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  • Author or Editor: R. D. Wright x
  • Journal of the American Society for Horticultural Science x
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Abstract

Inflorescence development and fruit set of ‘Burford’ holly was rapid at a day/night temperature of 26°/22°C and progressively slower at 22°/18° and 18°/14°. The number of flowers to set fruit, however, was increased at lower temperatures for both long photoperiod (LD = 9 hours + 3 hours dark interruption) and short photoperiod (SD = 9 hours). At 22°/18°, SD increased fruit set over LD. No significant temperature-photoperiod interaction was observed. A greater number of vegetative shoots developed as temperature increased and mean shoot length was correlated with the number of flowers to set fruit.

Open Access

Abstract

Rooted linears of Ilex crenata Thunb. ‘Helleri’ and ‘Rotundifolia’ were grown in polyvinyl chloride pipe sections from which longitudinal sections could be removed for root observations. Plants were fertilized at either 150 or 300 ppm N with a 20N–8.7P–16.5K soluble fertilizer. Rate of root and shoot growth was determined through 2-3 flushes of growth by taking weekly measurements of shoots and roots. Root growth of both cultivars was episodic in nature with active root growth usually preceding a shoot growth flush by 1 to 2 weeks. This growth pattern was observed in both fertility levels.

Open Access
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Abstract

Determinations of carbohydrates in the plant organs of Rhododendron spp. cv. ‘Sweetheart Supreme’ and ‘Hexe’, were made by chemical analysis, thin-layer chromatography (TLC) and gas-liquid chromatography (GLC). Reducing sugar content was 1.5 times higher in buds than in leaves for ‘Hexe’ with no significant differences for ‘Sweetheart Supreme’. Reducing sugars were also higher in the roots than stems with both cultivars. Sucrose content was 1.4 times greater in leaves than in buds of ‘Hexe’ and 1.6 times greater in ‘Sweetheart Supreme’. Starch was significantly higher in leaves and buds than in stems and roots. The predominant soluble sugars identified by TLC and GLC were sucrose, glucose, and fructose. Small but detectable amounts of raffinose and maltose and an unidentified compound were also found in the plant organs.

Open Access

Abstract

The effects of 3 nitrogen levels and 2 growth regulators on growth of winter- and summer-rooted cuttings of Ilex crenata cv. Helleri were studied. Nitrogen applications promoted bud break immediately after rooting on summer cuttings and also enhanced the growth of winter-rooted cuttings. Generally, plants grown at 300 or 150 ppm N had greater shoot numbers and length, height, width, and dry weight compared to plants grown at 50 ppm N. Also spring growth of these liners was markedly enhanced by the higher level of N applied the previous season. Benzyladenine (BA) at 600 ppm increased the number of breaks and suppressed stem length, while gibberellic acid (GA3) at 400 ppm decreased the number of breaks and increased stem length.

Open Access

Abstract

‘Burford’ holly (Ilex cornuta Lindl. et Paxt. cv. Burfordii) differentiates primordia in September which were subsequently identified as flowers. The pistillate flower only partially differentiated by early winter and consisted of a pedicel, 2 bracts, 4 petals, and 4 stamens. Completion of flower differentiation and anthesis occurred in the spring.

Open Access
Authors: and

Abstract

Greenhouse-grown branched liners of ‘Helleri’ holly were fertilized with either 0, 5, 10, 15, 20, 25, or 30 ppm P to establish a P level in the pine bark medium that resulted in maximum shoot dry weight. Pine bark P levels greater than 10 ppm did not result in increased shoot dry weight. Total mg of P in shoot tissues continued to increase with P treatments higher than 10 ppm, indicating luxury consumption of P. Total mg of P in root tissues increased to the 5 ppm P treatment. Total μg of Mn in shoot tissues increased while total pg of Mn in root tissues decreased with increasing pine bark P levels. In a subsequent experiment, dry shoot weights of ‘Helleri’ holly grown in a pine bark medium amended with either 270, 540, or 810 g/m3 of P supplied as superphosphate (9% P) or fertilized with 10 ppm P were not different, while root dry weights decreased with increasing P amendment. Water extractable P for the 810 g/m3 treatment decreased 245 ppm during the experiment and by week 5 was below 10 ppm.

Open Access
Authors: and

Abstract

Pine bark cation exchange capacity (CEC) (by Ba/Mg exchange on four particle size fractions) increased regularly from 38 to 98 meq/100 g between pH 4 and 7. Decreasing particle size from <2.38 to <0.05 mm did not result in the expected large increases in bark CEC. The Ba/Mg CEC of unsieved bark samples was less than that determined by the weighted average of component size fractions. Monovalent/monovalent-determined CEC was higher than Ba/Mg, indicating that a number of differing charge-specific sites are involved. The pH-dependent CEC increase between pH 4 and 7 was greater for divalent exchange than for monovalent. Ammonium/K CEC was higher than K/NH4 CEC, probably due to enhanced NH4 adsorption by carboxyl groups. Infrared analysis of pine bark revealed that surface functional group composition is similar to soil organic matter. The accurate measurement of CEC in pine bark is complicated by solution pH and ionic strength, as well as by the cations employed for exchange.

Open Access

Abstract

High correlation coefficients were found between plant growth (dry weight accumulation) and both leaf N content and soil solution nitrates, while low correlation coefficients were found between soil nitrates and plant growth of 3 holly cultivars, Ilex crenata Thunb. cvs. Helleri and Rotundifolia and Ilex cornuta Lindl. et Paxt. cv. Burfordi, grown in 3 liter container at 200, 300, 400 and 500 ppm nitrogen. Shoot growth of ‘Helleri’ and ‘Burfordi’ was not increased by N levels higher than 300 ppm, while 400 ppm was optimal for ‘Rotundifolia.’

Open Access

The influence of K nutrition (25, 75, 150, 300, 450, and 600 mg K/liter) and moisture stress conditioning (MSC) (exposing plants to four sublethal dry-down cycles) on leaf water relations, evapotranspiration, growth, and nutrient content was determined for salvia (Salvia splendens F. Sellow `Bonfire'). Potassium concentration and MSC had an interactive influence on osmotic potential at full (π100) and zero (π0) turgor. Differences in osmotic potential between MSC and non-MSC plants for π100 and π0 increased with increasing K concentration. Increasing K concentration and MSC resulted in active osmotic adjustment and, consequently, increased cellular turgor potentials. Foliar K content increased with increasing K concentration and MSC. High K concentrations and MSC both reduced plant evapotranspiration on a per-plant and per-unit-leaf-area basis. Greatest shoot dry weight occurred for plants grown with 300 mg K/liter and non-MSC. Total leaf area increased with increasing K concentration, but MSC had little effect.

Free access

We determined the influence of moisture stress conditioning (MSC) (exposing plants to four nonlethal dry-down cycles) on gas exchange and water loss of Salvia splendens F. Sellow `Bonfire'. During day 1 following final irrigation, no differences in leaf water potentials (ψL) were observed due to MSC. However, MSC plants had lower midday net photosynthesis (Pn), transpiration (E), and leaf conductance (gL) than controls. Stomatal inhibition of photosynthesis (SI) of MSC plants was greater than that of controls. Further, the lack of differences in mesophyll resistance to CO2(rm due to MSC indicate gas exchange differences during day 1 were stomatal in nature. During day 2, MSC plants exhibited greater Pn, E, and gL, while SI and rm were greater for controls. MSC plants maintained positive Pn rates and .turgor and lower ψL than control plants during day 2. Higher water-use efficiency estimates were observed for MSC plants than for controls.

Free access