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Claudine Ménard and Blanche Dansereau

The general objective of this project was to study the impact of preharvest growth conditions [supplementary lighting as high-pressure sodium (HPS) or metal halide (MH) lights, and fertilization] on the postharvest quality of greenhouse roses. On 25 Jan. 1991, 288 plants (Rosa × hybrida `Royalty', `After-Glow', and `Obsession') of 3× caliber were planted in pots. A split-split plot experimental design made up of four blocks was used. Light treatments (three) were main plots while fertilization (two) and cultivars (three cultivars; four plants per cultivar) were subplots and sub-sub-plots, respectively. The two fertilization regimes used had respective N: K (in ppm) ratios of 150 N: 300 K (F1) and 300 N: 300 K (F2). Three light treatments [ambient light conditions (control) and ambient light conditions + PPF of 100 μmol·m-2·s-1 supplied by 400-W HPS or MH lamps] were compared. Yields were significantly affected by supplemental light treatments, fertilization, or both regardless of cultivars. Results indicate that stems harvested from HPS and MH light treatments combined with fertilization F1 had a longer vase life than those grown with F2. HPS lamps significantly increased vase life compared to MH. The level of abscisic acid (ABA) was higher under MH than under HPS lamps at time zero (T0), and this was similar for all cultivars. Furthermore, when supplemental light was combined with the F1 fertilization, a lower ABA level was obtained. Low ABA levels were correlated to longer vase life expectancy.

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Bruce D. Whitaker

Plastids and microsomal membranes were isolated from pericarp tissue of mature-green and red-ripe bell pepper (Capsicum annuum L.) fruit harvested from greenhouse- and field-grown plants. The lipid composition of these membrane fractions changed much more with ripening of field-grown than greenhouse-grown fruit. Also, the phospholipid (PL), free sterol (FS), steryl glycoside (SG), and acylated steryl glycoside (ASG) content of microsomes and plastids from green and red fruit were very different under the two growing conditions. Total steryl lipids (TSL = FS + SG + ASG) and the TSL: PL ratio increased in microsomes and decreased in plastids with ripening. These changes were much greater in field-grown fruit. The ASG: SG ratio decreased with ripening in both membrane fractions under both growing conditions. Ripening and growth conditions affected the phospholipid and sterol composition in plastids much more than in microsomes. Lipid changes associated with the chloroplast to chromoplast transformation were similar in field- and greenhouse-grown fruit, including an increase in the galactolipid: PL ratio.

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Claudine Menard, Blanche Dansereau, and Yves Desiardins

The general objective of this project is to study the impact of pre-harvest growth conditions (supplementary lighting; HPS, MH: fertilization on the biochemistry and post-harvest quality of greenhouse roses. On January 25, 1991, 288 plants (Rosa × hybrida: `Royalty', `After Glow' and `Obsession') 3X caliber were planted in pots. A split-split plot experimental design made up of four blocks was used. Light treatments (3) were in main plot while fertilization (2) and cultivars (3 cultivars; 4 plants per cultivar) were in sub-plots and sub-sub-plots respectively. The two fertilization regimes used had respectively a nitrogen potassium ratio of 150N:300K ppm (F1) and 300N:300K ppm (F2). Three light treatments (ambient light conditions (control), and ambient light conditions + PPF of 100 μmolm-2 s-1 supplied by 400 W HPS and MH lamps) were compared. Since the beginning of this experiment 14 431 flowering stems have been harvested. Only the results obtained with `Royalty' and `After Glow' will be presented for the following harvest periods; (1) October 6 to December 6, 1991; (2) January 30 to April 22, 1992. Yields were significantly affected by light and/or fertilization regardless of cultivar. Preliminary results indicate that stems harvested from HPS and MH light treatments combined to fertilization regime F1 had a longer vase life than those grown with F2. Preliminary results indicate that HPS lamps significantly increased vase life compared to MH. The level of ABA was higher under MH then under HPS lamps at to and this was similar for all cultivars. Furthermore, when supplemental light was combined to the F1 fertilization a lower level of ABA was obtained. Low levels of ABA are correlated to longer vase life expectancy.

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Bruce D. Whitaker

Plastids and microsomal membranes were isolated from pericarp tissue of mature green and red-ripe tell pepper fruit harvested from greenhouse and field grown plants. The lipid composition of these membrane fractions changed far more with ripening of field grown than greenhouse grown fruit. Also, the phospholipid (PL), free sterol (FS), steryl glycoside (SG) and acylated steryl glycoside (ASG) content of microsomes and plastids from both green and red fruit were very different under the two growing conditions. Total steryl lipids (TSL = FS + SG + ASG), and the TSL/PL ratio, increased in microsomes and decreased in plastids with ripening. These changes were much greater in field grown fruit. The ASG/SG ratio decreased with ripening in both membrane fractions, under both growing conditions. Ripening and growth conditions affected the phospholipid and sterol composition in plastids much more than in microsomes. Lipid changes associated with the chloroplast – chromoplast transformation were similar in field and greenhouse grown fruit, including an increase in the galactolipid/PL ratio. Future studies will assess how differences in membrane lipid composition affect postharvest storage life of the fruit.

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Kh. A. Okasha and H. Gomma

This study was carded out on Asparagus (Asparagus officinalis L.) during the two successive seasons of 1987/1988 and 1988/1989 at the Agricultural Experimental Station of National Research Center at Shalakan Kaloubia Governorate The investigation was aimed to study the effect of cultivar, propagation methods and polyethylene mulching on plant growth and performance

The application of plastic mulching caused signficant increases in plant height. number of shoots. number of branches, fern fresh and dry weight and roots an rhizome fresh and dry weight

Covering the soil surface with black and transparent polyethylene enhanced the vegetable growth of asparagus plant significantly as compared with unmulched treatments. Mulching with transparent polyethylene increased soil temperature over black polyethylene mulch and both treatments were higher in soil temperature than the control. Concerning the variation existed among cultivars, UC 157 F1 showed a significant increment in vegetable growth compared with UC 157 F2.

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Srini C. Perera and Peggy Ozias-Akins

Petiole protoplasts of the sweetpotato [Ipomoea batatas (L.) Lam.] cultivars Red Jewel and Georgia Jet formed cell walls within 24 hours and divided in 2 to 3 days. Pretreating enzyme solutions with activated charcoal increased the viability and division frequency of protoplasts. Culture of protoplast-donor plants in a medium containing STS did not affect plant growth, protoplasm yield, or viability, but did increase the division frequency. Culture of protoplasts for 24 hours in a medium containing DB, a cell wall synthesis inhibitor, or staining of protoplasts with FDA did not significantly affect division frequency. The division frequency of protoplasts cultured in liquid medium was significantly higher than that of protoplasts cultured in agarose-solidified medium. Cell cycle analysis of petioles and freshly isolated protoplasts showed that the latter has a significantly higher proportion of nuclei in G1 phase. Protoplasts did not initiate DNA synthesis or mitosis within the first 24 hours of culture. Low-frequency regeneration of shoots from protoplast-derived callus was accomplished on MS medium containing 1.0 mg ldnetin/liter when preceded by MS medium modified to contain only (in mg·liter-1) 800 NH4NO3, 1400 KNO3, 0.5 2,4-D, 0.5 kinetin, and 1.0 ABA. Roots produced from protoplast-derived callus formed adventitious shoots after 4 weeks on MS medium containing 2% sucrose, 0.02 mg kinetin/liter and 0.2% Gelrite. Secondary shoot formation from regenerated roots will be a more effective means of obtaining plants from protoplasts than direct shoot regeneration from callus. Chemical names used: silver thiosulfate (STS): 2.6-dichlorobenzonitrile (DB); fluorescein diacetate (FDA): 2.4-diacetate (FDA); 2.4 dichlorophenoxyacetic acid (2,4-D); abscisic acid (ABA).

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Mudau N. Fhatuwani and Makunga P. Nokwanda

Bush tea (Athrixia phylicoides DC.) is a root perennial shrub used as indigenous tea and medicinal tea in South Africa. Thus, concurrent trials were conducted under different growing conditions as follows: in the glasshouse, field planted and wild, naturally grown, to investigate the effects of seasonal harvests and growing environments on carbohydrate reserves and quality parameters of bush tea. Of 50 plants, 25 single plants were allotted to each respective environment in a field and glasshouse conditions—and were arranged in a randomized complete block design. These were then harvested in summer, autumn, winter, and spring, respectively. For the wild bush tea trial, 25 single plants were randomly selected. Selected sugars and starch were quantified together with other quality parameters [total polyphenolic content (TPC), total flavonoid content (TFC), total tannin content (TTC), and total antioxidant activities). The study revealed that the glucose content of bush tea plant organs was significantly higher during winter, followed by autumn, as compared with the other seasons. Similar fructose and sucrose trends were evident. However, the content of amylopectin was also significantly higher during summer, followed by autumn, compared with the other seasons. In winter, plants exhibited higher amylopectin content when compared with other seasons. No significant differences were found in the amylose content. Both wild and cultivated bush tea plants yielded the highest specific sugars in the study. The phytochemicals present in the leaves of field-grown bush tea and wild bush tea during winter were higher than in those grown in summer, autumn, and spring. No significant difference in tannin contents was observed, irrespective of seasons and growing conditions. Regardless of growing conditions, autumn yielded lower total antioxidant activities using both the DPPH and ferric reducing antioxidant power (FRAP) assays when compared with other seasons. To better resolve the metabolomic data, principal component analysis (PCA) was used and the first principal component showed a strong correlation within all parameters recorded over PC2. Future ecophysiological studies are recommended to establish region- and season-specific metabolomic biomarkers with canonical distinction on beverage, pharmacological, and organoleptic attributes of bush teas.

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Jiffinvir Khosa, Robyn Lee, Srishti Joshi, Martin Shaw, John McCallum, and Richard Macknight

Bulb onion (Allium cepa L.) is a challenging subject for experimental studies because of its slow growth, genetic heterogeneity, and sensitivity to environmental and biotic stresses. Sharing of common germplasm and controlled propagation practices has underpinned research on model plants, such as Arabidopsis and tomato, but not in onion. To encourage wider evaluation of onion for physiological and molecular studies in controlled environments, we describe the growing practices we have developed over two decades of research on adaptive and nutrient assimilation traits. Key aspects covered include choice of germplasm, propagation media, nutrition, and environmental control. Adopting common onion genetics and cultivation techniques across laboratories will allow researchers to answer deeper research questions and increase the reproducibility of the research.

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Hanseul Park and Yeh-Jin Ahn

of the growth conditions examined. Fig. 3. Enhanced growth of the transformed Escherichia coli cell lines heterologously expressing Hsp17.7 under heat and antifoam conditions. Transformed E. coli and control cell lines were cultured at ( A ) an

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Marija Perić, Slavica Dmitrović, Suzana Živković, Biljana Filipović, Marijana Skorić, Ana Simonović, and Slađana Todorović

uniform plant material under controlled growth conditions may be valuable for pharmacological and metabolomic studies. Literature Cited Cuenca, B. Vieitez, A.M. 2000 Influence of carbon source on shoot multiplication and adventitious bud regeneration in