Consumer demand for broccoli has grown dramatically over the last 10 years and continues to expand. During that same 10-year period, Oregon broccoli production has dropped 33%. From a peak of more than 15,000 tons in 1987, only about 5,000 tons is expected to be processed in 2017. This reduction in acreage is the result of high labor costs associated with broccoli harvest. Many processed vegetable farms maintain crews of 3-5 workers but manual harvest requires crews of 9 or more. This project aims to develop a broccoli mechanical harvest system to reduce the number of harvest workers to 3–5. The project will scale up seed production of OSU-developed broccoli cultivars with exerted heads that are easily mechanically harvested, and it will evaluate the yield and processing quality of both OSU and commercial cultivars when grown with organic and conventional practices. It will evaluate the utility of selective seed harvest and seed processing to increase head maturation uniformity and facilitate single pass mechanical harvest. The project will support farmers in integrating a high school robotics team-developed visioning system into their farm-built harvesters. Because the demand for organic broccoli is growing, the project will also develop cost effective strategies to supply N from organic fertilizers, as broccoli is a high N demanding crop. This project should increase farm/farmer and processor economic sustainability as the result of increased broccoli production acreage and profitability. It should increase environmental sustainability by diversifying processed vegetable rotations and increasing organic and N-fixing cover crop acreage. It should increase the availability of US-grown broccoli to the consuming public as well as to public schools and federal institutions, resulting in a stronger and more nutritious national and regional food system and contributing to social sustainability.
Objective 1: Engage broccoli farmers in project development, delivery, results, and evaluation through the development of a farmer-led Broccoli Sustainability Task Force.
Objective 2: Evaluate available cultivars for mechanical harvest yield and processing quality under conventional and organic management and at varied planting densities
Objective 3: Describe and improve seed quality to improve maturation uniformity and facilitate single pass harvest
Objective 4: Engage farmers with a high school robotics team-developed harvester prototype to facilitate further development of inexpensive single pass mechanical broccoli harvesters
Objective 5: Develop cost effective organic broccoli fertilization regimes.
Hypothesis for Obj. 2: (Evaluate available cultivars for mechanical harvest yield and processing quality under conventional and organic management and at varied planting densities): Broccoli cultivars will differ in traits associated with yield and processing quality when grown in different management systems.
Hypothesis for Obj. 3: (Describe and improve seed quality to improve maturation uniformity and facilitate single pass harvest): Seed quality can be manipulated to improve uniformity of maturity by separating based on size and density.
Hypothesis for Obj. 4: (Engage farmers with a high school robotics team-developed harvester prototype to facilitate further development of inexpensive single pass mechanical broccoli harvesters): A prototype machine can be built that will allow direct harvest of broccoli.
Hypothesis for Obj. 5: (Develop cost effective organic broccoli fertilization regimes): A cost effective broccoli fertilizer regime can be developed.
Ob. 2: Spring and fall replicated yield trials were established. Transplants of hybrids were started in the greenhouse about May 1 (Spring trial) and July 10 (Fall trial). The spring trial was transplanted 7 June while the fall trial was planted 7 August. The spring trial consisted of four commercial cultivars (Cascadia, Emerald Pride, Monflor and Hancock) while the fall trial had the four commercial hybrids along with 16 OSU experimental hybrids. Hybrids were arranged one row plots 30 feet in length and replicated four times with in-row spacing of 12 inches. In addition to observation data, (including percent blind, head size, shape, firmness, exsertion, segmentation, uniformity, floret texture and color, and maturity) yield data was obtained. Heads from the plots were trimmed to a 6.5 inch length and weighed, after which leaves were stripped from the heads and heads were again weighed. Leaf percent was calculated from this data. Heads were sorted for those that were judged too young and small for the floretting process in the plant, and those that were culls (mostly too mature). A set of 10 heads were evaluated for diameter and hollow stem, and a subset of five heads was floretted and florets and stems weighed separately. Floret and stem weight data was used to calculate a floret:stem ratio. In the fall trial, the proportion of florets > 2.5 inches was also determined. Entries in the yield trial were taken to the OSU pilot processing plant for blanching and freezing. Frozen material was evaluated at the OSU winter cutting on 8 November and was displayed at the PNVA meetings in Kennewick, WA on 15 November.
Data for the total net yield of broccoli harvested from each grower’s field was collected from the Yield and Grade reports generated by the Norpac vegetable processing plant. Calculations of per acre net yield for Cascadia and Emerald Pride varieties of broccoli was estimated from these grading reports. Only field sites which had a contiguous planting of each variety and similar agronomic inputs was used for the calculations of yield. The estimated per acre yield of total florets and usable sized florets (i.e. < 2.5 inches) was also calculated and extrapolated from the data collected during the fall replicated yield trial.
Obj. 3: Seed production of selected hybrid combinations using a fertile inbred as a male and a CMS inbred as a female were evaluated in the field using six isolation plots (three at the Vegetable Research Farm, and three at the Lewis Brown Farm). Plots were at least a quarter mile apart. We started inbreds from rooted cuttings taken from flowering greenhouse-grown plants so that they would be flowering immediately upon establishment in the field. Cross combinations included O446/S454, O446/S462, O446/S471, O446/S473, O446/S475 and O462-1/S471. Parents were planted in 10 alternating rows approximately 20 ft. long with 12″ within row spacing. Honeybees were the predominant pollinator species.
Obj. 4: The Crescent Valley FIRST Robotics Team 955 developed and built a new prototype broccoli harvester in 2018. Cascadia was seeded and transplanted at approximately two week intervals at the OSU Vegetable Research Farm to provide a continuous supply of broccoli for testing by the “BroccoliBot”. This system was deployed to the field at the OSU Vegetable Research Farm and later during the season, in farmers’ fields.
Obj. 5: Fertilizer treatments for conventional and organic broccoli production were evaluated in replicated experiments at the OSU Vegetable Research Farm. Sidedress N fertilizer treatments included three rates of urea (conventional) or feather meal (organic). Sidedress N was applied two weeks prior to the buttoning growth stage. Soil samples (PSNT) served as criteria for N fertilizer application rates. Broccoli yield and quality was evaluated at harvest.
Ob. 2: Of the four commercial hybrids (Cascadia, Emerald Pride, Monflor and Hancock), all but Emerald Pride have the exserted head trait, but vary for other traits such as head segmentation, color, bead size and yield. In terms of Net yield, Cascadia, Monflor and Emerald Pride were not significantly different (4.1 – 4.6 T/A), but were significantly lower yielding than Hancock (8.9 T/A). Emerald Pride had the most leaves on the stem (22%) followed by Monflor (20%) with Cascadia (12%) and Hancock (7%) having the least. Hancock had a significantly greater percent florets compared to the others (70% vs. 56 – 61%), a high percentage of florets were > 2.5” and would require recutting in the plant. Cascadia had the best combination of quality traits followed by Emerald Pride. Of the commercial hybrids, Monflor has very deep branching and would require stems to be cut to a very long length to keep the head intact for floretting in the plant.
In the fall trial, yields were about 3 T/A lower than in the spring. Hancock had the highest Net T/A at 6.0 but the differential was not as great compared to other hybrids, which ranged from 3.3 to 5.4 T/A. Most OSU experimental hybrid did not have yield significantly different from Monflor and Emerald Pride. Cascadia had the lowest net yield at 3.3 T/A. It had the highest leave percentage (10.6%) suggesting that it was cut at a younger stage than the others. Percent florets ranged from 59.2 to 77.1% while usable florets ranged from 42.3 to 56.2%. While Hancock had the highest percent florets, it had the second to lowest usable florets. Emerald Pride ranked fourth from the bottom for usable florets while Cascadia was in the middle of the group and Monflor had the second highest percent usable florets. On a T/A basis, Hancock had the second highest weight (following Monflor and Emerald Pride) of usable florets, while Cascadia had the lowest. A number of OSU experimental hybrids were not significantly different from Monflor and Hancock. The lesson learned is that overall head weight is more important than proportion of the head that is made up of florets.
A heavy aphid infestation was observed in this trial and number of heads with aphid damage was recorded. Significant differences in aphid infestation were observed with some of the lowest numbers being for the four commercial hybrids. Among experimentals, S474/S446 had relatively low numbers.
Production of the first selected pair of female and male parents was initiated (O454 x S446). Following this, production of a new broccoli hybrid to be named Cascadia was initiated. The yield of seed from this production successfully met targets; in 2018, over 300 acres of Cascadia were grown and harvested on commercial farms in Oregon in 2018. Seeds from this production were also distributed for use in seed grade testing and density trials (obj. 3).
Grower’s yield data for Cascadia and Emerald Pride broccoli from four field sites in the Willamette Valley is shown below. Head yields for Cascadia and Emerald Pride were similar in two paired fields but Cascadia had lower yields in two other fields. Floret yield showed a similar pattern as did usable (<2.5in.) floret yield. Overall, Cascadia and Emerald Pride have similar yield potential, but Cascadia seems to be more variable over environments. Cascadia had fewer leaves on heads, better floret size and more uniform floret color.
- Per acre net yield 2. Total floret yield 3. Usable floret yield
Obj. 3: Activities this year were focused on producing the seed for the experiments critical to this objective, with these experiments to take place in 2019. Seed production from isolation plots was variable in 2018 and ranged from 31 seeds (O446/S471) to over 3000 seeds for O446/S473 and well over 5,000 seeds for O462-1/S471. S462-1/S471 was harvested from three levels on the plants to approximate seed produced early- mid- and late-season.
Obj. 4: The BroccoliBot prototype continued with the development of using a camera-based vision system to identify and locate broccoli in three-dimensional space. The prototype further developed the mechanical portion of field harvesting, specifically addressing whether the vision system could be adapted to allow a mechanical harvester to cut florets in the field rather than whole broccoli heads. This prototype was field tested over the course of the summer at the OSU research farm first, and there-after in multiple commercial farms. The camera-based vision system has demonstrated reliability, but the mechanical portion of the harvester was not successful in consistent cutting of florets in the field. The mechanical harvesting system was discussed at length with growers, and will be the focus of improvements in 2019.
Obj. 5: The major findings from the broccoli fertility trial in 2018 was 1) It is feasible to efficiently apply N via sidedress organic fertilizers. The N rate response curve for sidedressed organic fertilizer like feather meal was about the same as N rate response curve for urea. 2) By crediting N in irrigation water and nitrate-N in soil at sidedress time, the N input rate from fertilizer (organic or urea) that required for July-seeded broccoli is relatively small. The broccoli crop took about 250 lb N/acre, and maximum marketable head yield was attained at N input rates of 60 to 120 lb N/acre.
The project’s educational approach is to work closely with the broccoli sustainabilty task force (farmers, processors, researchers, extension professionals) to coordinate project activities, and to further extend project findings at Oregon Processed Vegetable Commission meetings and grower workshops.
Educational & Outreach Activities
OBJECTIVE 1: Engage broccoli farmers in project development, delivery, results, and evaluation through the development of a farmer-led Broccoli Sustainability Task Force.
The Task Force has been active for more than 3 years and developed this project. The task force will meet formally in winter 2019. During the production season, the task force coordinated:
1a Demonstration Field Day of mechanical harvester at Pearmine Farms – August 13th, 2018
1b. Broccoli breeding variety display table at Pacific Northwest Vegetable Association conference -November 14th & 15th 2018
– and also displayed at OSU food technology building on November 8th 2018
1c. Touring of the processing plant in Brooks OR.
1d. Field Demonstration of the robotic harvester at Pearmine farms in Brooks, Oregon.
1e. Field testing of the robotic harvester on the OSU research farm
- the importance of large scale field plantings to evaluate on-farm performance of new varieties before release
- how new varieties of broccoli are bred, and how this process can lead to new varieties with adaptions to a wider range of climatic variations and better uniformity
- performance of new OSU lines in comparison to current commercial lines of broccoli
As 2018 was the first year of this project, no surveys have been conducted as of yet to determine economic, environmental, and social benefits for broccoli farmers in this region. We are working collaborative with local broccoli farmers on a continuing basis to gain insights into their perspectives, problems, and how future research can provide solutions to increase the profitability of broccoli farming as a whole.