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Day (DT) and night temperature (NT), and irradiation (photosynthetic photon flux-PPF) treatment combinations were run from a rotatable central composite design. At flowering, response surfaces were plotted for `Royalty' rose for plant growth characteristics: node number, stem diameter, stem length, and dry weight of stem, leaves, flower bud, and total shoot. Overall development was recorded from pinch until visible bud, first bud color, and flowering. All characteristics except node number and stem length were significant (P=0.05) for a full quadratic model having ten estimated coefficients. Greatest dry weights were predicted at flowering for the lowest DT (15C) and NT (12C) combination, and required the longest time for development. Conversely, most rapid development and least dry weight accumulated for high DT (25C) and NT (22C). Thus, a compromise exists between rapid development and quality of the flowering stem. As PPF increased from 50 to 300 μmol m-2s-1, predictions for dry weights increased while developmental time decreased.

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Abstract

In the article “Evaluation of Nutrient Deficiency and Micronutrient Toxicity Symptoms in Florists’ Hydrangea”, by Douglas A. Bailey and P. Allen Hammer (J. Amer. Soc. Hort. Sci. 113(3):363–367, May 1988), the following corrections should be noted: 1) In Table 3, percent dry weight of N for the –N treatment should read “1.40”, not “4.40”; 2) the significance levels in footnote z of Table 3 should read “0.05 ≥ α ≥ 0.01 (*), at 0.01 ≥ α > 0.001 (**), or at α ≤ 0.001 (***)”; 3) Tables 4 and 5 are numbered incorrectly—they should be switched; and 4) the significance levels in footnote z of the renumbered Table 5 should read “0.01 ≥ α > 0.001 (**) or at α ≤ 0.001 (***)”.

Open Access

A central composite rotatable design was used to estimate quadratic equations describing the relationship of irradiance, as measured by photosynthetic photon flux (PPF), and day (DT) and night (NT) temperatures to the growth and development of Rosa hybrida L. in controlled environments. Plants were subjected to 15 treatment combinations of the PPF, DT, and NT according to the coding of the design matrix. Day and night length were each 12 hours. Environmental factor ranges were chosen to include conditions representative of winter and spring commercial greenhouse production environments in the Midwestern United States. After an initial hard pinch, 11 plant growth characteristics were measured every 10 days and at flowering. Four plant characteristics were recorded to describe flower bud development. Response surface equations were displayed as three-dimensional plots, with DT and NT as the base axes and the plant character on the z-axis while PPF was held constant. Response surfaces illustrated the plant response to interactions of DT and NT, while comparisons between plots at different PPF showed the overall effect of PPF. Canonical analysis of all regression models revealed the stationary point and general shape of the response surface. All stationary points of the significant models were located outside the original design space, and all but one surface was a saddle shape. Both the plots and analysis showed greater stem diameter, as well as higher fresh and dry weights of stems, leaves, and flower buds to occur at flowering under combinations of low DT (≤ 17C) and low NT (≤ 14C). However, low DT and NT delayed both visible bud formation and development to flowering. Increased PPF increased overall flower stem quality by increasing stem diameter and the fresh and dry weights of all plant parts at flowering, as well as decreased time until visible bud formation and flowering. These results summarize measured development at flowering when the environment was kept constant throughout the entire plant growth cycle.

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Abstract

Regression analysis of the height of ‘Ace’ and ‘Nellie White’ over time was used to develop prediction equations of Easter lily height (Lilium longiflorum Thunb.). Case-cooled (cooled before planting) and controlled-temperature-forced (cooled following planting) bulbs that received 6 or 7 weeks of cooling required different equations to predict height. Case-cooled bulbs precooled 6 weeks required 7.4 and 6.1 weeks of forcing for shoots to reach 50% of their final height for ‘Nellie White’ and ‘Ace’, respectively. Controlled-temperature-forced bulbs precooled 6 weeks required 11.1 and 9.0 weeks of forcing for shoots to reach 50% of their final height for ‘Nellie White’ and ‘Ace’, respectively. The equations provide a baseline of lily elongation over time.

Open Access

Abstract

Plants of Euphorbia pulcherrima Willd.‘Glory’ received seven biweekly 236.5-ml soil drenches, each containing either 0, 10, 40, 80,160, or 320 mg Mo/liter (0, 2.4, 9.5, 18.9, 37.8, and 75.7 mg/pot). No visible phytotoxic effects due to excess Mo were observed on any plants, and no treatment differences were evident for plant height at anthesis, days from start of short days to anthesis, or display bract diameter at anthesis. Foliar nutrient analyses indicated no effect on nutrient uptake due to treatment for any element except Mo. A level of 806 mg Mo/kg dry weight were recorded for poinsettia leaves without adverse effects on plant growth or appearance. Results suggest Mo toxicity is not a real threat in poinsettia production.

Open Access

Abstract

Seed of Lycopersicon esculentum Mill. ‘Champion’ and Petunia hybrida Vilm. ‘Snow Cloud’ were irrigated with either nonacidified solution (0.15, 0.30, or 0.45 ml) of 75% H3PO4·liter−1; or 0.11, 0.20, or 0.26 ml of 46.5% H2SO4·liter−1. Germination was not affected by acidification, yet seedling growth was enhanced for both species. Growing medium and plant shoots were analyzed for N, P, K, Ca, and Mg content. Although nutrient levels were affected by acidification, no nutrient deficiency or phytotoxicity due to irrigation water acidification was evident.

Open Access

Abstract

Nutrient imbalances were investigated to a) document nutrient deficiency and micronutrient toxicity symptoms in florists’ hydrangea (Hydrangea macrophylla Thunb.) and b) examine the possible relationship of single-element deficiencies and toxicities with a foliar malformation prevelant on hydrangeas grown at >30°C. Plants subjected to N, P, K, Ca, Mg, S, B, Fe, and Zn deficiency and B and Mn toxicity treatments produced visual symptoms of the corresponding nutrient imbalance. Visual symptoms did not develop in +Fe, +Cu, +Zn, +Mo, −Mn, −Cu, and −Mo treatments. None of the symptoms induced were similar to the foliar malformations observed on hydrangeas grown at >30°. Hydrangea leaf malformation does not appear to be correlated with any single nutrient imbalance within hydrangea leaves. Results of the nutrient deficiency and toxicity experiments offer a diagnostic tool for interpretation of nutrient analysis of hydrangea.

Open Access

Abstract

Plants of Hydrangea macrophylla Thunb. were grown in various environments to identify factors responsible for the appearance of malformed hydrangea leaves and to screen cultivars for tolerance to the foliar disorder. Ambient temperature, photosynthetic photon flux (PPF), and root system temperature were studied. Hydrangea leaf malformation is under thermal control and can be stimulated by ambient temperatures of 33/26C (light/dark), but these must be maintained to sustain the development of distorted foliage. Placement of plants with malformed leaves into a 26/22C (light/dark) environment resulted in subsequent development of typical leaves. A PPF of 506 μmol·s−1·m−2 resulted in a more rapid appearance of distorted leaves than a PPF of 224 μmol·s−1·m−2. Reducing the root system temperature below the ambient level of 32/28C to 20/18C (light/dark) reduced, but did not prevent, the development of malformed leaves. ‘Blau Donau’ and ‘Tricolor’ did not develop malformed foliage during 22 weeks of growth at 32/26C (light/dark). ‘Rose Supreme’, ‘Merritt's Supreme’, ‘Rosa Rita’, and ‘Dr. Bernard Steiniger’ had developed malformed leaves by week 8 of treatment. For ‘Rose Supreme’ and ‘Blau Donau’, leaves developing at the higher temperatures had shorter and narrower laminae, less fresh weight and surface area, and more dry weight per unit area than plants at the lower temperatures. Laminae developing at the higher temperatures were thicker due to an increase in adaxial palisade parenchyma tissue. Malformed ‘Rose Supreme’ leaves had fewer intercellular spaces than normal leaves and lacked an observable spongy parenchyma layer. However, laminae of ‘Blau Donau’ leaves developed a distinct, yet thinner, spongy parenchyma layer at the higher than at the lower temperatures; intercellular spaces were still prevalent in the spongy parenchyma layer at the higher temperatures.

Open Access

Abstract

The effects of repetitive subculturing, cytokinin species and concentration, basal medium, and gelatinizing constituent were studied to maximize shoot multiplication of Hydrangea macrophylla Thunb. ‘Rose Supreme’ shoot tip cultures. Cytokinin treatments of BA or 2iP at 2, 4, 8, 16, or 32 μm were incorporated into woody plant medium (WPM) solidified with 6 g·liter−1 Sigma agar. Cultures grown on 8 μm BA produced the greatest number of useable shoots per 4-week subculture. No treatment stimulated shoot multiplication until the 2nd subculture, after which shoot multiplication remained constant within treatments through the 5th subculture. Results indicate no difference in number of shoots produced per subculture on modified Gamborg's B5, modified Murashige and Skoog basal medium, or WPM when incorporating 8 μm BA and 6 g·liter−1 Sigma agar. No difference in shoot multiplication was observed between 6 g·liter−1 Sigma agar and 2 g·liter−1 Gel-Rite when incorporated into WPM containing 8 μm BA. However, culture fresh weight and shoot length was greater for cultures on Gel-Rite than for cultures on agar. Chemical names used: N-(phenylmethyl)-lH-purin-6-amine (BA) and N-(3-methyl-2-butenyl)-lH-purin-6-amine (2iP).

Open Access