Production Of Leafy Vegetables Research Articles

Effects of different colored film mulches on the growth and bolting time of radish (Raphanus sativus L.)

Radish (Raphanus sativus L.) is cultivated for the production of leafy and root vegetables and is one of the most economically important vegetables in Asia. Plastic film mulches are often used to improve vegetable yield. However, their effects on radish root zone temperature (RZT) and yield have not been well evaluated. The objective of this study was to determine the effects of RZT, as affected by different colored plastic mulches, on the growth and bolting of radish. Treatments were composed of three plastic film mulches (transparent, black, and green) with bare soil as a control. Two cultivation trials were conducted in spring and fall. For spring planting, the soil heat accumulation and the mean diurnal trend of RZT were the highest in the transparent group, followed by black, green, and bare soil. Moreover, film mulching significantly increased the root length, root diameter, and root weight compared to those in bare soil. The mean, maximal, and minimal RZTs at three different stages (seedling, shooting, and mature stages) were also measured and significant differences were found at seedling and shooting stages, but not at the mature stage. Thus, when the foliage of radish covered the top of the row at the mature stage, soil heat accumulation was possibly less affected by direct solar radiation. In the beginning of spring, the temperature often decreased to < 10 °C, which induces premature bolting, a serious problem for radish cultivation. The higher RZT detected under film mulches was significantly effective in suppressing bolting. Our results revealed that transparent film mulches have the best effects on radish yield and bolting, followed by black and green mulches. Further, the high soil heat accumulation mediated by film mulches is beneficial for vegetative growth and yield and delaying bolting in radish.

Profitability and technical efficiency of leafy vegetable production: a stochastic frontier production function analysis

ABSTRACT Smallholder leafy vegetable farmers are often faced with resource-use inefficiency in production. This work examined the profitability and technical efficiency of leafy vegetable production to determine sources of inefficiencies in smallholder production. The Maximum Likelihood Estimates of the Stochastic frontier production function indicated factors positively influencing production gross margin were education level, experience, seed, labor costs, fertilizer and farm-size; farmer age negatively influenced results, especially those who have less contact with extension agents. The mean efficiency score was 0.804 with R2 of 0.912. With more education, the application of required inputs could improve the yield of leafy vegetables.

Understanding Molecular Mechanisms of Seed Dormancy for Improved Germination in Traditional Leafy Vegetables: An Overview

Loss of seed viability, poor and delayed germination, and inaccessibility to high-quality seeds are key bottlenecks limiting all-year-round production of African traditional leafy vegetables (TLVs). Poor quality seeds are the result of several factors including harvest time, storage, and conservation conditions, and seed dormancy. While other factors can be easily controlled, breaking seed dormancy requires thorough knowledge of the seed intrinsic nature and physiology. Here, we synthesized the scattered knowledge on seed dormancy constraints in TLVs, highlighted seed dormancy regulation factors, and developed a conceptual approach for molecular genetic analysis of seed dormancy in TLVs. Several hormones, proteins, changes in chromatin structures, ribosomes, and quantitative trait loci (QTL) are involved in seed dormancy regulation. However, the bulk of knowledge was based on cereals and Arabidopsis and there is little awareness about seed dormancy facts and mechanisms in TLVs. To successfully decipher seed dormancy in TLVs, we used Gynandropsis gynandra to illustrate possible research avenues and highlighted the potential of this species as a model plant for seed dormancy analysis. This will serve as a guideline to provide prospective producers with high-quality seeds.

Nutritional Quality and Safety Traceability System for China’s Leafy Vegetable Supply Chain Based on Fault Tree Analysis and QR Code

Leafy vegetables are consumed in most daily xdiets worldwide. As living standards improve, food quality, safety requirements, and nutrition are becoming increasingly important to consumers when purchasing leafy vegetables. This study proposes an evaluation and traceability method that can be used to track the nutritional quality of leafy vegetables. Employing the principles of the Hazard Analysis and Critical Control Point (HACCP) system combined with fault tree analysis (FTA), a traceability model for the entire production and sale process of leafy vegetables is constructed. Four common leafy vegetables, spinach, rape, lettuce, and celery are examined in this research to establish a nutritional quality index system using fuzzy mathematics subordinate function method to evaluate nutritional quality. A nutritional quality and safety traceability system based on browser/server architecture and quick response (QR) code is then designed and developed for full traceability of leafy vegetable quality. This method can ensure food safety and hygiene through the control of key factors affecting food safety throughout the entire supply chain process.

Drivers and Constraints to the Adoption of Organic Leafy Vegetable Production in Nigeria: A Livelihood Approach

Nigeria, the seventh most populous country in the world, is plagued by livelihood challenges such as poverty and food insecurity, which are more pervasive among farming households and rural communities. Organic farming is being promoted by some domestic non-governmental organizations as a means of addressing the problem of poverty and food insecurity among farming households and rural communities in the country. Promoters consider organic farming to be well-suited to smallholder farmers’ socio-economic conditions in Nigeria, and that it can help improve their livelihood conditions through increased agricultural productivity and farm income. However, the adoption of the technology by smallholder farmers has been underwhelming, for reasons yet to be studied. Using a livelihood framework and through a case study of farmers in Ibadan, Oyo State, this study qualitatively explores and provides insights into the factors that influence, constrain, and gender the adoption of organic farming in Nigeria. Overall, it was found that a mix of factors, which include institutional considerations, farmers’ livelihood assets and vulnerability contexts, their livelihood activities, and gender-related variables shaped adoption decision-making. The policy implications of the findings were outlined.

Production of spinach in intensive Mediterranean horticultural systems can be sustained by organic-based fertilizers without yield penalties and with low environmental impacts

Agricultural production of leafy vegetables in Mediterranean countries aims to achieve high yields without elevated nitrate contents in the edible parts. This implies an adjusted nutrient management, especially of nitrogen (N), in irrigated horticultural systems under semiarid conditions. These horticultural systems are highly relevant in SE Spain from an economic perspective. However, the management of N fertilizer, generally applied in large amounts (150–250 kg N ha−1 in a split application), could trigger losses of reactive N to the environment. The use of novel fertilizers may fulfill the nitrogen requirements of the crop, but should also help to decrease the environmental impacts of production, thus achieving carbon-neutral horticultural systems through (e.g.) enhancement of carbon (C) stocks and greenhouse gases (GHG) emission abatement. In this experiment, eight different fertilizing scenarios at a normalized N application rate of 150 kg N ha−1 were assessed in terms of crop yields, nutrients uptake, C stocking capacity, and yield-scaled GHG emissions. Inorganic NPK fertilizers, digestates, biosolids, composts, and vermicomposts were included among this set of fertilizers. Our results show that organic-based stabilized materials, especially composts, lowered the NO3− concentration in spinach leaves, in comparison to organic raw materials and synthetic fertilizers. They also produced yields similar to those of slow-release synthetic fertilizers, but with a significant increase in soil organic C 61 days after application. In general, N2O emissions were positively affected by the treatments. Nevertheless, direct N2O emissions were generally low (the highest emission factor, 0.13, being for the biosolid treatment) due to the combined mitigating effect of both the edapho-climatic conditions and the management practices. In general, cumulative CO2 emissions were high in all organic scenarios compared to the control treatment (299 kg C-CO2 ha−1), the highest values being observed in the treatment with biosolid (589 kg C-CO2 ha−1), probably due to differences in the labile organic C contents. In conclusion, some of the organic-based treatments showed multiple positive effects: on crop quality (i.e. leaf N content), crop yields, and GHG mitigation potential. Based on our results, the use of these materials represents an optimized N fertilizer strategy to help achieve a circular economy, by closing nutrient loops and decreasing the environmental impacts of horticultural production systems in semiarid regions of southern Europe.

Fertilizer microdosing enhances biomass yield and water use efficiency of African indigenous leafy vegetable

ABSTRACT Inadequate nutrition is a limiting factor for African indigenous leafy vegetable (AILV) production. Fertilizer microdosing technology might be a method to increase yields and nutrient use efficiency in AILVs. Field experiments were conducted to determine the effects of fertilizer microdosing on biomass yield and water use efficiency (WUE) of the AILVs: local amaranth (Amaranthus cruentus L.), African eggplant (Solanum macrocarpon L.), and African basil (Ocimum gratissimum L.). Treatments consisted of factorial combinations of five microdosed nitrogen (N) rates and 2 N application dates under fully irrigated (dry season) and supplement irrigated (rainy season) conditions. Under full irrigation, microdosed N rates were 0, 10, 20, or 30 kg∙ha−1 N + 5 t∙ha−1 manure and an additional treatment of 40 kg∙ha−1 N without manure (half recommended rate; HRR). Under supplemented irrigation, microdosed N rates were 0, 20, 40, or 60 kg∙ha−1 N + 5 t∙ha−1 manure and an additional treatment of 80 kg∙ha−1 N without manure (full recommended rate; FRR). Nitrogen application dates were 0 and 14 days after transplanting for both experiments. Biomass yields and WUE of local amaranth and African eggplant under microdosed N level plus manure increased, but not for African basil. Yield and WUE of local amaranth and African eggplant increased with microdosed N combined with manure level up to 40 kg∙ha−1 with little, or no, increase above that. The FRR produced lower yield and WUE compared to any microdosed rate of N combined with manure by 45% for local amaranth, and 30% for African eggplant under full irrigation, and 89% for local amaranth and 18% for African eggplant during the rainy season with supplement irrigation. Time of N application had no effect. The combined microdose application of N of 40 kg∙ha−1 and manure is effective to enhance some African indigenous leafy vegetable yields and water use efficiency while reducing fertilizer input. Further studies are needed at different locations and should include other AILV species to confirm microdosing is efficacious for AILV production.

TECHNICAL EFFICIENCY OF ORGANIC AND INORGANIC LEAFY VEGETABLE PRODUCTION IN OGUN STATE, NIGERIA

The study was carried out to examine the technical efficiency of organic and inorganic leafy vegetable production in Ogun State, Nigeria. This study employed the use of multistage sampling technique in selecting one Local Government from each of the four ADPs zones in Ogun state using simple random sampling. A total of one hundred and seven (107) respondents were selected using multi-stage sampling technique and interviewed with the aid of well-structured questionnaires. The data were analyzed using descriptive statistics and stochastic frontier production function for the technical efficiency of the farmer. The study reveals that majority of the farmers practicing organic leafy vegetable and inorganic leafy vegetable farming are predominantly males and are married. The mean technical efficiency of the farmers was 0.679. This indicates a fair level of technical efficiency of leafy vegetable production in the study area. More importantly, the study showed that there is no difference between the two categories of farms in terms of technical inefficiencies. Other results from the estimated inefficiency model show that the age, educational level, household size, gender and age square are significant determinants of technical inefficiency. Gender, household size, extension agents’ visit and age squared have negative coefficients with consequent implication of decrease in technical inefficiency level as these variables increase. Age, level of education, farming experience, marital status and socio economic group have positive coefficients implying an increase in technical inefficiency level as these variables increase. The study recommends that the government should introduce the farmers to formal education through adult literacy education and establishment of demonstration farms should be strengthened among the farmers.

Hydroponic Production of Reduced-Potassium Swiss Chard and Spinach: A Feasible Agronomic Approach to Tailoring Vegetables for Chronic Kidney Disease Patients

Tailored foods are specifically suitable for target groups of people with particular nutritional needs. Although most research on tailored foods has been focused on increasing the nutrient content in plant tissues (biofortification), in populations with specific physiological conditions, it is recommended to reduce the uptake of specific nutrients in order to improve their health. People affected by chronic kidney disease (CKD) must limit their consumption of vegetables because of the generally high potassium (K) content in the edible parts. This study aimed to define an appropriate production technique for two baby leaf vegetables, spinach (Spinacia oleracea L.) and Swiss chard (Beta vulgaris L. ssp. vulgaris), with reduced K tissue content, minimizing the negative effects on their crop performance and overall nutritional quality. Plants were grown in a hydroponic floating system. The K concentration in the nutrient solution (NS) was reduced from 200 mg/L (K200, the concentration usually used for growing baby leaf vegetables in hydroponic conditions) to 50 mg/L over the entire growing cycle (K50) or only during the seven days before harvest (K50-7d). The reduction of K in the NS resulted in a significant decrease of K tissue content in both species (32% for K50 and 10% for K50-7d, on average), while it did not, in general, compromise the crop performance and quality traits or the bioaccessibility of K, magnesium, and calcium. The production of reduced-potassium leafy vegetables is a feasible tailored nutrition approach for CKD patients in order to take advantage of the positive effects of vegetable consumption on health without excessively increasing potassium intake.

An Analysis of the Factors Influencing Participation by Smallholder Farmers in Indigenous Leafy Vegetables (ILVs) Production: A Case of Mapuzi Village, Eastern Cape Province of South Africa

An Analysis of the Factors Influencing Participation by Smallholder Farmers in Indigenous Leafy Vegetables (ILVs) Production: A Case of Mapuzi Village, Eastern Cape Province of South Africa

Quality Control Techniques and Related Factors for Hydroponic Leafy Vegetables

Hydroponics has been an increasingly important field of vegetable production. However, a big issue with hydroponics is that certain crops can quickly accumulate high levels of nitrate-N (NO3 ± -N) from the hydroponic system. The objective of this research was to decrease NO3 accumulation and increase the nutritional value and yield of vegetable crops using lettuce and oilseed rape as a model under hydroponic production. In this study, two technologies were applied to leafy vegetable production: 1) using supplementary lighting (blue-violet diode) by manipulating illumination and 2) removing fertilization before harvest for a short term (3 or 5 days), thus providing a practical experiment for improving yield and edible qualities of hydroponic leaf vegetable production. Illumination was applied 4 hours a day (0500–0700 hr and 1700–1900 hr) during good weather, or 12 hours a day during bad weather with insufficient natural light (&lt;2000 lux) during the autumn and winter seasons. Results showed that the lettuce cultivar Ou-Luo and the oilseed rape cultivar Ao-Guan Pakchoi had increased yield (50.0% and 88.3%, respectively), decreased NO3 content (26.3% and 30.8%, respectively), and increased total soluble solids (24.1% and 30.6%, respectively). The 5-day fertilizer-free treatment before harvest resulted in 19.2%, 6.4%, and 16.5% yield increases; and 26.0%, 24.3%, and 47.8% NO3 decreases in oilseed rape cultivar Ao-Guan Pakchoi and lettuce cultivars Da-Su-Sheng and Ou-Luo, respectively.

Agro-industry composts as growing medium for growing baby-leaf lettuces in a floating system – added-value to suppress Pythium irregulare

Production of small leafy vegetables (baby leaf) in floating system can be affected by different diseases such as 'damping off', which is caused by fungi as Pythium spp. Compost can be used as an alternative to peat, a traditional substrate in floating system. In addition, the use of composts with suppressive effect may help control these pathogens and reduce the use of chemicals, being a more sustainable production system. The main issue to obtain added-value compost is by selecting appropriate, specific type and rate of feedstock, or by microbial inoculation. The objective of this work was to investigate the suppressive capacity of three agroindustry composts (C9, C11 and C14) in the pathosystem Pythium irregulare-lettuce. C9 was composed mainly by pepper sewage sludge, pepper peels, carrot and vineyard pruning material, C11 showed similar feedstock inoculated with Aspergillus niger and C14 was mainly composed by tomato and onion peels plus vineyard pruning material. Two different ratios compost/peat (70/30 and 100/0, v/v) were used to fill the trays and the percentage of seed germination and of plant survival was determined at 8 and 20 days after sowing. The highest percentages of seed germination and plant survival were obtained in C14 for both compost/peat ratios assayed, showing plants with less symptoms of infection. In addition, P. irregulare was measured by RealTime PCR in the growing media and in the roots at 20 days after sowing. C14 also showed the lowest pathogen amount compared to the rest of compost but only in the growing media. In this study, the initial composition of compost was relatively important, that permits to obtain a suppressive added-value compost.

Response of &lt;i&gt;Cleome Gynandra &lt;/i&gt;to Animal Manure

Low inherent soil fertility and high cost of synthetic fertilizers are some of the factors hindering productivity of indigenous leafy vegetables. Response of Cleome gynandra to cattle, goat and chicken manure was thus evaluated at Horticulture Research Institute, Marondera, Zimbabwe. The field trial was laid out as a Randomized Complete Block Design with seven treatments, replicated three times. Treatment levels comprised application rates of 50t/ha, 30t/ha and 0t/ha for cattle, goat and chicken manures. Results showed significant influence (P&lt;0.05) of manure on germination percentage, growth parameters and leaf yield. Goat manure performed better than cattle and chicken manure with the highest germination, plant height and leaf yield of 100%, 48.2cm and 32.68t/ha respectively. Thus production of C. gynandra using goat manure is recommended for optimum yield. However, further studies under different manure type combinations and the cost benefit analysis of using animal manures for C. gynandra production are also recommended.

Estimating Nitrogen and Chlorophyll Status of Romaine Lettuce Using SPAD and at LEAF Readings

Nitrogen (N) is an essential nutrient for plant growth and development and is especially important in the production of high quality leafy green vegetables. In this experiment, leaf N concentration, chlorophyll concentration (Chl) and weight above fresh matter (AFM) of romaine lettuce (Lactuca sativa L. var. longifolia) were estimated by correlations between in situ SPAD and atLEAF readings. Lettuce was grown in high tunnels during 42 days and was irrigated at five nitrogen levels: 0, 4, 8, 12 and 16 mEq·L-1 of NO3-, based on the Steiner nutrient solution. The N concentration, Chl concentration and AFM were determined in the laboratory, while SPAD and atLEAF readings were measured in situ weekly. SPAD readings had high, positive and significant linear correlations with N (R2 = 0.90), Chl (R2 = 0.97) and AFM (R2 = 0.98); atLEAF readings had a similar linear correlation with N (R2 = 0.91), Chl (R2 = 0.92) and AFM (R2 = 0.97). Besides, SPAD and atLEAF readings had high, positive, and significant linear correlation (R2 = 0.96). Thus, SPAD and atLEAF meters can be used to non-destructively and accurately estimate the N status of lettuce, in a reliable and quick manner during the crop production cycle. In addition, atLEAF is currently more affordable than SPAD.&#x0D; &#x0D; *********&#x0D; In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 3, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue.&#x0D; *********

Chapter 42: Guidelines for Chinese Leafy and Root Crop Vegetable Production in South Florida

This document is HS741, Horticultural Sciences Department, UF/IFAS Extension. Published November 2006.

Analysis of Health Risk Factors in the Vegetable Production Chain in the City of N&amp;#39;Djamena-Chad

Several market gardeners have settled in the city and supply urban markets with fresh vegetables throughout the year. Despite their nutritional importance, market gardening products may carry health risks. The objective of this study is to identify and analyse the potential risk factors that could lead to the appearance of microbiological and physicochemical hazards in the production chain of fresh vegetables from these market gardening operations. The work was carried out in 5 permanent market gardening sites in the city of N&amp;#39;Djamena (Chad, Africa) and involved 96 market gardeners surveyed. Data related to production methods were collected. Standard methods were used to carry out microbiological analysis tests on 15 samples of vegetables and fruits taken from 3 sites.The results of the survey show that urban market gardening in N&amp;#39;Djamena is dominated by two plant species: lettuce (Lactuca sativa) and rocket (Eruca sativa). It is geared towards the production of leafy vegetables. The health risks associated with the conditions of production are numerous and real: the proximity of roads, the use of dirty water for irrigation, the overdose of chemical fertilizers (urea) and pesticides, and finally the unhygienic harvesting and transport. The high-water content of fresh vegetables and the lack of processes for the elimination of pathogenic microorganisms also do not guarantee the sanitary quality of the vegetables produced and can thus increase the risk of foodborne infections. The results of the microbiological evaluation showed the presence of germs pathogens including Escherichia coli, Staphylococcus aureus, Aeromonas spp. and Salmonella sp. in vegetable and fruit. Therefore, the best strategy to obtain a healthy product is to educate producers on good agricultural practices including reasoned fertilization, clean water, treated wastewater, approved pesticides.

Differential Biomass Accumulation among African Leafy Vegetables as Affected by Wastewater Irrigation in Kitui County, Kenya

Water scarcity of fresh water in Sub-Saharan has led to utilization of the wastewater in home gardening and also in commercial production of vegetables. Wastewater is associated with various substances including nutrients and heavy metals hence it is pertinent to evaluate its effects on growth and yield of vegetables. An experiment was conducted to evaluate the effect of waste water released from the municipal council on the biomass accumulation in African leafy vegetables. Field experiments were carried out in two seasons and one greenhouse experiment. The field trial was laid out in a Randomized Complete Block Design (RCBD) and in the greenhouse the treatments were arranged in Complete Randomized Design (RCD) replicated three times. Four leafy vegetables were the treatments replicated three times. The vegetables were irrigated with waste water. Plant samples were collected at 6 WAP and 12 WAP, partitioned and dried in an oven and later weighed using electronic weighing balance. The findings revealed differences in biomass accumulation into various organs. Black nightshade depicted the highest leaf dry matter in the greenhouse at both 6 weeks after plant (WAP) and 12 WAP (24.62 g and 81.12 g respectively). Cowpea showed the highest increment (7 folds) in leaf weight between 6 to 12 WAP as compared to was paltry 3.6 folds. The highest stem dry weight was obtained in the amaranth species at 6 WAP and 12 WAP both in the greenhouse; recording 32.59 g and 90.12 g respectively. A similar trend was noted in root dry weight and root: shoot ratio. Cowpea had the least biomass accumulation potential across all the parameters in both seasons and in the greenhouse. The increased biomass growth is an indication sufficient availability of nutrient that promoted vibrant plant growth and also less toxicity from the heavy metals. Therefore, waste water can be put into use to enhance improved productivity of African leafy vegetables.

Improving traditional leafy vegetables production through water use efficiency and fertilizer microdosing technology in Benin Republic

In most developing countries, water and fertilizer management pose serious problems to vegetables production. This study aimed at determining the fresh leaf yields and Water Use Efficiency (WUE) under microdosed fertilizer technology of two main traditional leafy vegetables (TLVs) (Amaranthus cruentus L. and Solanum macrocarpon L.) that are consumed in Benin. A field experiment was carried out at Centre de Recherche Agricole d'INA, Northern Benin, under sprinkler irrigation at maximum evapotranspiration (MET) calculated from Cropwat 8.0. The study was laid out in a randomized complete block design with four replications and two factors: 1) urea (46% N) applied at D0, D20, D40, D60, D80 (kg ha-1) and 2) urea application timing at d1: early application (10 days after transplanting, DAT) and d2: later application (15 DAT). Following the MET (6.6 mm day-1), plants were irrigated twice a day (morning and evening) at 3.3 mm per watering. This irrigation rate was applied by operating the sprinklers with 0.078 mm min-1 of water flow for 44 min. Soil moisture and drainage were measured every week using TDR (time domain reflectometry) probe and micro-lysimeters respectively. The water balance was calculated using the trapezoidal method. WUE was determined using the ratio of dry biomass yields and real crop evapotranspiration (RET). Data were analyzed with R software following analysis of variance (ANOVA) and Pairewise t test at 0.05 level of probability. Quadratic regression was used to model TLVs response to fertilizer rates. At D60d1 and D40d2 we recorded the highest RET (35-42.45 mm week(-1)), highest fresh biomass yields (4.5-4.7 t ha(-1) for eggplant and 9.9-10.5 t ha(-1) for amaranth) and highest WUE (2.5-4 kg ha(-1) mm(-1)), respectively. Microdosed fertilizer technology may be therefore used to improve TLVs production and WUE because it may contribute to reduce fertilizer use by 2.5-10 times for urea and to 50% irrigation water while increase fresh leaf yield by 30-64%.

Yield-scaled N2O emissions as affected by nitrification inhibitor and overdose fertilization under an intensively managed vegetable field: A three-year field study

Vegetable fields exhibit contrasting characteristics of high nitrous oxide (N2O) emissions and low nitrogen use efficiency (NUE) compared with other croplands due to intensification. A three-year field experiment consisting of eleven successive vegetable crops was conducted to investigate the effects of wide range of overdose fertilization and chlorinated pyridine (CP, a nitrification inhibitor) on the N2O emissions, agronomic NUE, yield-scaled N2O emissions, marginal yield and marginal N2O emission. Five urea N input rates, combining without (U) or with CP (U-CP), were applied at 0, 587, 880 (the conventional N rate), 1173, and 1760 kg N ha−1 yr−1. Results showed that N2O emission responses to N rate fitted well with cubic models in both the U and U-CP group treatments. Meanwhile, CP addition significantly reduced annual cumulative N2O emissions and the N2O emission factor from 39.1 to 79.7 kg N ha−1 yr−1 and 2.7–3.6% to 31.6–56.2 kg N ha−1 yr−1 and 1.5–2.2%, respectively, in relation to the U treatments at the same N rate. Moreover, CP addition significantly decreased the yield-scaled N2O emissions from 0.30 to 0.52 kg N t−1 to 0.22–0.35 kg N t−1 without obvious influence on vegetable yield. The 587 kg N ha−1 yr−1 was the optimal N rate for both the U and U-CP treatments as indicated by the agronomic NUE and yield-scaled N2O emissions. Thus, one third reduction of the conventional N fertilizer rate combined with CP was recommended to mitigate N2O emissions and maintain the yield for the sustainable development of intensified leafy vegetable production.

Risk of Human Pathogen Internalization in Leafy Vegetables During Lab-Scale Hydroponic Cultivation

Controlled environment agriculture (CEA) is a growing industry for the production of leafy vegetables and fresh produce in general. Moreover, CEA is a potentially desirable alternative production system, as well as a risk management solution for the food safety challenges within the fresh produce industry. Here, we will focus on hydroponic leafy vegetable production (including lettuce, spinach, microgreens, and herbs), which can be categorized into six types: (1) nutrient film technique (NFT), (2) deep water raft culture (DWC), (3) flood and drain, (4) continuous drip systems, (5) the wick method, and (6) aeroponics. The first five are the most commonly used in the production of leafy vegetables. Each of these systems may confer different risks and advantages in the production of leafy vegetables. This review aims to (i) address the differences in current hydroponic system designs with respect to human pathogen internalization risk, and (ii) identify the preventive control points for reducing risks related to pathogen contamination in leafy greens and related fresh produce products.