Cell Trays Research Articles

Micropropagation of Robinia pseudoacacia L. Genotypes, Selected for Late Flowering Characteristics

Robinia pseudoacacia L., commonly known as black locust, is a nitrogen-fixing species characterized by multiple uses. Among these uses, black locust is of special interest to beekeepers due to its abundant flowering and delicious honey. Given the great importance of honey production in Italy, beekeepers are looking for genotypes that have a delayed flowering time. As a consequence, the aim of the present study was to develop a complete protocol of micropropagation for genotypes, which have been selected in the Veneto region due to their delayed flowering, i.e., about 3 months, in comparison with the normal flowering time (from late April to early June). The subsequent steps of the micropropagation protocol (explant decontamination, shoot induction, proliferation, and rooting) were investigated and optimized. The most effective decontamination treatment of explants (axillary buds from shoots developed in a greenhouse) was obtained using 50 mg/L AgNO3 for 20 min. This method resulted in the highest survival and regeneration rates for the explants (90%), although contamination was slightly higher than when using HgCl2 and NaOCl. The best medium for shoot establishment was MS with 1 mg/L of mT, which achieved 100% regeneration of the explants. In comparison with BA, mT at 1 mg/L was shown to be the best stimulator of shoot proliferation, especially in combination with 0.7 mg/L GA3 (Proliferation Rate, 4.7). An intermediate 2 h treatment with AgNO3, in combination with mT, was shown to be beneficial in improving the shoot proliferation and quality in the subsequent subculture in a gelled medium. As for shoot rooting, the shoots that were pre-treated in NH4NO3-free and mT-free MS medium gave the highest ex vitro rooting percentage in a cell tray (80%) and the highest number of roots per shoot (3.6). This optimized protocol opens the door to the massive micropropagation of valuable genotypes of black locust selected for delayed flowering. This is an outcome of extraordinary importance for beekeepers.

Tamanhos de parcelas e amostras para variáveis biométricas em mudas de alface

ABSTRACT: In order to ensure reliable inferences in scientific experiments, sampling criteria should be determined and defined during the experimental design phase. Determining plot and sample sizes without scientific criteria could result in resource and labor inefficiencies with no gain in experimental precision. In this work we estimate plot and sample sizes for biometric variable analyses in lettuce seedlings. The seedlings were sown in four expanded polystyrene foam transplant trays with 128 and 200 cells. Foliar area, stem diameter, shoot height, root length, root volume, root area, fresh and dry shoot and root masses. The methods described by Paranaiba (PARANAIBA et al., 2009) and Cochran (COCHRAN, 1977) were used for plot size and sample size estimations, respectively. Sample size varied according to the variables analysed and transplant tray cell number. Root variables required the highest number of samples. For a 10% margin of error, 12 seedlings were necessary for evaluations in a 128 cell tray, while 11 seedlings were required for analysis in 200 cell trays.

Conceptualization and development of a semi-automatic vegetable transplanter prototype for small landholdings

The process of seedling transplantation has significant importance within the realm of mechanical vegetable production in contemporary agriculture. A prototype of a two-row tractor-mounted semi-automatic vegetable seedling transplanter (SVT) was conceptualized and developed for small agricultural holdings. The functional behaviour of the prototype was examined with computer-aided design tools, and the various units of the prototype have been finalized. To develop the prototype, the feeding, metering, transplanting, drive train, and soil compacting/covering unit of the machine were developed and constructed using materials readily accessible locally. The machine has a set row-to-row spacing of 600 mm, and it may alter the plant-to-plant spacing when the machine's forward speed changes. The pace was customized to achieve the required 450 mm plant-to-plant spacing. A 12:1 speed reduction gearbox was used for the proper metering of seedlings. The effect of independent factors, namely tray cell type, feeding mechanism, soil covering/compacting wheel angle, and age of seedling, on the machine's actual field capacity (AFC) was examined. The prototype underwent preliminary field testing to assess the functional viability, and the functioning was satisfactory. The main effect of the feeding mechanism and soil covering/compacting wheel angle on AFC was statistically significant at 5 % for tomato and brinjal whereas their first-order interaction was found statistically significant on AFC for tomatoes. The findings demonstrate that this study's prototype can be marketed or used to further vegetable production studies.

Design and test of an efficient seedling pick-up device with a combination of air jet ejection and mechanical action

Low degree of transplanting automation will affect production efficiency and planting quality in vegetable cultivation. A new seedling pick-up device was designed and constructed to reduce direct grasping damages to seedlings and improve transplanting efficiency. The pick-up device consists of an air jet loosening device, a flexible pick-up manipulator, a parallel feeding device, and a multi-axis motion control system. Its working principle is to use air jet ejection to assist in loosening of seedling roots from the tray cells, grasp their stems for extracting with the pick-up manipulator, and finally transfer them to the delivery device for feeding into the planting device as needed. The mechanical structure and working parameters of each component were designed, and the control system was constructed according to the working requirements of ejecting, extracting, transferring, and discharging operations. A prototype of the new pick-up device was constructed, and its performance evaluation was conducted using an orthogonal experimental design using cucumber, pepper and caluiflower as test objects. The results showed that the test object, the root lump's moisture content and the loosening way (either as a whole or individual loosening of seedlings) had significant effects on the success ratio in picking up seedlings. Overall, the success in picking up seedlings from the cell was found to be influenced by horticultural and mechanical factors. Under the optimal level group, the maximum success ratio for automatic picking up seedlings was up to 94.49% for pepper while that of cucumber and cauliflower recorded 90.75% and 92.62%, respectively. The seedling pick-up performance was satisfactory for efficient transplanting requirements.

Effects of plug tray cell size on the growth of Atractylodes Chinensis (DC) Koidz seedlings

Effects of plug tray cell size on the growth of Atractylodes Chinensis (DC) Koidz seedlings

Development of Fast Method to Upscaling Microbial Inoculums on Two Seedling Testplants

We investigated the effect of different microbial species on the germination and growth of white mustard (Sinapis alba L.) and perennial ryegrass (Lolium perenne L.), tested for two weeks. The experiment was carried out in a cell tray, filled with sandy soil:compost (9:1) mixture. The following microorganisms were used as treatment: Enterobacter ludwigii, Bacillus megaterium, B. subtilis, Kosakonia cowanii, Pseudomonas fluorescens Hx1 bacteria and Trichorderma harzianum T-22 microscopic fungi. After two weeks, we assessed the number of germinated mustard seeds, the wet and dry weight of the mustard, the length of the mustard, the wet and dry weight and the length of the ryegrass. We measured the enzyme activity of the fluorescein diacetate hydrolysis analysis (FDA) of the soils and calculated the correlation of FDA with the parameters, tested on seedling-plants. FDA generally was positively correlated, however, the above findings could not be verified statistically. The simple and relatively fast method can be suitable for the cost-effective pre-testing of different microbes and for the pre-selection of strains that can be used in further field tests.

Development of an automated precision planter for solanaceous vegetable seeds

An automated precision planter was developed to mechanize the seedling preparation process. The machine was fabricated based on the seeds size and tray cells distance. It can precisely place single seeds per row in tray continuously. Tomato, eggplant, and pepper were used as test materials. Three vacuum pressures (0.68 kPa, 0.93 kPa, and 1.18 kPa) were used to determine the performance of the machine. Evaluated in terms of single seeds, double, multiple, missing cells, singulation efficiency, seed utilization efficiency, seeding efficiency and seeding capacity. Results showed it can plant single seeds with 57.81–86.98%, double with 4.95–29.43%, multiple with 0.09–4.25%, and missing cells with 4.43–36.89%. Also, the machine has a singulation efficiency of 63.98–93.91% with a seed utilization efficiency of 70.69–94.17%, seeding efficiency of 63.11–95.57% and a seeding capacity between 3,310 – 5,011 cells per hour which was 3.8 times faster than manual. The precision of the machine was affected by pressure and seed surface area which are highly significant on the performance of the machine. The total cost of the planter was $564.94 with a payback period of 1.41 years with a return on investment of 60.36 % using a custom rate of $0.055/tray.

Hydrodynamic and mass transfer correlations for SiC ceramic foam monolithic trays used in distillation column

AbstractBACKGROUNDCellular foam materials are excellent engineering materials for many applications in chemical engineering, especially process intensification of chemical conversions and separation. Recently, a silicon carbide (SiC) ceramic foam monolithic tray was developed as an excellent mass transfer tool to improve distillation and it showed an improved operational flexibility. Previous studies have revealed the effects of open cell diameter and tray thickness on the hydraulic performance and mass transfer efficiency of SiC foam monolithic trays, but relevant correlations are still missing, limiting their practical uses.RESULTSIn this study, based on the published experimental data, empirical correlations were developed to predict the hydrodynamic performance and mass transfer efficiency of SiC ceramic foam monolithic trays. The new correlations include the influence of the tray structure parameters, such as open cell (or pore) diameter and tray thickness, and of the operation conditions (such as the liquid and vapor volumetric flow rates), and the data obtained agree well with the experimental results.CONCLUSIONThe availability of such empirical correlations can be beneficial for the chemical engineering design of practical distillation processes based on SiC foam monolithic trays. © 2023 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Evaluation of Growth and Photosynthetic Rate of Cucumber Seedlings Affected by Far-Red Light Using a Semi-Open Chamber and Imaging System

Far-red light was excluded in photosynthetic photon flux; however, recent studies have shown that it increases photosynthetic capacity. In addition, there were few studies on the whole canopy photosynthetic rate and continuous changes of morphology on cucumber seedlings affected by far-red light. This study evaluated the effect of conventional white LEDs adding far-red light on cucumber seedlings using a semi-open chamber system for the measurement of the whole canopy gas exchange rate, and the Raspberry Pi-based imaging system for the analysis of a continuous image. In the image, through the imaging system, it was confirmed that far-red light promoted the germination rate of cucumber seedlings and enhanced early growth. However, the dry weight of the shoot and root did not increase. The measured net apparent CO2 assimilation rate was improved by an increasing leaf area during the cultivation period. The conventional white LED light source with added far-red light increased the photosynthetic rate of cucumber seedlings’ whole canopy. However, at the early seedling stage, plant height and leaf area of the whole canopy was increased by far-red light, and it was revealed that the image data saturated faster. It was considered that the photosynthetic efficiency decreased due to a shading effect of the limited planting density of the cell tray. The results found that using appropriate far-red light, considering planting density, could increase the photosynthetic rate of the whole canopy of crops, thereby promoting crop growth, but it was judged that the use of far-red light in the early growth stage of cucumber seedlings should be considered carefully.

Citocininas no acúmulo de biomassa de Limonium sinuatum sob restrição radicular durante a fase de viveiro

Abstract It has been suggested that the response of the specialty cut flower Limonium sinuatum to different abiotic stress situations related to the plug tray cell size during nursery could be associated with the synthesis and translocation of endogenous cytokinins produced in the root tips. To validate this hypothesis, the aim of this work was to evaluate the participation of cytokinins in the process of biomass accumulation in L. sinuatum plants through foliar spraying with a synthetic cytokinin (benzyl aminopurine, BAP) and an inhibitor of the synthesis of endogenous cytokinins (dopamine). Our results indicated that spraying L. sinuatum plants with BAP increased leaf area initiation and expansion, biomass accumulation through increased plant photosynthetic capacity, and differential partitioning towards the shoot apical meristem by a positive feedback mechanism that has a threshold of optimal response close to 100 mg L-1 BAP. Dopamine spraying appeared to affect the synthesis of endogenous cytokinins, reducing the previously mentioned responses. Responses were dose-dependent, with an optimum of 100 mg L-1 BAP and 200 mg L-1 dopamine. Our results allow concluding that the level of endogenous cytokinins during the abiotic stress such as root restriction during nursery is a determining variable of the biomass accumulation process in this species.

Linear relationships between biometric variables in lettuce seedlings

Seedling production is an important step in growing vegetables. The study of relationships between variables has applications in practically all areas of study and is useful in identifying relationships among quality variables in vegetable seedlings. Thus, this work aims to estimate linear relationships between biometric variables in lettuce seedlings. The seedlings were grown in expanded polystyrene trays (n = 4) with 128 and 200 cells each. Leaf area, stem diameter, shoot height, length, area, volume of the root, dry and fresh shoot mass variables were measured and evaluated with Pearson's correlation analysis, multicollinearity diagnosis, condition number and the variance inflation factor, path analysis and canonical correlations. The results show linear relationships between the variables. For the 128 cell trays, there was a relationship between the total fresh mass and fresh shoot mass variables and between the total fresh mass and dry shoot mass variables. For the 200-cell trays, significant correlation was observed between the characters total fresh mass and fresh shoot mass variables and between root area and root volume variables, indicating that the greater the total fresh mass, the greater the fresh shoot mass and the greater the root area, the greater the root volume.

Envolvimento de auxinas no crescimento inicial de mudas de Impatiens walleriana cultivadas em bandejas

Abstract The key role of auxins as integrators of environmental signals has become well-known in recent years, and emerging evidence indicates that auxin biosynthesis is an essential component of the overall mechanisms of plant tolerance to stress. However, although the knowledge of the involvement auxins in the responses related to the generation of roots and accumulation of biomass, studies in ornamental species concerning the commercial propagation in plug cell trays are scarce. Thus, the aim of this work was to evaluate the accumulation of pre-transplant biomass in Impatiens walleriana plants growing in two propagation systems (soilless medium-based plug cell trays and a floating system) with trays of different cell sizes and sprayed either with a single dose of the auxin indole acetic acid (IAA) or with two inhibitors of endogenous auxins, N-1-naphthylphthalamic acid (NPA) and 2,3,5-triiodobenzoic acid (TIBA). Our results demonstrate that plants from both floating system and those sprayed with IAA present both the highest leaf area and fresh and dry weight at the end of the experiment. Conversely, as a negative control, the use of NPA and TIBA as antagonists of the synthesis and translocation of auxins caused an opposite effect in such variables as compared to control plants. However, before making commercial recommendations, it would be necessary to evaluate the potential post-transplant effects of these treatments on the generation of I. walleriana yield.

Growth Characteristics by Plug Tray Cell Size, Soil Type, and Fertilizer Concentration for Plug Seedling Production of Veronica pusanensis Y.N. Lee

Background and objective This study was conducted to establish a stable seedling production system for Veronica pusanensis Y.N. Lee, a plant that is endemic to the Korean Peninsula and is a critically endangered species, distributed along the coast of Busan, Korea. Methods In order to investigate the plug cell size (72, 128, 200 cells), soil type (commercial substrate, and mixed substrates with peat moss and perlite at ratios of 1:1, 3:1, and 4:1), and fertilizer concentration (Peters 0, 500, 1,000, and 2,000 mg·L−1) conditions, the plug tray was filled with soil and seeds were sown. The sown trays were placed in the growth chamber (25°C, 70% RH, PPFD 100 μmol·m−2·s−1) for three repetitions per treatment. Results There was no difference in the growth of seedlings according to plug cell size. Therefore, it appears to be economically superior to produce seedlings in a 200-cell plug tray. In soil type, the seedling growth increased as the ratio of peat increased, but leaf chlorosis occurred from the 7th week after sowing. Examining the growth of seedlings based on fertilizer concentration, the greatest increase in growth was found to have occurred in the 1,000 mg·L−1 treatment. Conclusion Therefore, for the production of V. pusanesis seedlings, it was noted that when mixed soil with peatmoss and perlite at a ratio of 4:1 is filled in 200-cell plug trays, and the seedlings are fertilized with Peters 1,000 mg·L−1 once a week, growth will increase the most, demonstrating excellent cost-effectiveness. However, to mass-produce high-quality seedlings in a short period, it will be necessary to use a plug tray smaller than 200 cells or to conduct various fertilization composition studies.

Resposta da planta ornamental de forração Impatiens walleriana ao tamanho de recipiente e sistema de floating durante a fase de produção de mudas

Abstract In ornamental plants, the need to optimize nursery management has led to a tendency to decrease plug cell tray volume. However, in ornamental plants such as Impatiens walleriana, a lower plug cell volume can negatively affect leaf area expansion and biomass accumulation during the pre-transplant cycle. Because these results have been associated with a decrease in root growth, a floating system where roots come out of the plug cell has been proposed. The aim of this work was to describe pre-transplant biomass accumulation in plants from different plug cell volumes and the response to two propagation systems: media-based plug cell trays and floating system. The relationship found between plug cell volume and growth in both the media-based and floating systems is in agreement with that found in previous reports. With respect to the traditional media-based system, the floating system showed higher leaf area expansion, as a result of higher leaf appearance rate and relative leaf area expansion. Higher fresh and dry weight accumulation were estimated through the relative growth rate (RGR), with a strong relationship with the capacity of photo assimilate production (net assimilation rate) and RGR. However, all these changes cannot be exclusively associated with a higher root growth in the floating system. Our experiments validate the positive results in favor of the use of a floating system and also shows the physiological mechanisms involved.

Revisión de la acción de la citoquinina: los cambios anatómicos de la hoja juegan un papel clave en la promoción del crecimiento impulsada por la 6-bencilaminopurina en lechuga cultivada en maceta

Plants raised in small cell trays are often subjected to root growth restrictions. Root tips are a source of cytokinin, and insufficient biosynthesis and transport of this hormone to the aerial part severely impairs shoot development. Exogenous supply of cytokinin to the foliage has been shown to effectively counteract these effects in several horticultural crops, but the physiological processes involved are still unclear. The aim of this work was to study the effect of spraying the cytokinin 6-benzylaminopurine (BAP) on growth and development of plug lettuce seedlings focusing on the morpho-physiological mechanisms involved in plant response. Two experiments were conducted in a greenhouse. Lettuce (Lactuca sativa L. Crimor INTA) seedlings were grown for 35 days in 128-, 200- and 288-cells trays (17.37, 13.90 and6.18 cm3 ·cell-1 respectively), after which they were sprayed with BAP (6-benzylaminopurine) solutions (0, 5, 50 or 100 mg·L-1) either immediately before transplant, or 7 days after transplant. Seedlings were transplanted into larger (3,000 cm3) pots in which they grew for further 60 days. Decreasing plug cell volume resulted in a steep decrease in plant net assimilation rate and leaf net photosynthetic rate, but the impact on the relative growth rate was somewhat lower due to an increased leaf area ratio. BAP sprays increased plant biomass accumulation and enhanced the development of photosynthetic area, in parallel with a strong promotion of carbon assimilation, and these effects were more remarkable in plants raised in smaller plugs, and when hormone was supplied at the pre-transplant stage.

Pear and apple pomace compost as an alternative to commercial substrates in the production of tomato seedlings


 It is important to look for alternative substrates to replace non-renewable resources such as peat used in growing media in horticulture. The aim of this work was to evaluate if the compost of pear and apple pomace could be used as an alternative to a commercial substrate for the production of tomato seedlings. Two experiments were carried out on trays with alveoli of 100 cm3 (experiment 1) and 30 cm3 (experiment 2). In experiment 1, three substrates were used: commercial substrate (CS), mixture of CS and pomace compost (CS+C) and pure compost (C). In experiment 2 a fourth treatment with a mixture of compost and perlite (C+P) was incorporated. The obtained results indicate that the development of the seedlings using CS+C and CS as a substrate was similar in cells of 100 cm3 and higher in cells of 30 cm3. In addition, the growth of seedlings on C+P in relation to CS showed similar or higher values in some variables. These results indicate that it would be feasible to replace the use of non-renewable resources such as peat in the production of tomato seedlings by a product obtained from a residue.
 Tomato seedling growth was evaluated on trays with 100 cm3 alveoli and 30 cm3 alveoli on different substrates mixtures: commercial substrate (CS), mixture of CS and pomace compost (CS+C), pure compost (C) and mixture of compost and perlite (C+P).
 Highlights
 
 Seedling development using CS+C and CS as substrates was similar in cells of 100 cm3 and higher in cells of 30 cm3.
 Seedling growth on C+P in relation to CS, showed similar or higher values for some variables such as root dry weight, shoot dry weight, stem diameter and shoot height.
 In 30 cm3 cell trays of the compost and perlite treatment (3:1 v/v), obtained seedling quality would enable a high post-transplant survival percentage.
 Pear and apple pomace compost may be an alternative to a commercial substrate containing peat for tomato seedlings production (Lycopersicon esculentum Mill.).

The Effects of Plug Tray Cell Size and Seedling Age on the Growth and Yield of Spring Onion

The Effects of Plug Tray Cell Size and Seedling Age on the Growth and Yield of Spring Onion

First report of seedling damping off in forage ryegrass caused by Pythium aphanidermatum and P. periilum in Japan.

Italian ryegrass (Lolium multiflorum Lam.) and perennial ryegrass (L. perenne L.) are important for hay fields and grazing lands across Japan, with nearly 70,000 ha production, the largest share in forage grass cultivation. In August 2018, damping off of seedlings of both species was observed about 2wk after seeding in Tochigi Prefecture, central region of Japan. Roots were brown and decayed drastically with browning of basal stem. Nearly 90% of the row seedling stands were eradicated in some fields, especially ones seeded from August to early September, when the soil and air temperatures were around 25-30 ˚C. Six Pythium-like isolates were obtained by isolation from surface-sterilized diseased hypocotyls (1-2cm) placed on water agar. Six isolates were purified as single hyphal tips and deposited at the NARO genebank (https://www.gene.affrc.go.jp/index_en.php), with accession no. MAFF101946-101951. Two of them, MAFF101946 and 101948 were used for detailed study. The isolates were grown in the dark on clarified V8 juice agar for 10 days to produce oogonia. The oogonia of MAFF101946 were globose, colorless, smooth, 21 to 30 µm in size, and had 1(- 2) antheridia. Oospores were mostly aplerotic, and oogonia walls were 1.1 to 2.3 µm thick. The oogonia of MAFF101948 were globose, colorless, smooth, 19 to 27 µm in size, and had 2-5 antheridia. Oospores were mostly plerotic, and oogonia walls were 1.7 to 4.2 µm thick. The morphology of the MAFF101946 matched that of P. aphanidermatum (Edson) Fitzp.(abbr. PA) and the MAFF101948 matched P. periilum Drechsler (abbr. PP) (Van der Plaats-Niterink, 1981). DNA sequences of cox1 (Robideau et al, 2011) and rDNA-ITS regions (White et al,1990) of each isolate were analyzed. The cox1 sequences of the MAFF101946 and 101948 (GenBank Accession No. LC548774 and LC548775) matched 100% (680/680 bp) with that of PA (HQ708486) and PP (HQ708781), respectively. The rDNA-ITS sequence of the MAFF101946, LC592700, matched PA (772/777 bp; HQ643439), and the MAFF101948 (LC592701) matched PP (HQ643740), with 99% similarity (764/773 bp). The optimal growth temperature was 35 ˚C for both. Their pathogenicity was confirmed by seeding two Italian (cv. Inazuma and Minamiaoba) and perennial (cv. Yatsuyutaka and Natsugoshi-pere) ryegrasses cultivars in cell trays containing commercial potting mixture inoculated with the isolates. Barley grains autoclaved with a half volume of water and incubated with each isolate at 25 ˚C for about 2 wk were added to inoculate the potting mixture (5%, v/v). Separate trays were used for each isolate to avoid cross-contamination, sown with 60 seeds were sown per cv. and the trays were placed in a light thermostat chamber under the daily cycle of 16 hr light at 30 ˚C and 8 hr dark at 25 ˚C. About 3 wk later, seedlings on the inoculated soil exhibited the symptoms, but not in control (no inoculum) plots. Both inoculated organisms were re-isolated from the diseased plants to confirm their pathogenicity. PA was more aggressive with grater percent damping off compared to PP. Both species are known as pathogens of diverse plants including grasses and legumes (Abad et al, 1994; Ao et al, 2018), but to our knowledge, this is the first report of seedling damping off caused by these Pythium species in forage ryegrass in Japan. With the increased duration of hot, humid condition across temperate regions due to global warming, the damping off may become a problem in hay fields and pasture and resistance breeding for these pathogens may be needed.

Potential analysis of an automatic transplanting method for healthy potted seedlings using computer vision

Healthy seedlings transplanting is an important process in the production of vegetables and economic crops, and the transplanting quality directly affects crop yield. Automatic seedlings transplanting can improve the transplanting efficiency of seedlings. A physical prototype of potted seedling automatic transplanting with a conveyor and a transplanting end-effector was developed in the previous study. This work proposed an automatic transplanting method of healthy potted seedlings, which mainly included a detection part of seedlings growth status and a visual servo control part with the purpose of automatic transplanting seedlings high-efficiently. The seedlings and the tray cell were simultaneously detected for identifying healthy seedlings, damaged seedlings and empty cells using a machine vision algorithm when the tray was moving on the conveyor line. The visual servo model was applied to enable the collaborative operation of the machine vision and the end-effector for determining the position and attitude of grasping seedlings. The experimental results showed that the accuracy rates of the identification of empty tray cells, healthy seedling and unhealthy seedling were 96.42%, 98.77% and 89.95%, respectively. Under the successful identification of the healthy seedling, the accuracy rate of grasping seedling was 96.38%. It indicated that the proposed method can effectively transplant seedlings. Keywords: seedling recognition, automatic transplanting, computer vision, transplanting system DOI: 10.25165/j.ijabe.20211406.6638 Citation: Jin X, Tang L M, Ji J T, Wang C L, Wang S S. Potential analysis of an automatic transplanting method for healthy potted seedlings using computer vision. Int J Agric & Biol Eng, 2021; 14(6): 162–168.

Effects of test levels on creep and relaxation characteristic parameters of stem for rice seedlings grown in plastic cell tray

Creep and relaxation characteristics of stem for rice seedlings grown in plastic cell tray were studied by static tensile testing, in order to determine the relationship between characteristic parameters (rheological model parameters, stress components and strain components) and test levels (stress levels and strain levels). Rice seedling stem specimen used in the test was 40 mm in length. And the applied test values for the creep and relaxation test ranged from 1.0-3.0 MPa and 1.5%-3.5%, respectively, each for 5 levels. The results indicated that elastic modulus in the creep and relaxation model was not affected by test levels. However, except that viscosity coefficient ηkv was a constant and ηm1 decreased with the increase of test levels, other viscosity coefficient and rheological time nonlinearly increased as the test levels increased. And strain components in the creep model and stress components in the relaxation model significantly increased as the test levels increased. Keywords: model parameters, rheological property, stress relaxation, creep property, rice seedling stem, plastic cell tray DOI: 10.25165/j.ijabe.20201304.5673 Citation: Xiao J Q, Ma R J, Chen Y. Effects of test levels on creep and relaxation characteristics parameters of stem for rice seedling grown in plastic cell tray. Int J Agric & Biol Eng, 2020; 13(4): 19–28.