The growth and development of Anthurium andraeanum Andre cv. Kaumana flower before and after emergence from the subtending leaf base was studied. Eighty days before emergence, the anthurium flower was =0.3 cm long, enclosed by two tightly rolled stipules at the base of the subtending leaf petiole. During the rapid elongation stage of the leaf petiole, the flower (0.8 to 1.0 cm long) entered a period of slow growth 40 to 60 days before flower emergence. After the subtending leaf blade unfurled and had a positive photosynthetic rate, flower growth resumed. Spathe color development started =28 days before emergence when the flower was =50% of the emergence flower length (4.5 cm). At flower emergence, the spathe, excluding the lobes, was =75% red. The lobes did not develop full redness until 7 to 10 days after emergence. Peduncle growth was sigmoidal with the maximum growth rate 21 days after emergence. Spathe growth is characterized by a double sigmoid curve. The young, growing, subtending leaf blade had a negative net photosynthetic rate. Removal of this leaf blade advanced flower emergence by 18 days. The soft green leaf (25 to 30 days after leaf emergence) had a slightly positive measured net photosynthetic rate, and the removal of this leaf resulted in flower emergence 11 days earlier. A mature subtending leaf had the highest measured net photosynthetic rate, and its removal had little effect on flower emergence. The subtending leaf acted as a source of nutrients required for the developing flower. Altering the source-sink relationship by leaf removal accelerated flower emergence, probably by reducing the slow growth phase of the flower.
Cycasrevoluta Thunb., cultivated as an ornamental plant for indoor and outdoor use, is characterized by an extremely slow rate of growth. In spite of the occurrence in its coralloid roots of the nitrogen-fixing cyanobiont Nostoc, N fertilization is commonly used to accelerate Cycas growth. A greenhouse experiment was conducted to examine the effects of two forms of combined N on growth of Cycas plants and cyanobacterial nitrogenase activity, measured on intact plants. Cycas plants grown in pots were fertilized from June to September with nutrient solution containing macronutrients as P, K, Mg, and Hoagland's micronutrients. N (700 mg/plant) was supplied as KNO3, or applied as NH4NO3; control plants received nutrient solution without nitrogen. Treatments were applied monthly and repeated for three times. Each treatment consisted of 15 plants. The length of the new leaves was recorded during the growth cycle of the plants. The nitrogenase activity, based on acetylene reducing activity (ARA), was measured on the plants in situ in July and in October. N fertilization stimulated both the nitrogenase activity and the growth of the plants. In comparison with the control, average increases in ARA of more than 20% were observed in the treated plants. Nitrogenase activity was slightly better in the presence of NH4NO3 in July, whereas the values measured in October were about the same for two treatments. The two forms of nitrogen were the same also regarding the stimulus on growth: in N-treated plants the total length of the new leaves was more than double with respect to the control at the end of the growing season. Control plants grown without fertilizer N had a slow start to their growth cycles and were unable to recover and compensate later for the lack of transient N.
Poor blueberry leaf development is a serious problem in medium and low chilling regions which leads to smaller, later ripening fruit and reduced bush vigor. Dormex (hydrogen cyanamide) and Promalin or Accel (6-benzyl adenine plus gibberellins A4 and A7) were used in the experiments. Dormex 1991-1995 trials with applications at the end of the dormancy period (February) looked promising but were not uniformly successful. In 1996, applications were made starting in mid-dormancy (early-mid January) about 6-8 weeks before normal bud break. Spring vegetative bud development was greatly accelerated with minimal advance in flower development. Mid-dormancy Dormex rates of 1.5% to 2% appear promising. Dormex application after bud break or at excessively high rates will kill flower buds, but has excellent potential as a bloom thinning agent for juvenile blueberry plants. Promalin or Accel applications post bloom significantly accelerated spring leaf development. Late summer applications of Promalin significantly increased fall growth and number of side shoots.
The effects of altering, nutrient solution N:K ratio on growth of `TI-155' sweetpotato [Ipomoea batatas (L.) Lam] was evaluated in a greenhouse, as part of NASA's Closed Ecological Life Support Systems (CELSS) program for long duration space missions. Vine cuttings of `TI-155', were grown using nutrient film technique (NFT) in a modified half Hoagland's solution in channels (0.15×0.15×1.2 m). Plants were grown for 42 days in a culture solution in which N was doubled (6 mM) in order to accelerate foliage growth after which treatment N:K ratios of 1:2.4, (control) 1:4.8, and 1:7.2 were initiated. A randomized complete block design with 4 replications was used. The number of storage roots/plant increased linearly as K was increased in the solution. Storage root fresh and dry weights, growth rate (g m-2 d-1), fibrous root dry weight, foliage fresh and dry weights, and edible biomass index (root mass/total plant mass), though not significant all increased as K was increased in the nutrient solution. Nutrient solution analyses showed that K uptake was greatest in plants at the highest K level, while nitrate uptake was steady over the duration of crop growth regardless of treatments.
Abstract
Small seedlings of Philodendron selloum Koch and Brassaia actinophylla Endl. and rooted cuttings of Ficus benjamina L. were planted in 15-cm-diameter containers, and grown outdoors for 6 months under 63% shade at 7 different irrigation rates. Each plant species’ estimated actual evapotranspiration rate was applied as a base rate and the remaining 6 rates were all fractions of the base rate, 3 of which were applied for the entire duration of the experiment and 3 of which were only applied during the middle 2 months of the 6-month growing period. Each species grew at reduced rates under water rationing, but the magnitude varied with species, amount of rationing, and duration of rationing. Reduced growth in F. benjamina during the 3 short-term rationing treatments was followed by accelerated growth after the rationing ceased, and final growth was comparable to those not subjected to rationing. This recovery phenomenon was not exhibited by either P. selloum or B. actinophylla; both species had reduced growth for more than 2 months after cessation of short-term water rationing.
Abstract
Preplant chilling of rooted cuttings and postplant night lighting influenced the growth of ‘Hicks’ yew (Taxus × media Rehd. ‘Hicksii’). Supplemental light from high-pressure sodium (HPS) lamps, provided during the first year, enhanced shoot length and number in the first year, but not in the second. Compared to natural light, HPS increased shoot length 3 to 5 times and shoot number 3 and 4 times in the first year. The influence of incandescent light on growth was less, being significant on unchilled but not chilled plants, and not beneficial when continued for 2 years. In the second year, plants under natural light grew as much or more than plants under either HPS or incandescent light. The trend of increased shoot length in the first year by chilled plants under natural light was not evident for lighted plants, nor was there any benefit of chilling on shoot number. A trend for less growth in the second year by chilled plants was evident. The delay in initiation and development of buds on accelerated plants had an adverse effect on growth the second year.
Abstract
The growth of cutleaf crabapple [Malus toringoides (Rehd.) Hughes] seedlings was greatly accelerated by direct seeding under CO2-enriched atmospheres (400 or 2000 ppm) in controlled-environment chambers. CO2 treatment of 2000 ppm for 4 weeks from the time of seeding in the growth chamber produced the most striking results in terms of increase in node number and stem length. By the end of 4 weeks of treatment, stem lengths of seedlings treated for 4 weeks in the growth chamber with 2000 ppm CO2 were 3 times greater than those of plants grown at ambient CO2 (ca 350 ppm) in the greenhouse for 4 weeks, and 1.5 times greater than those treated in the growth chamber with 400 ppm CO2 for 4 weeks. The effect of CO2 enrichment on stem length was greater than that on node number. The stimulatory effects of CO2 enrichment persisted for 2-3 months after the plants were moved to the greenhouse at ambient CO2.
Two field studies (winter and summer) were performed to evaluate the effect of three different fertilizer programs and a urea formaldehyde resin foam (UFRF) soil amendment on sod establishment and anchorage. Fertilizer treatments involved were 1) a quick release (QR) granular fertilizer (12-12-17); 2) a slow release (SR) fertilizer (27-5-7); and 3) a foliar (FL) fertilizer (20-20-20). The application rate was 50, 30, 0.35 g·m-2 for QR, SR, and FL, respectively. The substrate consisted of sandy loam soil, and in half of the plots UFRF flakes were incorporated in the upper 100 mm at a rate of 20% v/v. The effects of the fertilizer and soil amendment on sod establishment were evaluated through measurements of the dry weight of clippings and roots and the visual quality of the turf. Sod anchorage was measured by determination of the vertical force required to detach a piece of sod. For each treatment the initial and final pH, EC, available P, exchangeable K, Ca, Mg, and Fe were also determined. It was found that FL reduced clipping yield but retained turf visual quality similar to the other fertilizer treatments except in winter, when it resulted in the worst quality ratings. However, FL fertilizer promoted root growth and provided high vertical detachment force values and therefore enhanced sod establishment. Slow release fertilizer resulted in moderate top growth and visual quality of the turf during winter, but delayed sod establishment. Quick release fertilizer increased top growth and improved turfgrass visual quality during the winter, but root growth and vertical detachment force were reduced, indicating poorer sod establishment. UFRF did not enhance sod establishment since there was a negative effect on root growth when temperatures were below 10 °C, without however affecting vertical detachment force. Differences in soil P, K, Ca, Mg and Fe between treatments were inconsistent between the two studies, except for final K concentration, which was higher for QR fertilization than SR and FL. Foliar fertilization can enhance sod establishment compared to QR and SR, by accelerating sod anchorage and root growth. QR can be used in late autumn to improve winter green up of the sod. UFRF does not improve or accelerate sod establishment and possesses a minimal capacity to improve soil properties of sandy loam soils.
Abstract
The relative efficiencies of high-pressure (HPS) and low-pressure sodium (LPS) lamps for plant growth were determined for 32 species of foliage and flowering plants in greenhouse under winter conditions at 37°N latitude. HPS with a relatively wide spectral emission peaking at 589 nm, and low-pressure sodium (LPS) with a monochromatic line at 589 nm were compared at 42 W/m2 irradiance in the 400–700 nm region for various lengths of time at various times of day. Although radiation in the far-red region (700–800 nm) differed, HPS and LPS equally accelerated rates of increase in fresh weights, and heights, and flowering of most herbaceous and tropical foliage plants evaluated. High-pressure sodium and LPS were ineffective, however, in promoting growth of deciduous trees and some woody plants and had no more effect than exposure of the plants to natural winter days with 0.9 W/m2 from incandescent lamps for 8 hrs (2000-0400) night interruption (long day controls). After 16 hours, about half the species showed photomorphogical differences between plants grown at intensities of 21 and plants grown at 42 W/m2 from LPS. All showed significantly better growth characteristics (fresh weight, height, early flowering) than the long day controls. Lighting during the day or night (42 W/m2 from 0800–1600 or from 2000–0400) was equally effective in promoting growth responses with 15 of the 32 species evaluated. Night lighting was more effective than day lighting with 10 of the 32 species tested. The majority of the species grew equally well when lighted 16 hours daily (0800-2400) with 21 W/m2 or 8 hours daily (2000–0400) with 42 W/m2. Effectiveness of the lighting was generally unrelated to the photoperiodic requirements of the plants. Many of the plants, which were previously classified as day-neutral (DN), flowered as if they were long day plants. Such day-neutral plants apparently required adequate light (intensity and duration) for photosynthesis. Increased daylength alone, without regard to intensity, was not sufficient to accelerate growth and early flowering of day-neutral plants. Since HPS and LPS were equally effective on most species tested, we concluded that light quality was less important than total irradiation (energy) for the growth and early flowering of many herbaceous plants.
Plug flats of Begonia × semperflorens-cultorum Hort. `Pizzazz Red', Vodka', and `Viva' were provided 0, 50, 125, or 200 μmol·s-1·m-2 metal-halide supplemental irradiance in the greenhouse for 0, 2, 4, 6, or 8 weeks. Treatments were initiated when seedlings were in the first true leaf stage (2 weeks after sowing). Plug-grown begonias reached transplantable dry weight and leaf area after 4 weeks of 125 μmol·s-1·m-2 supplemental exposure, while those under O and 50 μmol·s-1·m-2 required 6 to 8 weeks. Fewest number of days to visible bud and anthesis and the fewest number of nodes for all cultivars occurred after 2 weeks of 125 μmol·s-1·m-2 supplemental exposure. The same conditions achieved the greatest final leaf area and plant height; however, final dry weight was unaffected. Additional supplemental irradiance and/or exposure time did not accelerate flowering or improve vegetative growth of finished plants.