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  • Author or Editor: M. A. L. Smith x
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The only method for large scale production of pure hybrid seed in Zinnia elegans involves the use of male sterile individuals. The male sterile trait, however, is a three gene recessive which at best produces only 50% male sterile progeny from seed. Since no method of clonal propagation is available, seed-produced female lines require labor intensive field roguing to insure removal of all normal flowered individuals. Clonal micropropagation was investigated as a means of mass producing male steriles for use as female lines. Sterilization procedures were developed for seed and axillary bud explants. Shoot proliferation media containing various levels of BAP, 2ip, and kinetin were screened using in vitro germinated seedling explants of the inbred line `Orange Starlight'. Microshoots demonstrated a high rooting percentage after 2 weeks on basal medium without growth regulators. Plantlets were easily acclimated in 1 to 2 weeks in a high humidity environment. In vitro derived plants of identified male sterile plants were phenotypically evaluated as to their suitability for use in field production.

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The only method for large scale production of pure hybrid seed in Zinnia elegans involves the use of male sterile individuals. The male sterile trait, however, is a three gene recessive which at best produces only 50% male sterile progeny from seed. Since no method of clonal propagation is available, seed-produced female lines require labor intensive field roguing to insure removal of all normal flowered individuals. Clonal micropropagation was investigated as a means of mass producing male steriles for use as female lines. Sterilization procedures were developed for seed and axillary bud explants. Shoot proliferation media containing various levels of BAP, 2ip, and kinetin were screened using in vitro germinated seedling explants of the inbred line `Orange Starlight'. Microshoots demonstrated a high rooting percentage after 2 weeks on basal medium without growth regulators. Plantlets were easily acclimated in 1 to 2 weeks in a high humidity environment. In vitro derived plants of identified male sterile plants were phenotypically evaluated as to their suitability for use in field production.

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Abstract

Roots of sweet potato [Ipomoea batatas (L.) Lam.] and beet (Beta vulgaris L.) peeled with superheated steam, had higher peel and trim yields than did those peeled with saturated steam at the same pressure. Product recovery was greater with all steam-peeling methods than with caustic peeling. Direct injection of cold water into the partially pressurized steam atmosphere of the peeler also increased product recovery. Better color retention in processed beets was obtained from steam-peeled roots than from caustic-peeled roots.

Open Access

Industrial-scale cultivation of plant cells for valuable product recovery (e.g. natural pigments, pharmaceutical compounds) can only be considered commercially-feasible when a fully-automated, predictable bioprocess is achieved. Automation of cell selection, quantification, and sorting procedures, and pinpointing of optimal microenvironmental regimes can be approached via machine vision. Macroscopic staging of Ajuga reptans callus masses (ranging between 2-6 g FW) permitted simultaneous rapid capture of top and side views. Area data used in a linear regression model yielded a reliable, non-destructive estimate of fresh mass. Suspension culture images from the same cell line were microscopically imaged at 4x (with an inverted microscope). Using color machine vision, the HSI (hue-saturation-intensity) coordinates were used to successfully separate pigmented cells and aggregates from non-pigmented cells, aggregates, and background debris. Time-course sampling of a routine suspension culture consistently allowed pigmented cells to be detected, and intensity could be correlated with the degree of pigmentation as verified using spectrophotometer analysis of parallel samples.

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Interactions between irradiance levels (5–40 μmol·m-2·s-1) and iron chelate sources (FeEDTA and FeEDDHA) were observed for Carica papaya shoot tip cultures during both the establishment and proliferation stages of microculture. Reduced levels of irradiance (5 μmol·m-2·s-1) favored shoot tip establishment regardless of the source or level of iron. However, the highest percentage of successful explant establishment (100%), and significantly greater leaf length (1.16 cm; over double the size attained in any other treatment), resulted when a low concentration of FeEDTA alone was used at low irradiance. During the subsequent shoot proliferation stage, however, higher irradiance levels (30 and 40 μmol·m-2·s-1) were required, and FeEDTA failed to support culture growth when used as the sole iron source. The highest multiplication rates (3.6 shoots per explant) and leaf chlorophyll concentrations (0.22 mg/g fresh mass), and significantly improved shoot quality were achieved at 30 μmol·m-2·s-1 irradiance when both iron chelate formulations were combined (each at a 100 μM concentration) in the proliferation medium. Chemical names used: benzylamino purine (BA); ferric disodium ethylenediamine tetraacetate or FeNa2EDTA (FeEDTA); ferric monosodium ethylenediamine di(o-hydroxyphenylacetate), (FeNaEDDHA) or Sequestrene 138Fe (FeEDDHA); indoleacetic acid (IAA); 1-naphthaleneacetic acid (NAA).

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Tolerance of increased salinity by tomato is of great importance to the tomato processing industry, where increased conductivity of up to 6 dS m-1 is used to increase specific yield components. A new line of miniature dwarf tomato, Lycopersicon esculentum Mill. cv. Micro Tom, was evaluated for photosynthetic response to elevated salinity. Tomatoes were grown in solution batch culture and subjected to constant salt treatments of 2.4 (control), 7.6, 12.8, or 18 dS m-1. Weekly photosynthetic measurements were made beginning week 4 on the most recent fully open leaf or leaf opposite a fruit. Net photosynthesis decreased across all salt treatments over the last six weeks of sampling. As salinity level increased, net photosynthesis decreased compared to the control. The 18 dS m-1 treatment reduced net photosynthesis relative to 12.8 and 7.6 dS m-1. Although salinity increased succulence, limitations to net photosynthesis were due to diminished utilization of intercellular CO2, rather than reduced internal CO2 concentration or stomatal conductance.

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High salinity and boron often occur together in irrigation water in arid climates, but very little research has been done to study the interaction of the two. A greenhouse experiment was conducted at the US Salinity Laboratory in sand tanks to evaluate the interactions between B and saline drainage water on the performance of broccoli. Particular interest in this study was directed towards the composition of the salinizing solution to determine what role various salts have on the salinity-boron interaction. Results from this study indicate that both Cl-based salts and those characteristic of saline drainage water (i.e., a mixture of salts dominated by sodium sulfate) showed a significant salinity–boron interaction. At high salinity, increased B concentration was less detrimental, both visually and quantitatively (i.e., biomass), than it was at low salinity. That is, plants could tolerate a higher solution B-concentration at higher salinity. However, there was no significant difference between salt types. The effects on head weights were more exaggerated than those on shoot biomass. Shoot B concentration was influenced by salinity, but interestingly the direction of influence was dependent upon the B concentration in the solution. Regardless of the composition of the salinizing solution, increased salinity increased shoot B concentration when B concentrations in the solution were relatively low (i.e., 0.5 mg·L-1). At the highest solution B concentration (28 mg·L-1), increased salinity reduced shoot B concentration. Solution B in itself had very little influence on shoot ion accumulation, but both salinity (i.e., EC) and salinity composition had very strong influences on shoot tissue ion composition. Therefore, these data indicate that salinity and B are antagonistic.

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Natural plant pigments (produced as secondary metabolites in cell culture) can replace controversial synthetic chemical colorants to enhance the appearance of processed foods. Intensive bioreactor-based production systems designed for betalain pigment-producing cultures of Beta vulgaris are still not economically competitive, in part due to the slow, prohibitively expensive, and incomplete conventional methods (HPLC analysis, biomass estimates, cell counts) which must be used to assess culture status. As an alternative, software was written using Semper 6 (a high level programming language for image analysis) for collection of exacting morphometric (spatial) and photometric (spectral) process information from an intense violet cell line. Uniform, crisp images of 1 ml culture samples in multiwell plates were captured macroscopically, and the pattern of pigment production was traced at 3 day intervals over the course of a 15 day growth cycle with monochromatic color filters and image grey level data. Rod-shaped cells and aggregates were automatically sorted and measured using parameters of particle size, density, and circularity. The machine vision method offers greater opportunity to fine-tune cell selection for enhanced pigment content.

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