Fresh Market Carrots Research Articles

Assessing seed and breeding interventions for organic farming using a multiagent value chain approach

According to the EU’s organic regulation, the use of organic seed is generally binding in organic farming. Because of an organic seed shortage, derogations to use nonorganic seed can be obtained. By 2036, the EU plans to phase out these derogations and achieve 100% organic seed use. Previous attempts at achieving this, though, have failed. Ensuring organic seed supply is of particular EU-wide importance to meet EU policy goals, such as the farm-to-fork strategy. To assess the impact of measures to smooth this transition, we developed the VAL-MAS model (VALue chain Multi-Agent System). VAL-MAS is a multiagent model based on a heterogeneous agent population and mathematical programming that can provide insights into the performance of different seed system interventions. We selected organic fresh market carrots in Germany for their importance in the national and European organic sector as an example case. Our model suggests that the end of the derogation system poses a challenge to the seed value chain in terms of seed supply and farm incomes. The most effective mitigation solution is an investment in improved pest control during seed multiplication, accompanied by a stepwise phasing out of derogations for the use of nonorganic seed.

Spatial Variability of Nitrogen Uptake and Net Removal and Actual Evapotranspiration in the California Desert Carrot Production System

Nitrogen (N) and irrigation water must be effectively used in mineral soils to produce carrots with high yield and minimal environmental impact. This study attempts to identify optimal N and irrigation management practices for low desert carrot production in California by investigating consumptive water use and N uptake and removal rates in fresh market and processing carrots. Field experiments were conducted at the University of California Desert Research and Extension Center and nine farmer fields during two growing seasons. The actual evapotranspiration (ETa) was measured using the residual energy balance method with a combination of surface renewal and eddy covariance equipment. Crop canopy coverage, actual soil nitrate-N from multiple depths as well as total N percentage, dry matter, and fresh biomass in roots and tops were measured over the growing seasons. The length of the crop season had a wide range amongst the experimental sites: from a 128-day period in a processing carrot field to as long as 193 days in a fresh market carrot field. The seasonal ETa varied between 305.8 mm at a silty loam furrow irrigated processing carrot field and 486.2 mm at a sandy clay loam sprinkler irrigated fresh market field. The total N accumulated at harvest ranged between 205.4 kg ha−1 (nearly 52% in roots) and 350.5 kg ha−1 (nearly 64% in roots). While the mean value of nitrogen removed by carrot roots varied from 1.24 to 1.73 kg N/Mg carrot roots, it appears that more N was applied than was removed by carrot roots at all sites. Within the range of N application rates examined at the experimental sites, there was no significant relationship between carrot fresh root yield and N application rate, although the results suggested a positive effect of N application on carrot yield. Sufficient soil N availability over the growing season and the lack of significant yield response to N application illuminated that optimal N rates are likely less than the total amounts of N applied at most sites.

Consistency of long-term marketable yield of carrot and onion cultivars in muck (organic) soil in relation to seasonal weather

To identify carrot and onion cultivars that provide consistent marketable yields, we tracked the yields of five fresh market carrot [(Daucus carota L. subsp. sativus (Hoffm.) Arcang.] and six onion (Allium cepa L.) cultivars for at least 13 yr. Relationships between long-term weather variables and marketable yields were also investigated. The effects of cultivar, year and cultivar × year interactions on yield of carrots and onions were assessed. Cultivar and year had significant effects on carrot and onion yields, while the interaction was significant in only one of four data sets of carrot yield. Carrot cv. Cellobunch (95.4 t ha–1) and onion cv. Corona (74.1 t ha–1) had the highest mean marketable yields over the years studied. There was a slight positive correlation between mean yield of the assessed carrots and maximum temperatures in September (r = 0.44). Mean carrot yield was also somewhat negatively correlated with total rainfall in July (r = –0.43) and with number of days with rain in August (r = –0.43) and September (r = –0.44). Most onion cultivars showed stronger relationships between marketable yield and various weather patterns. Marketable yield of onions increased with an increase in the number of days with rainfall in June (r = 0.57). The mean marketable yield of the six onion cultivars decreased in relation to temperatures ≥30°C in June (r = –0.55) and August (r = –0.53). The mean yield of all the onions in the trials was negatively correlated (r = –0.78) with growing degree days (base 5°C, May to August). The results indicated that the data from long-term cultivar trials can be used to identify cultivars that yield well despite seasonal variations in weather. Key words: Daucus carota, Allium cepa, temperature, rainfall

Fresh-market Carrot Yield and Quality Did Not Respond to Potassium Fertilization on a Sandy Soil Validated by Mehlich-1 Soil Test

Potassium (K) is required for successful carrot (Daucus carota) production on sandy soils of the southeastern United States, yet there is little published research documenting most current university Cooperative Extension Service recommendations. Soil test methods for K in carrot production have not been rigorously validated. Excessive fertilization sometimes is practiced by carrot growers to compensate for potential losses of K from leaching and because some growers believe that high rates of fertilization may improve vegetable quality. Carrots were grown in three plantings during the winter of 1994-95 in Gainesville, Fla., to test the effects of K fertilization on carrot yield and quality on a sandy soil testing medium (38 ppm) in Mehlich-1 soil-test K. Large-size carrot yield was increased linearly with K fertilization. Yields of U.S. No. 1 grade carrots and total marketable carrots were not affected by K fertilization. K fertilizer was not required on this soil even though the University of Florida Cooperative Extension Service recommendation was for 84 lb/acre K. Neither soluble sugar nor carotenoid concentrations in carrot roots were affected by K fertilization. The current K recommendation for carrots grown on sandy soils testing 38 ppm Mehlich-1 K could be reduced and still maintain maximum carrot yield and root quality.

Potential for Carrot Production on Georgia Mountain Soils

Carrots (Daucus carota L.) have become an economically important vegetable crop for Georgia. Currently the harvest season extends from December through May. One possibility for extending the harvest season would be to produce carrots in the cooler mountain area of Georgia during the summer months. This study was undertaken to examine the potential for fresh-market carrot production on Georgia mountain soils and to evaluate which varieties of carrots might be most suitable for this area. Ten commercially available carrot varieties were direct seeded into a Transylvania clay loam soil on 28 May 1999 in Blairsville, Ga. Plots consisted of three twin rows of carrots each 20 feet in length. The twin rows were each three inches apart and there were 20 inches between each set of twin rows. Each plot was replicated four times. Base fertilizer of 20 pounds of nitrogen, potassium, and phosphorous were incorporated into the plots prior to seeding. Sidedress applications of 15 pounds each of N, P, and K were applied at 3-week intervals throughout the season. Recommended pest control practices were applied. A three-foot section of the center twin row was harvested on 23 Sept. 1999. The varieties `Pacific Gold' and `Topnotch' produced the highest marketable yield; however, all yields were below acceptable levels. Percent marketability was <60% for all varieties. Percent stand was extremely variable due to variability in seed size. All carrots had severe nematode damage although a nematicide was used preplant. The length of season for spring-planted carrots was too long for the life of the nematicide at the rate and method applied. Late summer–planted carrots would likely be a more viable option for this area.

Evaluation of Carrot Cultivars Over Multiple Locations for Suitability of Quality and Harvest Characteristics

Fresh-market carrots (Daucus carota L. sativus) have only been produced on any significant scale in Georgia since the early 1990s. Because most of the southeast U.S. carrot production is on muck-type soils, production practices had to be established for carrot production on mineral soils. Included in the establishment of these practices was the evaluation of varieties to find those of suitable yield. Additionally, these varieties had to possess low bolting, sufficient quality, and produce a sufficient top to be harvested mechanically. Many of the varieties produced in western states were not suitable for production in Georgia. After several years of testing under experiment station conditions, plots were established on farms at three separate locations. Plantings were established 1 Oct. and 24 Nov. 1997 in Jeff Davis County and on 4 Nov. 1997 in Wayne County. Plots consisted of three twin rows on a 1.-m bed with 35 cm between twin rows. Plots were a minimum of 6 m in length. Normal fertility and cultural practices were used. Evaluations of external color, length, overall marketability, smoothness, and top sufficiency were made on 27 Mar., 8 May, and 30 May, respectively. A total of 36 varieties were examined in replicated plots. Although there were some differences in smoothness and color, there were greater differences among varieties for marketability, and particularly length and top sufficiency. Several varieties were identified that would be suitable for production in Georgia.

Influence of Postharvest Handling Practices and Dip Treatments on Development of Black Root Rot on Fresh Market Carrots

Standard postharvest handling practices for fresh market carrots (Daucus carora) grown in organic soils in the Fraser Valley of British Columbia were monitored during 1990-1992 at two grading and packaging operations. Root samples were obtained from 29 loads over the harvest season (July to November) at various stages after carrots were washed, sized, graded, and packaged; and the samples were assessed for the development of black root rot, caused by Chalara elegans (Thielaviapsis basicola). Disease was not detected on carrots harvested by hand from fields infested with the pathogen, and was less than 5% on carrots sampled from the truck following mechanized harvesting

Development of black root rot caused byChalara eleganson fresh market carrots

Development of black root rot caused by<i>Chalara elegans</i>on fresh market carrots

CARROT RUST FLY CONTROL FOR ORGANIC FARMERS

The carrot rust fly (Psila rosae) lays eggs in the crowns of carrots, celery, and parsnips. Its larvae are dark brown maggots which burrow into the crown and roots of the plants making them unsalable. This is a pest of economic significance in coastal plantings. This project evaluated several non-chemical strategies available to organic farmers over three growing seasons. These included the use of traps to monitor populations and determine fields where infcstations are likely to occur, parasitic nematodes, the use of trap crops, and row covers as an exclusion technique. Floating row covers were the only successful treatment in reducing maggot damage in these fresh market carrots.

CARROT RUST FLY CONTROL FOR ORGANIC FARMERS

The carrot rust fly (Psila rosae) lays eggs in the crowns of carrots, celery, and parsnips. Its larvae are dark brown maggots which burrow into the crown and roots of the plants making them unsalable. This is a pest of economic significance in coastal plantings. This project evaluated several non-chemical strategies available to organic farmers over three growing seasons. These included the use of traps to monitor populations and determine fields where infcstations are likely to occur, parasitic nematodes, the use of trap crops, and row covers as an exclusion technique. Floating row covers were the only successful treatment in reducing maggot damage in these fresh market carrots.

REFLECTANCE CHARACTERISTICS OF FRESH-MARKET CARROTS

ABSTRACT Body reflectance was measured for normal, fresh-market carrots and carrots with dry rot, soft rot, black crown and cavity spot defects. The reflection was measured with an integrating spectrophotometer over the wavelengths from 486 to 1043 nm. The resulting data indicated that three of the four defects tested could be identified using radiation with wavelengths between 535 and 722 nm. Cavity spots could not be significantly distinguished from normal carrot tissue.

Seedbed Preparation for Carrot Production on Organic Soil1

Abstract Five sets of basic tillage operations were carried out for 5 consecutive years on an organic soil, each followed by seeding on the flat or on raised beds to determine the cultural methods that would provide the best yield of quality fresh market carrots (Daucus carota L.) without adversely affecting the soil structure. Raised beds offered no yield advantage in a wet season and no yield reduction in a dry season. In a wet season, the bed system favored harvesting operations by reducing soil moisture and rendering the field surface firmer. Minimum tillage consisting of a fall and a spring disking did not reduce yields or increase soil bulk density as compared to spring plowing and rototilling.