Carrot Seedlings Research Articles

Local mapping of root orientation traits by X-ray micro-CT and 3d image analysis: A study case on carrot seedlings grown in simulated vs real weightlessness.

Root phenotyping is particularly challenging because of complexity and inaccessibility of root apparatus. Orientation is one of the most important architectural traits of roots and its characterization is generally addressed using multiple approaches often based on overall measurements which are difficult to correlate to plant specific physiological aspects and its genetic features. Hence, a 3D image analysis approach, based on the recent method of Straumit, is proposed in this study to obtain a local mapping of root angles. Proposed method was applied here on radicles of carrot seedlings grown in real weightlessness on the International Space Station (ISS) and on Earth simulated weightlessness by clinorotation. A reference experiment in 1g static condition on Earth was also performed. Radicles were imaged by X-ray micro-CT and two novel root orientation traits were defined: the "root angle to sowing plane" (RASP) providing accurate angle distributions for each analysed radicle and the "root orientation changes" (ROC) number. The parameters of the RASP distributions and the ROC values did not exhibit any significant difference in orientation between radicles grown under clinorotation and on the ISS. Only a slight thickening in root corners was found in simulated vs real weightlessness. Such results showed that a simple uniaxial clinostat can be an affordable analog in experimental studies reckoning on weightless radicles growth. The proposed local orientation mapping approach can be extended also to different root systems providing a contribution in the challenging task of phenotyping complex and important plant structures such as roots.

Callus and suspension culture techniques optimized for use in carrot breeding studies (Daucus carota ssp. sativus var. atrorubens Alef and D. carota)

In this study, studies were conducted to optimize callus and suspension culture methods for in vitro mutation breeding in purple and orange carrots. Following this, the developed mutant lines were subjected to in vitro salt stress selection. The study determined the optimal agar dose. The first germination, 50% germination, root-cotyledon formation and genuine leaf formation in carrot seedlings were analyzed daily in the study, which was continued with the determined 7g/L agar dose. The cotyledon and hypocotyl explants from the seedlings were cultivated for callus production in mixtures of MS-1, MS-2 and MS-3 nutritional medium. In the second and fourth weeks following the second subculture, callus production percentages and weights were measured. The MS-3 (1 mg/L 2,4-D + 0.5 mg/L kinetin) nutritional medium and hypocotyl explant were found to be particularly effective at producing callus. The second subculture's data on the number of plants that had successfully regenerated per callus, showed that the MS nutritional medium with 0.2 mg/L Thidiazuron (TDZ) was the best medium for plant regeneration. The dispersed calli were grown in a nutritional medium designed for suspension culture in a nutrient medium mixture comprising MS+0.1 mg/L kinetin. The results obtained with the optimization steps were used in the ongoing study.

Back to the 'roots' of research: a hypothesis-driven approach provides predictive understanding of plant-herbivore-microbe interactions.

This article is a Commentary on Böttner et al. (2023), 239: 1475–1489.

A preliminary study on emergence and growth of carrot seedlings in response to varying proportions of vermicompost and copper

Vermicompost is a nutrient-rich amendment commonly used to restore soil health such as restoration of trace element contamination of growing media. A pot study was carried out to determine vermin compost and copper (Cu) interaction on little finger carrot (Daucus carota cv. Nantes) seedlings emergence and plant growth. The treatments were varying rates of Cu (i.e., 0, 100, 200 and 300 mg Cu l-1) and vermicompost (i.e., 0, 25, 50 and 75% w/w).At two weeks after sowing, the emergence rate of carrot seedlings in pots with no vermicompost (i.e., control) were 0.22, 0.25, and 0.32 folds higher than those that received the 25%, 50% and 75% vermicompost, respectively. Vermicompost, Cu and their interaction had significant (p<0.05) effects on leaf chlorophyll and anthocyanin contents. The 50% vermicompost combined with the 100 mg Cu l-1 resulted in greater leaf greenness and anthocyanin content. Plant height and number of leaves were significantly (p<0.05)increased by 0.07 and 0.16 folds following the application of the 25% and 50% vermin compost respectively, compared to the control. The 50% vermicompost had a strongly positive impact on the carrot shoot compared to the root. This preliminary study on little finger carrot cv. Nantes seedlings will require further detailed studies to explain vermicompost mitigation of Cu stress on carrot plants and productivity.

Mitigação do estresse térmico na germinação e desenvolvimento inicial de plântulas de cenoura por meio de reguladores de crescimento vegetal

ABSTRACT The adoption of technologies that allow the mitigation of environmental stresses, such as the use of regulators in seed treatment, is an alternative for crops in high temperatures regions. This study aimed to assess the heat stress mitigation on the germination and initial development of carrot seedlings using plant growth regulators. The study was divided into three experiments performed at the temperatures of 25, 30 and 35 °C. A 5 × 3 factorial arrangement was used, with fve carrot cultivars (Alvorada, Brasília, BRS Esplanada, Tellus and Tropical) and two products (Stimulate® and thiamethoxam), in addition to the control (untreated seeds). The following variables were evaluated: germination, first germination count, seedling length and dry mass. When the cultivars had their seeds treated with the plant growth regulators at 25 °C, the germination for the Tellus cultivar was 28 % higher than for the control, while, at 30 °C, the seed germination for BRS Esplanada and Tellus was twice as high as for the control, and showed a higher vigor than that of Alvorada, Brasília and Tropical. Overall, the thiamethoxam promoted increments at the initial development of carrot seedlings at 25 and 30 °C. However, the germination of the carrot cultivars was disrupted at 35 °C.

Effect of Plant Age, Temperature, and Vector Load on 'Candidatus Liberibacter solanacearum' in Planta Titer and Shoot Proliferation Symptoms in Carrot.

A decade ago, shoot proliferation symptoms (i.e., witches' broom) in carrots were believed to be the cause of 'Candidatus Phytoplasma' and Spiroplasma infection, yet in recent years this association appeared to have weakened, and a closer association was found with the yet-unculturable, psyllid-transmitted Gram-negative bacterium 'Candidatus Liberibacter solanacearum'. In Israel, carrots are grown throughout the year, yet shoot proliferation symptoms tend to appear only in mature plants and mostly in late spring to early summer. We hypothesized that factors such as plant age, temperature, and vector load, which vary during the year, have a critical effect on symptom development and examined these factors under controlled conditions. Here we show that young carrot seedlings are as prone as older plants to develop shoot proliferation symptoms after 'Ca. L. solanacearum' inoculation. Surprisingly, we found that the local 'Ca. L. solanacearum' haplotype was extremely sensitive to constant temperature of 30°C, which led to a significant reduction in bacterial growth and symptom development compared with 18°C, which was very conducive to symptom development. We have also found that inoculations with 10 or 20 psyllids per plant results in faster symptom development compared with inoculations with two psyllids per plant; however, the difference between vector loads in disease progress rate was not significant. These data provide important insights to the effects of plant age, growth temperature, and vector load on 'Ca. L. solanacearum' and its associated symptoms and further strengthen the notion that 'Ca. L. solanacearum' is the main responsible agent for carrot witches' broom in Israel.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Stimulated saprotrophic fungi in arable soil extend their activity to the rhizosphere and root microbiomes of crop seedlings.

SummarySaprotrophic fungi play an important role in ecosystem functioning and plant performance, but their abundance in intensively managed arable soils is low. Saprotrophic fungal biomass in arable soils can be enhanced with amendments of cellulose‐rich materials. Here, we examined if sawdust‐stimulated saprotrophic fungi extend their activity to the rhizosphere of crop seedlings and influence the composition and activity of other rhizosphere and root inhabitants. After growing carrot seedlings in sawdust‐amended arable soil, we determined fungal and bacterial biomass and community structure in roots, rhizosphere and soil. Utilization of root exudates was assessed by stable isotope probing (SIP) following 13CO2‐pulse‐labelling of seedlings. This was combined with analysis of lipid fatty acids (PLFA/NLFA‐SIP) and nucleic acids (DNA‐SIP). Sawdust‐stimulated Sordariomycetes colonized the seedling's rhizosphere and roots and actively consumed root exudates. This did not reduce the abundance and activity of bacteria, yet higher proportions of α‐Proteobacteria and Bacteroidia were seen. Biomass and activity of mycorrhizal fungi increased with sawdust amendments, whereas exudate consumption and root colonization by functional groups containing plant pathogens did not change. Sawdust amendment of arable soil enhanced abundance and exudate‐consuming activity of saprotrophic fungi in the rhizosphere of crop seedlings and promoted potential beneficial microbial groups in root‐associated microbiomes.

Role of Chitosan in Disease Suppression, Growth and Yield of Carrot

An attempt was made for controlling of Rhizoctonia canker caused by Rhizoctonia solani and southern blight caused by Sclerotium rolfsii in pot and field experiments under inoculated condition and also to increase the growth promoting factors and yield of carrot through the application of chitosan. Before setting the experiments in the field, laboratory experiments were carried out to select virulent isolates of R. solani and S. rolfsii and effective dose of chitosan on mycelial growth inhibition of virulent isolates of test pathogens. In the pathogenicity test, R. solani isolate R-1 and S. rolfsii isolate S-1 were found to be the most virulent against carrot seedlings. In vitro application of 1.0% chitosan was found to inhibit 100% mycelial growth of both tested pathogens. The field experiment was laid out following randomized complete block design with four treatments, where no treatment was done in T1, pathogen was inoculated in T2 and seed treatment and soil amendment with 1.0% chitosan was done in T3 and T4, respectively, in pathogen inoculated condition. Application of 1.0% chitosan as seed treatment or soil amendment significantly reduced post-emergence seedling mortality, incidence of diseases and enhanced seedling growth and also yields of carrot. On the contrary, post-emergence seedling mortality, incidence of Rhizoctonia canker and southern blight of carrot were highest in treatment T2 where soil was inoculated with pathogens. Chitosan could be used as an alternative of fungicide to suppress Rhizoctonia canker and southern blight in sustainable agriculture and improvement the yield of carrot.

Weed Detection in Images of Carrot Fields Based on Improved YOLO v4

The accurate weed detection is the premise for precision prevention and control of weeds in fields. Machine vision offers an effective means to detect weeds accurately. For precision detection of various weeds in carrot fields, this paper improves You Only Look Once v4 (YOLO v4) into a lightweight weed detection model called YOLO v4-weeds for the weeds among carrot seedlings. Specifically, the backbone network of the original YOLOv4 was replaced with MobileNetV3-Small. Combined with depth-wise separable convolution and inverted residual structure, a lightweight attention mechanism was introduced to reduce the memory required to process images, making the detection model more efficient. The research results provide a reference for the weed detection, robot weeding, and selective spraying.

COVER CROPS AND SOIL-BORNE FUNGI DANGEROUS TOWARDS THE CULTIVATION OF Daucus carota L.

The principles of good agricultural and horticultural practice, which considers both environmental protection and high yielding of plants, require modern methods of cultivation. Cover crops are used in the cultivation of various plants, including root vegetables such as carrot. The purpose of field and laboratory studies was to determine the effect of selected cover crops on the healthiness of carrot (Daucus carota L.). The field experiment took into consideration cover crops such as spring rye, white mustard, buckwheat, fodder sunflower and two systems of soil tillage, i.e.: tillage before winter (ploughing) + spring tillage (a combined cultivator) and only spring tillage (a combined cultivator). In each experimental treatment, the number and healthiness of carrot seedlings were determined. A laboratory mycological analysis made it possible to determine the qualitative and quantitative composition of fungi infecting the underground parts of carrot. Good emergencies and the healthiness of carrot plants were observed in the objects with rye and white mustard as cover crops. The cultivation system had no significant effect on the proportion of diseased seedlings of carrot. Rye and white mustard were more effective than buckwheat and sunflower in limiting the occurrence of fungi pathogenic towards carrot. Diseased seedlings and roots after harvest of carrot were most frequently colonized by Altenaria alternata, A. chartarum, A. dauci, A. radicina, Sclerotinia sclerotiorum, Rhizoctonia solani and Fusarium spp.

Vigor de sementes de cenoura recobertas com bioestimulante de Solieria filiformis

To guarantee seeds with high physiological quality performing in a uniform, resilient and tolerant to abiotic stress plant stand, procedures that can improve the potential of the processed seed. Biostimulants are considered promising alternatives, both to improve the physiological performance of plants and in resilience and stress tolerance. The objective of this study was to verify the effect of coatingseeds of different cultivars of carrots with biostimulant based on algae Solieria filiformison seed germination and seedling development under thermal stress. The experiment was conducted in a completely randomized design, with a 3 x 4 factorial scheme (temperaturesand doses), with five replications. Carrot seeds from the cultivars Brasília, Danvers, Esplanada and Planalto were used, and the seeds were coated with doses of 0, 2, 4 and 8 mL.L-1 of biostimulant. After covering, the seeds were submitted to the following: percentage and speed of germination, length of seedlings and dry mass of seedlings. The results obtainedwere found in the analysis of variation and in the analysis of regression (doses) and Tukey's test (moderate). The analysis and interpretation of the results obtained in the present study allowed to conclude the high thermal stress, for all varieties, at a temperature of 35 ° C, to reduce the reduction of the analyzed variables. Furthermore, the covering of carrot seeds with the biostimulant of Solieria filiformis, in general, does not promote improvements in seed germination and in the development of carrot seedlings under thermal stress (35 °C); however, we present beneficial results for the variables analyzed at 20 and 30 ° C.

Vegetable Crops Prefer Different Ratios of Ammonium-N and Nitrate-N in the Growth Media

Understanding the preference of a crop for forms of nitrogen (N) is important to ensure efficient use of N-sources in agriculture. A study was conducted to assess nutrient uptake and dry matter yield of six vegetable crops under different ratios of ammonium- N (NH4+-N) and nitrate-N (NO3–-N) in growth medium. Seedlings of cabbage, carrot, capsicum, knolkhol, lettuce, and tomato, were supplied with five N-treatments (NH4+-N: NO3–-N in the ratios of 0:100, 25:75, 50:50, 75:25 and 100:0) under controlled environment in sand culture. Six weeks after initiating treatments plants were harvested and dry matter recorded. Plants were analysed for total N, P and K contents. Dry-matter yield, N and K concentrations in shoot-tissues in response to Ntreatments were significantly different (p 0.05) by N-treatment. Supplying NH4+-N alone significantly reduced K concentration in shoot tissues in knolkhol, capsicum and tomato. This study revealed that performance of vegetable crops is affected by the NH4+-N: NO3–-N in the growth medium. This knowledge can be utilized to optimize fertilizer-N usage in vegetable cultivation.

Cladophora glomerata Extract and Static Magnetic Field Influences the Germination of Seeds and Multielemental Composition of Carrot

Abstract As carrot seeds are notoriously slow to germinate and are often irregular in breaking dormancy, new methods of stimulation are still sought. This study examines for the first time the effect of an algal extract and static magnetic field (SMF) and their synergistic effect on carrot seeds germination. The algal extract, produced from freshwater macroalgae - Cladophora glomerata, was used directly to the paper substrate at a dose of 20, 40, 60, 80 and 100 %. The exposure of seeds to the magnetic field (500 mT and 1 T) was applied for 3, 6 and 12 min. The highest germination ability of carrot seedlings was observed for 20 and 80 % algal extract. The weakest germination was observed for the highest concentration of algal extract causing the highest amount of abnormal and dead seedlings. Parallel use of seeds stimulated with magnetic field and algal extract did not increase the number of germinated seeds significantly. Carrot’s seeds treated with algal extract showed increased content of elements - macro- Ca, K, Mg, S and microelements Cu, Fe, Mn and Zn. Future experiments are required to confirm the stimulation effect of algal extract (optimal concentration) and magnetic field (various induction values) on seeds germination.

Biostimulants in vegetable seeds submitted to germination and vigor tests

The use of bioproducts, economically viable, are of extreme importance in the protection and stimulation of germination in vegetable crops. This work evaluated the effect of the microorganisms Azospirillum brasiliense, Bacillus sub-tilis, Trichoderma harzianum and the commercial seed treatment product (Fipronil + Pilaclostrobin and Methyl Thiophanate) on seeds and seedlings of lettuce (Lactuca sativa), carrot (Daucus carota) and tomato (Solanum lycopersicum). The seeds were inoculated before being submitted to the germination test. The chemical treatment proved ineffective in protecting the seed of all crops and stimulating germination. T. harzianum increased the germination index of lettuce seeds, had better values in root system size in tomato crop and stimulated radicle emission in carrot. B. subtilis stood out in dry matter accumulation in tomato crop. The microorganisms B. subtilis and T. harzianum present potential for vegetable seed treatment.

SOIL-BORNE MICROORGANISMS THREATENING CARROT CULTIVATED WITH THE USE OF COVER CROPS

Cover crops are used in the cultivation of various plants. They properly modify the composition of soil microorganisms and can protect of plants from phytopathogens. The purpose of the field and laboratory studies was to determine the quantitative and qualitative composition of microorganisms in the soil under carrot cultivated with the use of oats, tansy phacelia and spring vetch as cover crops. The paper presents also studies on soil-borne fungi threatening the healthiness of carrot roots. In the conventional cultivation of carrot the population of bacteria (including Pseudomonas spp. and Bacillus spp.) was the smallest, while after the application of oats it was the largest. Oats and spring vetch were most effective in limiting the occurrence of soil-borne fungi. Those plants and tansy phacelia caused an increase of the population of saprotrophic fungi (Albifimbria spp., Clonostachys spp. and Trichoderma spp.) in the soil. Intercrop plants had a positive effect on the healthiness of carrot seedlings and roots. Alternaria dauci, A. alternata, A. radicina, Fusarium oxysporum, Globisporangium irregulare, Neocosmospora solani, Phytophthora sp., Rhizoctonia solani and Sclerotinia sclerotiorum proved to be the most harmful towards the studied underground parts of carrot. Oats proved to be the most effective in inhibiting the occurrence of the pathogenic fungi for Daucus carota L.

Phytoplasma presence in carrot seedlings

Phytoplasmas are cell wall lacking bacteria, insect transmitted, and worldwide infecting carrots with severe epidemics. Molecular tests on up to 4-month-old carrot seedlings from phytoplasma-positive seed batches, carried out under insect proof conditions, indicated that in the early stages of the plant development, the phytoplasma-infected and not water-stressed plants are asymptomatic. The phytoplasma seed transmission could represent a dangerous source of infection.

Horta and composting project: solid waste treatment in public school in Urutaí

The cultivation of vegetables in school gardens with the participation of students contributes to food education, especially when the products are used in school meals. The objective of this work was to make the students aware of the importance of reducing, reusing and recycling the waste generated in the day to day, through composting and the use of the compost in the garden made in the school. This work was conducted at the Maria Cândida de Jesus Municipal School, in Urutaí, GO, with the target audience being the elementary school students and servers of this school. The project was based on a theme lecture (environmental question), proposing the recycling of organic waste generated at school, the practice of composting and its use in the school garden, demonstrating the importance of vegetables in food, botanical aspects and their main forms of cultivation. Then the compost was built with the objective of recycling the school's organic waste, so the compost with Californian worms was prepared so that students and servers could monitor the process weekly. The compost was used to fertilize the vegetables 120 days after the beginning of composting. For the construction of the garden in the school were prepared three raised beds with composted bovine manure. The seedlings of parsley, chives, cabbage, carrot, jiló, okra, zucchini and sweet potatoes were made in trays of expanded polystyrene with standard substrate. The results demonstrated the enthusiasm of the students in the participation of the proposed activities, through the selective collection of the residues, as well as the monitoring of the composting used in the garden and the implementation of the vegetable garden.

Simulated Storage Germination and Growth Responses in Carrot Seedlings Grown from Artificially-Aged Seeds

Simulated Storage Germination and Growth Responses in Carrot Seedlings Grown from Artificially-Aged Seeds

Biological control of the root-knot nematode Meloidogyne incognita on tomatoes and carrots by plant growth-promoting rhizobacteria

In the current study 27 plant growth-promoting rhizobacteria (PGPR) strains were screened for biocontrol activity against Meloidogyne incognita on 6-week old carrot seedlings that were inoculated with a suspension of J2 juveniles five days after treatment with the bacteria. Five of the PGPR strains, namely Bacillus firmus T11, Bacillus aryabhattai A08, Paenibacillus barcinonensis A10, Paenibacillus alvei T30, and Bacillus cereus N10w, caused 86.0, 85.2, 84.6, 81.5 and 82.1% reduction in gall numbers, respectively. In a subsequent greenhouse experiment on carrots, treatment with strain T30 caused a significant reduction in gall index and egg mass index compared to the control. The reduction in gall numbers caused by strain T30 was not statistically different from that obtained with CropGuard (furfural). Treatment with B. aryabhattai A08 gave the best results on tomato, significantly reducing gall index and egg mass index compared to the control. In vitro experiments with all five abovementioned strains resulted in second-stage juvenile (J2) paralyses. Induction of resistance was not observed in a split-root experiment conducted in the greenhouse, suggesting that secondary metabolites produced by the bacterial strains are responsible for the biocontrol activity. It is concluded that the bacterial strains P. alvei T30 and B. aryabhattai A08 have potential as biological control agents of M. incognita on carrots and tomatoes respectively.

Pigeon bean allelopathy on the germination and development of carrot seedlings

Carrot is an edible tuberous root with high economic value in Brazil. Carrot seeds may present uneven germination due to the presence of inhibitors in the epithelium. The presence of cover crops in the growing area may generate allelopathic compounds, with the potential to inhibit or stimulate germination of cultivated species. The work objective was verifying effect of pigeon bean extract levels on germination and development of carrot seedlings. The research was conducted in a completely randomized design, in a 3x5 factorial scheme (cultivars,Danvers, Flakker Giant and Nantes Milena and extract concentrations, 0, 25, 50, 75 and 100%). Were evaluate germination (first germination count, speed and final percentage), seedling root length and seedling dry mass. The data obtained were submitted to variance and regression analysis.