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Dharmalingam S. Pitchay and Bradford C. Bearce

Rooting performance was evaluated for three different hydrangea (Hydrangea macrophylla Thunb. `Blaumeise Lace Cap') cutting types in propagation media containing peat:sand amended with 0%, 25%, 50%, and 100% coal bottom ash (CBA) sieved through 2-mm mesh. Electrical conductivity (EC) values of all media were in acceptably low ranges, whereas pH was suboptimal in all but 100% CBA, ranging from 3.8 to 4.6 vs. 6.0 to 6.75 for 100% CBA. Available Ca was significantly higher at up to 189 mg·kg–1 in the 100% CBA. Rooted cuttings were analyzed for root counts and dry mass. Terminal tip cuttings produced 96.1 mean roots/stem compared to butterfly cuttings (76.4) and single-eye cuttings (60.7), and there was no significant difference in root dry mass among the different cutting types. Propagation media containing 50% CBA produced greater numbers of roots/stem (99.89 and 89.59, respectively). The dry mass of roots/stem was significantly higher in media with 100% CBA. Root numbers per cutting were higher in terminal tip cuttings grown in 50% and 100% CBA and butterfly cuttings in 50% CBA. On the other hand, dry mass per cutting was higher in 100% CBA as compared to the rest, except for the terminal tip and butterfly cuttings in 50% CBA. The higher pH and Ca concentration may be factors causing the better rooting performance in 100% CBA.

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Dharmalingam S. Pitchay and B.C. Bearce

Rooted cuttings of `Supjibi' poinsettia were potted in peat vermiculite, mixed with coal bottom ash at 0%, 25%, 50%, 75%, or 100% by volume. Values of pH were higher in media containing coal bottom ash. In general, pH increased for the first 4 weeks, during which time 50–100 ppm (N) fertilizer was being applied, decreased temporarily when 200 ppm fertilizer began, and then increased and stabilized for the last 5 weeks. At first, pH tended to be higher with increase in ash, but when 200 ppm fertilizer was begun, pH became the same in all coal ash levels. Once fertilization was stopped, pH tended again to be higher in ash media. Levels of EC remained low in all media when 50–100 ppm of fertilizer was applied, but increased after 200 ppm fertilizer was begun, increasing to excessive levels 2 weeks later. With more watering, EC declined in the 0% ash, but remained high in 50% to 100% ash media. Leaf Ca content increased with increase in media ash but was below the normal range in all plants. With increase in media ash, water capacity decreased, but bulk density increased. Bract color development in plants in ash media appeared delayed.

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Dharmalingam S. Pitchay and B.C. Bearce

Petunia and impatiens seedlings were planted in cell packs containing 0%, 25%, or 50% (by volume) coal bottom ash (CBA) mixed with peat: vermiculite. High soluble salts caused fresh and dry weights to be greatly reduced in 25% and 50% CBA. This was thought to be due to insufficient drainage in the shallow cell packs. Subsequent crops were grown in 4-inch pots. Double Pink impatiens in 4-inch pots showed no significant difference between control and ash media in the number of buds and flowers, plant heights and diameters, and fresh and dry weights. For `Mixed Shady Lady' impatiens, the number of flowers, and fresh and dry weights were greater in the control and 50% CBA. Plant heights were reduced in 25% and 50% CBA media. There were no differences in plant diameters among the media. Ivy geraniums showed no significant difference in the number of days from planting to first bloom and 50% florets opening; number of florets, buds, and inflorescences; and stem lengths. Shoot numbers were reduced in 25% and 50% CBA. There was also no significant difference in number of days from planting to first bloom and 50% florets opening, or number of buds and inflorescences for zonal geraniums. Number of florets increased for zonal geraniums in 25% CBA.

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Dharmalingam S. Pitchay and Paul V. Nelson

It is a common practice in greenhouses to apply fertilizers with a high proportion of N in the NO3 form to achieve short, compact shoots and a moderate (25% or greater) proportion of NH4 or urea for large shoots. However, this practice is not substantiated in the scientific literature. Two experiments were conducted in a greenhouse to assess effects of N form on development. In the first, Petunia hybrida `Mid-night Dreams' was treated with five ratios of NH4:NO3 or urea:NO3 in a factorial arrangement with three concentrations of N (50-low, 100-adequate, and 200-high mg/L at each irrigation). In the second experiment six species of bedding plants were treated in a factorial arrangement of five ratios of NH4:NO3 and two pH levels (acceptably low, 5.4-5.8, and unacceptably low, 4.6-5.2). In all comparisons, height and dry weight of shoots grown with 100% NO3 were equal or larger than the plants grown with combinations of N. There was a general trend for plants to be shorter and lighter at higher NH4 or urea proportions. These results refute the hypothesis that shoot size is under the control of N form. Depth of green foliar color correlated positively with proportion of NH4 or urea. Reputed NH4 toxicity symptoms of chlorosis, necrosis, and curling of older leaves occurred only at adversely low pH levels below 5.2 in experiment 2. Resistance of plants to this disorder under conditions of pH levels in the range of 5.4 to 5.8, high N application rates, and applications of 100% NH4 indicates that bedding plants during commercial production are fairly resistant to this disorder.

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Mark D. Sherratt, Dharmalingam S. Pitchay, and Bradford C. Bearce

Easter lilies (Lilium longiflorum Thunb. `Nellie White') were placed at three spacings of about 11, 22, or 44 plants per square meter (plants/m2). Above canopy light intensities, measured weekly at noon, ranged from 107.3 to 704.5 μmol·s–1·m–2 and were not significantly different among spacings. Mid canopy light intensities ranged from 16.5 to 229.0, 43.0 to 458.5, and 77.5 to 535.3 μmol·s–1·m–2 at spacings of 44, 22 and 11 plants/m2, respectively. On February 5, 1996, three plants from the 22 plants/m2 spacing were sprayed with a solution of 0.5 ml·L–1 of 1.8% (a.i.) of each of N-(phenylmethyl)-IH-purine-6-amine and gibberellins A4A7; and on March 5, three additional plants from each spacing were similarly sprayed. Beginning 5 Mar., weekly counts were made of yellow and brown leaves on all treated and control plants. Average per plant numbers of brown leaves increased on control plants at all spacings but increased on treated plants only at the 11 plants/m2 spacing. On 25 Mar., control plants averaged 15.6, 12.1, and 15.3 brown leaves per plant at spacings of 11, 22, and 44 plants/m2, respectively, while plants treated on March 5 averaged 10.7, 9.0, and 10.7 brown leaves. Plants treated on 5 Feb. averaged 3.5 brown leaves per plant and had an average mid leaf length of 13.8 cm compared to about 10.5 cm for all other plants. Spacing had no effect on average yellow or brown leaves per plant. This study demonstrated that early applications of Promalin can reduce leaf senescence which may occur during forcing time before bud appearance to opening of first bud. Some leaf enlargement may occur on plants treated very early.

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Rajeev Arora, Dharmalingam S. Pitchay, and Bradford C. Bearce

This study evaluated the effect of reversible water stress on heat stress tolerance (HST) in greenhouse-grown geraniums. Water stress was imposed by withholding irrigation until pots reached ≈30% (by weight) of well-watered (control) plant pots, and maintaining this weight for 7 days. Control plants were watered to just below field capacity, every other day. Leaf xylem water potential (LXWP, MPa), leaf-relative water content (LRWC,%), media water content (MWC, % fresh weight), and heat stress tolerance (HST, LT50) were determined for control and stressed plants. HST (LT50), defined as temperature causing half-maximal percent injury, was based on electrolyte leakage from leaf disks subjected to 25 to 60C. Control-watering was restored in stressed plants and above measurements made after 7 days of recovery. Data indicate: 1) LXWP, LRWC, and MWC in control and stressed plants were –0.378 and –0.804 MPa, 92.31% and 78.69% and 82.86% and 15.5%, respectively; 2) HST increased significantly in stressed as compared to control plants (LT50 of 55C vs. 51C); 3) control plants were near maximally injured by 53C treatment and sustained more than 3-fold greater injury than stressed plants at 53C. In recovered plants, LXWP and RWC reversed back to control levels, paralleled by loss of higher HST.

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Dharmalingam S. Pitchay, Mark D. Sherratt, and Bradford C. Bearce

Dormant budded plants of Hydrangea macrophylla (Thunb.) cvs. Blaumeise Blue and Pink were planted on 29 Jan. 1996 in 15-cm azaleas pots containing media with topsoil, peat, perlite, coal bottom ash, and mine soil, mixed in varying proportions. Media pH levels were initially adjusted with dolomitic limestone to a range of 6.0 to 6.1 for pink inflorescences and with ammonium sulfate to a range of 4.4 to 5.9 for blue inflorescences. Plants of Blaumeise Blue and Blaumeise Pink in low pH media were drenched on 29 Feb. with a solution of aluminum sulfate at 6 g·L–1. Number of shoots per plant were reduced in media with the highest proportion of coal bottom ash (40%, v/v) plus 30% mine soil. Plant diameter was affected very little by type of media. Tallest plants were `Blaumeise Pink' growing in media containing at least 20% top soil or mine soil plus 20% coal bottom ash. These mixes also contained 20% or 40% perlite. Inflorescence diameters ranged from 10.88 to 17.43 cm. and were mostly unaffected by media type. Inflorescence number per plant appeared to be reduced in `Blaumeise Blue' regardless of media. Inflorescence color brightness ranged from L = 55.26 to 61.38 and was affected very little by media type in both cultivars. Bluest inflorescences occurred on `Blaumeise Blue' plants growing in a combination of zero top soil, 40% peat, 30% perlite, 20% coal bottom ash, and 10% mine soil with no lime, and`Blaumeise Pink' plants growing in media with zero topsoil, 40% peat, and 20% mine soil. Blue color did not develop well in media containing top soil and no mine soil. This study demonstrated that florists' hydrangea can be satisfactorily forced in media containing substantial amounts of coal bottom ash and mine soil and that color regulation is also possible in some of these media.

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Jonathan M. Frantz, Dharmalingam S. Pitchay, Glen Ritchie, and Heping Zhu

Nitrogen (N) is often supplied to plants in excess to minimize the possibility of encountering N deficiency that would reduce the plant quality due to leaf chlorosis and necrosis. This is not only costly, but it can reduce the quality of plants, predispose the plants to biotic stress such as Botrytisgray mold, and extend the production cycle. Several tools can be used to identify N deficiency in plants, and most are based on chlorophyll reflectance or transmittance. While sensitive when plants are experiencing N deficiency, spectral signals can saturate in an ample N supply and make it difficult to discern sufficient and supra-optimal N nondestructively. Three diverse ornamental species (begonia, Begoniacea×tuberhybrida; butterflybush, Buddlejadavidii; and geranium, Pelargonium×hortorum) were grown with a broad range of N supplied (1.8 to 58 mm) in three separate studies that resulted in a range of 1.8% to 6% tissue N concentration. Using a spectroradiometer, we measured reflectance from the whole plants twice over a period of 3 weeks. A first-derivative analysis of the data identified six wavebands that were strongly correlated to both begonia and butterflybush tissue N concentration (r 2 ∼ 0.9), and two of these also correlated well to geranium N concentration. These wavebands did not correlate to chlorophyll peak absorbance, but rather blue, green, red, and far-red “edges” of known plant pigments. These wavebands hold promise for use as a nondestructive indicator of N status over a much broader range of tissue N concentration than current sensors can reliably predict.

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Dharmalingam S. Pitchay, Jonathan M. Frantz, and James C. Locke

Geranium (Pelargonium ×hortorum) is considered to be one of the top-selling floriculture plants, and is highly responsive to increased macro- and micronutrient bioavailability. In spite of its economic importance, there are few nutrient disorder symptoms reported for this species. The lack of nutritional information contributes to suboptimal geranium production quality. Understanding the bioenergetic construction costs during nutrient deficiency can provide insight into the significance of that element predisposing plants to other stress. Therefore, this study was conducted to investigate the impact of nutrient deficiency on plant growth. Pelargonium plants were grown hydroponically in a glass greenhouse. The treatment consisted of a complete modified Hoagland's millimolar concentrations of macronutrients (15 NO3-N, 1.0 PO4-P, 6.0 K, 5.0 Ca, 2.0 Mg, and 2.0 SO4-S) and micromolar concentrations of micronutrients (72 Fe, 9.0 Mn, 1.5 Cu, 1.5 Zn, 45.0 B, and 0.1 Mo) and 10 additional solutions each devoid of one essential nutrient (N, P, Ca, Mg, S, Fe, Mn, Cu, Zn, or B). The plants were photographed and divided into young, maturing, and old leaves, the respective petioles, young and old stems, flowers, buds, and roots at “hidden hunger,” incipient, mid- and advanced-stages of nutrient stress. Unique visual deficiency symptoms of interveinal red pigmentation were noted on the matured leaves of P- and Mg-deficient plants, while N-deficient plants developed chlorotic leaf margins. Tissue N concentration greatly influenced bioenergetic construction costs, probably due to differences in protein content. This information will provide an additional tool in producing premium geraniums for the greenhouse industry.

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Dharmalingam S. Pitchay*, Jonathan M. Frantz, and James C. Locke

Currently, formulation of inorganic fertilizers is based on cation amounts such as NH4, K, Mg, Ca, Fe, MN Cu, and Zn, whereas anion species and amounts are viewed, with few exceptions, as necessary fillers. The delivery of cations in the nutrient solution is associated with an anion such as Cl, SO4, NO3, PO4 or CO3. These anions at higher concentrations can result in different growth responses by altering the rhizosphere pH, soluble salts, and influencing the uptake of both cations and anions. The impact of these anions has not been extensively studied in the formulation of inorganic fertilizers. Several experiments assessed the effect of SO4 and Cl on root and shoot growth and development of bedding plants represented by petunia, impatiens, and vinca. In all treatments, plant height, shoot and root dry weight, and flower number decreased with an increase in Cl concentration. Root morphology was marked by fewer total roots and shorter primary and secondary roots when grown with Cl anions compared to the plants grown with SO4 anions. This indicates that anions have a larger role in determining optimum fertilizer formulation than previously believed. This information provides an additional tool in formulating fertilizers for greenhouse bedding plant production.