Plug Trays Research Articles

Development of a multi-adaptive feeding device for automated plug seedling transplanter

In order to improve the adaptability of the seedling feeding devices to different plug trays for various seedlings, a multi-adaptive plug seedling feeding device for automatic field transplantation was developed. Its efficiency and adaptability have been improved using a seedling delivery device equipped with a row of end-effectors, which were provided with continuous plug seedlings by a compact seedling tray conveyor carrying out a reciprocating action. Each operation for the seedling feeding device could work automatically through a control system. Three categories of plug seedlings, cucumber, pepper and tomato seedlings, were tested. The results of the performance test for the prototype demonstrated that the best performance emerged in the cucumber seedlings in 50-cell trays with the highest success rate of 88% at the feeding frequency of 6 groups/min. The lowest success rate was 73.33% for the tomato seedlings in 105-cell trays at the feeding frequency of 12 groups/min. It can be concluded that the automated feeding device developed in this study could be used for various plug seedlings as a result of its strong adaptability. Keywords: plug seedling, automated feeding device, vegetable transplanting, control system DOI: 10.25165/j.ijabe.20211402.6003 Citation: Shao Y Y, Han X, Xuan G T, Liu Y, Gao C, Wang G P, et al. Development of a multi-adaptive feeding device for automated plug seedling transplanter. Int J Agric & Biol Eng, 2021; 14(2): 91–96.

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

Rapid generation cycling transforms pyrethrum (Chrysanthemum cinerariifolium) into an annualized perennial

AbstractPyrethrum [Chrysanthemum cinerariifolium (Trevir.) Vis.] is an important “green pesticide” crop widely used for insect control on plants and for humans. Pyrethrum flowers have the highest Pyrethrin I/Pyrethrin II ratio (%Py) and are harvested at specific stages to maximize yield. Selection for correlative early seed germination and flowering in first year pyrethrum seedlings is challenging and has not been accomplished previously. The breeding objectives for this study were to sample a wide germplasm base to select for rapid generation cycling (RGC) traits of early and high germination in Weeks 1–4, earliness of visible bud date (VBD) and flowering, accelerated growth, high leaf unfolding rates per week, number of shoots, and %Py in the 1st–12th flowers. Seven seed lots were evaluated for germination rate and timing (N = 141,120 seeds) in Year 1 for RGC traits. Seedling germination was recorded weekly with toothpicking to identify germination weeks with successive selection occurring at transplanting. Grand mean percentage germination was low (24.5%), whereas individual seed lots varied (18.4–38.9%). Seedling death was 0.0–6.8%. On average, it took 34–39 wk to reach VBD and an additional 3–4 wk to flower. Thus, flowering in <1 yr without vernalization is a new trait (annualized perennial) selected in this crop. Germination week was significantly correlated with VBD and flowering dates and is an important trait to use for selecting early‐flowering genotypes in plug trays. Pyrethrum breeding programs could select the earliest germinating seedlings (Weeks 1–4 after sowing) at transplanting to enhance the likelihood of selecting early‐flowering genotypes in the first year and provide an additional year of harvest to increase yield.

Magnetic field distribution simulation and performance experiment of a magnetic seed-metering device based on the combined magnetic system

The magnetic seed-metering method is one of the universal approaches for plug tray seeding. Conventional electromagnetic and permanent-magnetic seed-metering devices either cannot supply a desirable magnitude of magnetic force or need a seed-clearing mechanism. Thus the objective of this research was to develop a combined magnetic system (CMS) seed-metering device for generating higher magnetic forces than the electromagnetic ones without using any auxiliary seed-clearing mechanisms. Firstly, the CMS component was designed and its magnetic field distributions in both attractive and clearing states were obtained by finite element method simulations. Secondly, based on the CMS components, a magnetic seed-metering device was developed and validated by a prototype experiment. The simulation results displayed that along the axial direction of the magnetic head, the maximum magnetic flux density in the clearing state was 21.03% of that in the attractive state. In addition, along the radial direction, the proportion was 24.16%. Concerning the spatial magnetic flux density distribution, the magnetic flux density on the seeding planes of CMS components (approximately 60 mT) was higher than that of transitional space between two CMS components (nearly 0 mT). As for the seeding performance experiment, when the rotational speed of the roller was 21 r/min and the exciting current was 0.15 A, the highest single rate was acquired (90.20%). In the same condition, the reseeding rate was 5.88% and the miss-seeding rate was 3.92%. The results suggest that the magnetic field distribution and seeding performance of the developed magnetic seed-metering device are acceptable. Therefore, the developed magnetic seed-metering device can be used in practical plug tray seeding processes. Keywords: seed-metering device, magnetic field, magnetic flux density, finite element method, simulation DOI: 10.25165/j.ijabe.20211401.5852 Citation: Liu W, Hu J P, Yao M J, Zhao J, Lakhiar I A, Lu C T, et al. Magnetic field distribution simulation and performance experiment of a magnetic seed-metering device based on the combined magnetic system. Int J Agric & Biol Eng, 2021; 14(1): 108–117.

Effects of Cell Size of Plug Tray and Growth Period on Wasabi Seedling Characteristics and Field Performance after Transplanting in Wasabi Fields

Effects of Cell Size of Plug Tray and Growth Period on Wasabi Seedling Characteristics and Field Performance after Transplanting in Wasabi Fields

Magnetic field distribution simulation and performance experiment of a magnetic seed-metering device based on the combined magnetic system

The magnetic seed-metering method is one of the universal approaches for plug tray seeding. Conventional electromagnetic and permanent-magnetic seed-metering devices either cannot supply a desirable magnitude of magnetic force or need a seed-clearing mechanism. Thus the objective of this research was to develop a combined magnetic system (CMS) seed-metering device for generating higher magnetic forces than the electromagnetic ones without using any auxiliary seed-clearing mechanisms. Firstly, the CMS component was designed and its magnetic field distributions in both attractive and clearing states were obtained by finite element method simulations. Secondly, based on the CMS components, a magnetic seed-metering device was developed and validated by a prototype experiment. The simulation results displayed that along the axial direction of the magnetic head, the maximum magnetic flux density in the clearing state was 21.03% of that in the attractive state. In addition, along the radial direction, the proportion was 24.16%. Concerning the spatial magnetic flux density distribution, the magnetic flux density on the seeding planes of CMS components (approximately 60 mT) was higher than that of transitional space between two CMS components (nearly 0 mT). As for the seeding performance experiment, when the rotational speed of the roller was 21 r/min and the exciting current was 0.15 A, the highest single rate was acquired (90.20%). In the same condition, the reseeding rate was 5.88% and the miss-seeding rate was 3.92%. The results suggest that the magnetic field distribution and seeding performance of the developed magnetic seed-metering device are acceptable. Therefore, the developed magnetic seed-metering device can be used in practical plug tray seeding processes. Keywords: seed-metering device, magnetic field, magnetic flux density, finite element method, simulation DOI: 10.25165/j.ijabe.20211401.5852 Citation: Liu W, Hu J P, Yao M J, Zhao J, Lakhiar I A, Lu C T, et al. Magnetic field distribution simulation and performance experiment of a magnetic seed-metering device based on the combined magnetic system. Int J Agric & Biol Eng, 2021; 14(1): 108–117.

Development of a multi-adaptive feeding device for automated plug seedling transplanter

In order to improve the adaptability of the seedling feeding devices to different plug trays for various seedlings, a multi-adaptive plug seedling feeding device for automatic field transplantation was developed. Its efficiency and adaptability have been improved using a seedling delivery device equipped with a row of end-effectors, which were provided with continuous plug seedlings by a compact seedling tray conveyor carrying out a reciprocating action. Each operation for the seedling feeding device could work automatically through a control system. Three categories of plug seedlings, cucumber, pepper and tomato seedlings, were tested. The results of the performance test for the prototype demonstrated that the best performance emerged in the cucumber seedlings in 50-cell trays with the highest success rate of 88% at the feeding frequency of 6 groups/min. The lowest success rate was 73.33% for the tomato seedlings in 105-cell trays at the feeding frequency of 12 groups/min. It can be concluded that the automated feeding device developed in this study could be used for various plug seedlings as a result of its strong adaptability. Keywords: plug seedling, automated feeding device, vegetable transplanting, control system DOI: 10.25165/j.ijabe.20211402.6003 Citation: Shao Y Y, Han X, Xuan G T, Liu Y, Gao C, Wang G P, et al. Development of a multi-adaptive feeding device for automated plug seedling transplanter. Int J Agric & Biol Eng, 2021; 14(2): 91–96.

Growth of Cucumber Scions, Rootstocks, and Grafted Seedlings as Affected by Different Irrigation Regimes during Cultivation of ‘Joenbaekdadagi’ and ‘Heukjong’ Seedlings in a Plant Factory with Artificial Lighting

Irrigation scheduling and programming are very effective tools for efficient water use in a plant factory with artificial lighting (PFAL). In order to confirm optimal irrigation schemes for the production of cucumber scions and rootstocks in a PFAL, in this study, four different start points of irrigation were applied by measuring the weight of the plug tray to compare the growth of cucumber scions and rootstocks cultivated in a PFAL. Additionally, the growth characteristics of cucumber seedlings grafted with scions and rootstocks cultivated between in a greenhouse and in a PFAL were investigated. Although the growth of cucumber scions and rootstocks was highest when irrigation was conducted at 70% of water content in a medium, the growth of grafted cucumber seedlings before and after transplanting was not significantly different among the irrigation treatments in a PFAL. However, water use efficiency (WUE) during cucumber scions and rootstock production in a PFAL was higher at 60% than at 70%. Considering seedling growth and the efficiency of irrigation such as WUE and irrigation schedule, the optimal start point of irrigation during the production of cucumber scions and rootstocks in a PFAL was determined as 60% of water content in a medium. When the optimal irrigation regime was applied to the production of cucumber scions and rootstocks in a PFAL, the morphological characteristics of cucumber scions and rootstocks cultivated in a PFAL were more suitable for grafting compared with that of the cucumber scions and rootstocks cultivated conventionally in a greenhouse. The favorable environmental conditions during the cultivation of cucumber scions and rootstocks in a PFAL also positively affected the flowering response of cucumber grafted seedlings after transplanting.

Design and Development of Chilli Seeder

India is the second-largest producer of chilli in the world. The seeds of chilli, capsicum etc. are commonly sown and developed in nurseries using plug tray for better germination. Then grown plants sent to farmland for further cultivation. It was observed that the process of sowing seeds in plug tray require more time because the seed are small and one has to drop it manually. Moreover, this is tedious work and the owner have to pay high for this. So, objective of the study was to evolve a Plug Tray Seeder which were affordable to nursery owners. Which work on pneumatic principle. It was designed in such manner that it has higher seedling rate and less power consumption. In addition, it should also reduce human effort and labour cost. The capacity of seeder, is assumed, depending on the tray size used which range between 27000 and 46800 cell per hour. The total cost of the precision plug seeder is estimated to be ₹17800 (US$242).

Biomass Accumulation in the Fern Asplenium nidus avis (L) under Root Restriction

Pot ornamental plant productivity is related to the environmental growth facilities but negatively affected by the pot root restriction syndrome. Most ferns showed a lower relative growth rate and long production cycles (24 months or more) for which growers use small pots to increase yield per unit area of greenhouse. The aim of this work was to analyze growth changes in response to different pot volume in plants of A. nidus avis spore-propagated under the hypothesis that it would play a role as an abiotic stress which decrease commercial productivity. Our results showed that the use of big pots increased fresh and dry weight and frond area (the main aesthetic trait). When growth parameters were performed, a higher the frond appearance rate (RLA), the frond area expansion (RLAE) and the frond thickness (SLA) were found in 1500 cm3 pot as well as the relative growth rate (RGR) and the net assimilation rate. The use of biggest pot for fern cropping stimulated biomass accumulation through a higher capacity to initiate and expand fronds, to increase photosynthetic rates and change photo assimilate partitioning which favor shoots. From the grower´s point of view, our results suggested that higher yields of A. nidus avis fern would be reached decreasing root restriction, that is, to use the biggest pot volume from the early transplant from plug trays.

Far-red Light Interacts with Plant Density to Change Photosynthate Allocation of Cucumber Seedlings and Their Subsequent Early Growth after Transplanting

The light competition in dense plant stands may be disadvantageous in transplant production because competition stimulates stem elongation and can reduce photosynthate allocation to leaves; this, in turn, may reduce the early growth rate after transplanting. In this study, we focused on how the proportion of far-red (FR) light affected light competition among cucumber (Cucumis sativus L.) seedlings and investigated the effects of the plant density × FR interaction on photosynthate allocation and subsequent early growth after transplanting. Seedlings at the cotyledon stage were planted into plug trays at densities ranging from 109 to 1736 plants/m2; then they were grown for 4 days under light-emitting diode (LED) light containing FR light (FR+) at approximately the same red-to-FR ratio as in sunlight (1.2) or under light containing no FR (FR−). The higher density significantly stimulated stem elongation under both FR+ and FR−, but the effect was small under FR−; this indicates that light competition in the dense stands was inhibited by reducing FR light. The higher plant density significantly increased photosynthate allocation to the stem and decreased allocation to the leaves under both FR+ and FR−; however, again, the effect was smaller under FR−. After transplanting the seedlings to pots, early growth decreased in the seedlings that allocated less photosynthate to their leaves. Our results indicate that light with reduced FR can mitigate the disadvantageous photosynthate allocation of transplants and the reduction of early growth after transplanting that are likely to occur as a result of light competition at high plant density.

Post-transplant Water Utilization of Zinnia Seedlings Grown in Humectant-amended Substrate Maintained at Two Moisture Thresholds1

Abstract Humectant treatment and substrate moisture content (SMC) were studied to determine their impact on post-transplant water utilization in ‘Thumbelina' zinnia (Zinnia elegans Jacq.). Four-week-old seedlings were transplanted from plug trays into pots containing soilless substrate amended with an aqueous solution of 1.6% Hydretain® or an equal volume of water (0% humectant). Seedlings were placed in an automated, sensor-controlled irrigation system and grown for 30 days at SMC levels of 0.45 or 0.25 cm3·cm−3 (0.06 or 0.03 fl oz·oz−1). Plant-water potential (Ψw) was significantly higher (less negative) in transplants grown in humectant-treated substrate at both SMC levels, and water-use efficiency (WUE) was 2X greater for seedlings grown in treated substrate maintained at 0.25 cm3·cm−3 than it was for transplants grown in untreated substrate at the same SMC level. No significant differences in height, stem diameter or shoot dry weight were observed when comparing plants grown in treated and untreated substrate. Root dry weight was significantly greater for seedlings grown in untreated substrate. Flowering was not affected by humectant treatment or by SMC. The results show that transplanted zinnia ‘Thumbelina' seedlings require less irrigation when grown at a lower SMC threshold in soilless substrate amended with 1.6% Hydretain®. Index words: automated irrigation control, cultural practices, plant-water relations, transplant establishment, water management, water-use efficiency. Species used in this study: ‘Thumbelina' zinnia (Zinnia elegans Jacq.). Chemicals used in this study: Hydretain® - a proprietary blend of sugar alcohols, polysaccharides, and neutral salts of alphahydroxyproprionic acid.

Synthetic Seed Technology Development and Production Studies for Storage, Transport, and Industrialization of Bracken Spores.

Bracken fern (Pteridium aquilinum var. latiusculum (Desv.) Underw. ex A. Heller) has long been grown industrially in South Korea. Conventional propagation methods, including planting rhizomes and in vitro seedling culture, are labor intensive and expensive, and thus not commercially suitable. We aimed to develop a system to produce synthetic seeds using fern spores (SFS). Synthetic seeds were prepared by mixing bracken spores and alginate matrix. Spore germination and gametophyte and sporophyte growth and development from SFS proceeded normally. Spore density affected gametophyte and sporophyte numbers. SFS prepared using cold (4 °C) long-term storage spores (even 7-year-old spores) could effectively form sporophytes. The highest germination was observed at 25 °C. Soaking-treated SFS successfully formed sporophytes, even after 30 days of storage at 4 °C; indeed, sporophytes formed even after five days of storage at 25 °C during transport conditions. SFS were sown in plug trays for commercial use. Young sporophytes grown from plug seedlings were greenhouse cultivated, and transplanting within eight weeks was effective for root growth and growing-point formation. Developing synthetic seeds is a feasible solution for facilitating efficient transport and the handling of small-sized fern spores; furthermore, this SFS technology provides the basis for fern seedling culture and fern spore industrialization.

Ex vitro recovery of rough lemon (Citrus jambhiri) hybrids and identification with SSR markers

Rough lemon (Citrus jambhiri Lush) is one of the leading citrus rootstock around the world besides sour orange. In the present studies, rough lemon was crossed with X 639 and Swingle citrumelo at Department of Fruit Science, PAU Ludhiana during 2015-16. Cent per cent seed germination was recorded for both the crosses under in vitro conditions but, the germination rates with growing media in plug trays were significantly lower (91.3 and 89.2% for RL× X and RL × SC, respectively). Higher proportion of multi-foliate seedlings (26.89%) was recovered by in vitro seed culture over the ex vitro seed germination (5.20%). All the multi-foliate seedlings were confirmed by SSR analysis using two primers (F 29 and F 87). The SSR analysis showed that only 85% multifoliate seedlings were zygotic while, the rest were not confirmed to be zygotic. The SSR analysis of the 50 unifoliate F1 seedlings each from both the crosses with 5 SSR primers differentiated seedlings into two groups, viz. zygotic and nucellar seedlings. In RL × X cross, the most efficient SSR marker was F29, which identified 30% F1 unifoliate seedlings to be zygotic followed by CCSME31, which identified 26% unifoliate seedlings as zygotic seedlings while the remaining seedlings were nucellar. In the cross RL × SC, the primer F29 was most efficient as it identified 28% zygotic seedlings and 72% nucellar seedlings whereas, the primer F87 identified 24 and 76% zygotic and nucellar seedlings, respectively.

Plug Cell Volume, Main Temperature and the Synthetic Cytokinin 6, Benzyl Aminopurine (BAP) Spray on Lettuce Biomass Accumulation during Nursery at Ambient Temperatures

Although nursery lettuce information is plentiful, the use of exogenous cytokinin (6, benzyl amino purine, BAP) as a plant growth regulator, which would increase vegetable nursery yield has only recent suggested. On the other hand, biomass relationships between plug cell volumes, BAP uses and main temperature during nursery is quite scarce. Our results showed that the growth response of lettuce seedlings during nursery is firstly related to mean air temperature, independently the environmental characteristics of the cultivar tested. From the view of a nursery grower, yield can be optimize when higher plug cell number per tray was used or a BAP spray was applied to limited plug trays (128- or 288-cells). One of the novelty result of this work reside in the objective protocol proposed (the marginal root dry weight accumulation rate) to decide the time to transplant. Finally, our results showed that plug purchaser would be change their visual criteria when they buy BAP-treated lettuce for increased field yield.

An Efficient Processing Approach for Colored Point Cloud-Based High-Throughput Seedling Phenotyping

Plant height and leaf area are important morphological properties of leafy vegetable seedlings, and they can be particularly useful for plant growth and health research. The traditional measurement scheme is time-consuming and not suitable for continuously monitoring plant growth and health. Individual vegetable seedling quick segmentation is the prerequisite for high-throughput seedling phenotype data extraction at individual seedling level. This paper proposes an efficient learning- and model-free 3D point cloud data processing pipeline to measure the plant height and leaf area of every single seedling in a plug tray. The 3D point clouds are obtained by a low-cost red–green–blue (RGB)-Depth (RGB-D) camera. Firstly, noise reduction is performed on the original point clouds through the processing of useable-area filter, depth cut-off filter, and neighbor count filter. Secondly, the surface feature histograms-based approach is used to automatically remove the complicated natural background. Then, the Voxel Cloud Connectivity Segmentation (VCCS) and Locally Convex Connected Patches (LCCP) algorithms are employed for individual vegetable seedling partition. Finally, the height and projected leaf area of respective seedlings are calculated based on segmented point clouds and validation is carried out. Critically, we also demonstrate the robustness of our method for different growth conditions and species. The experimental results show that the proposed method could be used to quickly calculate the morphological parameters of each seedling and it is practical to use this approach for high-throughput seedling phenotyping.

Influence of different shoot portion and media on vegetative propagation of pomegranate (Punica granatum)

An experiment entitled, influence of different shoot portion and media on vegetative propagation of pomegranate was carried out with two factors viz; shoot portion with three levels and media with seven levels making total twenty one treatment combinations. Experiment was laid out in Factorial Completely Randomized Design with three replications. The results of the present investigation on the basis of pooled data revealed that, minimum days to sprouting (11.33) was recorded with treatment s1 (Apical) whereas, significantly highest length of shoot (9.79 cm), maximum number of roots (8.92) and length of root (8.96 cm) was recorded with treatment s2 (Sub-apical). Among different treatments of media, significantly early sprouting (11.14 days), maximum number of roots per cutting (8.40) and highest length of roots per cutting (8.81 cm) and highest shoot length (9.36 cm) at 60 DAP were observed with treatment m4 (Vermiculite: Poultry Manure [1:1]+ Pseudomonas). Use of sub-apical cutting with Vermiculite: Poultry Manure [1:1]+ Pseudomonas media in plug tray for early sprouting, highest shoot and root parameters of pomegranate under greenhouse condition.

Effect of diniconazole on the growth and taking roots after transplanting of Sesamum indicum ‘Baekseol’ plug seedlings

Sesamum indicum ‘Baekseol’ plug seedlings were treated with the fungicide diniconazole as a growth retardant in comparison to paclobutrazole. Seeds were sown in 128-cell plug trays. Paclobutrazole (0, 15, 30, and 60 mg L−1) and diniconazole (100, 200, 300, and 400 mg L−1) were foliage sprayed when first leaves were developed. Stem growth was similar between paclobutrazole and the control, but strongly retarded by increasing concentrations of diniconazole. Leaf numbers did not differ in all treatments. As the diniconazole concentration increased, leaves became thicker, while leaf width and length decreased. In diniconazole treatment, shoot fresh weight decreased, but root fresh weight increased. Therefore, the T/R ratio was lowered by diniconazole treatment. After transplanting, the taking roots of paclobutrazol-treated plants were below average (< 50%), whereas, with diniconazole treatments, it was 100%, regardless of treatment concentrations. From the above results, 100 mg L−1 of diniconazole is the most appropriate for growth retardation of S. indicum ‘Baekseol’ plug seedlings.

An Optimal Combination of the Propagation Medium and Fogging Duration Enhances the Survival, Rooting and Early Growth of Strawberry Daughter Plants

Runner propagation is an important process in strawberry cultivation, which influences plant survival and fruit yield during the commercial production. In South Korea, this process is carried out on plug tray benches that are set off the ground in greenhouses, rather than in open fields. During the propagation, the propagation media and fogging systems play an important role in the survival and rooting of daughter plants. The aim of this study is to investigate the influences of the different types of propagation media and various fogging treatments on the rooting and early growth of strawberry daughter plants. Two strawberry cultivars—‘Maehyang’ and ‘Seolhyang’—in a glasshouse, grown in four different propagation media-a peat moss-based mixture (PBM), rockwool cube (RWC), granular rockwool (GRW), and a coir-based mixture (CBM)—combined with five fogging durations, 0, 3, 6, 9 and 12 days were tested. PBM with 9–12 days of fogging was the most ideal combination for the rooting and early growth of daughter plants of the two strawberry cultivars, which increased the ratio of survival and rooting, number of new leaves, root length and maximised the fresh and dry weights of the aboveground and belowground runner biomass. However, fogging treatments shorter than 9 days led to a lower survival rate and rooting. RWC and GRW are not recommended for young plants of these two strawberry cultivars because their strong water-retentive properties could subject the root to water stress, which can lead to root rotting. The purpose of this study is to provide a reference for strawberry growers to improve the quality of plants and efficiency of production during the propagation period.

Responses of Vegetable Seedlings Grown on Cylindrical Paper Pots or Plug Trays to Water Stress

Responses of Vegetable Seedlings Grown on Cylindrical Paper Pots or Plug Trays to Water Stress