Research Project: Water and Nutrient Management for Sustainable Production of Small Fruit and Nursery Crops

Location: Horticultural Crops Production and Genetic Improvement Research Unit

2020 Annual Report

Objectives
Irrigation and nutrient management are key factors that impact sustainable and profitable production of high-quality small fruit and nursery crops. The goal of this project is to develop new approaches that integrate water and nutrient management methods with other environmental and cultural constraints to improve the quantity and quality of berry, wine grape, and nursery crops grown in the Pacific Northwest (PNW) while protecting the environment. Objective 1: Determine requirements for high-quality berry crop production through monitoring and management of water, nutrients, and soil. [NP 305, Component 1, Problem Statement 1B] • Subobjective 1A: Adapt and refine remote sensing technology to monitor water and nutrient deficits and determine irrigation and fertilizer needs in berry crops. • Subobjective 1B: Assess the feasibility of using deficit or pulsed-drip irrigation to increase water use efficiency and protect regional water quality in berry crops. • Subobjective 1C: Develop new fertigation and soil management practices to increase production and fruit quality in blueberry. Objective 2: Develop approaches to manage vineyard canopies, soils, and nutrients for improved grape production, plant health, and fruit quality. [NP 305, Component 1, Problem Statement 1B] • Subobjective 2A: Develop an integrated nitrogen (N) management approach encompassing N use in both the vineyard and winery to identify the most effective and efficient manner to manage N inputs to improve wine quality and protect water quality. • Subobjective 2B: Examine how canopy architecture, vine density, and crop load interact to identify the most efficient use of sunlight and soil water resources to improve production efficiency of Pinot noir. • Subobjective 2C: Understand how N management practices influence beneficial arbuscular mycorrhizal fungi (AMF) in grapevines to develop more sustainable methods for farming grapes. • Subobjective 2D: Determine the impact of rootstocks on root development and AMF colonization when challenged by the northern root knot nematode. Objective 3: Evaluate the impact of management practices for water and nutrients on tolerance to abiotic and biotic stress in specialty crops. [NP 305, Component 1, Problem Statement 1C] • Subobjective 3A: Develop new management practices and disease control measures to minimize pathogen damage and losses for woody nursery plants. • Subobjective 3B: Define salinity thresholds for specialty crops so growers can reduce losses of planting stock, mitigate salinity impacts on quality, and broaden the use of more salt tolerant species in systems considered marginal for production of other crops. • Subobjective 3C: Develop and evaluate water and nutrient management practices for specialty crops grown in soilless substrates.

Approach
Experiments will be conducted in the greenhouse and field on small fruit (blueberry, raspberry, strawberry, grapevines) and other specialty crops including nursery crops (Rhododendron, Vaccinium, Basil), and in growth chambers on root pathogens. For Obj. 1 we will develop remote sensing based crop coefficients and water stress indices for irrigation of blueberry and raspberry, and will test the following hypotheses: Deficit irrigation will reduce water use but have no effect on yield or fruit quality when it is applied at early stages of fruit development or after harvest in blueberry or raspberry; Pulsed-drip irrigation will reduce water use and increase yield and production relative to conventional irrigation in blueberry and raspberry; Application of P and B by fertigation will result in greater yield and fruit quality than granular or foliar fertilizers in blueberry; Biostimulants are most effective when applied at low rates and during peaks in root production. For Obj. 2 we will test these hypotheses: Maintaining low N status in the vineyard will enhance wine composition as compared to boosting N supply in the vineyard; Varying N supply to Pinot noir alters berry and wine phenolic composition to a greater extent than P or K; Altering the VSP trellis to increase canopy solar exposure at midday will increase productivity but not alter ripening or fruit quality in Pinot noir; Soil and foliar applied N in vineyards reduces AMF colonization and P uptake; Nitrogen inhibition of AMF colonization in grape roots increases with N dose; Nitrogen is a more potent inhibitor of AMF as vine P increases; Root development and AMF colonization differ among rootstock genotypes when northern root knot nematode is present. We will test the following hypotheses for Obj. 3: Critical temperatures for vegetative growth and zoospore formation of Phytophthora isolates will be similar within a species; fungicide sensitivity of Phytophthora is greatest at the optimal temperature for growth; Root rot induced by flooding is more severe than rot under moisture conditions common in nurseries; Reducing water availability minimizes root damage caused by Phytophthora in rhododendron; Increasing N increases root damage caused by Phytophthora in rhododendron; Crop tolerance to salinity will differ among production systems; Southern highbush blueberry plants have different substrate needs than northern highbush blueberry; Strategies to improve water distribution in substrates will increase growth and production in blueberry. Measurements and techniques used in these studies will include standard approaches to measure plant growth, biomass, and yield, plant water status (pressure chamber, porometer), photosynthesis (gas-exchange), fruit quality (refractometry, titratation, HPLC, sensory perception), root production and mycorrhizal colonization (soil cores, microscopy), soil pH and EC, soil water content (TDR, tensiometers), plant and soil nutrients (CNS analyzer, ICP), and pathogen growth (microbiological media) and root damage (visual ratings). We will also utilize multi-spectral cameras and drones to develop new methods to measure plant water status.

Progress Report
This report documents progress for project 2072-21000-055-00D, "Water and Nutrient Management for Sustainable Production of Small Fruit and Nursery Crops," which began April 2020 and continues research from project 2072-21000-053-00D, "Integrated Water and Nutrient Management Systems for Sustainable and High-Quality Production of Temperate Fruit and Nursery Crops." Six commercial field sites were identified in support of Sub-objective 1A, including four fields each of blueberry and raspberry in Washington. Remote images will be collected at each site using a small unmanned aerial system (sUAS) equipped with a multispectral and a thermal imaging camera. Preliminary measurements indicate that the sUAS is capable of capturing 10 acres of imagery in a single 20-minute flight. The images will be used to monitor canopy development and assess spatial variability in water status of the fields. Any problems in the fields, such as plugged drip emitters and Phytophthora root rot, will also be identified. Data will be used to assess the effects of new and existing management practices on crop development and temperature. Four field trials were initiated in support of Sub-objective 1B in order to assess the effects of deficit and pulsed drip irrigation on fruit production and quality in blueberry and raspberry. Plants in the deficit trials will be fully or deficit irrigated (0% and 50% of estimated crop evapotranspiration) for two weeks during the late green stage of fruit development (late June) and after harvest (August). Pulsing has been programmed to operate for 30 min every two hours, up to eight times per day, as needed, while standard irrigation is programmed to operate once a day for up to four hours, as needed, using approximately the same amount of water as applied to the pulsed treatments. In support of Sub-objective 1C, trials investigating the value of fertigating with phosphorus (P) and boron (B) fertilizer in highbush blueberry were continued. P treatments are applied to two cultivars (Duke and Bluecrop) and include no P fertilizer, soil application of granular ammonium phosphate at the highest recommended rate of 67 kg/hectare P, and bi-weekly fertigation from mid-April to late-July with liquid ammonium polyphosphate at total rates of 34 and 67 kg/hectare P per year. B treatments are also applied to two cultivars (Earliblue and Aurora) and include no B fertilizer, soil application of sodium borate (Borax), foliar application of boric acid, and bi-weekly fertigation from mid-April to late-July with boric acid. Each B fertilizer is applied at a total rate of 1.5 kg/hectare B per year. The treatments were initiated in spring 2019 and will continue for at least two years. In support of Sub-objective 2B, vineyard management for a new study to examine how canopy architecture, vine density and crop level alter productivity and quality of Pinot noir was continued. Thus far this season, vines have been fertilized, shoot-thinned, and shoot-positioned two times. This project will provide a large-scale test of whether increasing midday solar capture by opening up the top of the canopy can improve the quantity of fruit produced without compromising quality or long-term vine health. In support of Sub-objective 2C, a new study was initiated to assess how different sources of nitrogen influence fine root growth, mycorrhizal colonization of roots, nitrogen uptake, and whether or not mycorrhizal fungi facilitate nitrogen uptake from organic nitrogen sources in grapevines. Results from prior experiments showed that mycorrhizal fungi did not enhance inorganic nitrogen uptake by grapevines over a range of nitrogen and phosphorus levels, and that vines obtained some nitrogen form the soil organic pool. We are now examining if mycorrhizal fungi will assist in uptake of nitrogen from organic sources and have planted vines and began collecting growth data. Information from these experiments is important in developing sustainable vineyard nutrient management strategies that can take advantage of beneficial mycorrhizal fungi and reduce inputs and potential nutrient losses to the environment. 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 in support of Sub-objective 3A. Experiments initiated during the last project cycle 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. In support of Sub-objective 3B, 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 initiated to evaluate how water and nutrient management practices for specialty crops grown in soilless media in the field in support of Sub-objective 3C. A new study was initiated to evaluate how fertilizer formulation and rate influence nutrient run-off from five different varieties of container-grown plants commonly grown in Pacific Northwest nurseries. Study plants were also used to investigate how remote sensing using unmanned aerial vehicles (UAVs) can be used to detect crop nutritional and water status. Results from this study are being used to modify a similar experiment planned for later in 2020. Results from these experiments will be used to develop nutrient management strategies than minimize nutrient run-off and develop management options for this type of high-value production system.

Accomplishments

Review Publications
Scagel, C.F., Lee, J. 2020. Salinity sensitivity and mycorrhizal responsiveness of polyphenolics in ‘Siam Queen’ basil grown in soilless substrate. Scientia Horticulturae. 269. https://doi.org/10.1016/j.scienta.2020.109394.
Kingston, P.H., Scagel, C.F., Bryla, D.R., Strik, B.C. 2020. Influence of perlite in peat- and coir-based media on vegetative growth and mineral nutrition of highbush blueberry. HortScience. 55(5):658-663. https://doi.org/10.21273/HORTSCI14640-19.
Weiland, G.E., Scagel, C.F., Grunwald, N.J., Davis, E.A., Beck, B.R., Foster, Z.S., Fieland, V.J. 2020. Soilborne Phytophthora and Pythium diversity from rhododendron in propagation, container, and field production systems of the Pacific Northwest. Plant Disease. 104(6):1841-1850. https://doi.org/10.1094/PDIS-08-19-1672-RE.