-control units on the plants in the field. For objective 2, root and soil samples will be collected from plants grown in both field and greenhouse experiments to test if diversity of arbuscular mycorrhizal fungi (AMF) is a function of sampling location, soil depth, and cover crop use in grape roots; and to ascertain whether AMF improve quality of floral geophytes by enhancing P uptake and allocation. For objective 3, field studies will be designed to determine whether alleyway cover crops and residue placement in vine rows increases root production, AMF colonization, and plant growth and nutrient uptake in young grapevines; if using organic mulches (sawdust or compost) under weed mat will enhance soil conditions, including availability of water and nutrients, and result in more growth and production in highbush blueberry; and whether overhead cooling with sprinklers or misters reduce heat damage in blueberry fruit when applied correctly at the proper temperature, rate, and frequency. Can-yard studies will likewise be designed to test whether increased N availability reduces cold tolerance or, alternatively, if application of cation fertilizers (K, Ca, Mg) increase cold tolerance in container-grown nursery plants. Measurements in the studies will include standard techniques for measuring plant water status (pressure chamber, porometer), photosynthesis (gas-exchange), photosynthetic efficiency (fluorometer), fruit quality (refractometry, acid titratation, colorimetry, HPLC), root production and turnover (minirhizotrons, soil cores), mycorrhizal colonization (microscopy), DNA sequencing (PCR), soil pH and EC, soil water content (TDR, tensiometers), and plant and soil nutrients (CNS analyzer, ICP). Data will be analyzed using ANOVA, ANCOVA, nonparametric, and regression techniques. In some cases, studies may need to be repeated due to poor weather conditions or the need for a wider range of treatments.

Progress Report
This is the final report for bridging project 2072-21000-053-00D, "Integrated Water and Nutrient Management Systems for Sustainable and High-Quality Production of Temperate Fruit and Nursery Crops," which has been replaced by new project 2072-21000-055-00D, "Water and Nutrient Management for Sustainable Production of Small Fruit and Nursery Crops." In support of Sub-objective 1.1, a study to address how nitrogen management in both the vineyard and winery can be used to obtain optimal fruit quality in red and white cultivars was continued. This on-farm trial involves collaborators from Oregon State University and industry. Plant productivity, and ecophysiology are being monitored periodically in the vineyard in response to vineyard soil and foliar nitrogen (N) applications. Must (freshly crushed juice from entire grape bodies) nitrogen is being manipulated in the winery, and fermentations are conducted and monitored by collaborators. Results show that soil nitrogen appears to be more effective than foliar nitrogen in boosting vine N status based on leaf blade and petiole tissue tests in both varieties. Soil nitrogen was more effective than foliar nitrogen in raising must yeast assimilable nitrogen (YAN) levels in Chardonnay, but both soil and foliar nitrogen increased must YAN to a similar extent in Pinot noir. The rate of fermentation in Chardonnay was dictated primarily by must YAN level, irrespective of where the nitrogen came from. Fermentation in Pinot noir was not altered as strongly as it was in Chardonnay by different YAN levels, but the vineyard applied nitrogen treatments (soil and foliar) completed ferments before the winery nitrogen treatments. Sensory analysis of the wines produced from this work is being investigated by collaborators on this project and soil nutrient analysis is yet to be completed. New studies in support of Objective 2 were initiated to assess how nitrogen use alters fine root growth and the extent of mycorrhizal colonization of roots in grapevines. We collected data from mature vineyards that were used for a vineyard versus winery nitrogen trial. We also conducted a greenhouse trial to examine how rates of soil or foliar applied nitrogen affect vine growth, mycorrhizal colonization, and whole plant nutrient uptake. A follow up greenhouse experiment was conducted where both nitrogen and phosphorus supply were altered in a factorial design. Results show that nitrogen application in the vineyard reduces mycorrhizal colonization and interferes with phosphorus uptake, but the greenhouse experiments show that our findings from the field cannot be explained in such a straightforward manner. This information is important in developing sustainable vineyard nutrient management strategies that can reduce inputs and potential nutrient losses to the environment. New work was conducted with collaborators at Washington State University to examine how different grapevine rootstocks respond to the northern root knot nematode. While rootstocks are still not used in eastern Washington vineyards due to concerns over winter kill of scions, the industry is interested in using rootstocks in future vineyard replanting scenarios where the northern root knot nematode has become established at very high levels. A trial to examine how different rootstocks performed under varying levels of nematode density was established and much of the field data was collected. Preserved root samples were prepared and colonization by mycorrhizal fungi has been examined. Understanding how different rootstocks respond to this nematode under field conditions and whether mycorrhizal colonization is impaired are important to the success of vine establishment. New studies were initiated to evaluate the impact of water and nutrient management practices on the tolerance of nursery crops to withstand abiotic and biotic stresses. Experiments to understand how the nursery production environment (irrigation, fertilizer, fungicide, and temperature) affects emerging and new pathogens prevalent in the region were continued. Results from these experiments will be used to develop new management practices and disease control strategies to minimize pathogen damage and losses for woody nursery plants. Experiments were continued to define salinity thresholds for specialty crops grown in different production systems. Results from this research will be used by growers to reduce losses of planting stock, mitigate the impact of salinity on quality, and broaden the use of salt tolerant species in environments that are not suitable for production of other crops. Experiments were continued to evaluate water and nutrient management practices for specialty crops grown in soilless substrates in the field. Results from these experiments will be used to develop management options for this type of high-value production system. Work was continued to evaluate alternative soil amendments for highbush blueberry to extend work from Sub-objective 3.2. Plants were grown in soil amended with biochar alone or in combination with bokashi (fermented wheat bran) at rates of 10% and 20%, by volume, and compared to those grown in soil only. Biochar was also tested with or without bokashi under field conditions in a new planting. In this case, the use of biochar was evaluated for two years and compared to the conventional practice of incorporating Douglas fir sawdust in the row or using soil only. A third study was conducted to evaluate the potential of using ammonium-enriched organic materials as soil amendments for production of blueberry. Results indicate that biochar could be a good soil amendment for commercial production of highbush blueberry. Benefits include more plant growth and higher yield in soil with biochar, as well as much greater levels of root colonization by mycorrhizal fungi when the plants were grown in a sandy soil. Biochar also improved soil aggregation and had relatively little effect on soil pH. Adding biochar to the planting hole was considerably more economical than applying it to the row and cost $1320/hectare less than the industry standard of incorporating sawdust in the row. These findings indicate that biochar is a promising soil amendment for commercial production of highbush blueberry. Ammonium-enriched douglas fir sawdust and wood chips were also excellent amendments for improving growth and N nutrition in highbush blueberry. Both substrates are highly porous in nature and work well as biofilters. Woody biofilters are highly efficient for treating odors associated with animal farms, biogas plants, and composting facilities, including ammonia gas and volatile organic S compounds. Once enriched with adsorbed N, these biofilters could be used as excellent sources of nutrients and organic matter for blueberry. New research was initiated to evaluate new remote sensing techniques for assessing the need for irrigation, including multispectral and thermal imagery. The images are collected using a small unmanned aerial system and analyzed to develop robust field-specific estimates of crop development and irrigation water requirements for highbush blueberry and red raspberry in the Pacific Northwest. The images are also useful for identifying weak zones in the field caused by poor irrigation or disease issues such as Phytophthora root rot. New studies that extend work from Objective 3 were initiated to evaluate new practices for reducing irrigation water use in berry crops, including deficit irrigation in blueberry and pulsed drip irrigation in raspberry. Initial findings suggest that reducing irrigation either during early stages of fruit development or after harvest may have a minimal effect on yield or fruit quality in blueberry. Use of deficit irrigation would lead to immediate water savings, and when coupled with remote sensing technology, could enable growers and irrigation managers to optimize on-farm and regional water use. When managed properly, pulsing could increase plant growth and production relative to applying water all at once each day or two and can greatly reduce runoff, evaporation, and leaching. Work was continued in support of Objective 3 to evaluate whether fertigating with potassium, phosphorus, or boron fertilizers is more effective than traditional methods of fertilizer application in highbush blueberry. The results indicate that potassium thiosulfate is a good source of potassium for fertigation and can be used with urea on soils with optimum pH for blueberry (4.5-5.5) and with ammonium sulfate on soils with pH > 5.5. Fertigating with potassium fertilizers containing organic acids or their derivatives is also useful, particularly for increasing availability and retention of potassium in the soil. However, there were no benefits to date from fertigation or granular application of potassium fertilizers on fruit production in two mature blueberry fields. The fertilizers had an immediate effect on pH and availability of potassium and other nutrients in the soil and after two years are beginning to influence the nutrient status of the plants. Early results in phosphorus and boron trials are limited at this point but strongly suggest that fertigation with boron is more effective than using a single spring application of granular boron fertilizer. The project builds on our previous work on nitrogen and will be used to develop complete guidelines for fertigation of highbush blueberry. The results will help growers improve production in the crop and enhance fruit quality for consumers.

Accomplishments
1. Critical temperatures for preventing fruit damage in blueberries. The blueberry industry loses millions of dollars of fruit each year due to heat damage. To contend with this problem, many growers are installing micro-sprinkler systems for cooling the berries but have many questions, including the temperature at which to run their systems. An ARS scientist at Corvallis, Oregon, and collaborators at Oregon State University, identified the critical temperatures for heat damage and determined that, in order to avoid damage, fields should be cooled at air temperatures greater than 90 degrees Fahrenheit when the berries are green and greater than 95 degrees Fahrenheit when the berries are pink or blue. Growers are using this information to decide when to initiate cooling and avoid disastrous fruit losses from heat damage.

2. Diversity of root rot pathogens in Pacific Northwest nursery production systems. Rhododendrons, an important part of the nursery industry valued at $42 million, are susceptible to root rot, yet little is known about which pathogens cause root rot on this crop. ARS researchers in Corvallis, Oregon, surveyed seven rhododendron nurseries, identified 31 pathogens associated with root rot, and determined that root rot damage was rare during the propagation stage, but severe root rot was common in container- and field-grown plants. The results indicate that Phytophthora species are the main cause of root rot and that most contamination by these pathogens occurs after the plants have been propagated. The researchers also discovered that one Phytophthora species, P. plurivora, has become more widespread than in the past. This information is important because most disease control measures for rhododendron root rot target a different Phytophthora species, P. cinnamomi. These options may not be as effective for P. plurivora and explain why root rot is still a significant problem for the rhododendron industry.

3. Potassium requirements and tissue test guidelines identified for Pinot noir. The optimal level of potassium required by Pinot noir wine grapes and its impact on fruit quality were unknown. An ARS scientist in Corvallis, Oregon, and collaborators from Oregon State University, identified potassium needs and developed new tissue test guidelines for potassium based on vine productivity and fruit quality metrics. Potassium supply had the greatest impact on must potassium levels and must pH, altering these fruit quality attributes before vine growth or crop yield were reduced by potassium limitation. Potassium limitation also caused late bunch stem necrosis on fruit clusters before yield was negatively impacted. Tissue test guidelines to manage potassium supply to avoid negative impacts on fruit quality were defined, which will allow Pinot noir producers to use potassium more efficiently and increase profits.

4. Depth in soil and nitrate influences arbuscular mycorrhizal fungi in grapevines. Understanding the factors that alter the diversity of arbuscular mycorrhizal fungi (AMF) that colonize plants, including grapevines, must be defined to develop best management practices to maintain healthy communities of these beneficial symbionts in soil. A researcher in Corvallis, Oregon, examined how depth in soil, time of year, and presence of roots from other plant species growing in the vineyard each influenced which AMF colonize the roots of grapevines. Depth altered the community of AMF in grapevine roots more than time of the year and more than the presence of other plant roots growing in close proximity to grape roots. The other plants in the vineyard harbored a different AMF community in their roots compared to grapevines, while the number of the most common types of AMF found in grapevine roots near the soil surface was lower in late spring than in late summer, and this was related to high soil nitrate in late spring. These findings indicate that reducing soil nitrogen levels will have a greater impact on the diversity of AMF in grapevines than how viticulturists manage the other plants grown in the alleys between the rows of grapevines.

5. Biochar promotes plant growth and root colonization by beneficial fungi in blueberry. Biochar is a carbonaceous byproduct of bioenergy production and is attracting particular interest as a soil amendment for agriculture. ARS scientists in Corvallis, Oregon, and collaborators at Oregon State University, evaluated the use of biochar, produced by a wood debris fired power plant, as a soil amendment for blueberry, and discovered that it increased plant growth by up to 70%. It also greatly increased the percentage of roots colonized by mycorrhizal fungi. These fungi are well known to be beneficial in many crops, including blueberry. These findings provide valuable new information that will help growers improve soil health and increase production of blueberries.

6. Oomycete microbiome composition in rhizosphere of rhododendron nursery plants. The microbial community of agricultural crops, known as the microbiome, influences plant processes, yet little is known about how a plant’s genotype and its environment influence the composition of the microbiome. ARS researchers in Corvallis, Oregon, compared how the fungal microbiomes of rhododendrons from Oregon nurseries differed among cultivars, growth conditions, and nurseries using DNA sequencing. Fungal communities were dominated by organisms that help with organic matter decomposition and those beneficial to plant health. Nurseries that grew plants in containers and in field soil had a significantly higher diversity of fungi than those that only grew plants in containers, but microbiome composition did not differ among cultivars. These findings show that the production environment plays a large role in structuring the root microbiome of rhododendrons, while the specific cultivars grown do not. Results will help growers develop production practices that enhance beneficial microbial communities in nursery crops.

7. Stomatal functioning and its influence on calcium accumulation in blueberries. Calcium is a key component of plant cell walls and is directly related to fruit quality in many crops, including blueberry. Foliar calcium sprays are commonly used in an attempt to improve fruit quality and storability, but recent studies revealed these sprays have no effect on firmness or fruit calcium content when they are applied to blueberries. An ARS researcher at Corvallis, Oregon, and collaborators at Washington State University and Oregon State University, determined that calcium accumulated early on when the berries were small and green and then stopped completely once they began turning blue. Movement of calcium was driven by transpiration, a process by which plants absorb water through the roots and then give it off as water vapor through small pores, referred to as stomata, in the leaves or, in this case, the berries. As the fruit ripened, the stomata became clogged by the natural development of wax on the berries, and as a result, transpiration was severely limited. This information is being used by researchers to develop new strategies for increasing calcium content and fruit quality of blueberries.

8. Best fertilizer practices for organic production of blueberries. Consumer demand for organic blueberries is increasing in the United States, but information on organic practices for the crop are needed. To address this issue, an ARS scientist in Corvallis, Oregon, and collaborators at Oregon State University, conducted a 10-year trial evaluating a variety of organic practices for blueberry, including the use of compost and organic fertilizers. Compost was found to be a good source of nutrients, but added considerable weed management costs during production and, over time, led to potentially toxic levels of potassium in the plants. Fish soluble fertilizer was also high in potassium and resulted in lower yields in certain cultivars. Feather meal was a good substitute for fish solubles and, when combined with raised beds and weed mat mulch, had a positive effect on yield and fruit quality. Growers are currently using this information to manage their plantings and improve organic production of blueberries.

9. Basil plant quality is more sensitive to salinity than productivity. Decreasing availability and rising costs of quality irrigation water results in more frequent use of saline water sources in many crop production systems. ARS researchers in Corvallis, Oregon, and Parma, Idaho, assessed quality (phenolic composition) of basil when grown with different levels of salinity from sodium chloride (NaCl) or calcium chloride (CaCl2) and inoculated or not with an arbuscular mycorrhizal fungus (AMF). Salinity altered the quality of basil before it reduced productivity, and crop yield was more sensitive to NaCl than CaCl2. While mycorrhizal fungi improved growth and phenolic composition under short duration of saline conditions, these fungi do not completely ameliorate the effects of salinity on basil quality and productivity during a longer duration of saline irrigations. The data highlights how different types of salts and how long plants are exposed to them alters the outcomes of the quality and productivity in basil production. Results will enable growers to more efficiently manage irrigation sources and crop selection.

10. Using perlite in soilless media could be detrimental in blueberry. Growing plants in soilless media is becoming an important system for producing blueberries, but scientific information on how to do it is limited. ARS scientists at Corvallis, Oregon, and collaborators at Oregon State University, examined the growth of two blueberry cultivars in media containing various amounts of peat, coir, and perlite. In one cultivar, growth was best in pure peat and progressively less as more coir or perlite was added to the media, while in the other cultivar, growth declined with increasing amounts of perlite but was unaffected by the ratio of peat and coir. The response of the plants to perlite did not appear to be a function of pH or nutrition and was most likely related to the effects of perlite on media water relations. Response to peat and coir, on the other hand, appeared to be due to nutrition and salinity of the media. These findings suggest that the use of high amounts of perlite in the media could be detrimental when growing blueberry in substrate and that some cultivars may grow better in peat than in coir. Results will help growers develop production practices for this important new berry production system.

Review Publications
Ezin, V., Houessou, F., Bryla, D.R., Ahanchede, A. 2019. Phenotypic plasticity of drought tolerance in tomato (Solanum lycopersicum L.) landraces and hybrid cultivars in Benin, Africa. Journal of Food Agriculture and Environment. 17(3/4):45-53. https://doi.org/10.1234/4.2019.5565.
Schreiner, R.P., Osborne, J. 2019. Potassium requirements for Pinot noir grapevines. American Journal of Enology and Viticulture. 71(1):33-43. https://doi.org/10.5344/ajev.2019.19043.
Strik, B.C., Vance, A., Bryla, D.R., Sullivan, D.M. 2019. Organic production systems in northern highbush blueberry: II. Impact of planting method, cultivar, fertilizer, and mulch on leaf and soil nutrient concentrations and relationships with yield from planting through maturity. HortScience. 54(10):1777-1794. https://doi.org/10.21273/HORTSCI14197-19.
Bryla, D.R. 2019. 4R nutrient stewardship in fruit crops. In: Srivastava, A.K., Hu, C., editors. Fruit Crops: Diagnosis and Management of Nutrient Constraints. Cambridge, MA: Elsevier. p. 509-520.
Yang, F., Bryla, D.R., Strik, B.C. 2019. Critical temperatures and heating times for fruit damage in northern highbush blueberry. HortScience. 54(12):2213-2239. https://doi.org/10.21273/HORTSCI14427-19.
Yang, F., Devetter, L.W., Strik, B.C., Bryla, D.R. 2020. Stomatal conductance and its relation to calcium accumulation in fruit of northern highbush blueberry. HortScience. 55(1):96-102. https://doi.org/10.21273/HORTSCI14482-19.
Foster, Z.S., Weiland, G.E., Scagel, C.F., Grunwald, N.J. 2020. The composition of the fungal and oomycete microbiome of Rhododendron roots under varying growth conditions, nurseries, and cultivars. Phytobiomes Journal. 4(2):156-164. https://doi.org/10.1094/PBIOMES-09-19-0052-R.
Sales, B.K., Bryla, D.R., Trippe, K.M., Weiland, G.E., Scagel, C.F., Strik, B.C., Sullivan, D.M. 2020. Amending sandy soil with a softwood biochar promotes plant growth and root colonization by mycorrhizal fungi in highbush blueberry. HortScience. 55(3):353-361. https://doi.org/10.21273/HORTSCI14542-19.