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Application of fatty alcohol to rootstocks used for vegetable grafting has been shown to increase the efficiency of producing grafted transplants by controlling cucurbit (Cucurbitaceae) rootstock meristematic regrowth and by allowing the rootstocks to accumulate carbohydrates, especially starch, over time in the hypocotyl and cotyledon. A grafting experiment was conducted to determine the effect of increased carbohydrates on survival of watermelon (Citrullus lanatus) grafts using standard grafting procedures. 'Carnivor' interspecific hybrid squash (Cucurbita maxima x C. moschata) and 'Macis' bottle gourd (Lagenaria sicereria) rootstocks at 1, 7, 14, and 21 days after fatty alcohol treatment were grafted with 'Tri-X 313' seedless watermelon using the one-cotyledon method. Graft survival on 'Macis' rootstock was acceptable or significantly increased up to day 14, with a slight decrease at day 21. Graft survival on 'Carnivor rootstock was also acceptable up to day 21, with a significant increase between days 1 and 7. The second experiment was conducted to determine whether the increased carbohydrates provide sufficient energy to successfully graft without the rootstock cotyledon, a method that has previously shown inconsistent results. Graft survival was improved by 90% using treated 'Carnivor' rootstock 7 days after fatty alcohol treatment and 'Macis' rootstock 14 days after fatty alcohol treatment. Adoption of the hypocotyl-only graft method in commercial production may increase efficiency by better using greenhouse space and could decrease disease probability by removing the cotyledons before grafting. [ABSTRACT FROM AUTHOR]

Abstract Three varieties of Hosta (‘Striptease’, ‘Minuteman’ and ‘Stiletto’) at four densities (40, 80, 120 and 200 explants per litre) were micropropagated on semi-solid agar and a thin-film liquid system with intermittent wetting of plant tissue. The mechanics of wetting by a small wave front required a larger rectangular vessel (11 × 27=297 cm 2) compared to the common cylindrical baby food jar (18 cm 2). Plants multiplied more rapidly in the agitated thin-film system than on agar. Lower plant densities increased rates of multiplication in liquid, but had little or no effect on multiplication rate on agar. Increasing plant density lowered the overall multiplication rate, but yielded greater numbers of plants per vessel. Yield, tabulated for utilization of shelf-space in growth room, was greater at all densities in rectangular vessels of liquid than conventional jars of agar media. Increased plant density lowered the sugar residual in media following the culture cycle and liquid media had less residual sugar than agar media. A liquid medium with 50 g l-1 sucrose was concentrated enough so that sugar depletion did not limit growth, even at the highest densities. The liquid system allows the technician to skip the step of manually spacing and orienting the freshly cut bud tissue at the transfer station. Harvesting 75–100 plants per vessel from the large rectangular vessels resulted in most efficient use of technician time. Plants from liquid and agar acclimatized to greenhouse. Increased multiplication, space utilization, sugar availability and worker efficiency was demonstrated to be greater in thin-film liquid than more conventional agar-based system.

The effects of storage temperature and shoot preparation of elephant ears (Colocasia antiquorum 'Illustris') were examined to determine how to successfully store plants prior to greenhouse forcing. A series of experiments were conducted that provided storage temperatures of 4, 7, 10, 13, or 16 °C (39.2, 44.6, 50.0, 55.4, or 60.8 °F), and plants were placed into storage with the shoots uncut or cut to 3.0 cm (1.18 inches) above the surface of the growing medium. The storage duration ranged from 40 to 49 days. All plants stored at 4 or 7 °C died. Plant survival was 89% to 100% at 10 °C, while plant survival was 100% at 13 or 16 °C. Shoot emergence and plant growth was faster following storage at 13 and 16 °C, than storage at 10 °C. Storage at 16 °C resulted in leaf growth occurring during storage, which was undesirable. Removing shoots prior to storage had no effect on plant survival and performance during forcing. A fungicide drench with iprodione immediately prior to storage did not improve plant survival. This study suggests that 13 °C is near the base temperature for leaf development of elephant ears, thus the plants survive at this temperature with no growth occurring. Shoot removal prior to storage is recommended in order to optimize storage room space. [ABSTRACT FROM AUTHOR]

Abstract The goal of this research was to investigate if culturing in high sucrose (5%) liquid media during multiplication phase (stage II) would enhance endogenous sugar levels and dry matter sufficiently to allow storage of in vitro plants in sugar free media without adversely affecting post-storage recovery. Hosta tokudama ‘Newberry Gold (NBG)’ and Hosta ‘Striptease’ were cultured in Murashige and Skoog (MS) media containing 5% sucrose during stage II and transferred to rooting phase (stage III) in MS medium without (0%) sucrose or with 3% sucrose for 4?weeks. At the end of stage III, cultures were stored, with the remaining media, at 10?°C with 5? µ mol?m -2 ?s -1 photosynthetic photon flux (PPF) from cool white fluorescent lamps for 7 or 14?weeks with or without a 2-week dark period prior to removal from storage. In both cultivars, stage III plants cultured in 3% sucrose media had higher soluble sugar levels and greater shoot and root biomass than those cultured in 0% sucrose media. Shoot and root soluble sugars decreased during storage. Shoot growth ceased during storage in both media. Root dry matter continued to increase in plants stored in 3% sucrose media but did not change in 0% sucrose media. Plants cultured in 3% sucrose media had less leaf chlorosis and less mortality after 7 or 14?weeks of low temperature storage than the plantlets from sugar free media. Extending the storage period from 7 to 14?weeks or introduction of 2-week dark period at the end of storage did not affect leaf chlorosis or plant mortality during acclimatization. Post-storage growth varied with the cultivar. Benefit of having sucrose in storage media was to develop a strong root system that aided the acclimatization and post-storage growth following 7 or 14?week storage. Sucrose ‘loading’ by culturing plants in liquid media containing 5% sucrose did not allow storage in sugar free media without adversely affecting post-storage growth in both cultivars.

Summary: Agitated layers of liquid medium were created on platform shakers in jars with 25–30 ml of medium (similar to conventional agar culture) rotating at 90 rpm. Thin films were scaled up in larger rectangular vessels on tilted shelves that periodically rock. In jars of liquid medium with a density of 180 explants per liter, multiplication rates of Hota tokudama var. ‘Newberry Gold’ were optimal with a media sucrose concentration of 5% [both with and without 1 μM benzyladenine (BA)]. Endogenous levels of soluble sugars were directly related to the concentration of sucrose in the medium. Three Hosta cultivars (‘Striptease’, ‘Minuteman’, and ‘Stiletto’) with plant densities of 40–200 explants per liter of medium were tested in larger, agitated, thin-film vessels in media with 5% sucrose and directly compared to agar medium. Higher rates of multiplication were observed in liquid than agar with the magnitude of the difference dependent on explant density. Pooled results for the three varieties with 200 explants per liter showed multiplication rates of 1.7x and 2.3x for agar and thin-film liquid, respectively. At 40 explants per liter, the multiplication rate was increased to 2.1x for agar and 3.4x for thin-film liquid. Sugar uptake was greater in liquid than agar and was greater in the higher densities, with the magnitude of the effect dependent on plant variety. Increased vessel size in the liquid, thin-film system and greater sugar uptake allowed more, larger plants to be harvested. Alocasia macrorrhizos was cultured in growth medium containing 1μM BA and 5% sucrose with plant densities in the range of 33–330 explants per liter. Dry weight and multiplication rate were greater in the liquid system than agar with the magnitude of the difference dependent on plant density. With approximately 165 explants per liter, and greater at the initiation of culture, plant density limited growth in both agar and liquid thin-film systems. In a multiplication medium (3 μM BA and 3 μM ancymidol) plant size was reduced by 50% and 60% (fresh weight) in liquid and agar, respectively. Initial density in the range of 165–330 explants per liter did not limit growth with the smaller plants in liquid or semisolid multiplication medium. Sugar uptake was greater in liquid than agar. While ample sugar was present in media for growth at any density on agar, sugar depletion was limiting growth at highest densities with the larger plants in liquid growth medium. In semisolid agar medium, sugar uptake by plants was more rapid than diffusion across the agar medium, resulting in non-equilibrium conditions following the culture cycle. In agitated, liquid medium, a greater transfer of sugars to plant tissue was related to accelerated growth.

The effects of sucrose concentration (1, 3, 5, or 7% w/v) in liquid media, in the presence and absence of benzylaminopurine (BAP), on internal carbohydrate status and growth of Hosta tokudamaTratt. ‘Newberry Gold’ during the multiplication phase (stage II) was investigated. Cultures from all treatment combinations were transferred to media containing 3% (w/v) sucrose during the rooting phase (stage III). At the end of the stage III, these micropropagules were subjected to 5 weeks of storage at 10 °C under low light (photosynthetic photon flux of 5 µmol m−2s−1). Endogenous concentrations of soluble sugars (glucose, fructose, and sucrose) in the plantlets increased linearly as the media sucrose concentration increased from 1% to 7% during stage II. Root and shoot biomass increased with increasing media sucrose concentration. BAP increased the biomass and multiplication rate but did not affect internal concentration of soluble sugars. While in storage, endogenous sugar levels and plantlet dry weight remained unchanged for all treatments. Following storage, plants originally cultured in 5% and 7% media sucrose had higher dry weight and less leaf chlorosis than those cultured in 1% and 3% media. Differences in endogenous soluble sugar levels at the end of stage III rooting, and after storage were related to the sucrose concentration of the initial stage II multiplication medium. Increased media sucrose levels during the multiplication cycle has a positive, long-term effect on plant morphology and quality.

Abstract: The aim of this investigation was to establish environmental factors which promote growth and photosynthesis of melon (Cucumis melo L.) shoot buds, in vitro, and determine if photoautotrophic shoots had superior root forming ability in photoautotrophic environments. Buds from the triploid melon clone ‘(L-14B)L-14’ were observed for 21 days after transfer from a multiplication MS medium with 3% sucrose and 10 μM benzyladenine (BA) to a shoot development medium with 1 μM BA at three levels of sucrose in the medium (0, 1 and 3%), and light (50, 100 and 150 PPF) and CO2 (500, 1000 and 1500 ppm) in the culture chamber. More shoot buds were observed with 3% sucrose in the medium. Increased light and CO2 had a positive interaction with shoot proliferation. Fresh and dry weights were greatest at 3% sucrose, 150 PPF light and 1500 ppm CO2. Shoot buds grew more slowly in sugar-free medium, but fresh and dry weight still doubled over 21 days of culture. Net photosynthetic rates (NPR) of buds were negative after four days in treatment conditions, but became positive after transfer to fresh, sugar-free medium. Two triploid genotypes of melon were (1) grown in vitro with sugar (photomixotrophic) and without sugar (photoautotrophic), (2) rooted in sugar-free media, both in a laboratory controlled environment chamber (in vitro) and a greenhouse acclimatization unit (ex vitro), and (3) compared for subsequent nursery growth in the greenhouse unit. The genotype ‘(L-14B)L-14’ produced more shoots than ‘(L-14B)Mainstream’ in both photomixotrophic or photoautotrophic conditions. ‘(L-14B)L-14’ rooted as well from either photoautotrophic and photomixotrophic shoots but ‘(L-14B)Mainstream’ rooted less frequently from photoautotrophic shoots. Seventy-six percent of the shoots in the laboratory controlled environment chamber were able to root photoautotrophically, whereas 47% of the shoots in the greenhouse acclimatization unit were rooted. Between 77% and 88% of plantlets from all treatment combinations survived transfer to the nursery. After growth in the nursery, the sizes of plants (fresh weight, dry weight, leaf area) were the same for either genotype, from either photoautotrophic or photomixotrophic shoots. Nursery plants that had been rooted in the laboratory controlled environment chamber were larger than those rooted in the acclimatization greenhouse chamber.

Growth of two Cattleya clones (Sophrolaeliocattleya Jewel Box 'Scheherezade' and Brassolaeliocattleya Rugley's Mill 'Mendenhall') over 6 or 8 months on microporous polypropylene membrane rafts was compared for several inorganic nutrient formulations: Murashige and Skoog at full, half and quarter strength; Hoagland's hydroponic medium; and three media formulated specifically for orchid culture (Knudson, Lindemann, and Vacin and Went). Greatest fresh weight and number of plants per vessel were obtained on Murashige and Skoog medium and dilutions thereof. Shoot growth was greater than root growth only on full strength MS media. Media uptake by tissue and evaporation from the vessels required additional water to maintain contact between membrane and liquid. Most rapid growth occurred in periods following addition of water. In more dilute media formulations, shifting growth from shoots to roots was a possible outcome of low concentrations of ammonium.

Abstract: Watermelon [Citrullus lanatus (Thunberg) Matsumura and Nakai] proliferating shoot meristems from established shoot cultures were inoculated on modified Murashige and Skoog salts medium supplemented with 10 μM 6-benzyladenine (BA) for shoot proliferation and on similar medium supplemented with 1 μM BA and 10 μM gibberellic acid (GA3) for shoot elongation. Agar-solidified medium and microporous polypropylene membrane rafts in liquid medium were used to support the tissues. Growth over culture time of proliferating and elongating tissues in liquid and agar-solidified media were compared. Nutrient depletion in liquid medium was monitored and quantified using ion selective electrodes. Tissue fresh weights in both proliferation and shoot elongation media were greater in liquid than in agar-solidified medium. Relative dry matter content, however, was greater in agar-solidified than in liquid medium. More shoots elongated in agar-solidified than in liquid medium. The numbers of buds or unelongated shoot meristems, however, were comparable for both the liquid and agar-solidified medium. Proliferating and elongating tissues in liquid medium used Ca++ and K+ minimally. NO 3− was utilized but not depleted by proliferating tissues. NH 4+ , however, was depleted. Most of the NH 4+ was utilized by the proliferating tissues within 21 days of culture when growth rate was greatest. At 35 days, residual Ca++, K+, NO 3− , and NH 4+ in proliferation medium were 81.0%, 67.8%, 55.7%, and 1.2% of initial levels, respectively. NO 3− and NH 4+ in shoot elongation medium were depleted. The greatest NO 3− and NH 4+ utilization was observed during the first 14 days of culture when the largest growth rate was obtained. The residual Ca++, K+, NO 3− , and NH 4+ in shoot elongation medium at 38 days were 63.5%, 37.9%, 21.2%, and 24.3% of initial concentrations, respectively. At the end of experiment, 72.3% and 42.8% of initial sugars were still remaining in the shoot proliferation and shoot elongation medium, respectively.