Lettuce Types Research Articles

Tocopherols, Phylloquinone, Ascorbic Acid, and Sugar Contents in Hydroponically Grown Lettuce

Growing vegetables in controlled environments (CEs), such as hydroponics, aquaponics, and vertical structures, is a rapidly expanding industry in Florida and the United States, especially in nearby urban areas. Although lettuce (Lactuca sativa) is still mostly produced in fields, growing in CEs proximal to urban areas has become increasingly popular because it may facilitate reduced transportation time and associated postharvest degradation. Lettuce is among the top-most consumed vegetables in the United States and could provide some of the nutrition missing in the US diet. This research was planned to understand the levels of some vitamins that are key for human health, including vitamin E (tocopherols), vitamin K1 (phylloquinone), and vitamin C (ascorbic acid), in lettuce grown in greenhouse hydroponics. Lettuce germplasm was grown using the hydroponic nutrient film technique system in three greenhouse experiments: at the beginning, middle, and end of the Florida, USA, growing season (from Aug 2020 to Mar 2021). Genetic variation for these vitamins were found among the germplasm tested in the four morphological types of lettuce, romaine, Boston, Latin, and leaf. In addition, a sugar analysis was conducted in this germplasm, of which fructose was the most abundant sugar. A significant genotype × environment (G × E) interaction was observed, indicating that the levels of these compounds, especially vitamins, was environment dependent. However, the presence of certain non-crossover G × E interactions indicates that selecting lettuce in a representative environment could result in new cultivars with higher vitamin content. This research marks the initial steps to improve lettuce for these vitamins, which can contribute to better health of US consumers, not for the highest amount of these compounds in lettuce but for the offset due to its high consumption.

First report of Choanephora rot on Lettuce (Lactuca sativa L.) caused by Choanephora cucurbitarum in Korea.

Lettuce (Lactuca sativa L.) is a vegetable belonging to the family Asteraceae, and one of the major leafy vegetables in Korea. Lettuce has long been consumed as a fresh vegetable. In 2020, 96,774 tons were produced in about 3,800 ha according to Statistics Korea, and various types of lettuce have been bred for year-round production in line with consumer needs (Jang 2007). In August 2020, symptoms of a disease on young leaves of green lettuce (cv. Cheongpungyeoreumchima) were observed in the commercial greenhouse, Jeongeup (35°37'17.5"N, 126°53'40.4"E), Korea. About 60% of plants in 500 m2 of the cultivation area were infected. The tips of infected leaves appeared water-soaked, with brown to black lesions and were covered with dark masses of sporangiophores. Two fungal isolates NC20860 and NC20861 were isolated from monosporous sporangiola in infected leaves. Two isolates produced fast-growing colonies on potato dextrose agar medium (PDA) with abundant white mycelium at the top and bright yellow pigmentation at the underside in only 2 days. Morphological characteristics of the two fungal isolates were investigated from 30 days after inoculation on PDA. Sporangiophores bearing sporangia were erect, non-septate, unbranched, hyaline, and straight. Sporangia were hyaline to brown, globose to subglobose, 28.4 to 33.6 µm diameter. Sporangiospores from sporangia were brown to dark brown, ellipsoid to ovoid, distinctly longitudinally striate, with hyaline appendages at each pole, 6.3 to 7.5 µm wide and 13.0 to 16.0 µm long. Sporangiophores bearing sporangiola were erect, unbranched, hyaline and sporangiola were fusiform, ellipsoid to broadly ellipsoid, 7.6 to 9.8 µm wide, 13.3 to 17.8 µm long. Based on the morphological and cultural characteristics, this fungus was identified as Choanephora cucurbitarum (Berk.&Ravenel) Thaxt (Kirk 1984). To identify the species of the two isolates, DNA was extracted by using the Maxwell® RSC PureFood GMO and Authentication Kit (Promega). The internal transcribed spacer (ITS) region of ribosomal DNA was amplified using nTaq-Tenuto polymerase chain reaction (PCR) kit and therein specified protocol (Enzynomics). The primers ITS1F and ITS4 were used for PCR and sequencing (Gardes 1991). The ITS sequences of the isolates NC20860 and NC20861 from Korea (NCBI GenBank accession no.MZ960299, MZ960300) and the sequences of C. cucurbitarum strains CBS 150.51 (MH856791.1), and KUS-F29113 (KU316934.1) were compared. The sequences of the isolates were identical to those of the reference strains of C. cucurbitarum CBS 150.51 (reference/isolates base pairs, 566/566) and KUS-F29113 (572/572) at the 100% of sequence similarity. Pathogenicity test was conducted using seedlings of 8-week-old green lettuce (cv. Cheongsimchima) by spraying spore suspension (2⨉104 spores/ml). The plants were covered with plastic bags and incubated at 25 ℃ and 70 to 90% RH with a 12-h photoperiod for 20 days. The symptoms were observed only on the inoculated plants within 20 days after inoculation. The inner leaves of the inoculated lettuces had water-soaked lesions. No symptoms were observed in controls. C. cucurbitarum was reisolated from inoculated lettuce, fulfilling Koch's postulates. This fungus has been reported as the causal pathogen of fruit and blossom rot in cucurbits and other plants (Akwaji 2014). However, to our knowledge, occurrence of this pathogen on lettuce has not been reported as yet. This disease is crucial for producers because infected leaves directly results in yield loss of lettuce. This is the first report of Choanephora rot on lettuce caused by C. cucurbitarum in Korea and worldwide.

Properties of Biochar from Coconut Waste and Application in Agriculture

Coconut plantation waste was in massive quantities affecting the environment in the community. Hence, the coconut plantation was charcoal full of carbon. The objective of this research was to study the properties of biochar from coconut plantation waste and the consequences of adopting biochar to mix with organic fertilizer on the growth and lettuce productivity by analyzing the physical and chemical properties of biochar from coconut plantation waste. The organic fertilizer mixed with the biochar on lettuce growth and productivity was investigated by three treatments no application of organic fertilizer (control), the application of organic fertilizer, and the application of organic fertilizer added with potassium humate. The result showed that the highest level of biochar from coconut shells had the total density, total porosity, water holding capacity, C/N ratio, and humidity at the highest level, equaling 0.58 gram/cubic centimeter, 56.50%, 54.25%, 67%, and 2.41%, respectively. The biochar from the coconut leaves had the highest air gap, pH, conductivity, organic carbon, phosphorus, calcium, and magnesium quantity, respectively (13.50%, 9.90, 2.34 dS/m, 58.94%, 0.12%, 1.25%, and 2.26%, respectively). The biochar from the fallen young coconut fruits had organic matter, cation exchange, nitrogen, and phosphorus quantity at the highest level: 72.37%, 36.19 cmol/kg, 0.57%, and 2.11%, respectively. The results of the organic fertilizer mixed with biochar and Potassium Humate added formula led to the growth and productivity in all 3 types of lettuce more than not applying organic fertilizers (p<0.05).

Quantification of total polyphenols, antioxidants, anthocyanins and secondary metabolites by UPLC VION IMS QTOF MS/MS analysis in green and red lettuce cultivars

Lettuce is an important leafy vegetable and an excellent source of phytochemicals in human diets. However, the metabolic levels in different green and red type lettuce varieties are not fully explored. Therefore, it is important to explore and identify the selected health promoting secondary metabolites in green and red type lettuce varieties with having different phenotypic characteristics. In this study, we explored the selected secondary metabolites, total polyphenol, antioxidants activities, total flavonoids and anthocyanin contents in 32 lettuce varieties of green and red color. The results showed that green and red type lettuce varieties showed a significant difference in lactupicrin, chlorogenic acid, caffeoylmalic acid, syringic acid and quercetin 3-D-galactoside. Selected metabolites showed a significant variation in green and red type lettuce varieties depends upon different color and phenotypic characteristics. Total flavonoids and anthocyanin contents were found more in red type lettuce varieties while the total polyphenols and total antioxidants were found significantly higher in green type lettuce varieties. Tentative identified 78 metabolites with online databases, the published literature and standards including phenolic acid, flavonoids and glycosylated flavonoids. The metabolomic profiling was present at significantly difference in green and red type lettuce varieties which suggested the significant variation between green and red type lettuce varieties to secondary metabolism. This study provides a selection of lettuce varieties for further studies on the basis of color and phenotypic characteristics for improving the nutritional value, quality and yield of lettuce.

GRF–GIF chimeric proteins enhance in vitro regeneration and Agrobacterium-mediated transformation efficiencies of lettuce (Lactuca spp.)

Key messageGRF–GIF chimeric proteins from multiple source species enhance in vitro regeneration in both wild and cultivated lettuce. In addition, they enhance regeneration in multiple types of lettuce including butterheads, romaines, and crispheads.The ability of plants to regenerate in vitro has been exploited for use in tissue culture systems for plant propagation, plant transformation, and genome editing. The success of in vitro regeneration is often genotype dependent and continues to be a bottleneck for Agrobacterium-mediated transformation and its deployment for improvement of some crop species. Manipulation of transcription factors that play key roles in plant development such as BABY BOOM, WUSCHEL, and GROWTH-REGULATING FACTORs (GRFs) has improved regeneration and transformation efficiencies in several plant species. Here, we compare the efficacy of GRF–GIF gene fusions from multiple species to boost regeneration efficiency and shooting frequency in four genotypes of wild and cultivated lettuce (Lactuca spp. L.). In addition, we show that GRF–GIFs with mutated miRNA 396 binding sites increase regeneration efficiency and shooting frequency when compared to controls. We also present a co-transformation strategy for increased transformation efficiency and recovery of transgenic plants harboring a gene of interest. This strategy will enhance the recovery of transgenic plants of other lettuce genotypes and likely other crops in the Compositae family.

Design and Development of a Low-Cost UGV 3D Phenotyping Platform with Integrated LiDAR and Electric Slide Rail.

Unmanned ground vehicles (UGV) have attracted much attention in crop phenotype monitoring due to their lightweight and flexibility. This paper describes a new UGV equipped with an electric slide rail and point cloud high-throughput acquisition and phenotype extraction system. The designed UGV is equipped with an autopilot system, a small electric slide rail, and Light Detection and Ranging (LiDAR) to achieve high-throughput, high-precision automatic crop point cloud acquisition and map building. The phenotype analysis system realized single plant segmentation and pipeline extraction of plant height and maximum crown width of the crop point cloud using the Random sampling consistency (RANSAC), Euclidean clustering, and k-means clustering algorithm. This phenotyping system was used to collect point cloud data and extract plant height and maximum crown width for 54 greenhouse-potted lettuce plants. The results showed that the correlation coefficient (R2) between the collected data and manual measurements were 0.97996 and 0.90975, respectively, while the root mean square error (RMSE) was 1.51 cm and 4.99 cm, respectively. At less than a tenth of the cost of the PlantEye F500, UGV achieves phenotypic data acquisition with less error and detects morphological trait differences between lettuce types. Thus, it could be suitable for actual 3D phenotypic measurements of greenhouse crops.

Limitações e proposta de metodologia para coleta de dados de perdas de hortaliças na produção primária

ABSTRACT Research discussed in this paper reports the difficulties related to on-farm data collection of leafy vegetables loss and proposes a method to estimate vegetable loss in an exploratory survey. Loss was estimated for rocket (Eruca sativa), coriander (Coriandrum sativum) and lettuce (Lactuca sativa) in two farms located in Federal District, Brazil. The best index to express loss due to unharvested plants was different whether the vegetable was marketed as plant units (lettuce) or bunches (rocket and coriander). The discard of rocket varied substantially between farms and between successive crops in the same farm. On Farm 1, it varied from 80.6% to 0.0% of the crop area and on Farm 2 from 42.4% to 72.4%. Loss of coriander on Farm 1 varied from 0.0% to 10.8% of the area, compared to 2.3% to 34.5% on Farm 2. The total loss for each lettuce type varied between and within farms. Considering individual surveys on both farms, the losses of lettuce varied from 1.6% to 84.8% of the plant population at harvest, depending on the lettuce type, crop and farm. Measuring losses of leafy vegetables at primary production proved to be quite challenging and time consuming. Two boundaries were particularly difficult to establish: marketable versus unmarketable produce and pre-harvest loss versus harvest loss. In view of the difficulties faced during the measurement of leafy vegetables loss at primary production, the methodology was changed in order to decrease the number of visits and the time of permanence in the farm necessary to accomplish a survey; be independent of data collection by the farmer and by the farm’ staff; reduce the costs of displacement to the farm.

基于随机森林算法的整株水培生菜缺素诊断

The phenotypic information of lettuce leaves can well reflect its health. In order to diagnose the nutrient deficiency types of hydroponic lettuce accurately, non-destructively and quickly in the mid-growth stage, a method for diagnosis of whole lettuce based on random forest algorithm (RF) was proposed. The images of lettuce under four different conditions, K-deficiency, Ca-deficiency, N-deficiency and Normal, were collected and segmented by Extra-green algorithm. Then, features of color, texture and shape were extracted. A RF classification model for the hydroponic lettuce nutrient deficiency diagnosis was constructed and compared with support vector machine (SVM) and back propagation neural network (BP). RF had the best classification effect among the three methods. The overall classification accuracy was 86.32%, Kappa coefficient was 0.82, and it can provide a basis for the prevention and remedies of lettuce deficiency and the scientific management of nutrient solutions.

Development of an evapotranspiration estimation method for lettuce via mobile phones using machine vision: Proof of concept

This study aims to elucidate the process of crop evapotranspiration (ETc) and develop models to estimate ETc as a crucial value to efficiently schedule irrigation. Accordingly, we propose a new idea for non-destructive online acquisition of ETc data via mobile phones. The greenhouse environmental data were collected by sensors and uploaded to a mobile phone for the Penman-Monteith (PM) calculations of reference crop evapotranspiration (ET0). The canopy coverage (PGC) was accurately extracted from mobile phone images using the super-green algorithm, and four machine learning algorithms (XGBoost, CatBoost, SVR, and RF) were used to construct an online computing model for crop coefficient (Kc), ETc=Kc*ET0 was used to dynamically monitor the change of water requirement of different types of lettuce. The results showed that the correlation coefficients for the four monitoring networks were in the range of 0.74–0.93, which could be used to estimate the Kc at different stages. The integrated models showed high accuracy and similar performance. Compared with that of the SVR model, the root mean square error (RMSE), mean absolute error (MAE), and mean square error (MSE) of the three algorithms were reduced. Regarding the generalisation and computational speed of the proposed approach, the estimation accuracy of the XGBoost model was improved by 17.31%, and the convergence speed was also increased by 12.57% relative to other models on different types of lettuce. The XGBoost model can be recommended as the Kc model for estimation. The daily mean values of leaf lettuce and head lettuce as measured in ETc were 2.38 mm d−1 and 6.22 mm d−1, respectively. The average errors were 3.48% and 6.36%, respectively. We further explored models of the mathematical relationship between Kc and the plant height (H), plant width (D), and normalised vegetation index (NDVI), to establish a new approach for reasonable and scientific irrigation management.

Natural variation and drought-induced differences in metabolite profiles of red oak-leaf and Romaine lettuce play a role in modulating the interaction with Salmonella enterica

Nutrients on produce surfaces are vital for successful enteric pathogen colonisation. In this study, we investigated natural variation in metabolite profiles of Romaine ‘Parris Island Cos’ and red oak-leaf lettuce ‘Mascara’ under regular and restricted watering conditions. We also investigated the impact of plant drought stress on the Salmonella – lettuce association. Salmonella Newport and Typhimurium were able to persist at higher levels on regularly watered Romaine than red oak-leaf lettuce. Drought treatment to lettuce impaired epiphytic Salmonella association, with S. Newport and Typhimurium being differentially affected. A higher log reduction of both serotypes was measured on drought-subjected red oak-leaf lettuce plants than controls, but S. Typhimurium was unaffected on water deficit-treated Romaine lettuce (p < 0.05). To assess Salmonella interaction with leaf surface metabolites, leaf washes collected from both cultivars were inoculated and found to be able to support S. Newport growth, with higher levels of Salmonella retrieved from Romaine washes (p < 0.05). The lag phase of S. Newport in washes from water restricted red oak-leaf lettuce was prolonged in relation to regularly-watered controls (p < 0.05). Untargeted plant metabolite profiling using electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) revealed natural variation between Romaine and red oak-leaf lettuce profiles for leaf tissue and leaf washes. Metabolite profile shifts were detected in both lettuce types in response to drought stress, but more unique peaks were detected in red oak-leaf than Romaine lettuce after drought treatment. Variation between the two cultivars was in part attributed to naturally higher levels of flavonoids and anthocyanins in red oak-leaf lettuce compared to Romaine. Moreover, red oak-leaf, but not Romaine lettuce, responded to drought by inducing the accumulation of proline, phenolics, flavonoids and anthocyanins. Drought stress, therefore, enhanced the functional food properties of red oak-leaf lettuce. Salmonella growth dynamics in lettuce leaf washes suggested that natural variation and drought-induced changes in metabolite profiles in lettuce could partly explain the differential susceptibility of various lettuce types to Salmonella, although the primary or secondary metabolites mediating this effect remain unknown. Regulated mild water stress should be investigated as an approach to lower Salmonella contamination risk in suitable lettuce cultivars, while simultaneously boosting the health beneficial quality of lettuce.

Prevalence of parasitic contamination of edible vegetables in Isfahan, Iran

Introduction: Today, the parasitic contamination of edible vegetables, which are usually consumed raw, is one of the important issues of human societies. Parasitic contamination has been repeatedly identified in previous studies on edible vegetables. Due to the changes in farmers’ behavior regarding the use of fertilizers for agricultural land fertility over recent years, some changes have certainly happened in the contamination level of these crops, which are investigated in this study. Objectives: The present study seeks to examine the changes in the infection of vegetables caused by the use of chemical fertilizers as an alternative to animal and human excretion for the fertilization of cultivatable soil. Materials and Methods: This study was conducted using the descriptive cross-sectional method in Isfahan, Iran. In this regard, 70 samples from 10 types of edible vegetables, including leek, basil, mint, spring onion, radish, parsley, lettuce, cress, tarragon, and coriander, were prepared from 70 vegetable shops of the city. Each sample was placed in a separate bag and evaluated after washing, centrifugation, sedimentation, and staining. Eventually, the results were reported as descriptive statistics. Results: None of the prepared samples were contaminated with the pathogen parasite in the present study. Conclusion: Due to the change in farmers’ behavior concerning fertilization of agricultural products, it seems that the parasitic contamination of these products has lowered, and it is necessary to focus on other contaminants of these products, such as chemicals.

Yield evaluation of lettuce grown in three modified NFT systems in pandemic times

Due to the pandemic caused by COVID-19 worldwide, it is necessary to rethink the way of producing vegetables taking advantage of free spaces at homes, since a large majority of the world's population has lost their jobs, and they need to generate income for their families. One way to grow plants at homes is through hydroponics or soilless culture. For this purpose, a trial was carried out to evaluate the growth and yield of a variety of crisp type lettuce in a modified NFT system. Three modified NFT systems were evaluated: 1) horizontal with eight growing channels, 2) pyramidal with 10 channels, and 3) pyramidal with 13 channels. Significant differences were found in the number of leaves, root length, dry and fresh weight of the plant and yield in kg/m2 and kg/NFT system. The highest fresh plant weight and yield were achieved in plants grown with the pyramidal NFT system with 10 growing channels. SPAD units and photosynthetic photon flux density were evaluated, but no significant differences were found. The yield (fresh weight, kg/m2, kg/system) and the utility achieved with the modified NFT system of ten growing channels were higher.

Phytochemicals, Nutrition, Metabolism, Bioavailability, and Health Benefits in Lettuce-A Comprehensive Review.

Lettuce is one of the most famous leafy vegetables worldwide with lots of applications from food to other specific uses. There are different types in the lettuce group for consumers to choose from. Additionally, lettuce is an excellent source of bioactive compounds such as polyphenols, carotenoids, and chlorophyll with related health benefits. At the same time, nutrient composition and antioxidant compounds are different between lettuce varieties, especially for green and red lettuce types. The benefit of lettuce consumption depends on its composition, particularly antioxidants, which can function as nutrients. The health benefits rely on their biochemical effect when reaching the bloodstream. Some components can be released from the food matrix and altered in the digestive system. Indeed, the bioaccessibility of lettuce is measuring the quantity of these compounds released from the food matrix during digestion, which is important for health-promoting features. Extraction of bioactive compounds is one of the new trends observed in lettuce and is necessarily used for several application fields. Therefore, this review aims to demonstrate the nutritional value of lettuce and its pharmacological properties. Due to their bioaccessibility and bioavailability, the consumer will be able to comprehensively understand choosing a healthier lettuce diet. The common utilization pattern of lettuce extracted nutrients will also be summarized for further direction.

Deep Learning Models to Determine Nutrient Concentration in Hydroponically Grown Lettuce Cultivars (Lactuca sativa L.)

Deep learning (DL) and computer vision applications in precision agriculture have great potential to identify and classify plant and vegetation species. This study presents the applicability of DL modeling with computer vision techniques to analyze the nutrient levels of hydroponically grown four lettuce cultivars (Lactuca sativa L.), namely Black Seed, Flandria, Rex, and Tacitus. Four different nutrient concentrations (0, 50, 200, 300 ppm nitrogen solutions) were prepared and utilized to grow these lettuce cultivars in the greenhouse. RGB images of lettuce leaves were captured. The results showed that the developed DL’s visual geometry group 16 (VGG16) and VGG19 architectures identified the nutrient levels of lettuces with 87.5 to 100% accuracy for four lettuce cultivars, respectively. Convolution neural network models were also implemented to identify the nutrient levels of the studied lettuces for comparison purposes. The developed modeling techniques can be applied not only to collect real-time nutrient data from other lettuce type cultivars grown in greenhouses but also in fields. Moreover, these modeling approaches can be applied for remote sensing purposes to various lettuce crops. To the best knowledge of the authors, this is a novel study applying the DL technique to determine the nutrient concentrations in lettuce cultivars.

The Breeding of Turkey Originated Yedikule Type Lettuce (Lactuca sativa L. var. longifolia) Genotypes with Pureline Selection

Marul, Compositae familyasının Lactuca cinsine bağlı tek yıllık bir sebze türüdür. Marulun anavatanı; Anadolu, Kafkasya, İran ve Türkistan olarak kabul edilmektedir. Ülkemiz, bitki genetik kaynakları ve genetik çeşitlilik açısından dünyanın eşsiz ve en önemli ülkelerinden birisidir. Yerel genetik kaynaklar, ıslah programlarının başarıya ulaşmasında en önemli faktörlerden birisi olan fenotipik varyasyonun temelini oluşturur. Bu çalışma 2020-2021 yılları arasında, Türkiye orijinli Yedikule tipi 28 marul genotipinin teksel seleksiyon ıslahı yöntemiyle değerlendirilmesi ve çeşit adayı olabilecek ümit var marul genotiplerinin belirlenmesi amacıyla yürütülmüştür. Ayrıca, marul genotiplerinde kendileme çalışmaları da yapılmıştır. Seleksiyonda; ilkbahar ve sonbahar yetiştirme dönemlerine uygun, sapa kalkmayan, orta irilikte, erkenci marul genotiplerinin belirlenmesi hedeflenmiştir. Bu amaçla, seleksiyon kriterleri tarafımızdan geliştirilmiş ve tartılı derecelendirme yöntemine göre değerlendirme yapılmıştır. Tartılı derecelendirme yöntemine göre Yedikule tipi marul genotipleri ilkbahar yetiştirme döneminde 254-484 arasında puan ve sonbahar yetiştirme döneminde ise 16-480 arasında puan almışlardır. Sonbahar döneminde bazı marul genotiplerinde erken sapa kalkma (bolting) durumu gerçekleşmiştir. Her iki dönem de seleksiyon kriterleri yönünden öne çıkan 6 genotip (YM-1, YM-5, YM-13, YM-14, YM-16 ve YM-19) ümit var marul genotipleri olarak seçilmiştir. Araştırma sonucunda öne çıkan marul genotiplerinin gelecekte çeşit ıslah çalışmalarında değerlendirilerek ticari üretime kazandırılması planlanmaktadır.

Bioactive compounds in lettuce: Highlighting the benefits to human health and impacts of preharvest and postharvest practices.

Lettuce is one of the most commonly consumed leafy vegetables worldwide and is available throughout the entire year. Lettuce is also a significant source of natural phytochemicals. These compounds, including glycosylated flavonoids, phenolic acids, carotenoids, the vitamin B groups, ascorbic acid, tocopherols, and sesquiterpene lactones, are essential nutritional bioactive compounds. This review aims to provide a comprehensive understanding of the composition of health-promoting compounds in different types of lettuce, the potential health benefits of lettuce in reducing the risks of chronic diseases, and the effect of preharvest and postharvest practices on the biosynthesis and accumulation of health-promoting compounds in lettuce.

Performance of Lettuce (Lactuca Sativa L.) Genotypes with Respect to Morphological, Yield and Quality Traits at Two Localities of Nepal

Lettuce is cultivated as minor crop in Nepal. However, people are becoming more health conscious in these days and demand for salad is increasing in food. The demand of lettuce is also gradually increasing but relatively few farmers are involved in this crop due to the lack of high-yielding and good quality genotypes. The research was conducted at two locations of Nepal; Kavre and Kaski with the aim of evaluating the performance of seven different hybrid lettuce genotypes in terms of its morphology, yield, and quality. The research was laid out on Randomized Complete Block Design with three replications at each location. Two types of lettuce were used on the research i.e. head type and leaf type. Among the head type, genotype Iceberg performed better with more plant spread (51 cm), head diameter (14.7 cm) and yield (738.4 g at Kavre and 725.8 g at Kaski) than other head type lettuce genotypes and among leaf type variety Green Oak was recorded with highest numbers of leaves (67 at Kavre and 40 at Kaski) and yield (572.3 g at Kavre and 641.9 g at Kaski). So, among head type lettuce genotypes Iceberg performed better as this had better plant spread, large head diameter, more yield and sweet flavor. Among leaf type genotypes Variety Green Oak was found most suitable for Nepali Market as this variety had highest number of leaves and yield among leaf type lettuce genotypes.

Nutrient Solution Temperature Affects Growth and °Brix Parameters of Seventeen Lettuce Cultivars Grown in an NFT Hydroponic System

Nutrient solution temperature in a hydroponic system affects °Brix and yield of lettuce; thus, it is important to maintain the water temperature within an appropriate range. Nutrient-film technique (NFT) trials were conducted to investigate the effects of different water temperatures (18.3 °C, 21.1 °C, and ambient) on growth and °Brix of 17 cultivars from five different types (Loose leaf, Romaine, Butterhead, Salanova, and Batavian) of lettuce. The average daily water temperature for ambient treatment was recorded to be 20 to 26.5 °C. The study was conducted in a split-plot design with three replications over time. Results indicated that water temperature affected root and shoot fresh and dry weight, plant width, and °Brix for lettuce. Lettuce grown at 21.1 °C were 15% greater for shoot fresh weight than plants grown at ambient conditions. All the growth and quality parameters of lettuce were found to be affected by cultivars, with “Coastal Star” showing the best results in both growth and °Brix parameters. All the cultivars of the Romaine type showed greater growth and °Brix, while Salanova lettuce did not perform well in all treatments compared to other lettuce types. For CO2 assimilation, the interaction between water temperature and cultivars was significant, with “Parris Island” having the greatest rate at ambient water temperature. These results suggested that maintaining water temperature at 21.1 °C produced lettuce with greater growth and biomass but had 26% lower °Brix than lettuce grown at 18.3 °C.

Effect of Light Emitting Diode (LED) Spectrum at Seedlings Production for Optimal Growth on Different Type of Lettuce in MARDI Plant Factory

Seedling production is a crucial part of the production of fresh vegetables in a plant factory. Light is one of the necessities for plants to produce a healthy seedling before being transplanted to the production area. Different light formulations resulted in different growth performances of the plant. Hence, this study was conducted to aim for suitable light formulation on various types of lettuce in the MARDI Plant Factory. The study was conducted in two stages: 1) seedling production and 2) production area. Treatments were evaluated at the seedlings' production stage using the split-plot experimental design with four replications. LED light treatments (LT) was the main factor with the various ratio of spectrum colour of Red (R), Blue (B), Green (G) and full spectrum. (LT 1; 5R:1B, LT 2; 1R:1B, LT 3; 1R: 2B, LT 4; 2R:1B, LT 5; 4R:1B:1G and LT 6; Full spectrum as control). The sub-factor was lettuce variety (V1; Butterhead, V2; Green Coral, V3; Red Coral and V4; Mini Cos). Variables measured at seedlings production were seed germination. Growth biomass and SPAD value were evaluated in the production area. At seedlings production, the full spectrum lighting shows significant seeds germination percentage compared to other LED lighting, and V1 performed well on germination percentage and time compare to other varieties. The interaction between light treatments and lettuce was observed on the leaf numbers, shoot fresh weight, leaf area, and the shoot-root ratio at the production area. LT 1 and LT 5 on butterhead and green coral significantly affected the number of leaves and leaf area, which were relatively influenced by light quality and ambient temperature. The yield on green coral lettuce grown under LT 1, LT 2, and LT 5 was significantly higher than others. However, plant biomass and SPAD value for all treatments were not significantly different. The allometry of plant was expressed on a shoot-root ratio with LT 2 on green coral shows a significantly higher shoot-root ratio than other treatments. The study's findings showed that light treatment with Red and Blue LED ratio of 5:1, 1:1, and Red, Blue, and Green LED ratio of 4:1:1 light arrangement on the seedling's productions provided optimal growing conditions in the production area butterhead and green coral lettuce in MPF cultivation.

English

Lettuce has a predisposition to nitrate accumulation and has led many researchers to develop research to reduce this accumulation. The objective of this study was to evaluate the effect of nitrate concentration (NO3-) and nitrate/ammonium ratio (NO3-:NH4+) on growth, production and accumulation of these nitrogen compounds in lettuce grown in a hydroponic system in southern Amazon. There were performed two experiments with Iceberg lettuce type, in a floating-hydroponic system under protected cultivation. In the first experiment, five nitrate concentrations (2.5, 5.0, 7.5, 10.0 and 15.0 mmol L-1) were evaluated. In the second experiment, the best NO3- : NH4+ ratio was evaluated with five proportions 0:100, 25:75, 50:50, 75:25 and 100:0 in the nutrient solution. At 35 days after transplanting, the evaluations were performed. The nutrient solution containing nitrogen (N) as nitrate source in the concentration of 15.0 mmol L-1 contributed to higher lettuce productivity, being the concentration recommended for hydroponic grown system in southern Amazon. It is recommended to use about 23% of the N in nutrient solution in ammonium form, where higher N-ammonium concentrations are not indicated for Icebeg lettuce type because it reduces the productivity of this green leaf vegetable, causing toxicity symptoms. Key words: Nitrogen, vegetable, nutrient solution, food security.