Progress 07/01/03 to 06/30/06
Outputs
Progress for this period is focused on evaluating best field production methods for large (17-22cm dia head) crown-cut broccoli as a crop alternative for growers. 2004 and 2005 summaries are provided. 2004. Expt.1. Performance of Early and Late Cultivars Using Two Planting Dates in Plasticulture, Conventional Tillage and No-till (with and without supplemental nitrogen) systems. The late cultivar had higher yield (10,556kg/ha) than early (8,330kg/ha), due to increased head weight (470 vs. 370gr), regardless of planting date or tillage system. Earlier planting date (20 July), yielded 1100kg/ha more than 10 Aug date. The later date resulted in lower head weight (27gr) but better peak harvest concentration (84 vs. 62pct). Plasticulture concentrated peak harvest by 5-15pct, increased head weights 76 to 232gr, and increased the percent large heads from 26 to 59pct compared to other production systems. Yields were also higher 12,339kg/ha vs. 11,057kg/ha (conventional tillage)
and 6724kg/ha and 7627kg/ha (minus/plus N No-till). Plasticulture increased stem hollowness by 20pct more compared to conventional tillage, and 40-45pct more than no-till treatments. Supplemental nitrogen in No-till increased yield and head weight (358 vs. 321gr minus N). 2004. Expt. 2. Evaluation of Five Planting Densities of Two Cultivars on Plasticulture. An early and a late cultivar were set at five in-row planting densities: 23, 30, 38, 46, 53cm, in double rows 30cm apart on the plastic bed. Best yield was obtained with higher densities (23-30cm) (up to 12992kg/ha), although target head size (17-22cm) was 32-50pct lower. The 38cm density maximized yield and head size,10976kg/ha, with 69pct target size. Yield was not significantly different between 38, 46 and 53cm densities, although individual head weight, (295gr at 23cm; 497gr at 53cm), hollowness (21pct at 23cm; 55pct at 53cm) and the percent large heads (84pct at 53cm) increased as density decreased. Cultivar response was
independent of planting density. The late cultivar Gypsy, had 45pct more stem hollowness, but a higher mean head weight than the early cultivar Everest (435gr vs. 350gr). 2005. Expt. 1. Evaluation of Six Densities Under Three Nitrogen Regimes. This expt. determined the effects of nitrogen fertility on crop densities on plastic mulch. Cv. Gypsy was set on plasticulture at six in-row densities: 23, 30, 38, 46, 53 and 60cm, on double rows 30cm apart on the plastic bed. Between transplanting and early heading, 28, 67, 112 kg total N/ha were split into 6 weekly applications across densities. Yields at 23 and 30cm were higher than all other densities (8817-8124kg/ha), compared to lowest yield of 7608kg/ha at 60cm. Average head weight increased as density decreased, from 176gr at 23cm, to 458gr at 60cm; with 77pct of heads at 60cm reaching target market size versus only 3.8% at 23cm. 69-76pct of stems at 53 / 60cm exhibited hollowness, while at 23cm only 16.3pct were hollow. As fertility
levels increased, total yield, average head weight, the pct of large heads and stem hollowness increased.
Impacts
Crown-cut (large17-22cm, single heads) broccoli production and marketing is emerging as a second-crop market opportunity for growers. Plasticulture results in improved yield and quality, and for Fall harvest, broccoli can be sequentially planted after a summer crop, helping to recover annual investments in plasticulture. Quality is improved with Fall-grown product, though increased maturity periods should be considered for late harvests, and the risk of freeze damage, with crop loss noted below neg 3C. Market window evaluations indicate that prices improve from end of Sept., peaking in early November. Thus it is a calculated risk to target later season windows. Lower densities result in a higher percentage of desirable large heads, but less total yield by area. Effective spatial arrangement can increase plant counts, but should allow for maximum sizing. Target head size is not reached by all plants, and smaller heads can be utilized by bunching. Continued cultivar
evaluation is needed for crown-cut suitability. No-till represents a sustainable means of production, however supplemental nitrogen is needed to compensate for reduced yields. Film wrapping with Modified Atmoshphere Packaging (MAP) materials is a superior method of handling broccoli versus icing, resulting in increased storage time and improved quality. This method allows production of this crop without expensive icing and reduces transportation cost. In-store comparisons indicate consumer preference for film wrapped versus iced, non-wrapped broccoli. Appearance, quality, and food safety were cited as reasons.
Publications
- Reddy, Y.V.R. 2004. Post Harvest Treatment Effects on Crown-Cut Broccoli Shelf Life, M.S. Thesis, Department of Food Science and Technology, Virginia Polytechnic and State University, Blacksburg, Virginia 24061
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Progress 10/01/03 to 09/30/04
Outputs
Project includes three objectives for development of film wrapped, crown-cut broccoli as a VA crop alternative. 2003 summaries are provided. Evaluation of 2004 data is in progress. Objective 1: Best Production Systems: 4 field trials conducted in 2003: Performance of Early and Late Cultivars Using Two Planting Dates in Plasticulture and Conventional Tillage Systems. Summary: Late DTM (days to maturity) cultivar yielded better (10,844kg/ha) than early (7,885kg/ha), regardless of planting date or system. This was due to increased head weight (0.42 vs. 0.32kg/head). Ideal planting window appears to be August 5-15, resulting in late Sept to early Oct. harvest, yielding 10pct higher than late July planting. Plasticulture advanced harvest (10pct), increased head weights compared to bare soil (0.40 vs. 0.33kg/head), and had a higher percent large (16-21cm) heads (73 vs. 35pct). Performance Under Plasticulture, No-till and Conventional Systems. Summary: Total yield was
10,976kg/ha in the plasticulture system as compared to no-till (7168kg/ha) or conventional tillage (10,304kg/ha). No-till resulted in good natural weed control, but head size was reduced compared to plastic and conventional (0.26kg vs. 0.42 and 0.41kg respectively). Conventional resulted in fewer large heads compared to plastic (52 vs. 63pct). Evaluation of 5 Planting Densities on Plasticulture. Summary: 5 planting densities: 23, 30, 38, 46, 53 cm between plants, in double rows 30cm apart on plastic mulched beds were tested. Total yields were increased by higher densities 23-38 cm (up to 13,708kg/ha), but the percentage of large heads was lower (31-68pct). Ideal spacing appears to be 46cm, which had yields of 12,051kg/ha, with 82pct reaching target size. Evaluation of 8 Cultivars for Fall Cropping. Summary: 8 cultivars were tested in 2003. Quality parameters were noted as well as yield and maturity times. Yields ranged from 7,716kg/ha (Coronado Crown) to 13,888kg/ha (Legacy).
Objective 2: Evaluation of Non-Iced Film-Wrap for Post-Harvest Post-Harvest Efficacy of Film-Wrapped and Iced Broccoli Using Delayed Processing Times and Two Cultivars Over a 5-Week Period. Summary: Weekly water loss of the cultivar Everest was higher under icing as compared to Gypsy but under film there was no difference. Total weight loss was less with film wrapping (5.3pct) compared to icing (28pct). A processing delay of 6 hours resulted in increased water loss over time in both film and ice, but film moderated this loss. Ascorbic acid content was not affected by use of film or ice, or delay to processing time, and dropped gradually over storage time (ca. 20pct). Product color and texture were better retained with film. Objective 3: Evaluate Market Acceptance, Develop Recognition of Virginia Product and Characterize Market Windows. Summary: In 2003, film wrapped, large, single crowns were introduced to consumers in two VA grocers. Product was competitively placed near non-wrapped
CA product, under equal pricing regime. Film wrapped outsold non-wrapped by a 2:1 margin. In 2004, sample lots designated Virginia Grown were introduced to commercial buyers. In 2004, market window analysis began.
Impacts
This project is in the early stages, but limited impact can be reported. Production and marketing trends are emerging to impact grower decisions: Production: Plasticulture results in improved growth and yield, and a superior product. For Virginia growers, fall broccoli after a summer crop can help recover seasonal investments in plasticulture. Increased days to maturity in scheduling should be considered for late harvests. Though cold tolerant, late fall harvest increases risks of freeze damage, with loss at less than neg 3C. Supplemental nitrogen should be applied to no-till systems to compensate for reduced yields. Low densities result in a high percentage of large heads, but decreased plant number is the trade-off. Effective spatial arrangement can increase head counts, but should allow for maximum sizing. Target head size is not reached by all plants, but can be improved by careful management. Continued evaluation is needed of new cultivars for crown-cut
suitability, and productivity under Virginia conditions. Marketing: Film wrapping appears to be a superior method of handling broccoli versus icing. This has far reaching impact to growers in Virginia and other production areas. It provides opportunity to grow this crop without need for access to icing, and reduces transportation costs. In-store comparisons indicate consumer acceptance of film wrapped, crown cut product over iced, non-wrapped broccoli. Appearance, freshness, quality, and useable mass in the head were likely reasons for preference, and food safety provided by film.
Publications
- 1. Reddy, Y.V.R. 2004. Post Harvest Treatment Effects on Crown-Cut Broccoli Shelf Life, M.S. Thesis, Department of Food Science and Technology, Virginia Polytechnic and State University, Blacksburg, Virginia 24061
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