Field-grown Vegetables Research Articles

Introduction - Florida Greenhouse Vegetable Production Handbook, Vol 1

Greenhouse vegetables cannot usually compete directly on a price basis in the same markets with field-grown vegetables. Greenhouse vegetable production is much more expensive and more intensive and the crops must be marketed as specialty produce. Since greenhouse production is very costly and intensive, and the market for the specialty items is volatile, the prospective grower must be keenly aware of the special and exacting requirements of greenhouse vegetable production. This publication presents the special considerations that must be understood by all new or perspective greenhouse vegetable growers. This document is a chapter of the Florida Greenhosue Vegetable Production Handbook, Volume 1, one of a series of the Horticultural Sciences Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. First Publication Date: December, 1990

The effect of host plant on the biological control efficacy of the predatory mite, Phytoseiulus persimilis Athias-Henriot against two-spotted spidermites, Tetranychus urticae koch on field-grown vegetables

Tetranychus urticae Koch (Acari: Tetranychidae) is one of the key pests causing economic losses in vegetable fields. Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) is used effectively in the biological control of this mite on many vegetable crops. The present study determined how different crops such as pepper, eggplant, cucumber and tomato affected the biological control of T. urticae when using P. persimilis in the field-grown vegetables in the Çanakkale of northwestern part of Turkey in 2016 and 2017. Predatory and prey mites were released at a ratio of 1:10 predator:prey on host plants and their numbers on leaves were counted weekly for a period of 8 weeks. The highest number of T. urticae and P. persimilis were counted on cucumber with 108.70 ± 8.14 and 81.00 ± 6.00 mites per leaf in 2016, and with 113.30 ± 10.95 and 24.00 ± 4.58 mites per leaf in 2017, respectively. Also, there was a significant difference for both the populations of T. urticae and P. persimilis on the crops on all weeks in both years. It was revealed that P. persimilis markedly suppressed T. urticae on eggplant and tomato compared to pepper and cucumber in both years. It is clear that the host crops is a key factor on the success of P. persimilis on the biological control of T. urticae on field-grown vegetables. Consequently, it is thought that these results should be taken into account in the biological control strategies of mite pests by using the predatory mites on field-grown vegetables.

First report demonstrating the presence of Toxocara spp. eggs on vegetables grown in community gardens in Europe

Toxocara canis and T. cati are zoonotic roundworm parasites of dogs, cats and foxes. These definitive hosts pass eggs in their faeces, which contaminate the environment and can subsequently be ingested via soil or contaminated vegetables. In humans, infection with Toxocara can have serious health implications. This proof-of-concept study aimed to investigate the presence of Toxocara spp. eggs on ‘ready-to-eat’ vegetables (lettuce, spinach, spring onion and celery) sampled from community gardens in southern England. The contamination of vegetables with Toxocara eggs has never been investigated in the UK before, and more widely, this is the first time vegetables grown in community gardens in Europe have been assessed for Toxocara egg contamination. Sixteen community gardens participated in the study, providing 82 vegetable samples fit for analysis. Study participants also completed an anonymous questionnaire on observed visits to the sites by definitive hosts of Toxocara. Comparison of egg recovery methods was performed using lettuce samples spiked with a series of Toxocara spp. egg concentrations, with sedimentation and centrifugal concentration retrieving the highest number of eggs. A sample (100 g) of each vegetable type obtained from participating community gardens was tested for the presence of Toxocara eggs using the optimised method. Two lettuce samples tested positive for Toxocara spp. eggs, giving a prevalence of 2.4% (95% CI =1.3–3.5%) for vegetable samples overall, and 6.5% (95% CI = 4.7–8.3%; n = 31) specifically for lettuce. Questionnaire data revealed that foxes, cats and dogs frequently visited the community gardens in the study, with 88% (68/77) of respondents reporting seeing a definitive host species or the faeces of a definitive host at their site. This proof-of-concept study showed for the first time the presence of Toxocara spp. eggs on vegetables grown in the UK, as well as within the soil where these vegetables originated, and highlights biosecurity and zoonotic risks in community gardens. This study establishes a method for assessment of Toxocara spp. eggs on vegetable produce and paves the way for larger-scale investigations of Toxocara spp. egg contamination on field-grown vegetables.

Assessment of potentially toxic elements in vegetables cultivated in urban and peri-urban sites in the Kurdistan region of Iraq and implications for human health.

Vegetable fields in and around urban areas in the Kurdistan region of Iraq may have higher than background concentrations of potentially toxic elements (PTEs) from contamination sources including municipal waste disposal and wastewater used for irrigation. The purpose of this study was to assess PTE concentrations in soils and the edible parts of field-grown vegetables to quantify potential health risks to the local population. In this survey, 174 soils and 26 different vegetable and fruit types were sampled from 15 areas around Sulaymaniyah and Halabja cities. Sampling was undertaken from fields in urban, peri-urban and rural locations including sites close to areas of waste disposal. The soils are calcareous (pH 7.67-8.21) and classified as silty loam, sandy or silty clay with organic matter content between 6.62 and 11.4%. Concentrations of PTEs were typically higher in waste disposal areas compared with urban, peri-urban and rural areas. Pollution load indices suggested that agricultural soils near waste disposal sites were contaminated with some trace elements. Potentially toxic element concentrations in vegetables were highly variable. Higher total concentrations of PTEs were measured in vegetables from the waste areas with decreasing concentrations in urban, peri-urban and rural areas. Risks to human health were assessed using hazard quotients (HQ). Vegetable consumption poses no risk for adults, whereas children might be exposed to Ni, As and Cd. Although HQs suggest elevated risk for children from consumption of some vegetables, these risks are likely to be lower when realistic dietary consumption levels are considered.

Glucosinolate Content and Sensory Evaluation of Baby Leaf Rapeseed from Annual and Biennial White- and Yellow-Flowering Cultivars with Repeated Harvesting in Two Seasons.

The chemical and sensory quality of field‐grown vegetables may be influenced by cultivar choice and agronomic factors but knowledge is lacking on the new rapeseed vegetables. White‐ and yellow‐flowering rapeseed cultivars were tested in two seasonally different field studies in Denmark at three different growing stages by early sowing the first year and late sowing the second year. Content of glucosinolates (GLSs) was analyzed, and the sensory quality of baby leaf samples was evaluated. The GLS content differed among cultivars across years in all growing stages, with biennial cultivars having the highest GLS content. In the second year, a higher content of all identified GLSs was found at two growing stages except for neoglucobrassicin and gluconasturtiin, compared to the first year. On the contrary, higher contents of all identified GLSs were found at a third stage in the first year except for progoitrin and 4‐methoxy glucobrassicin. Sensory evaluation of bitterness revealed differences among cultivars, higher intensities of bitterness in biennial cultivars, and a relationship between bitterness and content of bitter‐tasting and total GLSs. The effect of repeated harvesting on GLS content differed between the years and no general pattern was seen, except that the composition of individual GLSs was comparable for the biennial cultivars. We conclude that growing season and life cycle had a stronger influence on GLS content than stage at harvest. The link between bitter‐tasting GLSs and bitterness revealed that life cycle and seasonal effects affected the sensory profile of baby leaf rapeseed thereby making a healthier product due to high content of health‐beneficial GLSs.

Simultaneous determination of multiclass antibiotics and their metabolites in four types of field-grown vegetables.

The developed method was evaluated for the determination of 10 antibiotics belonging to four chemical classes (fluoroquinolones, sulfonamides, lincosamides, and metoxybenzylpyrimidines) and six of their metabolites in four vegetable matrices (lettuce, tomato, cauliflower, and broad beans). The reported method detection limits were sufficiently low (0.1-5.8ng/g dry weight) to detect target compounds in vegetables under real agricultural practices. Absolute and relative recovery values ranged from 40 to 118% and from 70 to 118%, respectively, for all targeted compounds at the spike level of 100ng/g dry weight. Regarding method precision, the highest relative standard deviation (RSD) was obtained for enrofloxacin in lettuce (20%), while for the rest of the compounds in all matrices, the RSD values were below 20% for the same spike level. Matrix effects, due to electrospray ionization, ranged from - 26 to 29% for 85% of all estimated values. In a field study, four of the 10 targeted antibiotics were detected in tested vegetables. For the first time, antibiotic metabolites were quantified in vegetables grown under real field conditions. More specifically, decarboxyl ofloxacin and TMP304 were detected in tomato fruits (1.5ng/g dry weight) and lettuce leaves (21.0-23.1ng/g dry weight), respectively. It is important to remark that the concentration of TMP304 was five times higher than that from the parental compound, emphasizing the importance of metabolite analysis in monitoring studies. Therefore, the method provided a robust, reliable, and simple-to-use tool that could prove useful for routine multiclass analysis of antibiotics and their metabolites in vegetable samples. Graphical abstract.

Agronomic biofortification of selected underutilised solanaceae vegetables for improved dietary intake of potassium (K) in Ghana

Agronomic biofortification is the deliberate use of mineral fertilizers to increase the concentration of a target mineral in edible portions of crops to increase dietary intake of the target mineral. Globally, increased dietary intake of potassium (K) is becoming a part of the strategy to address hidden hunger and related non-communicable diseases such as hypertension and cardiac disorders. This study aimed at demonstrating the efficacy of increasing the concentration of K in the edible portions of three commonly consumed but underutilized solanacea vegetables (Solanum aethiopicum, S. macrocarpon and S. torvum) in Ghana. The effects of different types and rates of K fertilizer application on the leaf- and fruit-K contents of the vegetables, as well as the K loss between the raw and cooked fruits were investigated. Five levels of each of three types of K fertilizer (liquid drench of potassium chloride, granular Muriate of potash and Sulphate of potash) were applied to each of the three field-grown vegetables. Yield data were collected and the fruits and leaves were analysed for the content of K, N, P, Ca, Fe, Zn and Cu. The results showed the rate of fertilizer application had significant effect on the yields of S. aethiopicum and macrocarpon but the yield of S. torvum was significantly affected by type, rate and interactive effect of type and rate of fertilizer application. Fruit K concentrations were greatest for S. aethiopicum (2130 mg K kg−1 DW) and S. torvum (1883 mg K kg−1 DW) with liquid KCl but with Sulphate of Potash for S. macrocarpon (1801 mg K kg−1 DW). There were higher K concentrations in leaves than in fruits of all the vegetables. Household cooking of the fruits resulted in the retention of over 70% of the K content in the raw fruits. Potassium fertilization increased the Ca, Fe, and Zn contents of S. aethiopicum and S. torvum. It is concluded that agronomic biofortification may be a useful strategy to increase K intakes and other important elements (e.g. Fe and Zn) in the vegetables studied.

Agricultural exposure and risk of bladder cancer in the AGRIculture and CANcer cohort.

Literature on agricultural activities and bladder cancer risk is scarce. However, farmers can be subjected to carcinogenic exposure (e.g. arsenic, previously used as a pesticide in France). This study aimed at assessing the role of a large range of agricultural activities and tasks on bladder cancer risk. The study population was the AGRIculture and CANcer cohort, a large prospective cohort of individuals affiliated to the agricultural health insurance scheme (MSA) in France. Incident bladder cancers were identified by cancer registries from enrolment (2005-2007) to 2009. Data on agricultural exposure during professional lifetime (5 animals, 13 crops, specific tasks) were obtained from the enrolment questionnaire. Associations between bladder cancer and agricultural exposure were analysed using a Cox model, adjusted for gender and smoking history. Among the 148,051 farm owners and workers included in this analysis, 179 incident bladder cancers were identified. We observed an elevated risk among field-grown vegetable workers [HR 1.89, 95% CI (1.20-2.99)], with an exposure-response relationship with duration of work [≥30years: HR 2.54, 95% CI (1.11-5.83), p-trend=0.02], and higher risk among women [HR 3.82, 95% CI (1.58-9.25), p-interaction=0.05]. Non-significantly increased risks were also observed in greenhouse farmers (HR=1.95), pea sowing (HR=1.84), rape sowing (HR=1.64); several tasks involving pesticide use, especially seed treatment (HR=1.24); and in activities and tasks potentially exposing to arsenic compounds via pesticide use (HR=1.49) or re-entry tasks (HR=1.63). Our analyses raise the question of a possible link between agricultural activity, especially field-grown vegetables, and greenhouse cultivation and bladder cancer.

Pharmaceuticals, Their Metabolites, and Other Polar Pollutants in Field-Grown Vegetables Irrigated with Treated Municipal Wastewater.

The reuse of treated municipal wastewater for crop irrigation is a necessity in arid and semiarid regions but a potential entrance for emerging contaminants into the food chain. However, little attention has yet been paid to the detection of micropollutants and possible metabolites in vegetables grown under realistic field conditions. In this study, the uptake of 28 micropollutants and carbamazepine metabolites in 10 different field-grown vegetable species (among them carrot, lettuce, potato, and zucchini) from Jordan was studied. A total of 12 micropollutants and six carbamazepine metabolites, four of which have never been analyzed before in plant-uptake studies, could be detected in all of the samples in concentrations ranging from 1.7 to 216 ng per g of dry weight. In edible tissues, the total concentration of micropollutants decreased in the order of leafy (247-533) > root (73-126) > fruit-bearing (5-76 ng per g of dry weight) vegetables. A preliminary health-risk assessment for nine compounds according to the TTC concept shows no risk for seven of the micropollutats; for ciprofloxacin and 10,11-epoxycarbamazepine, however, more-specific toxicity data would be required for a refined risk assessment.

Drought stress impact on vegetable crop yields in the Elbe River lowland between 1961 and 2014

The study is focused on drought stress that is detrimental to yield formation of field-grown vegetables in the lowland regions of the Czech Republic. Extensive vegetable yield losses are attributed to drought, often in combination with heat or other stresses. The objective of this research was to investigate, under field conditions, the effect of drought stress quantified by the Standardized Precipitation Evapotranspiration Index (SPEI) on yield variability of key vegetable crops growing in the Elbe River lowland, representing central European agriculture conditions. Additionally, we also tried to determine the period of crop with the highest sensitivity to drought (PCSD) of vegetable crops over the Elbe River lowland. Historical climate datasets for a regular gridded network with a high horizontal resolution of 10 km (CZGRIDS) and 305 climatological stations from the Czech Hydrometeorological Institute were applied. The SPEI at 1-, 3-, and 6-month lags was calculated for the period 1961-2014 based on precipitation and input dataset for the reference evapotranspiration (ETr) by the Penman-Monteith (PM) method. Moreover, the difference between daily precipitation and crop evapotranspiration (ETc) has been used to calculate the mean crop water balance (D) per main growth stages, as an indicator of plant stress. This improvement increased the applicability of the SPEI in agriculture drought impact on rainfed and/or irrigated field crops grown under various agronomic management systems. To understand how the SPEI, over the period 1989-2014, controlled the yield variation, we calculated the percentage of yield losses and gains for each crop. When the value of SPEI at 3-month lag–as a measure of the balance between the water availability and the atmospheric water demand–for PCSD was between -1.49 and 0.99, the yield moderately increased for Fruiting vegetables (e.g. tomatoes, cucumber). Conversely, when the SPEI-3 in the key development stage dropped below -3.0, the yield losses were about -30% and a negative influence is apparent from threshold of the SPEI≤-1.5. The effect of the SPEI on yield formation of vegetable cultivars grown under filed conditions was achieved up to 62% in the study region.

Fluoride in soil and plant

Fluorine is unique chemical element which occurs naturally, but is not an essential nutrient for plants. Fluoride toxicity can arise due to excessive fluoride intake from a variety of natural or manmade sources. Fluoride is phytotoxic to most plants. Plants which are sensitive for fluorine exposure even low concentrations of fluorine can cause leave damage and a decline in growth. All vegetation contains some fluoride absorbed from soil and water. The highest levels of F in field-grown vegetables are found up to 40 mg kg -1 fresh weight although fluoride is relatively immobile and is not easily leached in soil because most of the fluoride was not readily soluble or exchangeable. Also, high concentrations of fluoride primarily associated with the soil colloid or clay fraction can increase fluoride levels in soil solution, increasing uptake via the plant root. In soils more than 90 percent of the natural fluoride ranging from 20 to 1,000 μg g -1 is insoluble, or tightly bound to soil particles. The excess accumulation of fluorides in vegetation leads to visible leaf injury, damage to fruits, changes in the yield. The amount of fluoride taken up by plants depending on the type of plant, the nature of the soil, and the amount and form of fluoride in the soil should be controlled. Conclusively, fluoride is possible and long-term pollution effects on plant growth through accumulation of the fluoride retained in the soil.

Soil versus foliar iodine fertilization as a biofortification strategy for field-grown vegetables.

Iodine (I) biofortification of vegetables by means of soil and foliar applications was investigated in field experiments on a sandy loam soil. Supply of iodine to the soil in trial plots fertilized with potassium iodide (KI) and potassium iodate directly before planting (0, 1.0, 2.5, 7.5, and 15 kg I ha-1) increased the iodine concentration in the edible plant parts. The highest iodine accumulation levels were observed in the first growing season: In butterhead lettuce and kohlrabi the desired iodine content [50–100 μg I (100 g FM)-1] was obtained or exceeded at a fertilizer rate of 7.5 kg IO3--I ha-1 without a significant yield reduction or impairment of the marketable quality. In contrast, supplying KI at the same rate resulted in a much lower iodine enrichment and clearly visible growth impairment. Soil applied iodine was phytoavailable only for a short period of time as indicated by a rapid decline of CaCl2-extractable iodine in the top soil. Consequently, long-term effects of a one-time iodine soil fertilization could not be observed. A comparison between the soil and the foliar fertilization revealed a better performance of iodine applied aerially to butterhead lettuce, which reached the desired iodine accumulation in edible plant parts at a fertilizer rate of 0.5 kg I--I ha-1. In contrast, the iodine content in the tuber of sprayed kohlrabi remained far below the targeted range. The results indicate that a sufficient spreading of iodine applied on the edible plant parts is crucial for the efficiency of the foliar approach and leafy vegetables are the more suitable target crops. The low iodine doses needed as well as the easy and inexpensive application may favor the implementation of foliar sprays as the preferred iodine biofortification strategy in practice.

Dissipation, half-lives, and mass spectrometric identification of endosulfan isomers and the sulfate metabolite on three field-grown vegetables

Endosulfan 3 EC, a mixture of α- and β-stereo isomers, was sprayed on field-grown pepper, melon, and sweet potato plants at the recommended rate of 0.44 kg A.I. acre−1. Plant tissue samples (leaves, fruits, or edible roots) were collected 1 h to 30 days following spraying and analyzed for endosulfan isomers (α- and β-isomers). Analysis of samples was accomplished using a gas chromatograph (GC) equipped with a mass detector in total ion mode. The results indicated the formation of endosulfan sulfate as the major metabolite of endosulfan sulfite and the relatively higher persistence of the β-isomers as compared to the α-isomer. The initial total residues (α- and β-isomers plus endosulfan sulfate) were higher on leaves than on fruits. On pepper and melon fruits, the α-isomer, which is the more toxic to mammals, dissipated faster (T1/2 = 1.22 and 0.95 d, respectively) than the less toxic β-isomer (T1/2 = 3.0 and 2.5 d, respectively). These results confirm the greater loss of the α-isomer compared to the β-isomer, which can ultimately impact endosulfan dissipation in the environment. Additionally, the higher initial residues of endosulfan on pepper and sweet potato leaves should be considered of great importance for timing field operations and the safe entry of harvesters due to the high mammalian toxicity of endosulfan.

Mineral and Ascorbic Acid Concentrations of Greenhouse- and Field-Grown Vegetables: Implications for Human Health

Vegetable nutritional quality is related to concentrations of antioxidants and other phytonutrients. In Iran, vegetables can be produced in soil in climate-controlled greenhouses. Limited information is available on the quality of greenhouse-grown vegetables compared to field-grown vegetables. Concentrations of Ca, Mg, P, K, Fe, Zn, Cu, Mn, and ascorbic acid in greenhouse- and field-grown bell pepper (Capsicum annuum L.), cucumber (Cucumis sativa L.), and tomato (Solanum lycopersicum L.) were determined. Mean fruit K, P, and Mg concentrations in greenhouse-grown bell pepper, cucumber, and tomato were greater than expected levels. Mean fruit K concentrations in greenhouse-grown bell pepper, cucumber, and tomato were lower than that in field-grown vegetables. Greenhouse-grown vegetables accumulated greater amounts of P in fruit compared to field-grown vegetables. More than 48%, 38%, 30%, and 54% of greenhouse vegetables were Fe, Zn, Cu, and Mn deficient, respectively. Field-grown vegetables had lower contents of Cu, Mn, Fe, Zn, and ascorbic acid compared to greenhouse-grown vegetables. Calcium, Fe, Cu, Mn, and Zn intakes through consumption of greenhouse-grown vegetables for population study groups accounted for a negligible fraction of the recommended daily allowance (RDA), whereas daily intake of ascorbic acid was greater than the RDA requirement. Intake of micronutrients and ascorbic acid from field-grown vegetables was less than that from greenhouse-grown vegetables. In general, the nutritional quality (contents of micronutrients and ascorbic acid) of greenhouse-grown vegetables was better than that of field-grown vegetables, although fruit micronutrient concentrations of field- and greenhouse-grown vegetables were lower than expected levels. The results indicated that bell pepper is an excellent source of ascorbic acid and potassium for humans. Despite a protected system of cultivation, poor fertilizer management in greenhouses could adversely affect the nutritional value of vegetables. Improved nutritional management in greenhouses could enhance micronutrient concentrations in these vegetables.

Residual behaviour of profenofos on some field-grown vegetables and its removal using various washing solutions and household processing

Profenofos (Selecron 72% EC), was sprayed on field-grown pepper and eggplant at the recommended rate of 1.28 kg a,i/ha. Fruit samples were collected at 1 h to 14 days after application and analysed to determine the content and dissipation rate of profenofos. The effect of different washing solutions and some household processing on the removal of such residues from treated vegetables were also investigated. Profenofos residues were quantified by using gas chromatography. The results showed that the consumable safety time were found to be 10 days on sweet pepper and 14 days on hot pepper and eggplant fruits. The initial disappearance of profenofos appeared to follow first order kinetics with different rates of reaction of 0.38, 0.40 and 0.35 day −1 for hot pepper, sweet pepper and eggplant, respectively. The corresponding half-lives ( t 1/2) were 1.84, 1.74 and 1.96 days. Also, the results indicated that tap water, potassium permenganate and acetic acid solution gave high percent removal of profenofos residues from hot and sweet pepper fruits, while no detectable residues was found in eggplant fruit after washing with soap and acetic acid solutions. In general, all tested washing solutions gave higher percent removal of profenofos residues from eggplant fruit than the two other pepper fruits. Blanching and frying of pepper and eggplant fruits resulted in great reduction to almost completely removed (∼100%) of the deposited profenofos. In addition, pickling process removed 92.58 and 95.61% from hot pepper fruit after one week and after two weeks, respectively.

Options for managing foodstuffs contaminated with radiocesium and radiostrontium.

In the event of a future nuclear accident, foodstuffs with activity concentrations greater than specified intervention levels would be banned for human consumption. Three broad strategies could be used to manage such produce: in situ treatment, alternative uses, or disposal. This paper describes an assessment of the practicability of nine potential management options for contaminated arable crops for use in the UK. Practicability is affected by six factors: technical feasibility, capacity, cost, environmental impact, radiological impact, and acceptability. These were assessed quantitatively, where possible, through consultation with experts from a range of organizations, and a detailed radiological impact assessment was undertaken. Suggestions are made on the most practicable options for managing cereals, field-grown vegetables, and annual fruit contaminated with radiocesium and radiostrontium. Options are available for managing foodstuffs with activity concentrations of up to 8.3 x 10(4) Bq kg(-1) 134Cs, 2.1 x 10(5) Bq kg(-1) 137Cs, 7.7 x 10(8) Bq kg(-1) 89Sr and 3.0 x 10(5) Bq kg(-1) 90Sr, which are well in excess of those expected from design basis accidents.

Validating a Crop Production Budget for Containerized Specialty Vegetables

Growers producing new crops often do not understand how to price individual items. The prices of common container nursery stock items may be listed in monthly trade publications. Prices for fruits and vegetables fluctuate on a daily basis. A production budget for containerized specialty vegetables was adapted from one developed for ornamental nurseries, using some specific costs for field-grown vegetables. This gave a realistic way to calculate prices for individual products. Once the crops had been sold, the authors were able to validate the model by comparing actual costs with projected costs.

The H.O.R.T Project: A Hands-on Educational Experience

The Farm Management and Technology Program (FMT) is a 3-year post-secondary vocational agriculture program. FMT students may choose to specialize in horticulture. Since January 1995, all horticulture students have been involved in a hands-on, practical educational experience called “H.O.R.T.” (Horticultural Opportunities for Real Training). The students operate a small horticultural “business.” They must plant, maintain, harvest, and sell several horticultural crops, including greenhouse and field-grown vegetables, apples, berries, and potted flowers. H.O.R.T. lasts two semesters: January through April and September through December. Students may choose to do H.O.R.T. for 2 years to broaden and deepen their horticultural learning. Through active participation in H.O.R.T., students will achieve the technical competencies required by the FMT program and specified by Quebec's ministries of education and agriculture. Each year of H.O.R.T. counts for 5-2/3 credits out of a program total of 90-1/3 credits. The goals of H.O.R.T. are not so much the acquisition of “book knowledge” (lower part of the cognitive domain) as the development of technical skills, planning and decisionmaking abilities, business sense, and proper communication (higher-order cognitive skills as well as psycho-motor and affective skills).

Changes Needed to Facilitate Automatic Field Transplanting

A lthough automatic transplanting of several field-grown vegetables is a reality, some changes in seedling production are necessary if the full potential of automation is to be realized. In automatic transplanting machines (ATMs) that are available, containerized seedlings such as lettuce, cauliflower, and celery are removed from the seedling trays and planted into the ground without human intervention. The advantages of containerized transplants from a crop production perspective are widely recognized. It is time to recognize and emphasize the features of this growing system that aid in theengineering of automatic transplanting systems. From an engineers perspective, containerized seedlingsare in an orderly array, in a configuration that is repeated again and again, unlike bare-root seedlings, which come in random bunches. Each seedling tray can be treated like a gun-cartridge magazine and fed through an ATM, which removes the seedlings and then places them individually into the ground. Alternative arrangements for presenting seedlings to an ATM include connected paper cells (Nippon Beet Sugar Manufacturing Co., 1985), bandoliers (Boa, 1978) strips of seedling cells (Williams, 1986), and cells within trays (Brewer, 1990). Recently, several engineers from around the world used rectangular seedling trays, with some variations, for their ATMs.

Response of tomato and eggplant to mulching and nitrogen fertilization under tropical conditions

Black plastic, cassava peel, and giant star grass and guinea grass straw soil mulches were compared for field-grown vegetables under varying rates of nitrogen (N) fertilization. Black plastic mulch was most effective in weed control and resulted in more crop growth and higher fruit yield. Low weed control and a high incidence of fungal disease with cassava peel depressed yields, thus rendering cassave peel unsuitable for mulching. There was no advantage in applying fertilizer N beyond 80 kg N ha −1, irrespective of mulching or the type of mulch.