Seedling Tray Research Articles

Produtividade da couve-flor em função da idade de transplantio das mudas e tamanhos de células na bandeja

O experimento foi realizado de novembro de 2000 a abril de 2001, na UNESP em São Manuel (SP). Estudou-se o efeito do tamanho da célula da bandeja de poliestireno expandido e a idade de transplantio das mudas sobre a produção de couve-flor, híbrido Shiromaru II. Usaram-se bandejas com 128 e 288 células, correspondentes a 34,6 e 9,7 cm³/célula, respectivamente, e mudas transplantadas aos 27, 34, 41 e 48 dias após a semeadura. Os tratamentos foram arranjados como fatorial 2 x 4, dispostos no delineamento de blocos casualizados, com cinco repetições. Foram avaliados, por ocasião do transplantio, o número de folhas, peso fresco, peso seco e área foliar das mudas. A parcela experimental no campo foi constituída por dez plantas. Nas colheitas, avaliaram-se a porcentagem de plantas com cabeça comercial e nestas, o número de folhas, peso fresco e diâmetro da cabeça. A produção total por parcela foi obtida com a soma do peso fresco de todas as cabeças consideradas comerciais. A produção de mudas em bandejas com 128 células proporcionou maior porcentagem de plantas comerciais (64%) relativamente às bandejas com 288 células (45%), maior peso médio de cabeça (337 g na bandeja com 128 e 247 g na bandeja com 288 células) e maior produção de plantas comerciais (36,9 t/ha em bandeja de 128 células e 19,9 t/ha em bandeja de 288 células). As mudas transplantadas com 32 dias apresentaram maior peso médio de cabeça (319 g). Concluiu-se ser recomendável produzir mudas de couve-flor em bandejas com 128 células.

(423) Effect of Seed Radiography on Seed Quality

Radiography is a simple and nondestructive technique to detect empty, immature, and insect- and mechanically damaged seed during seed processing and testing. However, there is a lack of information on the effect of X-ray on seed quality despite recommendations by the Association of Official Seed Analysts for testing agricultural and forest tree seeds since 1979. Two experiments were carried out using lettuce seed of Seed Dynamics, Inc. (No. 52694) and Faxitron MX-20 cabinet X-ray unit set at 20 kilovoltage (kV) for 20 seconds, a standard setting to observe many species of flower seeds. In both experiments, the focus-object distance was 34 cm with no image magnification. The treatments in Experiment 1 were 0 (control), 4, 8, and 12 times of X-ray exposures and Experiment 2 were 0 (control), 15, 30, and 60 times of X-ray exposures on non- and 5-hour imbibed seed. In Experiment 1, germination was done in 288-cell seedling trays in soilless potting mix under greenhouse conditions with four replications of 50 seeds per replicate to observe germination rate, and cotyledon and young leaf discoloration and deformation. Experiment 2 was analyzed using computerized seedling imaging system on germination paper to examine seed vigor and germination rate. There were no significant differences in germination rate in both the non- and imbibed seed in the two experiments. The mean germination rates were 77.75% in Experiment 1 and 94.81% in Experiment 2. No cotyledon and young leaf discoloration and deformation were observed in Experiment 1 and no significant differences in vigor index were found in Experiment 2. The conclusion is that there was no observable effect of repeated X-ray exposures up to 60 times at 20 kV and 20 seconds on a seed lot for both non- and imbibed lettuce seed.

Comparison of direct-seeded, bareroot, and various tray seedling densities on growth dynamics and yield of long-day onion

Comparaison entre le semis direct, la transplantation a racine nue et diverses densites de plants en godets dans la dynamique du developpement et la production d'oignon de jour long. Developpement d'oignon transplante a densite augmentee. Le developpement de la racine, du bulbe et du tige d'oignon transplante obtenu a partir de plants en godets de 228 compartiments a ete etudie. Les traitements ont ete un (TC1), deux (TC2), ou trois (TC3) plants/compartiment, et une plante separee dans la transplantation de celles developpees avec deux (TC2-1) ou trois (TC3-1) plants/compartiment. Les controles ont ete: semis direct (DC) et transplantation a racine nue (BR). Les plantes transplantees ont ete disposees en rangee avec les distances suivantes: 5 cm (BR, TC1, TC2-1, TC3-1), 10 cm (TC2), et 15 cm (TC3). Pendant le premier et le mi-developpement le nombre de racines et le poids sec de racines a ete superieur pour TC 1 compare avec BR. La masse de feuilles des plantes transplantees s'est dessechee dans les 64 et les 80 jours apres la transplantation (DAT). Initialement, DS a eu un taux de formation de bulbe rapide, tandis que les plantes transplantees ont montre un taux plus rapide 60 DAT. Avant la maturite finale, TC1 a eu une taille des bulbes plus grande que DS et TC3. Les productions totales ont ete semblables, mais la production en classes de taille a differe de maniere significative entre les traitements. DS et TC3 ont eu une augmentation dans la taille des bulbes petits (35-50 mm de diametre). Tous les plants en godet, excepte TC3, ont eu une augmentation significative dans la taille des bulbes grands (60-70 mm). TC1 a eu 36 % de la production totale commercialisable avec la taille jumbo (> 70 mm) par rapport a 16 % pour le semis direct et a 24 % pour la transplantation a racine nue.

Top-dressing of paprika transplants in trays with fertilizers of phosphorus- and nitrogen surplus

By our experiments, we wished to answer the question: may top-dressing with nitrogen and phosphorus fertilizers, respectively, improve the quality of transplants grown in trays on a substrate enriched by 2 kg/m3 of retarded fertilizers?
 The experiments started in spring and autumn 2002, in a large volume plastic house. The seedlings were grown in trays. Seed was sown directly into KITE trays of 187 cells (28 cm3 volume per cell, 779 seedlings per square meter). The trays were filled by "loose filling" (without packing) with the following soil mixture: 50% Baltic highmoor peat, 50% 'Nitrite lowmoor peat, 1,5 kg/m3 feed chalk, 2 kg/m3 slow acting chemical fertilizer of phosphorus overweight, 2 kg/m3 superphosphate. The test plant was the vegetable paprika variety `Tizenegyes'.
 The trials were made in order to clear up if top-dressing done once or twice improves the quality of the seedlings. For this purpose, perfectly soluble fertilizers of phosphorus or nitrogen surplus were used. 3 I fertilizer solution of 0.2% concentration was given per square meter on every single occasion. The control plots received no top-dressing.
 The following parameters were registered: stem diameter, plant height, fresh weight of the top, dry matter content of the top, fresh weight of the root system per plant, dry matter content of the roots.
 The experimental results with top-dressing have clearly proved the insufficiency of mixing 2 kg/m3 of retarded fertilizer into the substrate, as usual in raising paprika seedlings in trays, because of the long period of transplant raising. According to our experiments the additional nitrogen fertilization influences positively the development of green parts of plants, while the multiple application of fertilizers with higher phosphorus-content helps to develop a strong root system. We suppose, that the more often applied additional fertilizers, maybe the combination of fertilizers with nitrogen and phosphorus amount could give use even better results.

Effects of cyazofamid against Plasmodiophora brassicae Woronin on Chinese cabbage.

Cyazofamid (4-chloro-2-cyano-N,N-dimethyl-5-p-tolylimidazole-1-sulfonamide) is a novel fungicide with high levels of activity against Oomycetes fungi and Plasmodiophora brassicae Woronin. The effects of cyazofamid were investigated against P. brassicae, the causal agent of clubroot disease in Chinese cabbage. Cyazofamid at 0.3 mg litre(-1) inhibited resting spore germination of this pathogen by about 80%. Cyazofamid at 3-10 mg litre(-1) exhibited fungicidal activity to resting spores of P. brassicae 1-10 days after treatment. When cyazofamid was applied to infested soil, both root-hair infections and club formation caused by P. brassicae were strongly inhibited at 1-3 mg kg(-1) dry soil. These results suggest that cyazofamid directly inhibits resting spore germination, thereby leading to the inhibition of root-hair infection and club formation. Cyazofamid at 3 mg kg(-1) dry soil also exhibited complete control of clubroot disease. The effect of broadcast soil application using a dust formulation at 2 kg AI ha(-1) (equivalent to 1.3 mg AI kg(-1) dry soil), and plug seedling tray application by a suspension concentrate formulation at 200 and 400 mg AI tray(-1) (30 x 60 x 4 cm3) against P. brassicae was also evaluated. Cyazofamid exhibited good efficacy against the pathogen. The sequential treatment including plug seedling tray application with cyazofamid and pre-plant broadcast soil application with the fungicide fluazinam also exhibited excellent levels of control. These results indicate that cyazofamid has a high potential to be an effective fungicide for the control of clubroot disease.

Economic evaluation of container seedling packing and disinfection machinery

Productivity and costs of packing container seedlings were studied in a mechanised line for packing and disinfecting seedling trays. The hypothesis was that adequate cost-efficiency could be achieved when some common principles of mechanisation were applied. Results indicated that the unit costs are lower than those of manual packing, if these principles were applied and the annual number of packed seedlings exceeded 6 million. However, most of the nurseries in Finland are still too small to gain a real advantage from large-scale production.

CONTROL OF PYTHIUM ROOT ROT OF VEGETABLE PEA SEEDLINGS IN SOILLESS CULTURAL SYSTEM

This study was initiated to develop non-pesticide methods to control Pythium root rot of vegetable pea seedlings in a soilless cultural system. The disease was not prevalent when new seedling trays were used for growing pea seedlings. However, when the cultural trays were used repeatedly for the same purpose, mycelia and oospores of Pythium aphanidermatum and P. ultimum produced by the infected roots contaminated the trays and became an important inoculum source to cause severe root rot. Drying the used trays under sunlight for months or immersing the trays in a calcium hypochlorite solution (2,000 ppm) for 24 hours before planting was effective in preventing this disease. Incidences of the disease were drastically reduced from 60-80% to less than 10% and yields of pea seedlings averaged 772 g/tray to 212 g/tray when the used trays were pre-treated with calcium hypochlorite solution comparing to the non-treated controls during hot growing season.

IT—Information Technology: Simulation of Automatic Tray-unloading Operations for Rice Seedlings

In Taiwan, rice nursery centres widely adopt gantry transport systems for transferring seedling trays to/from the hardening field. To facilitate the loading and unloading procedures, a tray-unloading machine riding on top of a gantry has been developed which can orderly lay down the trays on the ground for field hardening and also pick up the trays of grown seedlings onto the loading conveyer in sequence when they are ready for transplanting. The whole system can be run automatically in an open field for seedling preparation.A simulation model for seeded tray-unloading operations by the automatic tray-unloading machine has been developed and verified with six operational conditions. Judging by the slight difference between the simulated and observed results, it was concluded that the model can accurately predict the real tray-unloading operations and, therefore, can be used as a tool for further sensitivity analysis on the maximum operation patterns.A model simulation for the total system was set up and analysed by various operation combinations. The results indicate that the system throughput can be increased from 771 to 957 trays h−1 with 20 trays in a working row which represents an increase of 24·8%. Longer working rows will result in higher system throughput. The simulated results show that the system throughput changes from 771 trays h−1 for 10 trays per row to 1140 trays h−1 for 60 per row, with a significant increase of 48%.

Seedling herbivory by slugs in a willow hybrid system: developmental changes in damage, chemical defense, and plant performance.

We evaluated feeding preference and damage by the slug, Arion subfuscus, on seedlings of two willow species, Salix sericea and S. eriocephala, and their F1 interspecific hybrids. Trays of seedlings were placed in the field and excised leaves were presented to slugs in choice tests. Slugs preferred feeding on and caused the most damage to S. eriocephala seedlings. S. sericea seedlings were least preferred and least damaged. F1 hybrid seedlings were intermediate in preference and damage. Slug preference of and damage to these seedlings decreased over time, suggesting developmental changes in resistance. Seedlings were sampled for phenolic glycoside and tannin chemistry weekly to coincide with the field and laboratory experiments. Concentrations of phenolic glycosides and tannins increased linearly with seedling age, coincident with changes in slug preference and damage, indicating a developmental change in defense. Slug deterrence was not detected at low concentrations of salicortin when painted on leaves or discs, but both salicortin and condensed tannins deterred slug feeding at concentrations between 50 and 100mg/g, levels found in adult willows. Seedling performance was related to damage inflicted by slugs. Due to lower levels of damage when exposed to slugs in the field, S. sericea plants had significantly greater biomass than S. eriocephala plants. Biomass of F1 hybrids was equal to S. sericea when damaged. However, undamaged S. eriocephala and F1 hybrid plants had the greatest biomass. Because F1 hybrid seedlings performed as well as the most fit parent in all cases, slugs could be an important selective factor favoring introgression of defensive traits between these willow species.

The effect of natural enemies on the spread of barley yellow dwarf virus (BYDV) by Rhopalosiphum padi (Hemiptera: Aphididae).

The effects of two natural aphid enemies, adult Coccinella septempunctata Linneaus, a predator, and Aphidius rhopalosiphi de Stefani Perez, a parasitoid, on spread of barley yellow dwarf virus (BYDV) transmitted by the bird cherry-oat aphid, Rhopalosiphum padi (Linnaeus) were studied under laboratory conditions. Predators or parasitoids were introduced to trays of durum wheat seedlings and the patterns of virus infection were observed after two, seven and 14 days of exposure. More plants were infected with BYDV in control trays without A. rhopalosiphi than in trays with the parasitoid present, both seven and 14 days after the introduction of parasitoids. Patterns of virus infection were found to be similar over time in trays with a parasitoid present and in control trays. More plants were infected in trays with C. septempunctata present than in control trays, both two and seven days after the introduction of the coccinellid. The spread of virus infections progressed differently over time for the two treatments (predator and parasitoid), differences between treatments being most marked after two days and seven days, when more plants exposed to predators but fewer exposed to parasitoids were infected with BYDV compared to their respective controls. However, by the 14th day 88% of all plants were infected and there was no significant difference between the two treatments. The role of natural enemies in spread of BYDV is discussed.

First Report of Pre- and Postemergence Damping-off of Cowpea Caused by Pythium ultimum in South Africa.

During a disease survey of cowpea (Vigna unguiculata (L.) Walp.) in Southern Africa in 1999, a major problem recorded by small-holder rural farmers in areas with wet soil types was reduced seedling emergence. Nongerminated, diseased seeds in these fields were either a brown blotchy color or had a soft rot and disintegrated upon touch. Germinated seedlings failing to emerge above the soil line were characterized by water-soaked lesions girdling the hypocotyl. Emerged seedlings had necrotic taproots and few lateral roots. Infected hypocotyls above the soil line had light brown lesions, and seedlings showed symptoms of wilting. Diseased seeds and seedlings were collected, surface-sterilized, plated on 2% water agar, and Pythium ultimum was isolated. Identification was based on characteristics given in van der Plaats-Niterink (1). Sterile soilbased compost, infested by mixing with P. ultimum mycelia (10 CFU/g of compost), was used to fill 104-cell plastic seedling trays (40 × 28 × 3.5 cm). A single cowpea seed was planted at a depth of 2 cm in each cell, and trays were maintained in a greenhouse at approximately 20°C. Seeds and seedlings showed symptoms identical to those in the field 10 days after planting, and the pathogen was successfully reisolated. Seedlings in noninoculated compost remained symptomless. This is the first report of P. ultimum on cowpea in South Africa. Reference: (1) A. J. van der Plaats-Niterink. Monograph of the Genus Pythium. Centraalbureau voor Schimmelcultures, Baarn, 1981.

Containerized Muskmelon Transplants: Cell Volume Effects on Pretransplant Development and Subsequent Yield

Muskmelon (Cucumis melo L. cvs. Superstar and Mission) transplants were grown in cellular seedling trays of polystyrene or styrofoam, with individual cells ranging in volume from 7 to 100 cm3, transplanted to the field, and grown to maturity in Florida and Indiana during the 1993 and 1994 growing seasons. Seedling leaf area, shoot and root weights before transplanting, and shoot dry weight 20 days after transplanting increased linearly with increasing cell volume in Florida. Thirty days after transplanting, vine length showed significant linear and quadratic trends with respect to cell volume in Indiana. In Florida, early and total yields increased linearly as transplant cell volume increased for `Mission' in both years and for `Superstar' in 1994. In Indiana, early yields increased linearly as transplant cell volume increased for `Mission' in 1994 and for `Superstar' in both years, but cell volume did not consistently affect total yield. Transplant tray effects on early and total yield unrelated to linear or quadratic effects of cell volume occurred in both locations, but these effects were not consistent.

Machine Vision Assisted Robotic Seedling Transplanting

A machine vision assisted robotic transplanter was developed to improve the quality of the grow-out trays that contain transplanted plugs. The machine vision system was designed to identify and locate empty positions in the transplanted seedling trays. The detection algorithm was able to inspect uneven height growth medium blocks in randomly oriented seedling trays. Fifteen species of seedlings were used in evaluating the integrated machine vision assisted robotic system. The overall vision system success rate in identifying mistransplanted empty growth medium blocks in the transplanted seedling trays is 95%.

Conceptual Modeling Automated Seedling Transfer from Growing Trays to Shipping Modules

Automated field transplanters can plant several hundred seedlings per row per minute if the seedlings are presented to the transplanter in modules. Seedlings are grown in trays and transferred to the modules so that each cell in each module has a good seedling. If the operations to transform seeds into seedlings transplanted in fields are automated, then machines to transfer seedlings from trays to modules must be developed. An experimental machine built in 1991 ejected plugs from cells, gripped stems of seedlings and lifted them, transferred seedlings from tray to module, and dropped seedlings into a module. The machine was slow and incomplete. This article reports on a design which was conceptually modeled on a computer to correct the deficiencies of the experimental machine that was build. Projections from the conceptual model indicate that three 200-cell trays of seedlings can be transferred per minute, which is about 80% of the rate required by one field transplanter.

Changes Needed to Facilitate Automatic Field Transplanting

A lthough automatic transplanting of several field-grown vegetables is a reality, some changes in seedling production are necessary if the full potential of automation is to be realized. In automatic transplanting machines (ATMs) that are available, containerized seedlings such as lettuce, cauliflower, and celery are removed from the seedling trays and planted into the ground without human intervention. The advantages of containerized transplants from a crop production perspective are widely recognized. It is time to recognize and emphasize the features of this growing system that aid in theengineering of automatic transplanting systems. From an engineers perspective, containerized seedlingsare in an orderly array, in a configuration that is repeated again and again, unlike bare-root seedlings, which come in random bunches. Each seedling tray can be treated like a gun-cartridge magazine and fed through an ATM, which removes the seedlings and then places them individually into the ground. Alternative arrangements for presenting seedlings to an ATM include connected paper cells (Nippon Beet Sugar Manufacturing Co., 1985), bandoliers (Boa, 1978) strips of seedling cells (Williams, 1986), and cells within trays (Brewer, 1990). Recently, several engineers from around the world used rectangular seedling trays, with some variations, for their ATMs.

VARIETAL RESPONSE OF LANDSCAPE ANNUALS TO GREENHOUSE-APPLIED TRIAZOLE GROWTH REGULATORS

Seven to 9 cvs each of Begonia semperflorens, Tagetes erecta, T. patula, and Petunia hybrida (grandiflora and multiflora types) were sown into seedling trays. One to 3 weeks after transplanting to flats (75 cm3/cell), paclobutrazol (PB) was sprayed at concentrations of 10 (begonia), 60 (marigold) or 100 (petunia) mg liter-1 at a 200 ml m-2 rate. Uniconazole (UC) was applied at one-half the PB concentrations. Plant height was measured before planting in the field May 17 and monthly through July. Species were analyzed separately and generally, there were no cultivar by triazole interactions. During the greenhouse phase, the triazoles controlled height of both marigold species compared to control, but in July the PB and UC treated plants were 100 and 91%, respectively, of control plant height. Flowering was delayed up to 4 days for UC treated T. patula plants. Height of triazole-treated petunias was 60-67% of control height during the greenhouse phase and 84-95% after 2 months in the field. Begonia height was reduced by triazoles during both phases. After 2 months in the field, PB and UC treated begonias were 72 and 44%, respectively, of control plant height.

Effect of early transplanting upon growth and development of spruce and pine seedlings in paperpot containers

Black spruce (Picea mariana [Mill.] B.S.P.) and jack pine (Pinus banksiana Lamb.) seedlings were transplanted into Japanese paperpots at five different stages of development between the occurrence of an erect hypocotyl and 14 days after initiation of primary needles. Transplanting difficulty increased between the first and last treatments, and transplanting generally became impracticable after the stage of primary-needle initiation. Transplanting had a relatively minor effect on the eventual size of 12-week-old pine and 16-week-old spruce seedlings, although the incidence of root deformities inside the container increased rapidly as transplanting was delayed beyond the erect-hypocotyl stage. These deformities persisted after seedlings were outplanted, but did not appear to have a negative effect on the subsequent growth of new roots into the planting medium. Despite the absence of major adverse effects, it is recommended that transplanting be avoided as a routine practice for supplementing stocking in trays of containerized seedlings because of possible biological risks, the difficulty of ensuring careful transplanting and high labor costs.

Enhancing the Container-Stock Seeding Efficiency in Forest Nurseries

By modelling seed-count distributions per seedling tray, it is possible to determine the optimal seeding rate that leads to lowest labour costs for maximal container-stock production. The optimal seeding rate decreases with increasing seeding precision, seed viability, and seed costs. These results are illustrated for Paper pots and Jiffy pots seeded with black spruce. Survey-type information is provided for other species (jack pine, red pine, Norway spruce, white spruce). Key Words: Seeding, seed costs, transplanting, thinning, Binomial distribution.

An Improved Electro-Hydraulic Vegetable Seedling Block Transplanting

Atwo-row electro-hydraulic vegetable seedling block transplanter was designed and tested. The transplanter automatically depotted-cylindrical seedling soil blocks from a seedling tray and transplanted them onto a pre-formed seedling bed. The transplanter was carried on a semi-mounted frame pulled by a tractor. Results of field tests were satisfactory.

Formation of ectomycorrhizae on Pinustaeda seedlings exposed to simulated acidic rain

Effects of simulated acidic rain on formation of ectomycorrhizae were studied with Pinustaeda seedlings grown in plastic trays in a greenhouse. Trays of ectomycorrhizal seedlings were exposed 37 times over 16 weeks to simulated rains adjusted to pH 5.6, 4.0, 3.2, or 2.4. After exposures, mean percentages of short roots that were mycorrhizal (%M) were greatest (62.2%) for seedlings exposed to rains of pH 2.4. Values of %M exhibited a quadratic relationship with rain acidity (%M = 146.49 − 48.96 (rain pH) + 5.68 (rain pH)2). Values of R/S (root/shoot ratio) were negatively correlated (P < 0.01) with %M. Responses of ecetomycorrhiza formation and associated shoot growth to acidity of simulated rains suggest that rains of intermediate acidity (pH 4.0 and 3.2) inhibited ectomycorrhiza formation, or that increased soil acidity or other factors induced by rains at pH 2.4 enhanced ectomycorrhiza formation.