Search Results (18)

Cover crops and mulches are widely used techniques for limiting weeds and pests’ effects on crops. This study compared six practices over two growing seasons in two organic farms in Cuneo province, North-West Italy: two bio-based biodegradable mulch sheets (BM01 and BM02), dead mulch (hazelnut shells), living mulch (Trifolium repens L.), mechanical control, and an untreated control. Spring crops included Lactuca sativa L. var. capitata, Allium cepa L. cv. ‘Tropea’, and Brassica oleracea L. var. italica, while autumn crops were Lactuca sativa L. var. capitata, Allium fistulosum L., and Brassica oleracea L. var. italica. Weed infestation was evaluated through density (n/m²), biomass (g/m²), and diversity (Shannon Index), alongside crop yield and quality. Biodegradable mulch sheets provided the greatest weed suppression, followed by hazelnut shells, while living mulch and untreated control showed the highest weed pressure. Crop yield varied significantly among practices and species: BM01 and BM02 resulted in the highest yields, while living mulch consistently produced the lowest. Lettuce displayed the best quality across both farms, whereas onion quality varied by site. The highest quality scores were observed under biodegradable mulches and mechanical control, while living mulch and untreated control yielded the poorest results. Overall, biodegradable mulches emerged as the most effective balance between weed suppression, crop yield, and quality in organic systems. Full article

The present study aimed to evaluate crop characteristics, including morpho-anatomical features and nutritional and health-promoting composition, of head lettuce cultivated in greenhouses covered with transparent glass (control) and glass containing a red luminophore (red). The plant material comprised two lettuce types: butterhead and iceberg. Alterations were observed in head dimensions, morphology, and leaf mesophyll structure of plants from the red greenhouse. Butterhead lettuce plants exhibited unaltered head area under tested conditions but displayed a reduction in accumulated sugars and amino acids, resulting in a decline in dry matter content. Conversely, an increase in soluble and insoluble sugars and amino acid content, along with no change in nitrate content, was observed in iceberg lettuce. However, the growth intensity of iceberg lettuce decreased, while its dry matter content increased. Moreover, phenols and vitamin C concentration were lower in iceberg lettuce than in the butterhead one. In the red greenhouse, the phenolic content declined in both lettuce types, but vitamin C levels were reduced in butterhead lettuce and remained unchanged in iceberg lettuce. The data clearly demonstrate that the extent of variation in crop characteristics observed in lettuce cultivated in the red greenhouse depended on the tested lettuce type, with notable alterations occurring in iceberg lettuce. Full article

As potable water becomes limited, alternative water sources, such as reclaimed wastewater, for crop irrigation have gained attention. However, reclaimed wastewater for irrigation may expose edible crops to compounds of emerging concern (CECs), which may include pharmaceutics, hazardous waste, and volatile substances. Of these CECs, carbamazepine (CBZ) is of particular interest because only 7% of CBZ is filtered out during traditional wastewater treatment processing methods. Two trials were designed to evaluate the uptake and partitioning of CBZ in lettuce grown in a deep-water culture system (DWC) at low and high concentrations. The first trial (0 µg L⁻¹, 12.5 µg L⁻¹, 25 µg L⁻¹, and 50 µg L⁻¹) of CBZ had few effects on lettuce (Lactuca sativa var. capitata) growth, and low concentrations of accumulated CBZ were found in lettuce tissues. As a result, increased concentrations of CBZ were used in the second trial (0 mg L⁻¹, 21 mg L⁻¹, 41 mg L⁻¹, and 83 mg L⁻¹). Greater amounts of CBZ accumulated in plant tissues and the application of higher rates of CBZ negatively affected the growth and overall health of the lettuce. Further research is needed to determine the impacts of CECs on plant uptake and growth, as well as the environmental conditions. Full article

Soilless cultivation systems are sustainable innovations in modern agriculture, promoting high efficiency per unit area, supporting food sustainability, and addressing the growing demand for high-quality produce with minimal environmental impact. This study evaluates the effects of fulvic acid, amino acid, and vermicompost biostimulants on the growth, yield, and nutrient profile of soilless-grown iceberg lettuce (Lactuca sativa var. capitata) in floating culture under controlled glasshouse conditions. Two experiments were conducted to determine the most effective concentrations and combinations of biostimulants. In the first experiment, varying doses of fulvic acid (40 and 80 ppm), amino acid (75 and 100 ppm), and vermicompost (1 and 2 mL L⁻¹) were tested alongside a control. Optimal doses were identified based on their positive effects on lettuce growth and yield. The second experiment examined combinations of fulvic acid, amino acid, and vermicompost extract compared to a control. Biostimulants improved lettuce growth, nutrient uptake, and antioxidants. Vermicompost boosted root biomass and leaf area, while fulvic acid and amino acid reduced nitrates and increased dry matter. Fulvic acid and vermicompost resulted in the highest yield (17.15 kg/m², 18.2% increase), and the combined treatment maximized antioxidants, increasing vitamin C by 17.16%, total phenols by 52.54%, and flavonoids by 52.38%. These findings highlight the potential of biostimulants as eco-friendly solutions for optimizing lettuce production in soilless systems. Full article

Drought is a major challenge for agriculture worldwide, being one of the main causes of losses in plant production. Various studies reported that some soil’s bacteria can improve plant tolerance to environmental stresses by the enhancement of water and nutrient uptake by plants. The Atacama Desert in Chile, the driest place on earth, harbors a largely unexplored microbial richness. This study aimed to evaluate the ability of various Bacillus sp. from the hyper arid Atacama Desert in the improvement in tolerance to drought stress in lettuce (Lactuca sativa L. var. capitata, cv. “Super Milanesa”) plants. Seven strains of Bacillus spp. were isolated from the rhizosphere of the Chilean endemic plants Metharme lanata and Nolana jaffuelii, and then identified using the 16s rRNA gene. Indole acetic acid (IAA) production, phosphate solubilization, nitrogen fixation, and 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity were assessed. Lettuce plants were inoculated with Bacillus spp. strains and subjected to two different irrigation conditions (95% and 45% of field capacity) and their biomass, net photosynthesis, relative water content, photosynthetic pigments, nitrogen and phosphorus uptake, oxidative damage, proline production, and phenolic compounds were evaluated. The results indicated that plants inoculated with B. atrophaeus, B. ginsengihumi, and B. tequilensis demonstrated the highest growth under drought conditions compared to non-inoculated plants. Treatments increased biomass production and were strongly associated with enhanced N-uptake, water status, chlorophyll content, and photosynthetic activity. Our results show that specific Bacillus species from the Atacama Desert enhance drought stress tolerance in lettuce plants by promoting several beneficial plant traits that facilitate water absorption and nutrient uptake, which support the use of this unexplored and unexploited natural resource as potent bioinoculants to improve plant production under increasing drought conditions. Full article

Organomineral fertilizers (OFs) can provide the macro- and micronutrients contained in organic matter slowly and gradually throughout the crop cycle. However, the residual effect of this slow release is still unclear and needs to be better evaluated. In this context, the objective of this study was to evaluate the use of different doses of OF in the cultivation of vegetables and to quantify the residual effects of P, B, and Zn in the soil. A randomized block design was applied, using different doses of fertilizer as a P source, with four replications. In the randomized block design, different doses of OF were evaluated as a source of P (all with four repetitions): T1 = no P supplied (zero dose); T2 = 200 mg dm⁻³ of P₂O₅; T3 = 400 mg dm⁻³ of P₂O₅; T4 = 800 mg dm⁻³ of P₂O₅; and T5 = 1200 mg dm⁻³ of P₂O₅ plus an additional treatment with mineral fertilizer (MF) (200 mg dm⁻³ of P₂O₅). The fresh weight (FW) and dry weight (DW) and the nutritional status of the lettuce and cabbage were determined through leaf analysis at harvest. Soil analysis was also conducted before planting and immediately after harvest in order to assess soil P, B, and Zn content. The FW and DW cabbage production was higher when fertilization was used for the crop (either OF or MF). No differences were observed in the effects of the OF and MF doses in cabbage production, which ranged from 281.2 g plant⁻¹ to 341.8 g plant⁻¹, while lettuce production was highest in MF (45.1 g plant⁻¹), followed by OF doses of 800 mg dm⁻³ (37.1 g plant⁻¹) and 1200 mg dm⁻³ (36.8 g plant⁻¹) of P₂O₅. OF fertilization had a beneficial residual effect on lettuce production, the FW and DW production of which increased as the OF doses increased (from 18.8 g plant⁻¹ to 36.8 g plant⁻¹ for FW and from 2.4 g plant⁻¹ to 4.0 g plant⁻¹ for DW). The highest doses of OF increased the availability of P and Zn in the soil and facilitated the absorption of nutrients by the cabbage and lettuce crops. In the cultivation of cabbage and lettuce, the residual effects of the P, B and Zn in the soil were higher under the highest doses of OF. An antagonistic effect between the P and Zn in the soil was evidenced in this study, and this needs to be confirmed in other subsequent studies. Full article

Due to rising food demand and the limitation of water resources, achieving water security is essential. The lettuce crop is affected when grown under limited water supplies as it produces small heads, especially during the late growing stage. For this reason, it is important to maximize water use efficiency and crop productivity. Two successive experiments were conducted during 2021 and 2022 to reduce losses via deep percolation using a geotextile layer at different soil depths under different irrigation levels of the lettuce crop (Lactuca sativa L. var. capitata). This study aims to reduce water losses due to deep percolation and improve crop growth and yield parameters for iceberg lettuce under subsurface drip irrigation in sandy loam soil conditions. In order to achieve these aims, different amounts of irrigation (100, 80, and 60% of crop evapotranspiration “ETc”) and a geotextile layer at different soil depths (20, 30, and 40 cm from the soil surface) were used. The results revealed that the use of a geotextile layer with 20 and 30 cm depths significantly improved irrigation application efficiency and noticeably increased soil water content in the root zone. The observed results during both seasons showed that geotextile layers at 20, 30, and 40 cm depths under irrigation of 100% ETc significantly increased vegetative growth characteristics (plant height, head diameter, head circumference, head volume, plant fresh weight, and leaf area) and crop productivity compared to the control (without geotextile). In particular, the geotextile layer at a 30 cm depth under irrigation of 100% of ETc was the most statistically effective treatment in this study, with yield values of 69.3 and 67.5 t ha⁻¹ in the two seasons, respectively. However, the treatments of geotextile layers at 20 and 30 cm depths under irrigation of 80% of ETc also recorded statistically effective results for crop growth parameters and yield in this study. In general, geotextiles can be used at different depths as an irrigation management practice to reduce deep percolation in the field. Full article

Cabbage maggot, Delia radicum (L.) (Diptera: Anthomyiidae) is a serious pest of Brassica such as broccoli (Brassica oleracea var. italica Plenck) and cauliflower (B. oleracea L. var. botrytis) in California’s Central Coast. Since there are limited non-chemical options available for growers to manage D. radicum, there is an urgent need to develop alternative tactics. The objective of this study was to determine the effects of side-by-side plantings of turnip (Brassica rapa var. rapa L.), lettuce (Lactuca sativa L.), cauliflower, and cabbage (B. oleracea L. var. capitata) with broccoli on D. radicum infestation. In 2013 and 2014, the experiments were conducted in Salinas, California. Significantly greater numbers of eggs and larval feeding damage were found on turnip compared with broccoli. Lettuce (Asteraceae), a non-Brassica crop, was compared with broccoli; however, lettuce did not reduce oviposition or larval feeding damage on broccoli. The larval feeding damage on cauliflower was significantly lower than on broccoli when planted side-by-side. The effects on cabbage were not significantly different from broccoli in terms of oviposition and larval feeding damage. This new information generated from the Central Coast of California will be further utilized to develop a trap crop to effectively tackle the D. radicum problem in Brassica fields. Full article

An autumn-winter trial was carried out in Southern Italy in open-field conditions on butterhead lettuce to investigate the effect of the nitrogen (N) fertilizer rate (0, 50, and 100 kg ha⁻¹, N0, N50, N100) and the application of the azoxystrobin, sprayed twice in an earlier vs. a later application scheme, specifically at 65/85 or 65/100 days after transplantation. An untreated control was also included. The evaluation of the product quality was conducted on fresh and stored shredded leaves. The N50 was a suitable rate for autumn-winter butterhead lettuce, but it does not guarantee the color appearance of the fresh leaves (lowest h°, highest L*). Concerning post-harvest changes, the N50- and N100-product were less suitable for storage, accounting for higher decay of visual quality (h°) and physiological senescence (EL) indices. Irrespective of N rate and application time, azoxystrobin improved growth and yield (+16%), visual (lower L*, higher h°, and chlorophylls), and nutritional (higher carotenoids and antioxidant capacity) quality of the fresh leaves. The application of azoxystrobin improved the shelf-life of butterhead lettuce leaves, by keeping higher turgidity (RWC), lower color decay (CHLs, h°), and higher nutritional value (carotenoids), and by limiting the browning spreading in shredded leaves. Full article

The application of hydroponic cultivation fertilized with biologically nitrified synthetic urine can produce nitrate-rich fertilizer for lettuce (Lactuca sativa var. capitata L.). The mounting water crisis and depletion of natural resources makes nitrogen recovery from human urine a practical option. Nitrified urine can be used in indoor vertical hydroponic cultivation and is characterized by a high degree of element recovery. Because of its high ammonium content, hydrolyzed fresh urine may be toxic. A nitrification sequencing batch reactor with suspended activated sludge biomass ensured urine stabilization and biological conversion into nitrate-rich fertilizer. The diluted nitrate-rich fertilizer was then supplied for soilless cultivation. The results show that diluted nitrified urine is an excellent source of bioavailable nitrogen and phosphorus and, with proper enrichment with microelements, could replace commercial fertilizers in hydroponic systems. The yield and quality parameters of lettuce cultivated with enriched urine were comparable to those obtained with a commercial fertilizer. The mass balance calculation showed that industry-scale lettuce production can be based on urine fertilizer collected from a few hundred people for a single unit. Full article

Microbial disease outbreaks related to fresh produce consumption, including leafy green vegetables, have increased in recent years. Where contamination occurs, pathogen persistence may represent a risk for consumers’ health. This study analysed the survival of E. coli and L. innocua on lettuce plants watered with contaminated irrigation water via a single irrigation event and within stored irrigation water. Separate lettuce plants (Lactuca sativa var. capitata) were irrigated with water spiked with Log₁₀ 7 cfu/mL of each of the two strains and survival assessed via direct enumeration, enrichment and qPCR. In parallel, individual 20 L water microcosms were spiked with Log₁₀ 7 cfu/mL of the individual strains and sampled at similar time points. Both strains were observed to survive on lettuce plants up to 28 days after inoculation. Direct quantification by culture methods showed a Log₁₀ 4 decrease in the concentration of E. coli 14 days after inoculation, and a Log₁₀ 3 decrease in the concentration of L. innocua 10 days after inoculation. E. coli was detected in water samples up to 7 days after inoculation and L. innocua was detected up to 28 days by direct enumeration. Both strains were recovered from enriched samples up to 28 days after inoculation. These results demonstrate that E. coli and L. innocua strains are able to persist on lettuce after a single contamination event up until the plants reach a harvestable state. Furthermore, the persistence of E. coli and L. innocua in water for up to 28 days after inoculation illustrates the potential for multiple plant contamination events from stored irrigation water, emphasising the importance of ensuring that irrigation water is of a high quality. Full article

Growing demand for horticultural products of accentuated sensory, nutritional, and functional quality traits has been driven by the turn observed in affluent societies toward a healthy and sustainable lifestyle relying principally on plant-based food. Growing plants under protected cultivation facilitates more precise and efficient modulation of the plant microenvironment, which is essential for improving vegetable quality. Among the environmental parameters that have been researched for optimization over the past, air relative humidity has always been in the background and it is still unclear if and how it can be modulated to improve plants’ quality. In this respect, two differentially pigmented (green and red) Salanova^® cultivars (Lactuca sativa L. var. capitata) were grown under two different Vapor Pressure Deficits (VPDs; 0.69 and 1.76 kPa) in a controlled environment chamber in order to appraise possible changes in mineral and phytochemical composition and in antioxidant capacity. Growth and morpho-physiological parameters were also analyzed to better understand lettuce development and acclimation mechanisms under these two VPD regimes. Results showed that even though Salanova plants grown at low VPD (0.69 kPa) increased their biomass, area, number of leaves and enhanced Fv/Fm ratio, plants at high VPD increased the levels of phytochemicals, especially in the red cultivar. Based on these results, we have discussed the role of high VPD facilitated by controlled environment agriculture as a mild stress aimed to enhance the quality of leafy greens. Full article

Considering that functional components of plant foods are mainly secondary-metabolism products, we investigated the shaping of health-promoting compounds in hydroponically grown butterhead lettuce (Lactuca sativa L. var. capitata) as a function of the strength of the nutrient solution utilized. To this aim, untargeted metabolomics profiling, in vitro antioxidant capacity (total phenolics, 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), cupric reducing antioxidant capacity (CUPRAC), and ferric reducing antioxidant power (FRAP) assays), and the inhibition of selected enzyme activities were investigated in two butterhead lettuce cultivars with different pigmentation, i.e., green and red Salanova. Full-strength nutrition, together with half- and quarter-strength solutions of macronutrients, was tested. Our results indicate that by reducing the nutrients strength, we could elicit a distinctive shaping of the phenolic profile of lettuce. It is noteworthy that only specific classes of phenolics (namely, lignans and phenolic acids, followed by flavones and anthocyanins) were modulated by the induction of nutritional eustress (fold-change values in the range between −5 and +11). This indicates that specific responses, rather than a generalized induction of phenolic compounds, could be observed. Nonetheless, a genotype-dependent response could be observed, with the red cultivar being much more responsive to nutritional deprivation than the green Salanova lettuce. Indeed, analysis of variance (ANOVA) confirmed a genotype x nutrition interaction in red Salanova (p < 0.001). As a consequence of the changes in phenolic composition, also the antioxidant capacity (p < 0.001) and amylase inhibition (p < 0.001) properties were affected by the growing conditions. However, the effect on cholinesterase and tyrosinase inhibition was poorly affected by the nutritional strength. Provided that yields are not compromised, the application of a controlled nutritional eustress in hydroponically cultivated lettuce may represent a valuable strategy to produce food with tailored functional features in a sustainable manner. Full article

Proximal sensors in controlled environment agriculture (CEA) are used to monitor plant growth, yield, and water consumption with non-destructive technologies. Rapid and continuous monitoring of environmental and crop parameters may be used to develop mathematical models to predict crop response to microclimatic changes. Here, we applied the energy cascade model (MEC) on green- and red-leaf butterhead lettuce (Lactuca sativa L. var. capitata). We tooled up the model to describe the changing leaf functional efficiency during the growing period. We validated the model on an independent dataset with two different vapor pressure deficit (VPD) levels, corresponding to nominal (low VPD) and off-nominal (high VPD) conditions. Under low VPD, the modified model accurately predicted the transpiration rate (RMSE = 0.10 Lm⁻²), edible biomass (RMSE = 6.87 g m⁻²), net-photosynthesis (rBIAS = 34%), and stomatal conductance (rBIAS = 39%). Under high VPD, the model overestimated photosynthesis and stomatal conductance (rBIAS = 76–68%). This inconsistency is likely due to the empirical nature of the original model, which was designed for nominal conditions. Here, applications of the modified model are discussed, and possible improvements are suggested based on plant morpho-physiological changes occurring in sub-optimal scenarios. Full article

Heavy payloads in future shuttle journeys to Mars present limiting factors, making self-sustenance essential for future colonies. Therefore, in situ resources utilization (ISRU) is the path to successful and feasible space voyages. This research frames the concept of planting leafy vegetables on Mars regolith simulant, ameliorating this substrate’s fertility by the addition of organic residues produced in situ. For this purpose, two butterhead lettuce (Lactuca sativa L. var. capitata) cultivars (green and red Salanova^®) were chosen to be cultivated in four different mixtures of MMS-1 Mojave Mars simulant:compost (0:100, 30:70, 70:30 and 100:0; v:v) in a phytotron open gas exchange growth chamber. The impact of compost rate on both crop performance and the nutritive value of green- and red-pigmented cultivars was assessed. The 30:70 mixture proved to be optimal in terms of crop performance, photosynthetic activity, intrinsic water use efficiency and quality traits of lettuce. In particular, red Salanova^® showed the best performance in terms of these quality traits, registering 32% more phenolic content in comparison to 100% simulant. Nonetheless, the 70:30 mixture represents a more realistic scenario when taking into consideration the sustainable use of compost as a limited resource in space farming, while still accepting a slight significant decline in yield and quality in comparison to the 30:70 mixture. Full article