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  • Author or Editor: P. V. Nelson x
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Abstract

Soil solution is the aqueous liquid phase of the soil and its solutes consisting of ions dissociated from the surfaces of the soil particles and other soluble materials (11). It can be divided into 2 components: that portion of the electric double layer in which cations and anions are dissociated from the surfaces of root-media particles but are not in equilibrium with each other, and the bulk solution outside this layer. The electric double layer refers to a negatively charged soil particle surface and the balancing cations dissolved in the soil solution. The balancing cations become less dense with increasing distance from the soil surface to a point where dissolved anions are in equilibrium with cations; i.e., ions are not influenced by the exchange surface. At this point we leave the electric double layer and enter the bulk solution. The terms soil solution and bulk solution are nearly synonymous from the standpoint of nutrient uptake. It would be more desirable for ornamentalists to use bulk solution, since many root media do not contain soil, and bulk solution better represents the immediately available nutrient pool.

Open Access

Abstract

Twelve cultivars of Elatior begonia (Begonia X hiemalis Fotsch.) were exposed to O3 at 25 and 50 pphm. The ‘Schwabenland’ group, ‘Whisper ‘O’ Pink’, and ‘Improved Krefeld Orange’ were the most sensitive, whereas ‘Ballerina’, ‘Mikkell Limelight’, and ‘Turo’ were the least sensitive. ‘Rennaisance’, ‘Heirloom’ ‘Nixe’, and ‘Fantasy’ were intermediate in sensitivity. The dry weight of foliage (stems plus leaves) of 9 cultivars exposed to O3 was significantly less than that of control plants. Ozone at 25 and 50 pphm inhibited flower growth (including peduncles) and development in 4 and 8 of the 12 cultivars, respectively. Differences in flower weight ranged from 43 to 105% of the control at 25 pphm and from 25 to 98% of the control at 50 pphm, depending on cultivar.

Open Access

Abstract

The effect of SO2 (0.5 ppm) and O3 (0.25 ppm) were tested alone and in combination using 5 cultivars of Elatior begonia (Begonia × hiemalis Fotsch). ‘Schwabenland Red’ and ‘Whisper ‘0’ Pink’ were the most sensitive to O3 based on foliage and flower weight. ‘Fantasy’ was the most sensitive to SO2 and flower production was significantly reduced without visible injury at 0.5 ppm SO2. The only significant (SO2 × O3) interaction occurred with flower weight of ‘Schwabenland Red’, where the combined effect of the 2 pollutants was less than expected from the linear additive model.

Open Access

Abstract

Chemical growth retardants (2-chloroethyl)trimethylammonium chloride (chlormequat), succinic acid-2,2-dimethylhydrazide (SADH, daminozide) and α-cyclopropyl-α-(ρ-methoxyphenyl)-5-pyrimidinemethanol (ancymidol) were tested on Reiger Elatior begonia ‘Schwabenland Red’ (Begonia × hiemalis Fotsch). Chlormequat applied as a spray of 0.30% active ingredient (a.i.) (1:40 dilution of commercial product) caused height retardation in high and low light periods, being most effective in the winter. A 0.30% drench was excessive under low light conditions whereas both 0.30 and 0.60% drenches were ineffective under high light conditions. No significant height retardation was found when SADH was applied as a spray at concentration up to 0.50% a.i. Ancymidol was effective as a drench at 0.125 mg per 15 cm pot under both high and low light conditions. Ancymidol sprays at concentrations up to 33 ppm were ineffective.

Open Access

Two experiments were conducted to determine the effects of applied ancymidol, chlormequat, daminozide, paclobutrazol, and uniconazole on early spring (March) and late (May) spring forcing of Dutch-grown Bleeding Heart [Dicentra spectabilis (L.) Lem.] as a flowering pot plant. Most of the plant growth regulator (PGR) treatments delayed flowering, however, the average time to flower after planting was from 17 to 21 days for untreated plants and delays were only 3 to 6 days with PGR treatments. Thus, the effect is not important commercially. Acceptable plant quality and height control not only at flowering but also 14 days later was obtained with two sprays of 3000 mg·L-1 (ppm) daminozide or two sprays of 50 mg·L-1 paclobutrazol. Uniconazole reduced total plant height, however, because the inflorescence did not elongate, plant quality was greatly reduced. Most ancymidol sprays were phytotoxic producing a chlorosis of the leaf margins. Media drenches of ancymidol or chlormequat did not control total plant height. Sprays and media drenches of ancymidol, daminozide, paclobutrazol, and uniconazole produced plants with a very deep green leaf color, but chlormequat did not. The total number of shoots per tuberous root, the number of shoots with flowers, and stem strength were not significantly affected by PGR treatments. If the tuberous roots have been properly cold treated, they initiate growth rapidly after planting. Thus, the first PGR spray must be applied immediately after shoot growth is initiated, which was 6 to 8 days after planting, followed by a second spray 5 days later. Two applications are necessary because of uneven shoot emergence and growth from the tuberous roots.

Full access

The results of six experiments conducted over 3 years were analyzed to develop a relationship between nutrient uptake rate and growth rate in hydroponically grown Dendranthema ×grandiflorum (Ramat.) Kitamura, cv. Fiesta. Plants subjected to two levels of CO, and three levels of irradiance in four greenhouses were periodically analyzed for growth and the internal concentration of 11 mineral elements. The resulting data were used to determine relative accumulation rate and relative growth rate, which were included in linear regression analyses to determine the dependence of uptake on growth. The regression equations were significant, with a slight trend toward nonlinearity in some elements. This nonlinearity seems to be related to the aging of the plant and suggests a process in the plant capable of controlling uptake rate, perhaps as a result of changes in the rate of formation of different types of tissues.

Free access