John M. Dole

1-Methylcyclopropene: a review

Since the discovery of 1-methylcyclopropene (1-MCP) as an inhibitor of ethylene action, over 100 studies have examined details of its action, application and effects on ethylene inhibition. This plant growth regulator is a tool that can help scientists make major advances in understanding the role of ethylene in plants. 1-MCP prevents ethylene effects in a broad range of fruits, vegetables and floriculture crops. Effective concentrations are low and range from 2.5 nl l 1 to 1 m ll 1 . Concentration interacts with temperature such that low concentrations of 1-MCP applied over longer durations may be as effective as high concentrations. 1-MCP is most commonly applied at 68/77 8F (20/25 8C), but can be used at lower temperatures in some commodities. Generally, treatment durations of 12/24 h were sufficient to achieve a full response. A variety of factors may need to be considered when using 1-MCP including cultivar, developmental stage, time from harvest to treatment, and multiple applications. Depending on the species being treated, 1-MCP may hav ea variety of effects on respiration, ethylene production, volatile production, chlorophyll degradation and other color changes, protein and membrane changes, softening, disorders and diseases, acidity and sugars. This review compiles what is known about the technological uses for 1-MCP, defines where discrepancies exist between reports, and aims to define areas requiring further study. # 2003 Elsevier Science B.V. All rights reserved.

Kenaf (Hibiscus cannabinus L.) core as a containerized growth medium component

Kenaf (Hibiscus cannabinus L.) stems contain two distinct fiber types, bast and core. The absorbent, low density core (xylem) is a possible potting mix component. Two greenhouse studies were conducted during 1993 and 1995 to determine the feasibility of substituting kenaf core for vermiculite and bark. In Study 1, fine-grade kenaf was substituted for vermiculite in three volume ratios (1, 2 or 3) with sphagnum peat moss and perlite (1:1) and compared to a 1:1:1 ratio of vermiculite:sphagnum peat moss:perlite. In Study 2, coarse-grade kenaf was substituted in three volume ratios (1, 2 or 3) with sphagnum peat moss and compared to a 1:1 ratio of pine bark:sphagnum peat moss. Plant height, canopy diameter, shoot weight, and root weight of periwinkle (Vinca minor) seedlings were determined 10 weeks after transplanting into the media contained in 12.5-cm diameter pots. The substitution of fine-grade kenaf for vermiculite at a 1:1 ratio reduced to some extent all periwinkle yield parameters except root dry weight. As the volume of fine-grade kenaf increased, all yield parameters decreased compared to the vermiculite media. Substitution of coarse-grade kenaf for pine bark in a 1:1 ratio produced equivalent or greater yield components. This research indicates that kenaf core can be a suitable containerized growth medium component, depending on the size and percentage of kenaf used, the plant growth requirements, and the specific physical characteristics desired in the containerized growth media.

Floral foam and/or conventional or organic preservatives affect the vase-life and quality of cut rose (Rosa × hybrida L.) stems

Summary We studied the effects of floral foam (Oasis®), with or without conventional or organic preservatives, to determine the optimum treatment to extend the vase-life of the cut rose (Rosa × hybrida L.) cultivars ‘Freedom’ and ‘Charlotte’. In general, floral foam resulted in similar or reduced vase-lives in cut ‘Freedom’ and ‘Charlotte’ rose, and had no influence on the symptoms of senescence in either cultivar. ‘Freedom’ showed more petal browning and rot, as well as reduced flower bud opening, compared to ‘Charlotte’. Vase solutions containing either of two conventional preservatives resulted in longer vase-lives in the stems of both cultivars than stems in deionised (DI) water. Floral foam saturated with DI water resulted in greater changes in the pH of the vase solution in both cultivars. Among the preservatives tested, conventional products such as Floralife Premium Rose Food or Chrysal Rose Vase (each at 10 ml l–1) extended the vase-life by 5.5 d or 3.9 d, respectively; whereas organic products such as Vita Flora or Vita One Step (each at 0.53 ml l–1) resulted in statistically similar vase-lives (9.3 d or 8.3 d, respectively) as stems in DI water (7.5 d), irrespective of the use of floral foam. These findings suggest that floral foam should not be used during the post-harvest handling of cut rose stems. Moreover, conventional preservatives were more effective than the organic products.

Preservatives and packaging material have an impact on the post-harvest longevity of cut Rosa hybrida L. ‘Kardinal’ flowers

Summary We studied the effects of various preservatives (sucrose, ascorbic acid, salicylic acid, and acetylsalicylic acid) alone, or in various combinations, on the post-harvest performance of cut Rosa hybrida L. ‘Kardinal’ flowers. The effects of packaging material, including boxes (used boxes without vents), newspaper, butter paper (a waxy paper used to avoid moisture loss), craft paper (a thin, less-waxy paper used for wrapping floral bunches), cellophane paper, single cardboard boxes with or without a cellophane lining, and standard double cardboard boxes with or without a cellophane lining, were also studied. Among the preservatives, 4% (w/v) sucrose alone, or combined with 100 mg l–1 acetylsalicylic acid, 200 mg l–1 salicylic acid, or 600 mg l–1 ascorbic acid resulted in longer vase-lives (7.1, 5.6, 5.5, or 5.3 d, respectively). Individual or combined applications of ascorbic acid and/or salicylic acid had no effect on vase-life. Stems in deionised (DI) water or 4% (w/v) sucrose alone had larger petal areas and flower diameters compared to all other preservatives. Pulsing with 0.5 mM silver thiosulphate (STS) for 2 h at room temperature further extended the vase-life, maintained flower diameter, increased petal area, and increased the uptake of vase solution during the first 2 d of the vase period. Stems packed in double-cardboard floral boxes lined with cellophane, or cellophane alone, gave a longer vase-life than newspaper, butter paper, or the spent boxes used by growers in the study area. Packaging in single or double cardboard floral boxes, with or without a cellophane lining, maintained flower quality, increased flower diameter, and increased ion leakage from petals (possibly due to the longer vase-life) more than spent boxes, craft paper, butter paper, or newspaper. By increasing the duration of storage from 2 d to 8 d, vase-life and ion leakage decreased from 4.2 d to 2.6 d, and from 102% to 85%, respectively, while subsequent flower diameter increased to 0.61 cm from a decrease of 0.16 cm.

Correlation of poinsettia graft union development with transmission of the free-branching characteristic

Abstract Euphorbia pulcherrima Willd. ex. Klotzsch cv. ‘Eckespoint C-1 Red’ (CR), a restricted-branching poinsettia, and TR, a free-branching poinsettia, were approach grafted. Graft unions were removed for anatomical study at 0, 5, 10, 15, 20, 25 or 30 days after grafting, and the portion below the graft union was allowed to regrow. CR and TR plants had not yet adhered at 5 days after grafting. By 10 days after grafting, CR and TR parenchyma cells were actively dividing, producing new parenchyma cells (callus) on both sides of the necrotic layer. Parenchyma cells differentiated into nodules for the formation of new cambium by 25 days after grafting. TR and CR plants were not connected by new vascular tissue until 30 days after grafting. However, CR plants showed increased branching (axillary shoot development on lowermost nodes) by 10 days after grafting, indicating that vascular connections were not needed for transmission of the free-branching agent, which has been tentatively identified as a phytoplasma. Callus connecting TR and CR stems allowed transmission of the phytoplasma through the graft union.

MEDIA CONSTITUENTS, MICRONUTRIENT FERTILIZER SOURCE, AND CALCIUM APPLICATIONS INFLUENCE IRON, MANGANESE, AND ZINC LEACHING*

Sphagnum moss peat (PM), perlite (PR), pine bark (PB), sand (SN), and two media formulated from these constituents (3 PM + 1 PR and 3 PB + 1 PM + 1 SN, by volume) were used to determine the effect of individual media constituents and mixes on iron (Fe), manganese (Mn), and zinc (Zn) leaching with a granular-incorporated (GIF) or a water-soluble (WSF) micronutrient fertilizer source and calcium (Ca) surface application. Leachate electrical conductivity increased with increasing Ca application rate regardless of fertilizer source. Leachate from PR and SN contained more Fe, Mn, and Zn than leachate from other media regardless of micronutrient source. More Fe leached from SN and more Mn and Zn leached from PR than from any other medium when WSF was applied. In contrast, when GIF was the fertilizer source, more Fe leached from PR, and more Mn and Zn leached from SN than from any other medium. Perlite and SN provide aeration and stability, but should be used in combination with other media components that permit ion retention in the media. *Approved for publication by the Director, Oklahoma Agricultural Experiment Station. This research was supported by project H-2324.

Fertilizer Source Affects Iron, Manganese, and Zinc Leaching, Nutrient Distribution, and Geranium Growth

Abstract The effect of various sources of iron (Fe), manganese (Mn), and zinc (Zn) on growth and visual quality of geranium (Pelargonium X hortorum L. “Orbit Red”) seedlings, nutrient leaching, and nutrient distribution in the growing medium was determined in two experiments. In the first experiment, Fe, Mn, and Zn were applied as a commercially formulated water‐soluble fertilizer (WSF), granular incorporated fertilizer (GIF), or no micronutrient (NOM) fertilizer was applied. In the second experiment, the commercially formulated GIF was applied, but WSF was specially formulated to apply the same amount of each element from the same chemical sources as the GIF. Also a 50% GIF and 50% WSF (50 GIF/50 WSF) treatment was included. In both experiments, shoot relative growth rate (RGR) tended to be greater when WSF was applied than when GIF was used. Plant visual quality did not differ regardless of fertilizer used in either experiment, but plants receiving NOM fertilizer were of lower quality than plants receiving any micronutrient fertilizer. The amount of Fe, Mn, and Zn leached from the medium was greater with GIF than with WSF or 50 GIF/50 WSF when the same amount of each element was applied regardless of fertilizer source. Analysis of the growing medium at the end of each experiment revealed higher amounts of Fe, Mn, and Zn in the upper portion than in the middle or lower portions of the medium with WSF. The micronutrients studied were evenly distributed throughout the medium when applied as a GIF. #Approved for publication by the Director, Oklahoma Agricultural Experiment Station. This research was supported by project H‐2324.

Foliar Symptomology and Tissue Concentrations of Nutrient‐Deficient Vegetative Strawflower Plants

Abstract Elemental deficiencies of nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, manganese, copper, zinc, or boron (N, P, K, Ca, Mg, S, Fe, Mn, Cu, Zn, or B) were induced in plants of Florabella Pink strawflower [Bracteantha bracteata (Vent.) A. A. Anderberg]. Rooted stem cuttings were planted in 4.87‐L plastic containers and fertilized with a complete modified Hoaglands solution or this solution minus the element that was to be investigated. Plants were harvested for tissue analyses as well as dry weights when initial foliar symptoms were expressed and later under advanced deficiency symptoms. Deficiency symptoms for all treatments were observed within 7 weeks. The most dramatic expression of foliar symptoms occurred with N (chlorotic lower foliage leading to necrotic margins on the mature leaves), Ca (black necrotic spots on the tips of the young leaves), S (uniform chlorosis of young leaves and recently mature leaves), B (thick, leathery, and deformed young leaves), Fe (uniform yellowish‐green chlorosis on the young leaves), and Zn (brownish‐gray necrosis on the tips of the mature leaves). At the initial stage, only Fe‐deficient plants weighed less than the control, whereas K‐, Ca‐, and Mg‐deficient plants had greater dry weights than plants receiving the complete modified Hoaglands solution (control plants). Dry weights of plants treated with solutions not containing N, P, Ca, S, Cu, or Mn were significantly lower when compared with the control plants under an advanced deficiency. Foliar‐tissue concentration data will assist plant‐tissue analysis laboratories in establishing foliar symptom standards for growers.

Bio-control activity of bacterial strains on postharvest performance of Gladiolus L. Hybrids ‘Mammoth’

Gladiolus (Gladiolus L. hybrids), one of the most popular bulbous cut flowers of the world, has the problem of shorter vase life due to vascular occlusion by bacteria. Stem blockage in cut flowers is generally caused by bacterial proliferation along with their decay products (Teixeira-da-Silva, 2003). Bio-control through bacteria represent a potential alternative management approach (Jetiyanon and Kloepper, 2002) and may help in developing an organic method for effectively controlling detrimental microbes in the vase solutions (Carlson et al., 2015). The bio-control agents are used for biological management of pests to control a specific microbe (Shanmugam et al., 2011; Sajjad et al., 2014). Among bacterial antagonists, Pseudomonas fluorescens is most effective against a wide range of plant pathogens infecting different plants such as carnation, bean, radish, cucumber, tomato, and tobacco (van Loon et al., 1998), while P. fulva has extended vase life of cut zinnia stems (Carlson et al., 2015). Moreover, Burkholderia cepacia and Bacillus spp. (spore forming Gram-positive bacteria) have effectively been used to control plant diseases (Kloepper et al., 2004). Use of compatible and multiple bio-control agents in various groups also helps to control plant diseases, such as combinations of bacteria (Raupach and Kloepper, 1998; Shanmugam et al., 2002), fungi (Paulitz et al., 1990), bacteria and fungi (Duffy et al., 1996), yeasts (Janisiewicz, 1996), and bacteria and yeast (Janisiewicz and Bors, 1995). An experiment was conducted to compare different beneficial bacterial strains for their efficacy to control detrimental bacteria in vase solutions with gladiolus stems. There is dire need to develop organic preservatives for keeping flower organic grown without chemicals until end of vase life. However, there are currently no effective organic preservatives available in the market and those available are not effective (Ahmad et al., 2014). Organic carbohydrate source and acidifier are available but organic biocides are not available. Therefore, this study was conducted to elucidate the effect of bio-control bacterial strains, some of which have been proved effective for various agronomic crops, in controlling detrimental bacteria in vase solutions and effect on the postharvest water relations and quality characteristics of cut gladiolus. Moreover, the findings of the study would help develop an organic floral preservative to be used for handling organically grown cut flowers. Pak. J. Agri. Sci., Vol. 53(3), 593-598; 2016 ISSN (Print) 0552-9034, ISSN (Online) 2076-0906 DOI:10.21162/PAKJAS/16.3769 http://www.pakjas.com.pk

Postharvest performance of cut ‘White Prosperity’ gladiolus spikes in response to nano- and other silver sources

Abstract: A study was conducted to compare the efficacy of nano-silver (NS), silver thiosulfate (STS), and silver nitrate as novel postharvest treatments, and evaluate the potential of nano-silver pulse (higher concentration) or vase (lower concentration) applications on postharvest performance of cut gladiolus (Gladiolus hybrids ‘White Prosperity’) spikes. Among silver compounds, spikes kept in silver nitrate had longest vase life. Spikes placed in STS at 10 or 20 mg L-1 had longer vase life than stems placed in NS, but similar to the stems placed in water. For NS pulse applications, spikes pulsed with 50 mg L-1 NS for 1 h at 20 ± 2 °C had 2.2 d longer vase life compared to the spikes in water. Pulsing of spikes for 1 h extended the vase life of cut gladiolus compared with 4 or 8 h pulsing durations. Spikes kept continuously in NS until end of vase life resulted in 4.2 d longer vase life at a lower concentration of 0.01 mg L-1. With increasing NS concentration to 10 mg L-1, vase life decreased to similar vase life as with tap water. The results demonstrated that NS at a 50 mg L-1 pulse for 1 h or 0.01 mg L-1 vase application can be used for extending vase life of cut gladiolus spikes.