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- Author or Editor: Kimberly A. Moore x
Two experiments were conducted to compare the growth of `Ultra White' petunia (Petunia ×hybrida) plants in a subirrigation system versus in a hand-watered system. In Expt. 1, petunia plants were watered with 50, 100, or 150 ppm (mg·L-1) of N of Peter's 20-10-20 (20N-4.4P-16.6K) and in Expt. 2, Nutricote 13-13-13 (13N-5.8P-10.8K) type 100, a controlled release fertilizer, was incorporated into the growing substrate, prior to transplanting, at rates of 3, 6, or 9 lb/yard3 (1.8, 3.6, or 4.5 kg·m-3). In both experiments, there was no difference in petunia shoot dry mass or final flower number between the irrigation systems at the lowest fertilization rate but differences were evident at the higher fertilization rates. In Expt. 1, shoot dry mass and flower number of subirrigated petunia plants fertilized with 100 ppm of N was greater than for hand-watered plants fertilized at the same rate. However, subirrigated petunia plants fertilized with 150 ppm of N were smaller with fewer flowers than hand-watered petunia plants fertilized with 150 ppm of N. Substrate electrical conductivity (EC) concentrations for petunia plants subirrigated with 150 ppm of N were 4.9 times greater than concentrations in pots hand-watered with 150 ppm of N. In Expt. 2, subirrigated petunia plants fertilized with 6 and 9 lb/yard3 were larger with more flowers than hand-watered plants fertilized at the same rates. Although substrate EC concentrations were greater in subirrigated substrates than in hand-watered substrates, substrate EC concentrations of all hand-watered plants were about 0.35 dS·m-1. Subirrigation benches similar to those used in these experiments, appear to be a viable method for growing `Ultra White' petunia plants. However, the use of Peter's 20-10-20 at concentrations greater than 100 ppm of N with subirrigation appeared to be detrimental to petunia growth probably because of high EC concentrations in the substrate. On the other hand, the use of subirrigation with Nutricote 13-13-13 type 100 incorporated at all of the rates tested did not appear to be detrimental to petunia growth.
Salvia (Salvia splendens) `Red Vista' or `Purple Vista,' french marigold (Tagetes patula) `Little Hero Orange,' bell pepper (Capsicum annuum) `Better Bell,' impatiens (Impatiens wallerana) `Accent White,' and wax begonia (Begonia ×semperflorens-cultorum) `Cocktail Vodka' were grown in 0.95-L (1-qt) containers using a 5 pine bark: 4 sedge peat: 1 sand substrate (Expts. 1 and 2) or Pro Mix BX (Expt. 2 only). They were fertilized weekly with 50 mL (1.7 fl oz) of a solution containing 100, 200, or 300 mg·L-1 (ppm) of nitrogen derived from 15N-6.5P-12.5K (1N-1P2O5-1K2O ratio) or 21N-3P-11.7K (3N-1P2O5-2K2O ratio) uncoated prills used in the manufacture of controlled-release fertilizers. Plants grown with Pro Mix BX were generally larger and produced more flowers or fruit than those grown with the pine bark mix. With few exceptions, plant color, root and shoot dry weights, and number of flowers or fruit were highly correlated with fertilization rate, but not with prill type. There appears to be little reason for using the more expensive 1-1-1 ratio prills, since they generally did not improve plant quality and may increase phosphorous runoff from bedding plant nurseries.
Native aquatic plants are important to maintaining a balanced ecosystem, but they often are displaced by exotic invasive plant species. The research on the control and growth of the invasive aquatic species hydrilla (Hydrilla verticillata) using sand substrates and controlled-release fertilizers (CRF) provides a potential production technique for other aquatic plants. We questioned if we could use hydrilla production techniques to grow southern naiad (Najas guadalupensis), a Florida-native aquatic plant that is often mistaken for hydrilla. We grew southern naiad cuttings in containers filled with 100:0, 75:25, 50:50, 25:75, or 0:100 coarse builder’s sand and sphagnum moss (by volume). Before planting, containers were fertilized with 0, 1, 2, or 4 g·kg−1 CRF (15N–4P–10K). Containers were submerged in large storage tubs filled with rainwater and grown for 8 weeks. Southern naiad shoot dry weight was greater in the 100% sand substrate than that in the 0% sand substrate. Substrate electrical conductivity (EC) levels were greater in the 0% sand with no difference among the other substrates. Shoot and root dry weight of plants fertilized with 1–2 g·kg−1 CRF were greater than 0 or 4 g·kg−1 CRF. Substrate EC also increased as fertilizer rate increased, with the highest EC observed at 4 g·kg−1 CRF. Based on our results, we would suggest growing southern naiad in substrates with 100% sand and fertilized with 1–2 g·kg−1 CRF.
As the horticulture industry enters the 21st century, advances in horticulture science will continue to be more rapid and frequent creating the need for more innovative approaches in information delivery. Moreover, decentralization continues to be a widespread trend. Land-grant universities have a long tradition of providing outreach, but with the development of new telecommunication technologies, larger audiences now can be reached. Many universities throughout the world have developed distance education programs through the use of modern telecommunication technologies. However, the University of Florida has responded to the needs of place-bound students by developing off-campus resident Bachelor of Science (BS) degree programs in horticulture at three locations in the state. These off-campus programs combine on-site instruction augmented with distance education courses to giveplace-bound students a flexible, efficient, and interactive alternative to degree programs offered at the main campus.
Bougainvillea (Bougainvillea sp.) plant inflorescence number will vary in response to multiple cues such as changes in temperature, water, light intensity, pruning, and photoperiod. Previous research reports that the application of plant growth regulators (PGRs) to bougainvillea grown under varying photoperiods improved inflorescence number, probably as a result of changes in gibberellic acid (GA) levels. There are many bioactive plant GAs, but we chose to investigate differences in gibberellic acid 3 (GA3) levels and inflorescence number in response to the application of ethephon (2-cholorethylphosponic acid) or abscisic acid (ABA) to ‘Afterglow’ bougainvillea (Bougainvillea ×buttiana) grown under 14-hour photoperiod [long-day (LD)] conditions. Plants were 5 inches tall with seven visible lateral nodes and were grown in a greenhouse in 4-inch pots filled with 5-mm coarse aquarium zeolite. Ethephon was applied as a foliar spray at 0.05, 0.07, 0.10, 0.15, or 0.20 mg/plant. ABA was applied as a soil drench at 1, 1.5, 3, 6, 8, or 10 mg/plant. Endogenous levels of GA3 were measured 1 and 48 days after treatment to calculate the change in GA3 (∆GA3). A short day (SD) control of 8 hours was included to measure differences in inflorescence number and ∆GA3 between photoperiods. ‘Afterglow’ plants grown under SD conditions had the greatest decrease in ∆GA3 (–1.09 µg·g–1) over 48 days and the most inflorescences (10.6) compared with LD control plants with a decrease in ∆GA3 of –0.09 µg·g–1 and fewer inflorescences (1.0). Plants grown under LD conditions and treated with 0.05 mg/plant ethephon had inflorescence numbers (9.6) and levels of ∆GA3 (–0.74 µg·g–1) similar to the SD control. As ethephon rate increased to more than 0.05 mg/plant, inflorescence number on LD plants decreased and ∆GA3 increased. Exogenous ABA rates of 1 mg/plant produced inflorescence numbers (1.4) and ∆GA3 (–0.10 µg·g–1) similar to the LD control. As the rate increased, ∆GA3 increased and inflorescence number decreased. Plants treated with ABA rates of 3 mg/plant and more were defoliated and had no inflorescences.
Experiments were conducted during two different time periods to determine if hybrid phalaenopsis orchid (Phalaenopsis spp.) liners accumulate silicon (Si) and if this element can affect liner growth. A total of 800 liners were evaluated and Si fertilization was performed by applying potassium silicate (KSiO3) as a drench with three treatments (0.5%, 1.0%, and 2.0% v/v) and a control (water, no Si fertilization). The application of KSiO3 affected overall growth of phalaenopsis orchid liners, where Si content of the plant ranged from 0.5% to 1.7%. Overall, Si applied at 0.5% and 1.0% increased fresh weight and dry weight (DW) and at 1.0% Si significantly increased DW of root, shoot, and whole plant over the control. Increases in DW ranged from 27% up to 118%. Results from the second experiment were similar. Other plant parameters evaluated such as leaf number and size, root number, and length were unaffected by Si application. Although leaves of phalaenopsis orchid liners treated with Si appeared darker green when compared with the control, no significant differences were observed in chlorophyll content of leaves. Reduced growth was observed when 2.0% Si was applied affecting Si tissue concentrations and substrate electric conductivity. The data obtained from this study indicate that hybrid phalaenopsis orchid liners are Si accumulators and that this element influences their growth. Further studies are warranted to address the long-term effects of Si fertilization on the complete life cycle of hybrid phalaenopsis orchids.
Previous research indicated that acceptable quality annual and perennial plant species can be grown in the landscape with low nitrogen (N) inputs. However, information on the impact of soil conditions and N use by ornamental plants grown in central Florida is lacking in the literature. Our objective was to evaluate plant growth and quality response of eight warm-season annuals, seven cool-season annuals, and four herbaceous perennial species to a range of N fertilizer rates when plants were grown in landscape beds containing native field soil or subsoil fill. A slow-release N source (42N–0P–0K) was applied every 12 weeks at annual N rates of 3, 5, or 7 lb/1000 ft2 for a period of 18 weeks (annual species) or 1, 3, or 5 lb/1000 ft2 for a period of 54 weeks (perennial species). Plants were evaluated for aesthetic quality every 6 weeks and shoot dry weight was measured at completion of the experiment. Dry weight production and aesthetic quality of most species evaluated was unaffected by N rate. For several species, shoot dry weight was higher when planted in the field plots containing native soil [alyssum (Lobularia maritima) ‘Bada Bing White’ wax begonia (Begonia ×semperflorens-cultorum), dahlberg daisy (Thymophylla tenuiloba), ‘Survivor Hot Pink’ geranium (Pelargonium ×hortorum), gomphrena (Gomphrena globosa), ‘Blue Puffs Improved’ (‘Blue Danube’) ageratum (Ageratum houstonianum), blanket flower (Gaillardia pulchella), goldenrod (Solidago chapmanii), ‘Mystic Spires’ salvia (Salvia longispicata ×farinacea)]. Quality response to soil condition was mixed over the course of the study. Several species performed as well (or better) in the field as when planted in the subsoil fill soils. These results illustrate that some landscape plant species are able to survive and thrive under various soil and fertility conditions. These “tougher” species may be good choices for installation in landscapes with marginal native soils or disturbed urban landscape soils.
Evidence is presented that native populations of Rudbeckia hirta L. (Blackeyed Susan) may be adapted to regional conditions. Two Florida ecotypes, one from north Florida (NFL) and one from central Florida (CFL), were better able to withstand the low fertility sites under three AHS Heat Zones (9, 10, 11) in Florida than were plants grown from Texas (TEX) seeds. Plants from TEX seed were the largest and showiest (generally the greatest number of flowers; largest flowers) but the shortest-lived. Most of these plants did not survive beyond August (about 6 months after transplanting) regardless of site. The CFL plants were especially tolerant of flooding conditions at Ft. Lauderdale. Under garden conditions, CFL Black-eyed Susan may be a highly desirable wildflower for subtropical or tropical summers.