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High Soluble Salts Affects Water Loss and Bract Necrosis of x Poinsettia .pdf




'Angelika White' poinsettias (Euphoria pulcherrima Willd.ex. Klotzch) were grown hydroponically with modified solution concentrations of 2 or 8 mS.cnr1. The 8-mS.cm-1 rate was imposed by proportionate increases in Ca(N03)2, KN03, and MgS04. Water use, whole plant fresh mass, and panevapo ration were measured gravimetrically twice weekly over a 2-week period beginning 12 Oct. 1995. Poinsettia leaf water loss (g H20/dm2of estimated leaf area per day) was 0.30 and 0.22 times pan evaporation (g H20/dm2 of pan area per day) for the plants in the 2and 8mS.crrr1 solutions, respectively (a 25% reduc tion in water loss for plants in the 8mS.cm-1 solution), as compared to plants in the 2 mS.cnr1 solution. At initial anthesis, a reciprocal transfer of plants be tween the 2 and 8 mS-crrr1 solutions was used to investigate the time when plants were sensitive to high soluble salts for bract necrosis. Other plants were maintained throughout the experiment in the 2 and 8mS.cnr1 solutions. On 15 Jan. 1996, plants were harvested and total lamina surface of leaves and bracts, number of necrotic bracts, and dry mass of leaves, bracts, stems, and roots were recorded. The results indicated that exposure to high soluble salts (8 mS^cm-1) prior to anthesis significantly increased the percent incidence of bract necrosis and decreased root growth. The smaller the root dry mass as a percent of total plant dry mass the greater the incidence of bract necrosis (Y =0.0972X2-3.78X +38.7, /2 =0.69). (jd&c^'i gv^ -tfko^ effectiveness ofNl long-day lighting treatments delivered at different night temperatures in promoting flowering of several herbaceous perennials. Ten herbaceous perennial species were grown under natural short days augmented with a 4-hr Nl. Night temperatures were 2.5,5,10,15,20,and 25°C with day tempera tureof25°Cforalltreatments. Plantswere transferred to9-hrdaysata constant 20°C after 7weeks oftreatment. Results onflowering percentage, date ofvisible bud and flowering, node count, flower bud count, andplant height atflowering will bepresented. 335 Plantand PinchNumber forAlternative HangingBasket Crops Affect Qualityand Scheduling Jerri Woods Starman*, Millie S. Williams, andJames £ Faust Dept. ofOrna mental Horticulture and Landscape Design, Inst, ofAgriculture, Univ. ofTennes see, Knoxville, TN 37901-1071. The objective was todetermine the optimum number ofplants and the num ber of pinches required tomarket a basket for hanging basket production using alternative floriculture species. The number of plants per pot varied from one to four, and the number of manual pinches per basket ranged from 0to2.Several specieswereevaluated in spring of1996and heattolerance wasassessed through outthe summer. Plugs (50-95 plugs perflat)weretransplanted into 25-cm hanging baskets in a22/18°C (venting/night temperature setpoints) glasshouse. Three to four plants were necessary for Scaevola aemula 'Fancy Fan Falls' and Evolvulus glomeratus 'Blue Daze' to produce a marketable basket. One plant per pot was sufficientfor Abutilonhybrid'Apricot', Portulacao/eraceae'Apricot', and Tibouchina 'Spanish Shaw' without sacrificing quality; however, an additional 1to3weeks production time was needed in comparison tothe four plants per pot treatment. Abutilonand Portulacarequired one pinch, while TibouchinaM not require pinch ing. All plants xpinch combinations produced quality basketswith Suteracordata 'Mauve Mist' and Diascia hybrid'Ruby Fields'; therefore, production methods should be based on growers' scheduling and cost analysis. Abutilon, Evolvulus, Portulaca, Scaevola, and Tibouchinaperformed well inhanging baskets through out the summer. Two species in the trial, Orthosiphon stamineuslavender' and Tabernamontana coronaria, displayed upright growth habits and would bebest for usesother than hanging basket production. 336 Pruning Method Influences Stem Length and Number of Four Woody CutSpecies John M. Dole*, Janet C. Cole, and Vicki Stamback, Dept. ofHorticulture and Landscape Architecture, Oklahoma State Univ., Stillwater, OK 74078 Rooted cuttings of four woody cut species, Buddleia davidii 'Black Knight' (butterfly bush), Forsythia xintermedia lynwood Gold', Salix chaenomeloides (Japanese pussywillow), and Salixmatsudana'lotiuosa' (corkscrewwillow)were planted outdoors in 23 Apr. 1992. During the next year, forsythia, pussywillow, and corkscrew willow plants were either unpruned orpruned to30—45 cm above the ground: 1)during dormancy or immediately after harvest (winter); 2) 3to 4 weeks after start of shoot growth (spring); or3)in early June (summer), and number and length of stems harvested was recorded for three years. Butterfly bush was either unpruned or pruned to 8cm above the ground during: 1) winter or 2) spring, and number and length of stems recorded for 2years. Stem length and number increased each year for all four species, and all species produced harvestable stems within 1 year after planting. Forforsythia, no differences due to treatment were found, although year by treatment interactions were noted. The unpruned control produced the longest and greatest number of stems for pussy willow. Winter or spring pruning produced the longest and greatest number of stems for corkscrew willow. For butterfly bush, spring or no pruning produced the greatest number of stems, and year by treatment interactions were noted. 334

Keywords: Hoagland's Hydroponically necrotic bracts Evaporation

Libraries: Floriculture

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