Search Results

You are looking at 21 - 28 of 28 items for

  • Author or Editor: Raul I. Cabrera x
  • All content x
Clear All Modify Search
Free access

Raúl I. Cabrera, Alma R. Solís-Pérez, and John J. Sloan

Greenhouse rose (Rosa × spp. L.) production is facing the use of poor-quality irrigation waters and regulatory pressures to recycle runoff and drainage effluents. Two experiments (were conducted to evaluate the yield and quality and ion accumulation responses of roses grafted on various rootstocks to increasing salinity stress. In Expt. 1, the scion ‘Bridal White’ grafted on ‘Manetti’, R. odorata (Andr.), ‘Natal Briar’, and ‘Dr. Huey’ were irrigated over four flowering cycles with complete nutrient solutions supplemented with NaCl at 0, 5, and 30 mm. In Expt. 2, plants of ‘Red France’ on ‘Manetti’ and ‘Natal Briar’ were irrigated over six flowering cycles with complete nutrient solutions supplemented with NaCl + CaCl2 (2:1 m ratio) at 0, 1.5, 3, 6, 12, and 24 mm. Salt concentration increases significantly and negatively affected the biomass, cut flower production, and foliage quality of the roses in both experiments, but the responses were modulated by rootstock selection. ‘Manetti’ plants in general sustained better absolute and relative biomass and flower yields, accumulated less Na+ and Cl in its tissues, and showed less toxicity symptoms with increasing salinity than the others. ‘Natal Briar’ also had similar absolute productivity responses as ‘Manetti’ but were afflicted by a significantly different mineral nutrient profile, including higher accumulations and toxicities with Na+ and Cl that led to lower foliage visual ratings. Conversely, the relative yields of plants on ‘Dr. Huey’ and R. odorata were similarly reduced by increasing salinity, but the former had lower Na+ and Cl concentrations in its tissues and better visual scores than the latter, which fared as the worst. A combined analysis of the results suggests that on a productivity basis (biomass and flower yields), greenhouse roses could withstand overall maximum electrical conductivities (i.e., osmotic effects) of applied fertigation solutions of 3.0 ± 0.5 dS·m−1. On the other hand, and considering the aesthetic responses (visual scores) of on-plant and harvested foliage (cut flower shoots), greenhouse rose tolerance to applied Na+ and Cl concentrations (ion-specific effects) could range up to 10 ± 2 mm.

Free access

S.M. Lutfor Rahman*, Jeffrey T. Baker, Raul I. Cabrera, Dennis J. Timlin, and Bruno Quebedeaux

We collected growth and yield data on eight cantaloupe cultivars and constructed a simple phenology model that uses local weather data to allow growers to quantify phenological growth and development to project harvest dates. Main vine plastochron interval (PI), time to harvest, and final yield were determined. PI was calculated for each cultivar × transplanting date combination as the reciprocal of the slope of main vine node number vs. growing degree days. Among the tested cultivars,`Ovation' and `Primo' produced significantly higher yields of marketable melons (51.3 Mg/ha, 49.5 Mg/ha, respectively), whereas `Santa Fe' produced the lowest (28.6 Mg/ha). The rest of the tested cultivars produced on average 34.4 Mg/ha. Fruit weight was significantly higher in `Morning Ice' (2.7 kg/fruit) and lowest in `Mission' (1.4 kg/fruit). There were also significant differences among cultivars in the number of marketable melons/ha, which ranged from 11500 melons/ha for `Morning Ice' to 32300 melons/ha for `Ovation'. Plant dry matter production was higher in `Ovation' and `Mission' than all the other cultivars. The relative days to maturity were significantly higher in `Morning Ice' and `Honey Brew' (115 days) and lower in `Gold Rush' (72 days). There were no differences found in days to maturity for `Mission', and `Ovation'(82 days). The average % of soluble solids content ranged from 9.5 for `Ovation' to 14.5 for `Mission' and `Honey Brew'. The variety cantaloupensis types are earlier in maturity than inodorus types. PI was significantly different for all cultivars. Main vine node number was a useful descriptor of vegetative development for cantaloupes. Procedures for calibrating and fitting the model for these cultivars will be discussed and outlined

Free access

Raul I. Cabrera, L. Rahman, Genhua Niu, Cynthia McKenney, and Wayne Mackay

In this preliminary study, we evaluated the salinity tolerance of selected herbaceous perennials. Liners of Rudbeckia hirta `Becky Orange', Phlox paniculata `John Fanick', Coreopsis grandiflora `Early Sunrise', Lantana ×hybrida `New Gold' and Cuphea hyssopifolia `Allyson' were transplanted to 4-gal plastic containers filled with peat moss: pine bark: sand (3:1:1) medium amended with dolomite, Micromax and Osmocote 18-6-12 (at 2, 0.6, and 6 kg·m3, respectively). The plants were irrigated for 14 weeks with tap water containing 0, 1.5, 3, 6, 12, and 24 mM of NaCl: CaCl2 salt mixture (2:1 molar ratio). Increasing salt stress had differential effects on plant growth and quality, with Rudbeckia and Phlox being the most adversely affected even by the lowest salt treatment of 1.5 mM, with dry weight reductions of ∼25% compared to the controls. Conversely, Lantana and Cuphea tolerated extremely well salinity up to 12 mM, where dry weight reductions were less than 10% of the nonsalinized controls. The Lantana and Cuphea plants also presented the lowest leaf Cl accumulation with increasing salinity, whereas Coreopsis showed the highest Cl accumulations at any salinity level. Plots of leaf Cl concentration against dry weights showed steeply declining relationships for Rudbeckia and Phlox plants, confirming our observations and assessment that these species are to be considered salt-sensitive. Leaf Na accumulation is currently being analyzed.

Free access

Johnn Jairo Franco Hermida, Martha Cecilia Henao Toro, Miguel Guzmán, and Raul I. Cabrera

Greenhouse-grown cut roses are an economically important and intensive horticultural cropping system receiving large water, fertilizer, agrochemicals, and labor inputs. This study was conducted to establish and validate norms for the nutrient diagnosis techniques Diagnosis and Recommendation Integrated System (DRIS) and Compositional Nutrient Diagnosis (CND) for cut roses (Rosa spp. L.) growing on soil beds within greenhouses in the Bogotá Plateau, Colombia. Information used in this study was obtained from a database of plant tissue and soil analyses, including 1914 foliar analyses of different rose cultivars grafted on the rootstock R. × ‘Natal Briar’. Theoretical validation proved that the generated norms are suitable for crop nutrient status diagnosis, allowing for the correlation of nutrient balance indices with crop flower productivities across a range of cultivars and plant ages. Analysis of the results provided by both DRIS and CND procedures indicated that element relations associated with nitrogen, phosphorous, magnesium, manganese, and boron had a higher influence on the nutritional balance and productivity of roses growing under the conditions of the studied region. In addition, it was preliminarily determined that the use of these diagnostic norms could be extended to rose crops growing under other, and different, rootstocks, production and environmental conditions, and management.

Full access

Genhua Niu, Raul I. Cabrera, Terri W. Starman, and Charles R. Hall

Full access

John J. Sloan, Raul I. Cabrera, Peter A.Y. Ampim, Steve A. George, and Wayne A. Mackay

Organic and inorganic amendments are often used to improve chemical and physical properties of soils. The objective of this study was to determine how the inclusion of light-weight expanded shale in various organic matter blends would affect plant performance. Four basic blends of organic growing media were prepared using traditional or alternative organic materials: 1) 75% pine bark (PB) + 25% sphagnum peatmoss (PM), 2) 50% PB + 50% wastewater biosolids (BS), 3) 100% municipal yard waste compost (compost), and 4) 65% PB + 35% cottonseed hulls (CH). Light-weight expanded shale was then blended with each of these mixtures at rates of 0%, 15%, 30%, and 60% (v/v). Vinca (Catharanthus roseus), verbena (Verbena hybrida), and shantung maple (Acer truncatum) were planted into the growing media after they were transferred into greenhouse pots. Vinca growth was monitored for 3 months before harvesting aboveground plant tissue to determine total biomass yield and elemental composition. Verbena growth was monitored for 6 months, during which time aboveground plant tissue was harvested twice to determine total biomass yield. Additionally, aboveground vinca plant tissue was analyzed for nutrients and heavy metal concentrations. In the absence of expanded shale, verbena and shantung maple trees produced more aboveground biomass in the 50-PB/50-BS blends, whereas vinca grew more biomass in the pure compost blends. Inclusion of expanded shale in the various organic matter blends generally had a negative effect on plant growth, with the exception of shantung maple growth in the 65-PB/35-CH blend. Reduced plant growth was probably due to a lower concentration of nutrients in the growing media. Macro- and micronutrient uptake was generally reduced by addition of expanded shale to the organic growing media. Results suggest that organic materials that have been stabilized through prior decomposition, such as compost or PM, are safe and reliable growing media, but expanded shale offers few benefits to a container growing medium except in cases where additional porosity is needed.

Free access

Genhua Niu, Denise S. Rodriguez, Raul I. Cabrera, Cynthia McKenney, and Wayne Mackay

Relatively little work has been done to determine the water requirements of ornamental plants. To meet this need, five woody ornamental species including Abelia grandiflora `Edward Goucher', Buddleia davidii `Burgundy', Ilex vomitoria `Pride of Houston', Euonymus japonica, and Nerium oleander `Hardy Pink' were investigated to determine their water use and crop coefficients. Parallel experiments were conducted by growing the shrubs both in 56-L (15 gal) drainage lysimeters and in aboveground 10-L containers. Water use per plant, crop coefficients, and overall growth parameters differed by species and culture system. Of the five species tested, Buddleia and Nerium had higher water use per plant in the lysimeters than in the containers. There was no significant difference in water use per plant for Abelia, Euonymus, and Ilex between the two culture systems. Crop coefficients and growth indices of Abelia, Euonymus, and Ilex were statistically similar between the two systems. The growth index of Buddleia and Nerium was much higher in the lysimeters than in the containers. Abelia and Euonymus had more growth in the containers than in the lysimeters while Ilex had slightly larger leaf area in the lysimeters than in the containers. The culture system did not affect the water use per unit leaf area of all species. Therefore, our results indicated that by quantifying the leaf area, the plant water use in the two culture systems is convertible.

Free access

Xinwang Wang, Phillip A. Wadl, Cecil Pounders, Robert N. Trigiano, Raul I. Cabrera, Brian E. Scheffler, Margaret Pooler, and Timothy A. Rinehart

Genetic diversity was estimated for 51 Lagerstroemia indica L. cultivars, five Lagerstroemia fauriei Koehne cultivars, and 37 interspecific hybrids using 78 simple sequence repeat (SSR) markers. SSR loci were highly variable among the cultivars, detecting an average of 6.6 alleles (amplicons) per locus. Each locus detected 13.6 genotypes on average. Cluster analysis identified three main groups that consisted of individual cultivars from L. indica, L. fauriei, and their interspecific hybrids. However, only 18.1% of the overall variation was the result of differences between these groups, which may be attributable to pedigree-based breeding strategies that use current cultivars as parents for future selections. Clustering within each group generally reflected breeding pedigrees but was not supported by bootstrap replicates. Low statistical support was likely the result of low genetic diversity estimates, which indicated that only 25.5% of the total allele size variation was attributable to differences between the species L. indica and L. fauriei. Most allele size variation, or 74.5%, was common to L. indica and L. fauriei. Thus, introgression of other Lagestroemia species such as Lagestroemia limii Merr. (L. chekiangensis Cheng), Lagestroemia speciosa (L.) Pers., and Lagestroemia subcostata Koehne may significantly expand crapemyrtle breeding programs. This study verified relationships between existing cultivars and identified potentially untapped sources of germplasm.