Search Results

You are looking at 1 - 10 of 37 items for

  • Author or Editor: J.L. Paul x
Clear All Modify Search
Authors: and

Abstract

Container-grown plants of sweet gum (Liquidambar styraciflua L.) were transplanted to the Held and soil moisture tension of the transplanted rootball was recorded following transplantation and irrigation. Tension in the transplanted rootball increased more rapidly than in the control or in the soil adjacent to the rootball. Greater moisture loss from the transplant is attributed to loss of available water from the rootball as a result of drainage by the field soil profile following irrigation. To avoid moisture stress irrigation frequency of a new transplant may need to be even greater than required had it remained in the container.

Open Access
Authors: and

Abstract

An aspect of mist propagation which may be important in rooting cuttings is the quality of water used in misting. This may be particularly important in arid regions where many waters contain significant concentrations of salts. Although waters have been classified (1) for general irrigation purposes on the basis of total salts, sodium rating, boron concentration, etc., the propagator sometimes overlooks these properties of his mist water.

Open Access

Abstract

Rooted cuttings of Euonymus japonica Thunb. were grown in solution culture for 3 months and rates of NO3 -, Ca2+, K+, and Mg2+ absorption were measured by their disappearance from solution. During shoot elongation, absorption rates for these ions declined and the pH of the nutrient solution decreased to about 4. As a flush of shoot elongation ended, the absorption rates for the ions rose to much higher levels and the pH of the nutrient solution increased to 6 or above. The changes in the nutrient solution pH appear to be caused by changes in the relative cation-anion absorption.

Open Access

Abstract

Pot chrysanthemums (Chrysanthemummorifolium Ramat. ‘Bright Golden Anne’) were grown vegetatively for 5 weeks at 10 application rates of K. Two critical K levels were determined by correlating top fresh weights with K concentration in the most recently mature leaves. The critical foliar level associated with maximum yield was 2.3% K and that associated with 90% of maximum yield was 1.3% K. Potassium concentrations in leaves showing the earliest signs of K deficiency symptoms ranged from 0.6 to 0.7% K.

Open Access
Authors: and

Abstract

The construction and evaluation of a small, inexpensive tensiometer fitted with a pressure transducer (PT) and suitable for container media measurements is presented. The PT must be calibrated against known tensions before use, because the millivolt output from the PT varies with input voltage. The air volume above the liquid in the tensiometer that is sampled by the PT should be about 0.25 ml for an accurate (within 4%) and quick (10-20 sec) response. Tension measured with a PT was nearly identical to that measured with a mercury manometer in the range from 6.8 to 196 kPa (7-200 cm of water) during dry-down of a container with a plant (Paulownia tomentosa).

Open Access
Authors: and

Abstract

Chrysanthemum morifolium cv. Brilliant Anne was grown in 13 different media under frequent irrigation such that all media were nominally at container capacity. Media were selected to represent a range in airfilled porosity (0–20%) at container capacity with a depth of 12 cm. Substantial addition of organic amendment (40–90% v/v) improved aeration in a poorly aggregated loam and in two sands. Peat plus vermiculite had the best aeration of all media. Thirty day top yields were related to aeration properties of the media measured at container capacity. A value of 10–15% air-filled porosity was generally related to best growth. Oxygen diffusion rate (ODR) for the medium profile provided a better correlation with plant growth than air-filled porosity. A profile ODR of 45g O2 × 10‒8 cm-2 min-1 and above gave best growth.

Open Access

Abstract

Chrysanthemum cuttings were rooted in peat having different levels of exchangeable Mg and Ca. When exchangeable Mg was greater than 80% rooting was severely impaired. Mist waters containing increasing proportions of Mg caused rooting failure in both sand and peat when the percentage of total cations was 70% Mg. Ca deficiency symptoms developed in the highest Mg mist treatment. Leaching of Ca from the leaf is indicated.

Open Access

Extractable activities of α-amylase, β-amylase, and starch phosphorylase were investigated in order to understand the mechanism of starch degradation in buttercup squash (Cucurbita maxima Duchesne ex Lam. `Delica') with the ultimate goal of improving the conversion of starch into sweet sugars. During rapid starch synthesis (0 to 30 days after flowering), extractable activities of α-amylase and β-amylase were low, but those of starch phosphorylase increased. After harvest, during ripening at 12 °C, or in fruit left in the field, activities of α-amylase and β-amylase increased. Starch contained 20% to 25% amylose soon after starch synthesis was initiated and until 49 days after harvest irrespective of whether the crop remained in the field or in storage at 12 °C. Maltose concentrations were low prior to harvest, but levels increased during fruit ripening. Data suggest starch breakdown is hydrolytic in buttercup squash, with α-amylase being the primary enzyme responsible for initiating starch breakdown.

Free access

Abstract

Tomato (Lycopersicon esculentum Mill. ‘Floradel’) plants were grown under greenhouse conditions in a modified Hoagland’s solution to determine the influence of NO3:NH4 ratio (100:0, 75:25, 50:50, 25:75) on vegetative growth, fruit development, and tissue levels of N, P, K, Ca, and Mg at 3 stages of maturity. Vegetative growth prior to fruit set was increased significantly by adding 25% of the N as NH4, although higher NH4 ratios reduced vegetative growth. During flower and fruit development, the number of fruit formed with each flower cluster was not influenced by the NO3:NO4 ratio, although fruit weights were reduced significantly when NH4 supplied any part of the N form. With each increment of NH4 in the N ratio, tissue P increased whereas K, Ca, and Mg decreased. Kjeldahl N (less NO3-N) in the vegetative tissue at all harvests increased with each increment of NH4 in the N ratio. It is concluded that the use of Kjeldahl N as an indicator of the N status of the plant without consideration of the effect of N form on the percentage of N as well as the uptake and distribution of other essential elements could be misleading and potentially a misuse of this diagnostic tool.

Open Access

Abstract

Toyon [Heteromeles arbutifolia (Ait.) M.J. Roemer] cuttings were grown in container media having air-filled porosity (Ea) values ranging from 1% to 20%. Plants were inoculated with Phytophthora cinnamomi Rands zoospores, and all media were maintained at or near container capacity for 3 weeks, after which plants were evaluated for root rot symptoms. Inoculated plants grown in media with <10% Ea developed severe root rot, while those grown in media having Ea values of 10-20% appeared relatively healthy. Roots of noninoculated plants growing in low-Ea media were not adversely affected during the experimental period.

Open Access