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Allison Hurt, Roberto G. Lopez, and Joshua K. Craver

, 2005 ; Styer, 2003 ). This low DLI can be detrimental to seedling quality, as previous research has determined that a DLI of 10 to 12 mol·m –2 ·d –1 is required for the production of high-quality seedlings ( Pramuk and Runkle, 2005 ; Randall and

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Masahumi Johkan, Kazuhiro Shoji, Fumiyuki Goto, Shin-nosuke Hashida, and Toshihiro Yoshihara

with other light sources. In this study, we determined the effects of raising seedlings with different light spectra such as with blue, red and blue + red LED lights on seedling quality and yield of red leaf lettuce plants. Photosynthetic pigments

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Joshua K. Craver, Jennifer K. Boldt, and Roberto G. Lopez

relative chlorophyll content), and had a higher root mass than those produced under greenhouse supplemental lighting or ambient lighting conditions. Increases in radiation intensity and DLI have been reported to increase seedling quality and decrease

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Z. Mganilwa, M. Nagata, H. Wang, and Q. Cao

Based on seedling properties and stage of growth for cucurbitaceous and solanaceous vegetables, separate robots are being marketed for each. Full automatic grafting robots are used for solanaceous vegetables like tomato and egg-plant employing ordinary splice method by making a diagonal cut through the hypocotyl of both the scion and the rootstock. However, cutting one piece of cotyledon diagonally from the rootstock does grafting of cucurbitaceous vegetables like cucumber, melon, and pumpkin. This method had the advantage of easy recovery and high survival rate of seedlings. Only semi-automatic robots are marketed for this kind of plants because a fixed cotyledon orientation is required for grafting operation. Both the scion and the rootstock are loaded manually to their corresponding feeding devices. To replace the manual loading operation, this study proposed a neural network based automatic seedling loading system. The system automatically estimates the quality and determines the cotyledon orientation of seedling for guiding the loading device of the grafting robot. As a first step toward solution, we report the development of a model for seedling quality estimation and orientation detection using image processing and neural network techniques. The model has a learning ability and can judge seedlings according to the training patterns. A seedling leaves feature extraction model of 10 characteristics was proposed and a three-layer neural network was constructed. The experimental results indicate that the seedling leaves orientation was accurately detected with an average error of 3 degrees within 360 degrees of freedom and the machine vision system could properly classify seedlings into three classes (A-good, B-fair, and C-bad) according to the training pattern.

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Thomas M. Gradziel

All of the major California almond varieties are self-incompatible necessitating the interplanting of pollinizer varieties. The incorporation of self-compatibility into the dominant variety Nonpareil through mutation or genetic engineering would greatly improve cropping efficiency. Negative effects of inbreeding on resultant seed and seedling quality could negate production advantages. Inbred seed of Nonpareil were obtained by: a) enclosing mature trees in pollination cages containing bees at flowering, and, b) controlled crosses to a Nonpareil mutation (Jeffries) which is unilaterally compatible when used as the seed parent. Selfed seed set from caged trees was less than 0.001% of available flowers. Seed set from crosses to the Jeffries mutation averaged 34.4% which was not significantly different than outcrossed controls. No significant loss in kernel weight and dimensions were observed in any of the inbred material when compared with outcrossed controls though a higher proportion of the inbred seed and seedlings failed to develop fully. Both average tree height and trunk diameter after 1 year of growth was significantly lower in inbred vs. outcrossed material. Results suggest no major penalty to kernel quality following self-pollination, though losses in progeny vigor should be a concern when utilizing selfed seed in variety development programs.

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Silvana Nicola

Root architecture can be very important in plant productivity. The importance of studies on root morphology and development is discussed to improve seedling growth. Root systems of dicotyledonous species are reviewed, with emphasis on differences between growth of basal and lateral roots. The presence of different types of roots in plant species suggests possible differences in function as well. The architecture of a root system related to its functions is considered. Classical methods for studying root systems comprise excavation of root system, direct observation, and indirect analyses. While the first method is destructive and the third is effective in understanding root architecture only on a relatively gross scale, observation methods allow the scientist a complete a nondestructive architectural study of a root system. The three groups are reviewed related to their potential to give valuable information related to the root architecture and development of the seedling, with emphasis on the availability of a medium-transparent plant-growing system, enabling nondestructive daily observations and plant measurements under controlled environmental conditions. Effects of CO2 enrichment on seedling growth is reviewed, emphasizing the effects of CO2 on root growth.

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Ming Ding, Beibei Bie, Wu Jiang, Qingqing Duan, Hongmei Du, and Danfeng Huang

( Kaczperski and Armitage, 1992 ). Although low-temperature storage preserves seedling vigor and inhibits overgrowth, it reduces seedling quality to some extent. The interruption of photosynthesis and the low-temperature stress were regarded to be the important

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Anthony S. Davis, Matthew M. Aghai, Jeremiah R. Pinto, and Kent G. Apostol

forest tree species. This promising new technology needs further investigation before being used operationally. If subirrigation was shown to be effective in maintaining seedling quality compared with overhead irrigation, the water conservation benefits

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Carlos A. Parera and Daniel J. Cantliffe

Poor emergence and low seedling vigor are characteristics of many supersweet sweet corn (Zea mays L.) cultivars carrying the shrunken-2 (sh2) gene. Four sh2 sweet corn cultivar seeds [`How Sweet It Is' (HSII), `Crisp N' Sweet 711' (CNS-711), `Sweet Belle' (SB), and `Dazzle' (DZ)] were solid-matrix-primed (SMP), SMP with sodium hypochlorite (SMPcl), treated with a fungicide combination (F) (Imazalil + Captan + Apron + Thiram), or primed with the aforementioned fungicides (SMPf). The seed treatments were tested in the laboratory and the field. Seed imbibition and leachate electrical conductivity were lower in SMP seeds than in nonprimed seeds. In the field, emergence percentage and rate of CNS-711 and SB (high-vigor seeds) were not improved by the seed treatments compared to the nontreated seeds. Emergence percentage and rate of HSII and DZ (considered low-vigor seeds) were improved as a result of SMPcl, SMPf, or F treatments compared to nonprimed seeds. Compared to the F treatment, the SMPcl presowing treatment increased DZ seedling emergence rate and percentage. The combined SMP and seed disinfection via NaOCl seems to be a promising fungicide seed-treatment substitute that improves the stand establishment and seedling vigor of sh2 sweet corn cultivars. Chemical names used: 1-[2-(2,4-dichlorophenyl)-2-(2-propenyloxy)ethyl]-1 H imidazole (Imazalil); N-[(trichloromethyl)thio]-4-cyclohexene-1,2-dicarboximide(Captan); N- (2,6-dimethylphenyl)- N -(methoxyacetyl)alanine methyl ester (Apron); tetramethylthiuram disulfide (Thiram).

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Nancy Kokalis-Burelle, C.S. Vavrina, M.S. Reddy, and J.W. Kloepper

Greenhouse and field trials were performed on muskmelon (Cucumis melo) and watermelon (Citrullus lanatus) to evaluate the effects of six formulations of plant growth-promoting rhizobacteria (PGPR) that have previously been shown to increase seedling growth and induce disease resistance on other transplanted vegetables. Formulations of Gram-positive bacterial strains were added to a soilless, peat-based transplant medium before seeding. Several PGPR treatments significantly increased shoot weight, shoot length, and stem diameter of muskmelon and watermelon seedlings and transplants. Root weight of muskmelon seedlings was also increased by PGPR treatment. On watermelon, four PGPR treatments reduced angular leaf spot lesions caused by Pseudomonas syringae pv. lachrymans, and gummy stem blight, caused by Didymella bryoniae, compared to the nontreated and formulation carrier controls. One PGPR treatment reduced angular leaf spot lesions on muskmelon compared to the nontreated and carrier controls. On muskmelon in the field, one PGPR treatment reduced root-knot nematode (Meloidogyne incognita) disease severity compared to all control treatments.