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  • Author or Editor: R.D. Caldwell x
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Carrot (Daucus carota L. var sativus) production in Nova Scotia is challenging as carrots are grown under cool temperatures, rainfed conditions, and in mineral soils usually of low fertility. Growers must rely on fertilizer inputs to optimize yields. Excess application can result in high costs and may lead to soil and environmental problems. There is no up-to-date solidly-based, fertilizer recommendation available for carrot production in Nova Scotia. A greenhouse trial was conducted to identify the critical tissue(s) at various growth stages and optimal tissue nutrient concentrations for yield and quality. This will provide a diagnostic tool for assessing plant nutrient health and the opportunity to correct nutrient deficiencies to prevent yield losses, as well as provide an up-to-date fertilizer recommendation. Dicer carrot seeds, variety Red Core Chatenay were grown in sand culture system that used a gravity-fed drip irrigation system. Nine fertility treatments consisting of a complete 20-20-20 plus micronutrients fertilizer was used to deliver at 0, 50, 100, 150, 200, 250, 300, 350, and 400 ppm equivalent of N, P, and K. Soil and plant tissue samples were taken at 4 and 9 weeks and at final harvest at 13 weeks. Critical tissues varied for each element studied at each of the growth stages. Results suggest 0 and 50 ppm treatments did not provide enough fertilizer to obtain maximum growth while plants receiving above 300 ppm were found to be more susceptible to disease. The treatment with 100 ppm N, P, and K was optimal, being significantly higher in yield and quality than all treatments except 150 ppm.

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Field experiments were conducted in 2002 and 2003 to evaluate the effects of selected plant growth regulators on propagule production in Hemerocallis `Happy Returns' and Hosta `Gold Standard'. Benzyladenine (BA), chlormequat chloride (Cycocel), ethephon (Ethrel), prohexadione calcium (Apogee), and an experimental preparation of commercial seaweed extract (Acadian Seaplants Limited Liquid Seaweed Concentrate) amended with BA and IBA were tested at two times of application and three rates of application. Results with Hemerocallis showed that the application of the seaweed/PGR mixture at 3000 mg·L–1, Cycocel at 3000 mg·L–1 or BA at 2500 mg·L–1 applied at flowering, increased the number of plants producing two divisions compared to control plants. In Hosta, no increase in divisions under any treatments was observed.

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Field experiments conducted in 2002 and 2003 evaluated the effects of timing of inflorescence removal on propagule formation, growth and development of Astilbe ×arendsii, Hemerocallis spp. and Hosta spp. Four timings of inflorescence removal were tested: 1) no removal (control), 2) removal at inflorescence emergence, 3) removal at preflower, and 4) Removal at full flower. Propagule formation in Astilbe was not enhanced by inflorescence removal. Hemerocallis plants with their inflorescences removed at emergence produced 25% more divisions than plants with their inflorescences removed at preflower. For Hosta, plants with inflorescences removed at pre- and full flower produced respectively 40% and 53% more divisions than control plants. These results have economic implications for commercial bare-root production, which need to be verified on a larger field scale.

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Aglaonema is among the most popular tropical ornamental foliage plants used indoors because of its bright foliar variegation, low light and humidity tolerance, and few pests. Aglaonema, however, has been labeled as one of the most chilling-sensitive foliage plants. The dark, greasy-appearing patches on leaves injured by chilling can result in completely unsalable plants. With recent breeding activity, more and more Aglaonema cultivars have been developed and released. How new cultivars respond to chilling temperatures is, however, mostly unclear. This study was undertaken to evaluate cultivar chilling responses to identify chilling-resistant cultivars. Twenty cultivars were chilled at 1.7, 4.4, 7.2, 10, and 12.7 °C for 24 h using a detached single-leaf method and also whole-plant assay. Results indicate that great genetic variation exists among the cultivars, ranging from no injury at 1.7 °C to severe injury at 12.7 °C. A popular cultivar, Silver Queen, is the most sensitive, while the cultivar Stars is the most resistant. There was also a chilling response difference based on leaf maturity. Young leaves showed less injury than did either mature or old leaves. In addition, there was a significant correlation between the single-leaf and whole-plant assay for chilling resistance in Aglaonema'; the single leaf assay could be particularly useful for a quick test.

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Stand establishment is critical for optimizing yield and quality in carrots. Low soil temperatures and moisture conditions often challenge seed germination and emergence. Providing an artificial exosperm with appropriate germination promoters, stress conditioners and growth invigorators to the seed may facilitate uniform germination and emergence. Germination patterns and velocity of germination of `Oranza' carrot was studied. Seeds were mixed in different types of gels at various ratios and incubated at either 5 or 20 °C. Gels used were Laponite RD, Laponite RDS, guar gum, algenic acid, and agar. Data on germination percentage was collected and the velocity of germination was calculated. Germination was delayed at 5 °C. Both at 5 and 20 °C, Laponite RD promoted and enhanced germination and vigor, and resulted in the highest mean germination percentage (90% at 20 °C and 89% at 5 °C). Laponite RD at 2.5% has shown an overall advantage in germination percentage (94% at 20 °C and 87% at 5 °C) over other gel types and concentrations.

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Anthurium cultivars are being produced primarily as cut-flower plants. Whether Anthurium can be used as a flowering interiorscape plant is not well documented. Therefore, five finished Anthurium cultivars were evaluated in interior acclimatization rooms under two light intensities provided by cool-white fluorescent lamps for 12 hours daily: 16 mmol·m–2·s–1 (low light) and 48 16 mmol·m–2·s–1 (high light). Temperature of the rooms was maintained at 24 °C with a relative humidity of 60%. Total number of open flowers and number of senesced flowers were recorded weekly over 5 months. In addition, plant canopy height and width and total number of leaves were measured monthly. Number of open flowers per week ranged from 1.4 to 4.7 under low light and 2.4 to 6.3 under high light. The cultivar Red Hot showed the best performance with a weekly average flower count of 4.7 under low light and 6.3 under high light. All cultivars continued to produce new leaves, ranging from one to five per month under low light and two to five leaves under high light. Leaves were dark green and shiny under the interior conditions. Growth index of `Red Hot' increased 31% under low light and 20% under high light. Results from this study demonstrate that Anthurium can continue to grow and produce flowers under interior environmental conditions. Variation among cultivars indicates that genetic potential exists for selecting improved cultivars based on interior performance.

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Abstract

Net photosynthesis (Pn) rates of greenhouse-grown apple leaves were unaffected for at least 24 hours after shoot detachment. With shoots detached from orchard trees, overnight holding did not affect Pn rates nor stomatal resistance. Use of detached shoots for Pn and dark respiration (Rd) determinations in apple leaves was concluded to be a valid technique.

Open Access

A reduction in the atmospheric deposition of sulfur (S) and S-containing fertilizers has greatly reduced S inputs to the soil in recent years. At the same time, S removal from the soil has increased as a result of increased crop production and higher yields. Sulfur deficiency has been found to reduce yields in several crops. A study was conducted to gain an understanding of the S status of Nova Scotia soils that support carrot production, as well as to examine the effects of rate of S application, method of S application, and type of S fertilizer on carrot uptake, distribution, yield, and recovery. Initial S concentrations in carrot-producing fields ranged from 52–440 kg·ha-1 of S. In general, King's County soils were lower in S than Colchester County soils. In the S trial, banding and broadcasting S on the side of carrot rows improved yield, and recovery compared to placing the S in the seed row. Banding S also significantly increased undersize carrots, leaf fresh weight, leaf dry weight, and root fresh weight. Rate of S application did not affect yield, recovery, or growth of carrots. At this time, S supplies from the atmosphere and soil are sufficient to meet the demands of carrots produced for processing in Nova Scotia. Growers do not need to apply S as fertilizer at this time to improve carrot yields. Monitoring of the S status of soils should be periodically conducted to assess S concentration as SO2 emissions and crop production continue to change.

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