Peace lily (Spathiphyllum Schott) is one of the most popular tropical ornamental foliage plants and is used worldwide for interiorscaping. However, little information is available on the genetic relationships of cultivars. Using amplified fragment length polymorphism (AFLP) markers with near-infrared fluorescence-labeled primers, this study analyzed genetic relatedness of 63 commercial cultivars and breeding lines. Forty-eight EcoRI + 2/MseI + 3 primer set combinations were initially screened, from which six primer sets were selected and used in this investigation. All cultivars were clearly differentiated by their AFLP fingerprints, and the relationships were analyzed using the unweighted pair-group method of arithmetic average cluster analysis (UPGMA). The 63 cultivars were divided into four clusters. All commercial cultivars or breeding lines resulted from crosses of some of the cultivars, a total of 45, were positioned in cluster I with Jaccard's similarity coefficients between 0.61 and 0.88. There was only one cultivar in cluster II. Cluster III contained 16 cultivars; they are either species or breeding lines generated from interspecific hybridization. Cluster IV had one unknown species. This study provides genetic evidence as to why cultivars from cluster I and III are not readily crossable because the Jaccard's similarity coefficient between the two clusters was only 0.35. Results also indicate that commercial cultivars are genetically close. Strategies for increasing genetic diversity of cultivated peace lily should be sought for future breeding efforts.
Jianjun Chen, Richard J. Henny, Pachanoor S. Devanand, and Chih-Cheng T. Chao
A.A. Watad, K.G. Raghothama, M. Kochba, A. Nissim, and V. Gaba
Explant growth and shoot multiplication of Spathiphyllum and Syngonium were compared on agar-solidified medium and interfacial membrane rafts floating on liquid medium. After 25 d of culture, greater shoot multiplication and fresh mass gain were achieved by plant material grown on rafts. Shoot multiplication of Spathiphyllum and Syngonium on membrane rafts reached a maximum at 25 d, whereas the fresh mass increased throughout the culture period (40 d). The number of shoots of Spathiphyllum and Syngonium material grown on membrane rafts remained constant between 25 and 40 d of culture. The plants grown on membrane rafts also developed more roots.
D.J. Norman, J.M.F. Yuen, and R.J. Henny
Twenty-two spathiphyllum cultivars were evaluated for resistance to Cylindrocladium root rot (CRR). Four isolates of the fungus Cylindrocladium spathiphylli Shoult., El-Gholl & Alf. were selected from two different locations each in Florida and Hawaii. Spores of isolates were applied as a soil drench in replicated experiments using a randomized complete block design. The most severe symptoms were those produced by C. spathiphylli isolates from Hawaii. None of the spathiphyllum cultivars tested were highly resistant to CRR although resistance among the cultivars was observed. The cultivars Chris and Textura were the most promising cultivars, having fairly uniform resistance to the four isolates of C. spathiphylli. The cultivars Cupido, Daniel, Frederik, Jetty, and Vanessa were moderately resistant when combined data from all tests were analyzed. Results from this research permit the selection of more resistant breeding lines and also creates a baseline against which resistance of newly developed cultivars can be compared.
Robert H. Stamps
Impatiens `Dazzler Violet', Petunia × hybrida `Carpet Blue', and Spathiphyllum `Ty's Pride' plugs were planted in 10-cm pots containing a commercial peat-based soilless growing medium composed of Canadian 60 peat: 20 vermiculite: 20 perlite (by vol) not treated with surfactant. Growing medium was treated, or not treated, 1) at planting, 2) during production, and/or 3) preshipment with experimental surfactants. The production phase consisted of growing plants on raised benches in a greenhouse until they reached marketable size. Phytotoxicity, plant water use and growth were determined. At the beginning of the postproduction phase, growing medium in all pots was brought to container capacity. Plants were then dried to wilting three times. Water loss and water retained on rewatering and times to wilt and recovery were recorded. Surfactant treatments caused no foliar phytotoxicity and did not delay flowering for petunia or spathiphyllum. However, surfactant treatments delayed flowering for impatiens by ≈4 days. Surfactant treatments increased top growth of petunia but not of the other crops. Postproduction, water retention at rewatering, and times to wilt were increased for petunia and spathiphyllum when they were in surfactant-treated medium. For impatiens, treatments had no effects on water retention or wilting, probably due to the small root systems and limited attendant medium dewatering for this crop. Generally, all three experimental surfactants performed similarly and weekly and preshipment surfactant applications were of no additional benefit compared to a single initial application at planting.
R.J. Henny, T.A. Mellich, and D.J. Norman
Thirty-one spathiphyllum (Spathiphyllum Schott.) cultivars were evaluated for flowering response following treatment with gibberellic acid (GA3). Greenhouse-grown plants were treated once with 250 mg·L-1 (ppm) GA3 applied as a foliar spray. Within 16 weeks after treatment all GA3-treated plants had flowered but none of the untreated controls produced flowers. `Vickilynn' (14.1 flowers/plant after 16 weeks), `Piccolino' (12.8), `Mascha' (12.6), `Chris' (11.7), `Alpha' (11.7), and `Daniel' (11.0) produced significantly more flowers than other cultivars. The cultivars producing the fewest flowers per plant after 16 weeks were `Sierra' (2.5), `S1008' (3.2), `Rica' (3.4), `Sonya' (4.3), `Vanessa' (5.1), `S18' (5.5) and `S4002' (5.6). `Alpha,' `Textura,' `Daniel,' `Mascha,' `S1007', and `Showpiece' had significantly better flower quality. `S1008,' `Codys Color', and `Petite' had poor flower quality. `Mascha' was the earliest cultivar to bloom producing maximum flower counts during weeks 9 to 10 after treatment while `Vanessa' was the latest to flower with peak bloom occurring 15 to 16 weeks after treatment. Most cultivars reached peak bloom at 11 to 13 weeks after treatment. Results indicate sufficient genetic variability in spathiphyllum flowering response to GA3 treatment exists to permit cultivar selections based on differences in flowering time, number of flowers and flower quality.
Ricardo Campos and David Wm. Reed
Salinity is a limiting factor in plant growth. The combination of water high in soluble salts and water-soluble fertilizers can induce salt damage in plants. The objective of this work was to investigate the effects of salinity in irrigation water on optimal fertilization rates in Spathiphyllum `Petite'. The combination of 5 levels of fertilizers and 5 salinity levels were tested. Maximum growth was observed at 250 mg l-1 N and no salts, and with 2000 mg l-1 salts at 125 mg l-1 N. As salt levels increased, height and leaf area decreased. Tissue calcium, sodium, and chloride increased with increasing levels of salinity. Tissue nitrogen, phosphorus, and potassium generally increased with increasing levels of fertilizers, and were not affected by salinity level. It is possible that high sodium and chloride concentrations in leaves, petioles, and roots produced an ion toxicity.
Matthew W. Kent and David Wm. Reed
Greenhouse cultural methods must change rapidly to minimize runoff and to keep pace with environmental regulation aimed at protecting water resources. Two experiments were designed to investigate the effect of N fertilization rate on New Guinea impatiens (Impatiens ×hawkeri) and peace lily (Spathiphyllum Schott) in an ebb-and-flow subirrigation system. Maximum growth response for impatiens was centered around 8-mM N levels as measured by root and shoot fresh and dry weight, height, leaf number, leaf area, and chlorophyll concentration. For peace lily, growth peaked around 10 mM N. Growing medium was divided into three equal layers: top, middle, and bottom. Root distribution favored the middle and bottom layers, and the relative distribution of roots was consistent as N level increased. Soluble salts remained low in middle and bottom layers at N concentrations below 10 mM, but increased significantly for all soil layers at levels above 10 mM. The top layer contained two to five times higher soluble salt levels than in the middle or bottom layers at all N levels. Increased nitrate concentration mimicked increases in soluble salts, while pH decreased as N concentration increased for both impatiens and peace lily.
Matthew W. Kent and David Wm. Reed
Greenhouse cultural methods must minimize runoff to keep pace with environmental regulation aimed at protecting water resources. Two experiments were designed to investigate the effect of N fertilization rate on New Guinea impatiens (Impatiens ×hawkeri) and peace lily (Spathiphyllum Schott) in an ebb-and-flow subirrigation system. Maximum growth response for impatiens was centered around 8 mm N levels as measured by root and shoot fresh and dry weight, height, leaf number, leaf area, and chlorophyll concentration. For peace lily, growth peaked at about 10 mm N. Growing medium was divided into three equal layers: top, middle, and bottom. Root distribution favored the middle and bottom layers, and the relative distribution of roots was consistent as N level increased. EC remained low in middle and bottom layers at N concentrations below 10 mm, but increased significantly for all layers at levels above 10 mm. The EC for the top layer was 2 to 5 times higher than in the middle or bottom layers at all N levels. Increased nitrate concentration paralleled increased EC, while pH decreased as N concentration increased for impatiens and peace lily.
Stacie L. Aragon, Keng-Chang Chuang, and Adelheid R. Kuehnle
Isolation of high quality nucleic acids from aroids can be difficult due to the presence of carbohydrates, phenolics, and other compounds that bind to and/or co-precipitate with the DNA or RNA. Methods previously used for marine algae, mango, and papaya were modified and successfully used for the simultaneous isolation of high quality genomic DNA and RNA from Anthurium, Colocasia, and Spathiphyllum leaves. Genomic DNA yields averaged 477 μg·g-1 fresh weight for Anthurium and 322 and 177 μg·g-1 fresh weight, respectively, for Colocasia and Spathiphyllum. Total RNA yields averaged 129 μg·g-1 fresh weight for Anthurium and 61 and 50 μg·g-1 fresh weight, respectively, for Colocasia Spathiphyllum. This method may be useful in co-isolating high quality nucleic acids from additional aroids and other plants.
Monica L. Elliott and Timothy K. Broschat
A commercially available microbial inoculant (Plant Growth Activator Plus) that contains 50 microorganisms, primarily bacteria, was evaluated in a soilless container substrate to determine its effects on root bacterial populations and growth response of container-grown plants at three fertilizer rates. The tropical ornamental plants included hibiscus (Hibiscus rosa-sinensis `Double Red'), spathiphyllum (Spathiphyllum `Green Velvet') and areca palm (Dypsis lutescens). The bacterial groups enumerated were fluorescent pseudomonads, actinomycetes, heat-tolerant bacteria, and total aerobic bacteria. Analysis of the inoculant before its use determined that fluorescent pseudomonads claimed to be in the inoculant were not viable. The plant variables measured were plant color rating, shoot dry weight and root dry weight. Only hibiscus shoot dry weight and color rating increased in response to the addition of the inoculant to the substrate. Hibiscus roots also had a significant increase in the populations of fluores-cent pseudomonads and heat-tolerant bacteria. From a commercial production point of view, increasing fertilizer rates in the substrate provided a stronger response in hibiscus than did addition of the microbial inoculant. Furthermore, use of the inoculant in this substrate did not compensate for reduced fertilizer inputs.