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Jonny E. Scherwinski Pereira and Gerson R. de L. Fortes

The present work aimed to evaluate the plant growth of the apple rootstock Marubakaido during the acclimatization process, after receiving different treatments of temperatures. Apple shoots were rooted in vitro and transplanted to greenhouse, where they remained for 2 weeks. After this period, the plants were treated under temperature of 4 ± 1 °C and 10 ± 1 °C, 16-h photoperiod at 5μmol·m-2·s-1 radiation for 0; 360, 720, 1080, and 1440 h. The plants were transferred to the greenhouse where their growth internode length and bud number were evaluated during 2 months. It was verified that there was an increase up to 697% in the height of the plants when they were treated for 1440 h, independently of the temperature. The internode length was also larger when the plants were treated for greater periods. The temperature of 10 ± 1 °C led to a decrease in the bud number, while at 4 ± 1 °C, significant differences were not observed. These results suggest that the use of higher temperatures (10 ± 1 °C), can also recover the plant growth during the acclimatization process.

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Zhenyong Wang, Manit Kossitrakun, and David R. Dilley

The “scald-like” disorder of `Empire' apples is a CO2-linked disorder. In this study we investigated the factors of acclimatization of preclimacteric fruits at 3°C in air or low O2 levels prior to elevating the CO2 concentration. Fruits were harvested at the immature stage, which had higher potential to suffer the disorder. Establishing CA conditions of 5% CO2 + 1.5% O2 at 3°C within 1 day of harvest resulted in the highest incidence of the `Empire' disorder, followed by 3% CO2 + 1.5% O2 > 5% CO2 + 3% O2 > 3% CO2 + 3% O2. The fruits had to be acclimated at 3°C for 3 to 4 weeks at 1.5% or 3% O2 to become insensitive to 5% or 3% CO2. Holding the fruits in air for 1 week prior to administering 3% or 5% CO2 was insufficient to control the disorder, whereas the fruits tolerated 3% or 5% CO2 after holding the fruits in air for 2 weeks. But, the 2-week delay to CA resulted in accelerating flesh softening. Supplemental carbon dioxide was not necessary for at least 1 month to maintain flesh firmness at near harvest values where fruits were kept at 1.5% O2. Whereas at 3% O2, the presence of 3% or 5% CO2 from the beginning of the storage period was required to retard flesh firmness decrease. Fruits stored for the entire storage duration without CO2 softened markedly. In summary, we conclude that establishing CA conditions of 3% to 5% CO2 with 1.5% or 3% O2 at 3°C within 1 week of harvest can lead to serious incidence of the `Empire' disorder with preclimacteric fruits. Moreover, fruits acclimate better in air than at low O2 levels with respect to tolerating CO2. This suggests a requirement of oxidative metabolism in acclimatization for CO2 tolerance. Beyond 7 days, acclimatization in air at 3°C before CA is established results in excessive flesh softening, even though it does prevent the disorder incidence.

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Astrid Kubatsch, Heiner Grüneberg, and Christian Ulrichs

Conover, C.A. Poole, R.T. 1977 Effects of cultural practice on acclimatization of Ficus benjamina L J. Amer. Soc. Hort. Sci 102 529 531 Dawson, I.A. King, R.W. van der Staay, R. 1991

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Yi-Chen Chen, Wei-Chun Chang, San-Tai Wang, and Shu-I Lin

robot ( Lee and Oda, 2010 ). Furthermore, the seedlings produced via the grafting method are healthy and strong ( Lee and Oda, 2010 ), and there is no need to remove the tube after successful grafting. Proper acclimatization, which includes healing and

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R.N. Trigiano and R.A. May

A tissue culture laboratory exercise illustrating regeneration of whole plants from leaf segments of chrysanthemum by organogenesis is described. Using simple, common media, shoots can be generated in 5 weeks and rooted after an additional 3 weeks. Acclimatization of plants can be accomplished in a simple mistbed in the greenhouse. The exercise is adaptable to depict genotype differences among cultivars, optimization of shoot induction, effects of growth regulators, and experimental design. Callus is typically not formed during shoot formation; however, co-cultivation of leaf segments with a virulent strain of Agrobacterium tumefaciens produces callus with a strain of disarmed A. tumefaciens harboring NPTII construct affects regeneration of plants resistant to kanamycin.

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Michio Kanechi, Masakatsu Ochi, Michiko Abe, Noboru Inagaki, and Susumu Maekawa

The effects of natural ventilation and CO2 enrichment during the rooting stage on the growth and the rates of photosynthesis and transpiration of in vitro cauliflower (Brassica oleracea L.) plantlets were investigated. In vitro plantlets were established in airtight or ventilated vessels with or without CO2 supplied (≈1200 μg·L-1) through gas permeable films attached to the vessel's cap for 15 days before transplanting ex vitro. Leaves generated in vitro in ventilated vessels had a higher photosynthetic rate than those produced in airtight vessels, which lead to greater leaf expansion and shoot and root dry matter accumulation during in vitro culture and acclimatization. Enhanced photosynthesis in leaves of ventilated plantlets was positively correlated with chlorophyll content. Increasing photosynthetically active radiation from 70 to 200 μmol·m-2·s-1 enhanced the growth of in vitro plantlets under ventilated conditions but it depressed photosynthesis of the leaves grown photomixotrophically with sugar and CO2 enrichment which might be due to the feedback inhibition caused by marked accumulations of sucrose and starch. Higher CO2 levels during in vitro culture enhanced photosynthesis under photoautotrophic conditions, but inhibited it under photomixotrophic conditions. Fifteen days after transplanting ex vitro, high photosynthetic ability and stomatal resistance to transpiratory water loss of ventilated plantlets in vitro had important contributions to rooting and acclimatization. Our findings show that the ventilated culture is effective for accelerating photoautotrophic growth of plantlets by increasing photosynthesis, suggesting that, especially for plantlets growing in vitro without sugar, CO2 enrichment may be necessary to enhance photosynthetic ability.

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Dennis Y. Yeo and Barbara M. Reed

Explants of three rootstock selections Pyrus calleryana Dcne `Oregon Pear Rootstock (OPR) 157', P. betulifolia Bunge `OPR 260', and P. communis L. `Old Home' × `Farmingdale 230' (`OH × F 230') were initiated from forced branches of field-grown trees. `OPR 260' and `OH × F 230' shoots cultured on Cheng medium with IBA proliferated better than those on NAA. NAA and IBA at concentrations >0.5 μm inhibited shoot multiplication. Overall, the best micropropagation medium for `OPR 260' and `OH × F 230' was Cheng medium with 8 μm BA and 0.5 μm IBA. Shoot multiplication of `OPR 157' was best on 8 μm BA and better on low NAA (0.5 μm) or no auxin than on IBA. `OH × F 230' rooted easily (>80%) with all IBA and NAA treatments. The best rooting treatment (42.9%) for `OPR 260' was 10 μm IBA in darkness for 1 week; for `OPR 157' (23.9%), it was a 15-second dip in 10 mm NAA. Only rooted plantlets survived 4 weeks of greenhouse acclimatization. Chemical names used: N6-benzyladenine (BA); indole-3-butyric acid (IBA); napthaleneacetic acid (NAA).

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Pious Thomas and John W. Schiefelbein

A novel combination of in vitro and in vivo approaches was employed to generate sufficient stock of an introduced grape (Vitis vinifera L.) cv. Arka Neelamani which significantly accelerated the multiplication rate. The in vitro part included induction of root and shoot growth in shoot tip and nodal microcuttings in MS medium containing 1 μm IAA, sequential pruning of shoots at 1, 1.5, and 2 months, leaving the basal one to two nodes, resulting in fresh sprouts on the stump, and use of remaining stumps for in vivo establishment. The in vivo part included acclimatization of in vitro rooted plantlets and stumps, use of single node cuttings from 1.5- to 2-month-old in vivo shoots for the subsequent propagation, and utilizing the fresh sprout growth from these cuttings and in vivo stumps for further propagation. Employing both in vitro and in vivo approaches, we achieved a multiplication rate unparalleled to the general micropropagation or conventional propagation and significant stock was obtained within 6 months of introducing the material. The in vivo plants exhibited adult characters like distichous phyllotaxy, three lobed leaves and normal pattern of tendril development within 2 months from planting.

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Yves Desjardins, André Gosselin, and Michel Lamarre

Asparagus (Asparagus officinalis L.) transplants and in vitro-cultured clones were grown and acclimatized under two photosynthetic photon flux (PPF) conditions (ambient and ambient + 80 μmol·s-1·m-2) and three atmospheric CO2 concentrations (330, 900, and 1500 ppm). Short- and long-term effects were measured in the greenhouse and after two seasons of growth in the field, respectively. In the greenhouse, CO2 enrichment (CE) and supplemental lighting (SL) increased root and fern dry weight by 196% and 336%, respectively, for transplants and by 335% and 229%, respectively, for clones. For these characteristics, a significant interaction was observed between SL and CE with tissue-cultured plantlets. In the absence of SL, CE did not significantly increase root or shoot dry weight. No interaction was observed between CE and SL for transplants, although these factors significantly improved growth. It was possible to reduce the nursery period by as much as 3 weeks with CE and SL and still obtain a plant size comparable to that of the control at the end of the experiment. Long-term effects of SL were observed after two seasons of growth in the field. Supplemental lighting improved survival of transplants and was particularly beneficial to in vitro plants. Clones grown under SL were of similar size as transplants after 2 years in the field.

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Hua Q. Zhao, Qing H. He, Li L. Song, Mei F. Hou, and Zhi G. Zhang

acclimatization. For rooting, each shoot was cultured on 1/2 MS basal medium supplemented with 0, 0.2, 0.5, or 0.8 mg·L −1 IAA, IBA, or NAA. The culture conditions were similar to those used for regeneration of shoots. Each treatment was repeated three times and