Soilless long-cane production of blackberry

SOILLESS LONG-CANE PRODUCTION OF BLACKBERRY

Sponsoring Institution

National Institute of Food and Agriculture

Project Status

ACTIVE

Funding Source

AFRI COMPETITIVE GRANT

Reporting Frequency

Annual

Accession No.

1032083

Grant No.

2024-68013-42265

Cumulative Award Amt.

$749,001.00

Proposal No.

2023-09682

Multistate No.

(N/A)

Project Start Date

Jul 1, 2024

Project End Date

Jun 30, 2028

Grant Year

2024

Program Code

[A1102]- Foundational Knowledge of Agricultural Production Systems

Recipient Organization
UNIVERSITY OF ARKANSAS
(N/A)
FAYETTEVILLE,AR 72703

Performing Department
Horticulture

Non Technical Summary
Consumer demand is increasing for fresh-market blackberries, but the ability for U.S. blackberry producers to meet this demand and stay profitable is threatened. Main issues include declining yield caused by soilborne pathogens and climate variability, and rising production costs which continue to erode profit margins. Breeding for disease resistance is an option, but this is time-consuming, does not solve all issues, and should not be relied on solely. The future sustainability of blackberry production and improved food security requires (i) development of new knowledge and innovative approaches to increase yields and (ii) outreach efforts targeting a broad fruit grower audience spanning across food systems. We propose an integrated research and extension project evaluating novel soilless long-cane production techniques for the increased success and profitability of blackberry production. Objectives 1 and 2 develop new information on how cultivar selection and targeted cultural practices influence long-cane yield and fruit quality. Objective 3 evaluates breakeven and risk analyses for both long-cane and field-based blackberry systems and quantifies the magnitude of key profitability drivers. Objective 4 focuses on rapid and long-term application of research results targeting small and large operations. Soilless systems that reduce losses from disease and increase yields will also increase the profitability and success of blackberry producers, benefitting local and regional economies. Considering the national scope and increasing trend for soilless culture, we anticipate the output from this project will be critical in progressing the blackberry industry forward and building food system resilience.

Animal Health Component

100%

Research Effort Categories

Basic

Applied

100%

Developmental

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
205	1129	3100	100%

Knowledge Area
205 - Plant Management Systems;

Subject Of Investigation
1129 - Berries and cane fruits, general/other;

Field Of Science
3100 - Management;

Keywords

Goals / Objectives
The long-term goal of this Foundational Knowledge of Agricultural Production Systems project is to increase fresh food resiliency with soilless "long-cane" production of blackberry. The context of this goal is that consumer demand is increasing for fresh market blackberries, but the ability for U.S. blackberry producers to meet this demand is threatened by declining yields and consistency from (i) soil-borne diseases, particularly Fusarium, and (ii) increased climate variability and extreme weather events. Soilless "long-cane" production techniques are designed to mitigate these and other production issues; these systems are used in other countries and by early adopters in North America and show promise to help strengthen and sustain the growth of the U.S. cane berry industry.Our objectives for reaching our goals include the following:Evaluate cultivar effects on yield and fruit quality in long-cane blackberry.Evaluate long-cane cultural strategies for effects on yield and fruit quality.Evaluate the economic feasibility and risk of long-cane blackberry.Develop novel extension outreach materials targeting long-cane and field producers.

Project Methods
Soilless long-cane production systems. Long-cane experiments will be conducted in plastic-covered high tunnels located at the University of Arkansas Agricultural Field Station, Fayetteville, AR, as well as the University of Arkansas Fruit Breeding Station, Clarksville, AR (see Facilities and Other Resources, Budget Justification). Fayetteville and Clarksville are approximately 100 miles apart and have USDA Hardiness Zone designations of 6b and 7a, respectively. A new larger high tunnel will be installed at Fayetteville (year 1) to match the size of the Clarksville location tunnel for Objectives 1 and 2. Tunnels will be equipped with long-cane trellises, pressure-compensated drip irrigation, multi-injector, and fertilizer stock tank systems.During experiments plants will be fertilized at each irrigation using a custom long-cane fertilizer recipe supplied by Nourse Farms (Whately, MA) and modified by PD Dickson. Irrigation controllers will pulse irrigate approximately 8 to 20 times per day depending on climate conditions and to ensure a 20%-30% leaching fraction, following standard guidelines for soilless culture. Solution volume, electrical conductivity (EC), pH, and nutrients will be monitored daily in the applied and leached fertilizer solution for each research plot to monitor root zone fertility, moisture levels and leaching, and to make fertilizer decisions (standard practice for soilless culture). Row spacing will be 2 m for each experiment, in-row spacing will depend on treatment (see below).Sourcing of blackberry long-cane materials and supplies. For each experiment, dormant long-cane blackberry plants will be purchased from a professional and licensed long-cane propagator in the U.S. (Nourse Farms, Whately, MA) and shipped frozen to the appropriate research location (Fayetteville or Clarksville, AR). Plant material will meet European quality specifications of a 2-m tipped height, at least 25 nodes per cane, and 5 canes per plant. Plants will be stored in PD Dickson's cold storage facility at -1.5°C until needed for experimentation.Cultivar selection for long-cane research. Blackberry cultivars with high-yielding potential as long-canes (determined by Co-PIs Worthington and Fernandez) will be selected from the University of Arkansas Fruit Breeding Program. 'Von' and 'Loch Ness' will be trialed as standard reference (control) cultivars in Objective 1 since these are already used in long-cane production.Up to 12 long-cane blackberry cultivars will be evaluated over three pull-out dates for effects on yield and fruit quality over time. For pull-out date treatments, dormant plants will be removed from cold storage and transferred into production during (approximately) February, March, and April. Experiments will be held at Fayetteville and Clarksville locations under the direction/supervision of PD Dickson and Co-PI McWhirt and repeated over years 1 and 2 for sufficient replication and estimations of yield variance. For each experimental run, dormant plants will be repotted in 7-L containers in 100% coconut coir substrate (FibreDust, LLC), placed in tunnels at 2-m between-row spacing and 0.7 m in-row center spacing with drip fertigation. During production, the developing lateral branches which produce flowers and fruit will be trained horizontally and supported by the long-cane trellis. Weather stations placed at canopy level will record climate conditions (air temperature, photo flux density, humidity) every 15 minutes. Fruit harvesting will occur twice per week and harvest data for each experimental unit will consist of measuring ripe berry number and total harvested fruit weight per plant. Harvested fruit will also be separated into marketable and unmarketable (misshapen or deformed fruit) categories. Sub-samples of marketable fruit will be taken at each harvest event and stored at -20°C for later determination of fruit soluble solids (°Brix) and titratable acidity (citric acid equivalents). Calculated response variables per experimental unit will include individual weight of marketable berries, percent marketable fruit, marketable yield per linear meter and per square meter, and the soluble solids:titratable acidity ratio of marketable fruit (important fruit quality and taste parameter) per experimental unit. Cultivar and pull-out date effects on each response variable will be evaluated over time (harvest events) and between locations/years.Co-PI Knuth will collect data to use later with eye-tracking software for each experiment and cultivar (see Objective 3). This will involve Co-PI Knuth traveling to Arkansas experiment sites, taking high-resolution videos/pictures of harvestable crops, tracking the time it takes workers to harvest in research plots where videos/pictures were taken, and going back through the research plots to carefully measure harvest efficiency. Data will also be collected on the same blackberry cultivars grown in the field using a standard T-trellis at the Clarksville location (location of AR Fruit Research Station), where these cultivars are already maintained and harvested as part of the Arkansas Fruit Breeding Program. Prior to harvesting, Co-PI Knuth will provide basic training to workers to match commercial harvesting practices. These data will be collected at >10 harvesting events for each cultivar treatment per experimental run and location for sufficient replication and statistical power. It is not feasible for Co-PI Knuth to travel to AR for each data collection event and therefore she will provide training to PD Dickson and Co-PI McWhirt staff to take pictures/videos, train workers, and collect these data in her absence.In addition to cultivar selection, we have identified several plant management strategies from commercial long-cane raspberry growers likely to have major effects on blackberry long-cane yield and harvesting efficiency: planting density, thinning of lateral branches and fruit, and the practice of "double-cropping" for long-cane. Increasing the planting density is expected to increase total yield/acre but decrease harvesting efficiency, fruit yield per plant, and individual fruit weight (also affects costs). The removal of developing lateral branches, which essentially removes developing fruit (a.k.a. fruit thinning), is reported by growers to increase individual fruit weight (a desirable market trait) and percent marketable fruit, with little or no effects on total yield. The practice of "double-cropping" long-canes is intended to achieve two harvests per season and is based on the concept that only a fraction of a blackberry's flowering/fruiting potential occurs naturally due to mechanisms within the plant's morphology and physiology [24], and a higher potential can be realized through horticultural manipulation. The double-cropping strategy involves removing the inflorescences and fruit receptacles from the lateral branches after all berries have been harvested from the first main flush of flowering/fruiting, leaving lateral branches with only vegetative leaf tissue. This followed by an increase in nitrogen fertilization of approximately 30% to stimulate additional growth from each remaining leaf node, creating a second flush of flowers that would otherwise have remained dormant.

Progress 07/01/24 to 06/30/25

Outputs
Target Audience:The target audiences in this reporting period has been blackberry growers/farmers, breeders, and professional members of allied industries(i.e. substrate, fertilizer, plastics, agrichemical companies, etc.) in the United States. The first year of this project has been primarily project set-up, facilities upgrades, and the start of experimentation for Objectives 1 and 2. Experiments are ongoing at this time, andstakedholder efforts and outreach will be reportedin the nextperiod. Changes/Problems:The project is going extremely well with no major problems. There have been a couplechanges, described below, that will ultimately benefit the project as a whole. We originally planned and budgeted to purchase a new high tunnel for this project. However, surprisingly we were able to secure two larger high tunnels already at the University of Arkansas research stations. We decided to use these tunnels and redirect equipment funds to make modern upgrades to the structures and fertigation systems. The result is we have increased the production space for this project while spending less, increasing the efficiency of the budget. For the blackberry variety trial, we were unable to purchase the number of long-cane varieties we anticipated needing from one supplier. As a result, we scaled the variety number down to three, however, unfortunately a shipping issue occurred the supplier end, and were only able to successfully identify 2 varieties. For the sake of conducting a quality variety trial research, we opted to use only Caddo (bred at UofA) and Von (bred at NCSU) for the variety trial. However, we expanded the variety trial to include both a greenhouse and high tunnel location for more robust evaluation. This has paid dividends, and we are learning more about the effects of growing environment (tunnel versus greenhouse) on berry yield and quality. To make up for the lack of long-cane varieties tested, we included a separate experiment testing the effects of transplant type (8 total) on long-cane growth and yield, which includes varieties Ponca (bred at UofA) and Von. This experiment is already showing incredibly useful results to common industry questions. For example, a key question has been is there any impact of overwintering small transplants from tissue culture before growing them as long-canes, versus growing long-canes directly from tissue cultured plants. The overwintered plants have more than twice the vigor compared to the tissue cultured plants for both Von and Ponca. We delayed the industry/grower survey to initiate in the second reporting period. The grant team needed more time to carefully construct the questions and verify their scientific and industry merit. There was some industry pushback to asking about detailed grower/farmer financials, so we are making the survey less intrusive to individual business details. We do not anticipate IRB approval being necessary for the udpated survey. What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?We plan to accomplish the following in the next reporting period. Finish experiments under Objectives 1 and 2. This includes the blackberry variety, transplant type, and pruning trials. At the time of writing this report, these trials are underway and should be finished before the year-end. Data analysis and interpretation should also commence. Conductcane and planting density trials under Objective 3. The plants for this objective are currently growing in our outdoor nursery pad and we are collecting data. The plants will be overwintered in cold storage, and planting density treatments will be evaluated in two locations during the next reporting period. The grower and industry survey will be initiated as part of Objective 4.

Impacts
What was accomplished under these goals? Accomplishments included major facilities upgrades to support the research objectives as well as the initiation of two major experiments. The facilities upgrades included the expansion of the greenhouse, nursery pad, and high equipment for blackberry long-cane production. The experiments included a variety trial and transplant trial (Objs. 1 and2), and plant material was started for next year's research with Obj. 3.Below is a summary of progress and preliminary results. Overview of greenhouse, tunnel, and nursery system upgrades A trellis system was constructed to support the pots, plants and canes, and fruiting laterals as well as to elevate plants off the floor for the greenhouse. It was constructed using cedar wood and white plastic gutters (Bato; Hort Americas; Bedford, TX, USA) placed on top of pine wood planks. Bailing twine was threaded through the center of the wooden trellis posts to support the plants. The gutter prevented leachate solution from covering the greenhouse floor, which helped prevent algae growth on the floor. The wooden plank and gutters were sloped towards the south-side of the greenhouse so that leachate solution could drain into 189-L drain bins. The wooden trellis structure had eye hooks nailed every 15.2 cm on the outer surface so that bailing twine (TygerTwine; ULINE; Pleasant Prairie, WI, USA) could be threaded through the hooks to support the developing branches. Cinderblocks were used to weigh down the trellis posts. The greenhouse contained two 12-m rows, each with five wooden trellis posts installed every 3 m. The rows were spaced 2.4 m apart. The high tunnel was upgraded with a new, UV resistant 6 mm clear plastic cover (Farm Plastic Supply; Addison, IL, USA), a black plastic ground cover for weed suppression, and additional metal T-posts for trellising plants which were placed every 3 m in three rows. The three rows were spaced 2.4 m apart, and each row was 12 m long. To protect the crops from high-speed wind and hail, netting was placed on the sides of the tunnel using the existing wiggle wire, and wind blockers were installed on the north and south-facing sides of the tunnel. The nursery needed the least number of repairs. Additional posts were installed in each of the three rows, with 10 posts per row spaced 3 m apart, and the row spacing in the nursery was 3.1 m apart. Additional wooden steps were added to the posts so that the trellis lines are spaced 30.5 cm apart. In all three locations, an irrigation system was constructed to include three in-line fertilizer injectors which diluted concentrated fertilizer stock solutions into the irrigation water from their respective stock tanks. The stock tanks consisted of 167-L trash cans filled with the following concentrated fertilizer salt solutions: the first tank (tank A) contained calcium nitrate, the second (tank B) contained macro- and micro-nutrients (5-12-26; JR Peters, Allenstown, PA), and the third tank (tank C) contained a strong acid (sulfuric acid) for pH adjustment. The irrigation dosing system included a water filter before irrigation reaches the injectors, two mixing chambers for in-line fertilizer mixing, a hose bib to fertilize plants with a hose as needed, and a solenoid valve controlled by an irrigation controller. The main differences in the irrigation system among the three locations include the irrigation controller, which is battery-powered in the high-tunnel, and outlet-powered irrigation controller in the greenhouse and nursery. Each container in every location was irrigated with 1.9 l/h pressure-compensating emitters attached to 6.35-mm spaghetti tubes with dripper stakes at the end. The plants in the greenhouse and high-tunnel had two drippers per container, while the plants in the nursery had one dripper per container. For each location, each row had a 5-gallon bucket and lid where one or two drippers were threaded through a hole to collect the applied solution pH, electrical conductivity (EC), and water volume on a daily basis. In the greenhouse and high tunnel, each row had a plant in the middle that was chosen to be placed inside a 19-L bucket with a drain hole at the bottom. The hole allowed the excess drainage from the container to be collected in a separate 8-L bucket below in order to measure drain pH, EC, and water volume on a daily basis. The drip and drain water volume was used to calculate leaching fraction (LF, %) using the following equation: drip volume/drain volume x 100. Drip refers to the irrigation water being delivered to the plants, which contains fertilizer, and drain refers to the leachate from the bottom of the containers that occurs after irrigation events. We were unable to set up a drain bucket system in the nursery, so we opted to collect leachate pH and EC data from six random plants once per week using the pour-thru method. Crop management and data collection Standard crop management practices were implemented for each experiment, designed to mimic commercial production practices and to help us track labor and resource inputs. These management practices can be separated into the following categories: plant maintenance, fertilizer and irrigation program, integrated pest management, climate monitoring, and harvesting. Each task involving blackberry production was captured by clocking in and out with the use of labor tracking codes. Other tasks that involved using materials, such as mixing fertilizer and spraying pesticides, were logged in separate QR codes since we tracked labor and the amount of materials used for each location. The responseswere automatically stored in an Excel form when a response was submitted. The Excel document from the QR-code forms was linked to Microsoft Power BI to generate a live dashboard of the drip and drain pH, EC, and leaching fraction, allowing management decisions on fertility and irrigation to be made as soon as possible. Update on Experiment 1: Cultivar evaluation in a greenhouse and high tunnel. Preliminary results: At the time of writing this progress report, all plants still had green fruit, and no harvest data had been collected. However, preliminary observations and summaries of the tracking data collected are highlighted below. Caddo plants from the nursery were taller and had one more cane compared to the Von plants. Since Caddo plants were taller, it could have also contributed to their higher initial number of nodes. The long-cane plants in the high tunnel developed flowers and fruit earlier than the plants in the greenhouse. In addition, the tunnel-grown plants have visibly more green fruit and appear more generative and less vegetative (smaller leaves, less foliage relative to fruit) compared to the greenhouse-grown plants. We hypothesize the plants in the tunnel are more generative because of the higher temperatures and daily light integral. Von has produced more green fruit compared to Caddo. Overall, Caddo appear very vegetative in both the greenhouse and tunnel, and yields are expected to be low. Update on Expt #2: Transplant type effects on long-cane growth and yield. Preliminary results: Plants are currently in the outdoor nursery environment to develop to continue developing primocanes. The environmental conditions for each production phase mimic that of outdoor conditions of deciduous and temperate regions; native to plant species that require prolonged chilling hours between 0 °C and 6 °C in the winter to produce flowers in the spring and summer.

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