Baby Leaf Research Articles

Cadmium uptake by onions, lettuce and spinach in New Zealand: Implications for management to meet regulatory limits

Paired soil and plant samples collected from the main commercial growing areas for onions (Allium cepa), lettuce (Lactuca sativa) and spinach (Spinacia olearacea) in New Zealand were used to assess the influence of plant and soil factors on cadmium (Cd) uptake in these crops. Differences in Cd concentration between eight lettuce sub-types were not consistent across sites, nor were differences in Cd concentrations in three crisphead cultivars assessed at two sites. Similarly, differences in Cd concentrations between four onion cultivars were inconsistent across sites. Mean lettuce Cd concentrations in eight lettuce varieties (range 0.005–0.034 mg∙kg−1 (fresh weight, FW) were markedly lower than those in baby leaf and bunching spinach, (range 0.005–0.19 mg∙kg−1 FW). Significant regional variation was observed in Cd concentrations in one onion cultivar (mean range 0.007–0.05 mg∙kg−1 FW). Soil Cd concentration, pH and region were statistically significant predictors of onion Cd concentration, explaining low (38% for soil Cd and pH) to moderate (50% for all three parameters) percentage of the variation. Soil Cd concentration and exchangeable magnesium or total carbon were statistically significant predictors of Cd concentration in baby leaf and bunching spinach, respectively, explaining a moderate percentage (49% and 42%) of the variation in Cd concentration. Increasing pH and soil carbon may assist in minimising Cd uptake in onion and bunching spinach, respectively. The low to moderate proportion of explained variation is partly attributable to the narrow range in some measured soil properties and indicates factors other than those assessed are influencing plant uptake. This highlights a challenge in using these relationships to develop risk-based soil guideline values to support compliance with food standards. Similarly, the inconsistency in Cd concentrations in different cultivars across sites highlights the need for multi-site assessments to confirm the low Cd accumulation status of different cultivars.

GREEN PEA SPROUT RESPONSE TO MICROBIAL INOCULATION AND INCREASING ATMOSPHERIC CO2 CONCENTRATION

Baby pea (pisum sativum L.) shoots is a new ready to eat baby leaf vegetable sprouts in Egypt. The overall quality change of baby pea shoots is greatly affected by surrounding environmental conditions especially increased elevation of carbon dioxide concentration in the air. This work focus on the impacts of predicted climate changes conditions on the quality of baby pea shoots by using two carbon dioxide concentrations (600 and 800 ppm) compared with ambient air (control) in interaction with three microbial inoculants and their combinations, in semi-automated growth chambers using tray sprouting method. The obtained results showed the largest yield of pea sprouts per unit area in 800 ppm CO2 concentration with increasing about 20% more than ambient air (control) followed by 600 ppm with increasing about 9.4% than ambient air. Also, it revealed that using CO2 at 800 ppm increased pea sprout crude protein content 37.8%, lipid 46.9% and energy 19.5% per unit area when compared to ambient air. While pea sprout treated by 800 ppm CO2 and inoculated by combination of Az. chroococcum + B. megaterium + Ps. fluorescens recorded the highest significant shoot length in the second cut and highest significant chlorophyll in first and second being 13.25 cm, 57.3 and 58.9 μg Chl./cm (SPAD) and the highest significant protein, lipids, and ash content being 48.65, 4.95, 10.69% as well as the highest significant mineral values of P, Ca, Mg, Fe and Zn being 0.545, 3.535, 0.620% and 61.3 ppm respectively. Current study suggests that high CO2 concentration in the presence of Az. chroococcum + B. megaterium + Ps. fluorescens improve the yield and the quality of baby pea shoots.

An agroindustrial compost as alternative to peat for production of baby leaf red lettuce in a floating system

Peat alternatives are being developed using materials such as agroindustry compost. The aim of this work was to study whether an agroindustrial compost could be used as substitute for peat in a floating system for cultivating baby leaf red lettuce. For this, two different experiments were carried out over two growing cycles (summer and autumn) in the same greenhouse at the same time. The first experiment compared the two organic substrates (peat and compost) and the second involved a suppressive bioassay using both substrates inoculated with Pythium irregulare. The results showed that compost increased the percentage of seed germination and the quality of baby leaf red lettuce by reducing nitrate accumulation and increasing the antioxidant capacity and vitamin C content of leaves compared with peat. Furthermore, under P. irregulare pressure plants grown in compost showed less incidence of the disease (a higher percentage of plant survival) and produced higher yields. It is concluded that the agroindustrial compost used in this study shows promise as an alternative to peat for use as organic substrate in a sustainable soilless production system for baby leaf red lettuce, since it is not only able to control the effect of P. irregulare, but also improve the yield and quality of the product.

Modification of the existing maximum residue levels and setting of import tolerances for pyraclostrobin in various crops.

In accordance with Article 6 of Regulation (EC) No 396/2005, the applicant BASF SE submitted two requests to the competent national authority in Germany. The first one, to modify the existing maximum residue levels (MRL) for the active substance pyraclostrobin in various crops and to set import tolerances for sugar canes and American persimmons; the second one to set import tolerances for pineapples and passion fruits/maracujas. The data submitted in support of the requests were found to be sufficient to derive MRL proposals for mandarins, grapefruits, lemons, limes, passion fruits/maracujas, pineapples, flowering brassica, head cabbages, lamb's lettuce, cresses and other sprouts, land cresses, rucola, red mustards, baby leaf crops, globe artichokes and leeks. For oranges, American persimmons, spinaches and similar leaves and sugar canes, data gaps were identified which precluded the derivation of MRL proposals. The data submitted did not provide evidence that the existing MRLs for crops belonging to the group of lettuces and maize have to be modified to accommodate for the intended uses. For escaroles, no MRL was proposed as the intended use was found to lead to residues for which a potential consumer health risk cannot be excluded. EFSA concluded that the short‐term intake of residues resulting from the uses of pyraclostrobin according to the reported agricultural practices assessed is unlikely to present a risk to consumer health, except for escaroles, where the expected intake was found to exceed the toxicological reference value. Taking into account the existing and the proposed new MRLs, a long‐term intake concern for consumers was not identified.

Effects of solid and liquid digestate for hydroponic baby leaf lettuce (Lactuca sativa L.) cultivation

Digestate was evaluated as an alternative and sustainable growing medium and nutrient solution in the hydroponic cultivation of baby leaf lettuce (Lactuca sativa L.). Nine hydroponic combinations of substrate and fertilization (agriperlite + standard solution, agriperlite + liquid digestate, solid digestate + standard solution, solid digestate + liquid digestate, soil + standard solution, peat moss + standard solution; peat moss + liquid digestate, pelleted digestate + standard solution and pelleted digestate + liquid digestate) were tested and compared for the cultivation of baby leaf lettuce, in three different experiments. During the crop cycles, yield as other agronomical and microbiological parameters were investigated. The combination of agriperlite + liquid digestate, solid digestate + standard solution and pelleted digestate + standard solution enhanced plant growth by affecting the root, the shoot, the total dry weight and SPAD parameters, in the all investigated experiments (+32%, +40%, +29%, +17% respectively). Based on the obtained results, digestate represents a sustainable and alternative growing media or nutrient solution for the production of baby leaf lettuce cultivated in hydroponic system.

계절별 수송 온도가 MA 포장한 어린잎 비트의 저장성에 미치는 영향

계절별 수송 온도가 MA 포장한 어린잎 비트의 저장성에 미치는 영향

Influence of aeration of the nutrient solution on quality changes of two baby leaf lettuce cultivars grown in a floating system at harvest and during shelf-life as fresh-cut product

Influence of aeration of the nutrient solution on quality changes of two baby leaf lettuce cultivars grown in a floating system at harvest and during shelf-life as fresh-cut product

The floating growing system can assure a low microbial contamination of baby leaf vegetables at harvest

The floating growing system can assure a low microbial contamination of baby leaf vegetables at harvest

Effects of OTR Film Type on the Quality of Lepidium sativum L. Baby Leaf Vegetable during MA Storage

Effects of OTR Film Type on the Quality of Lepidium sativum L. Baby Leaf Vegetable during MA Storage

NaCl stress enhances silicon tissue enrichment of hydroponic “baby leaf” chicory under biofortification process

Abstract The effects of saline stress on the silicon (Si) tissue enrichment (Si biofortification) of ready-to-eat “baby leaf” chicory in hydroponic floating system were studied. Four combinations of Si and NaCl levels in the nutrient solution were compared: i) 0 mM Si - 0 mM NaCl (‘Control’); ii) 3.6 Si - 0 NaCl (‘Si’); iii) 0 Si - 50 NaCl (‘NaCl’); and iv) 3.6 Si - 50 NaCl (‘Si + NaCl’). Si in combination with salt stress enhanced the Si tissue enrichment with respect to biofortification under control conditions [11.4 vs 3.06 mg 100 g−1 fresh weight (FW), respectively]. However, Si was not able to restore growth of plants under salinity compared to normal conditions. Bioaccessible Si in chicory under ‘Si + NaCl’ treatment was the highest in the experiment (3.73 mg 100 g−1 FW). The nitrate content was not influenced by salinity neither by Si, while the oxalate content was extremely low in all treatments, thus not compromising the enhanced nutritional value of the biofortified chicory. Application of salt stress could be considered an effective strategy to enhance the silicon tissue enrichment of hydroponic chicory under biofortification process.

Zinc biofortification of hydroponic baby leaf lettuce grown under artificial lighting with elevated wind speed and root zone temperature

Zinc biofortification of hydroponic baby leaf lettuce grown under artificial lighting with elevated wind speed and root zone temperature

Dissipation Dynamics and Risk Assessment of Thiacloprid 240 SC in Jasmine (Jasminum sambac L.) Buds

Thiacloprid effectively managed budworm, Hendecasis duplifascialis Hampson and blossom midge, Contarinia maculipennis Felt infesting jasmine buds. At the recommended dose of 0.6 mL L−1 on the jasmine flower buds, the residues persisted up to 5 d, being below detectable level on the 7th d at the limit of quantification (LOQ) of 0.01 mg kg−1. The half-life was 1.04 d. Based on the maximum residual limit (MRL) on lettuce, herbs, and baby leaf brassica (2.0 mg kg−1), the safe waiting period for plucking the flowers for usage in concrete preparation or for production of jasmine tea was 0.40 d (∼ 10 h).

Evaluation of metabolic changes in oxalate-rich plant Rumex obtusifolius L. caused by ion beam irradiation

Some Rumex species such as sorrel are edible as baby leaf salad greens. On the other hand, Rumex plants accumulate soluble oxalate, a toxic metabolite which causes serious diseases such as renal syndrome. We attempted to produce low-oxalate plants of R. obtusifolius, a perennial weed which has higher vitamin C and amino acid content and higher tolerance to stress than many other Rumex species. Ion beams are ionising radiation with high linear energy transfer that causes a wide spectrum of mutations. Thus, in the present study we evaluated the effects of ion beams on oxalate and other primary metabolites in leaves of R. obtusifolius using CE-MS. The results showed that oxalate content was increased by irradiation with carbon ion beams. Metabolome analysis revealed that ion beams affected carbon flow to the isocitrate pathway, which is involved in oxalate synthesis. These observations suggested that modulation of carbon flow to the isocitrate pathway is important to regulate oxalate levels in plants.

Health-Promoting Phytochemicals from 11 Mustard Cultivars at Baby Leaf and Mature Stages.

Mustard is a Brassica vegetable that provides a number of phytonutrients. However, the phytonutrient profile of mustard has been relatively limited. We analyzed the glucosinolates and their hydrolysis products, carotenoids, total anthocyanin and phenolic contents, and antioxidant capacity of the leaves of 11 mustard cultivars grown in a greenhouse at the baby leaf and mature stages. An aliphatic glucosinolate sinigrin and its hydrolysis products allyl isothiocyanate and 1-cyano-2,3-epithiopropane were the major phytonutrients in the mustard leaves. Carotenoids β-carotene, lutein, violaxanthin, and neoxanthin were detected. We found phytonutrient concentration and their change with plant growth were cultivar-dependent. The %RDA value for vitamin A calculated using β-carotene content and retinol activity equivalents suggests that mustard cultivars used in this study can be a good source of vitamin A. Phenolic contents and antioxidant capacity also varied among cultivars and between physiological stages. Our results suggest that mustard leaves are rich in various phytochemicals and their composition depends on cultivar and the physiological stage. This is the first report on phytochemical composition in various mustard cultivars at different physiological stages.

Postharvest physiology of Corchorus olitorius baby leaf growing with different nutrient solutions

ABSTRACTThe storage at 4°C in darkness of Corchorus olitorius L. baby leaf as a ready-to-eat (RTE) vegetable has been studied for the first time. C. olitorius was cultivated in a floating system with different nutrient solutions: standard (NS100%) or halved (NS50%). Several quality factors of this produce were evaluated during season (spring, summer, autumn) considering treatments and days of storage in order to understand the interactions. During storage, sucrose, total and reducing sugars, nitrate, phenolic compounds, anthocyanins, chlorophylls, and carotenoids were measured. Results showed that chlorophylls decreased by 20–30% for both treatments and the changes were statistically different during spring. Carotenoid content did not change until the end of the storage and values ranged from 0.60 g kg−1 to 0.75 g kg−1 fresh weight depending on the season. Phenols and anthocyanins decreased within 10 days: −40% of phenols and −50% of anthocyanins, respectively. No interaction between nutrient solutions and storage behaviour was reported. Thus, C. olitorius resulted to be a good source of nutraceutical compounds and it is able to maintain these components during storage. Moreover, the public interest in regards to nutritional and healthy food is rapidly increasing, promoting the discovery of new vegetables, like C. olitorius, for RTE commercialisation.

Effects of Harvest Time on Growth and Phytochemical Contents of Baby Leaf Vegetables in Multi-layer System

Effects of Harvest Time on Growth and Phytochemical Contents of Baby Leaf Vegetables in Multi-layer System

Impact of the source of organic manure on persistence of E. coli O157:H7 gfp+ in rocket (Diplotaxis tenuifolia) and Swiss chard (Beta vulgaris cicla)

The influence of organic nitrogen sources on the establishment of E. coli O157:H7 and the occurrence of other potentially human pathogenic bacteria on baby leaf salads was evaluated. Greenhouse-grown rocket and Swiss chard were spray-inoculated with gfp-tagged E. coli O157:H7 twice a week from when their first true leaves reached a length of 2 cm until three days before harvest. Analysis of nitrogen content in leaves revealed differences between treatments. Untreated plants had the lowest values, followed by plants fertilized with pig hair pellets and chicken manure. The same pattern was seen for the growth medium at the day of harvest. The applied strain showed similar establishment (measured using culture-dependent methods) irrespective of treatment, but Swiss chard hosted significantly more E. coli O157:H7 than rocket. Differences in the risk of infection were found for the crops, with plants fertilized with pig hair pellets showing a slightly higher risk. No relationship was found for total nitrogen content in leaves and colonization with E. coli O157:H7 gfp+. Isolating dominant Enterobacteriaceae from leaves, some strains showed conformity to bacterial species that have previously been identified to influence the establishment of E. coli O157:H7 in the phyllosphere. In this study, no inhibitory effects were observed in vitro.Colonies showing matching characteristics for Listeria spp. and Salmonella spp. were detected up to 5.5 and 5 log CFU g−1 fresh weight, respectively. However, presumptive Listeria spp. and Salmonella spp. could not be confirmed by sequencing of the 16S rRNA gene.

Impact of solar radiation exposure on phyllosphere bacterial community of red-pigmented baby leaf lettuce

Solar radiation has been identified as a stress factor affecting phyllosphere associated bacteria colonization and survival during primary production. In the present study, the impact of different solar radiation doses on the phyllosphere microbiota of red-pigmented baby leaf lettuce cultivated in open field under commercial conditions was evaluated. Four weeks before harvest, the growing field was divided into four plots; each one was consecutively covered with one-week-interval with a light-excluding plastic to reduce the sunlight exposure. Four different solar radiation treatments were generated and cumulative photosynthetically active radiation (PAR) was used to differentiate treatments as follows: 4889 ± 428 μmol/m2/s (uncovered), 4265 ± 356 μmol/m2/s (covered for 1 week), 3602 ± 225 μmol/m2/s (covered for 2 weeks) and 3115 ± 313 μmol/m2/s (covered for 3 weeks). The size and composition of the phyllosphere bacterial community were determined by cultivation-depended (plate count) and independent (qPCR) techniques. Exposure to decreased levels of cumulative PAR did not produce significant differences in total bacterial community size, regardless of the chosen quantification techniques. However, total bacteria size quantified by qPCR was around 3.5 orders of magnitude higher than those obtained by plate count. The observed differences between cultivation-depended and independent techniques could be attributed to the presence of non-viable or viable but non-culturable (VBNC) bacteria. The bacterial community structure was analyzed using temperature gradient gel electrophoresis (TGGE), and significant differences were detected when the four solar treatment were compared. A qPCR approach was applied to the quantification of specific bacterial phyla and classes, previously identified in the phyllosphere of plants available literature, confirming that Proteobacteria, Bacteroidetes, Actinobacterias and Firmicutes were the most abundantly represented phyla in lettuce. Treatment comparison revealed higher proportions of Gammaproteobacteria as opposed to the Betaproteobacteria on the lettuce exposed to the lowest cumulative PAR dose (3115 ± 313 μmol/m2/s). The obtained results demonstrated that the solar radiation is a relevant environmental factor influencing the relative abundance of specific-groups of phyllosphere-associated bacteria in pigmented baby leaf lettuce.

Mineral Content Differs among Microgreen, Baby Leaf, and Adult Stages in Three Cultivars of Kale

Kale (Brassica oleracea L. and other species) is considered a rich source of important minerals. Kale at the early stage of leaf development is assumed to contain higher levels of minerals than at maturity. However, literature supporting this assumption is scarce. In this study, the concentrations of macronutrients [potassium (K), calcium (Ca), magnesium (Mg), and phosphorus (P)] and micronutrients [sodium (Na), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu)] either essential to plant growth and development, or important to human health, were determined. Three kale cultivars (green leaf ‘Dwarf Blue Curled’ and red leaf ‘Scarlet’ in B. oleracea, and green leaf with purple midvein ‘Red Russian’ in Brassica napus) were evaluated at five different leaf developmental stages; cotyledon [microgreen 1 (MG1)], two true leaf [microgreen 2 (MG2)], four true leaf [baby leaf 1 (BL1)], six true leaf [baby leaf 2 (BL2)], and adult. As kale matured, total mineral (ash) decreased from 14.6–19.1% at the microgreen stages to 3.9–6.4% at the adult stage, on a dry weight (DW) basis. Microgreen kale contained higher concentrations of most minerals than adult kale, on a DW basis, in all cultivars. On a fresh weight (FW) (as consumed) basis, the highest level of total mineral concentration was detected at baby leaf stage 1 (1.3–1.7%) and there was no difference between microgreen and adult stages. Fresh microgreens generally contained lower K, Ca, Mg, Fe, and Zn than fresh baby leaves, and lower concentrations of Ca and Mg and higher Na compared with fresh adult kale. Overall, water content deceased from 95.1% at MG1 stage to 80.0% at adult stage. The variation in water content and mineral accumulation during leaf development might contribute to the discrepancy. In addition, fresh leaves of ‘Scarlet’ contained higher concentration of total minerals than that of ‘Dwarf Blue Curled’ or ‘Red Russian’. Although ‘Dwarf Blue Curled’ and ‘Red Russian’ are different species, their mineral content profile during leaf development was similar. Together, cultivar and leaf developmental stage influenced mineral content in kale.

Introduction of sorghum [Sorghum bicolor (L.) Moench] green manure in rotations of head salads and baby leaf crops under greenhouse

This paper deals with the introduction in tunnel-greenhouses of sweet sorghum cultivated in short, summer cycle as green manure with the aim to amend soils with biomass grown on farm. This practice has been spreading in tunnels of Sele river Valley (Salerno, Italy) where baby leaf crops are cultivated in numerous cycles (up to 5-7) per year. Three sorghum varieties for forage or biomass (Goliath, BMR 201, and BMR 333) were cultivated in two farms at Eboli and San Marzano sul Sarno with the aim of studying their responses in term of fresh and dry aboveground biomass yielded, carbon (C) and nitrogen (N) content of the biomass incorporated in soil, and C balance in amended soils after one year of ordinary cash crop sequences. No differences, with regard to all the parameters measured, were pointed out among the tested varieties in each site. The sorghum cycle lasted 45 days at Eboli, yielding on average 98 and 13 t ha–1 of fresh and dry biomass, respectively; soil biomass incorporation supplied on average 5.8 t ha–1 of organic C and 273 kg ha–1 of total N. In the farm of San Marzano, sorghum cycle lasted 68 days, yielding 116 and 18 t ha–1 of fresh and dry biomass, respectively; soil biomass incorporation supplied on average 8 t ha–1 of organic C and 372 kg ha–1 of total N. After one year, the plots amended with sorghum biomass showed a soil organic carbon (SOC) concentration not different from the starting point, while SOC decreased in fallow plots. At Eboli, initial SOC content was 12.3 g kg–1, but one year later it resulted 12.3, 12.8, 12.2 and 11.3 g kg–1 in BMR 201, BMR 333, Goliath and control plots, respectively. At San Marzano, initial SOC content was 11.4 g kg–1, but one year later it resulted 11, 12, 10.7 and 10.5 g kg–1 in BMR 201, BMR 333, Goliath and control plots, respectively. The annual C balance put in evidence that the green manure with sorghum biomass caused SOC losses higher than those detected in fallow plots. This let us suppose a prime effect in boosting the soil microbial C mineralisation. Only cv BMR 333 in the Eboli trial pointed out a positive SOC change of 1.8 t ha–1. Further studies are requested to better understand the real efficacy of sorghum cover crop in soil amendment under tunnels devoted to intensive vegetable crop sequence.