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Johnny Carter and Sauveur Mahotiere

Effects of BA, Promalin and Dikegulac-sodium on frond number and overall growth in Boston Fern (Nephrolepis exaltata L.) were studies. Four weeks after transplanting, fern liners were sprayed with aqueous solutions of BA, Promalin and dikegulac-sodium. Chemical concentrations of BA and promalin ranged from 0 to 150 mg. liter-1 at 50 mg. liter-1 increments. Chemical concentrations of dikegulac-sodium ranged for 0 to 750 mg.liter-1 at 250 mg.liter-1 increments. Chemical treatments were arranged in a randomized complete block design with 6 replications. BA and Promalin significantly increased the number of fronds, average frond length, leaf area and dry weight as the concentration of the chemicals increased. In contrast, dikegulac-sodium significantly suppressed the average frond length, leaf area and dry weight when compared to the control. Similarly to BA and Promalin, dikegulac-sodium increased the number of fronds as the concentration of the chemical increased.

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F. Ponton, Y. Piché, S. Parent, and M. Caron

The horticultural Boston fern [Nephrolepis exaltata (L.) Schott cv. Verona] was micropropagated in vitro using commercial techniques. Rooted plantlets were transferred into pots containing one of three test substrates made of peat and vermiculite and subsequently inoculated with one of two species of Glomus. Survival of uninoculated control plants growing on a black peat-based mix was less than that on a brown peat-based mix. Vesicular-arbuscular mycorrhizal (VAM) inoculation significantly increased survival on the former, but not the latter, substrate. The growth of roots was enhanced in brown peatmoss, but VAM colonization was faster with black peatmoss. Compared to uninoculated controls growing under the same fertilization regime, inoculated plants had significantly higher frond P and N concentration and also showed better frond and root growth. On a growth-increment basis, our results suggested that the brown peat-based mixed was more suitable for fungal activity and fern growth.

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F. Ponton, Y. Piché, S. Parent, and M. Caron

Rooted plantlets of in vitro micropropagated Boston fern [Nephrolepis exaltata (L.) Schott var. Whitmanii] were transferred to pots containing a brown peat-based mix and simultaneously inoculated with one of four species of Glomus. Glomus intraradices and G. clarum formed rapid and extensive infection in Nephrolepis exaltata roots, while Glomus vesiculiferum and G. versiforme showed a significantly slower rate of infection. The high P fertilized control performed better than the other treatments, except in the number of fronds, which was similar. From the four mycorrhizal treatments, plants inoculated with Glomus vesiculiferum showed the most significant increase in growth when compared with the low P fertilization control. These results led us to re-examine vesicular-arbuscular mycorrhizal inoculation as an alternative to higher P fertilization in horticultural Boston fern production.

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Robert H. Stamps

One of the most difficult times to balance crop nitrogen (N) requirements with concerns about nitrate-N leaching occurs during crop establishment, when root systems are poorly developed and not widely distributed in the growing medium. This dilemma can be exacerbated when producing a slow-growing plant such as leatherleaf fern (Rumohra adiantiformis [Forst.] Ching) on sandy soils in shadehouses in areas with significant rainfall. Rhizomes were planted in 36 drainage lysimeters containing Tavares fine sand located in a shadehouse. Nitrogen fertilizer was applied at nine rates using liquid and/or controlled-release fertilizer. Nitrogen application rates were varied as the rhizomes became established and spread into unplanted areas of the lysimeters. Irrigation and rainfall were monitored and the amount of water not lost to evapotranspiration was determined. Nitrogen (ammoniacal, nitrate/nitrite, total Kjeldahl) concentrations in leachate collected below the rootzone were determined. Stipe sap nitrate and frond total Kjeldahl nitrogen (TKN) were determined to try to develop a production monitoring technique. Initially, only leachate samples from controlled-release fertilizer plots treated at 21 and 42 kg of N/ha per year and liquid fertilizer at 28 kg of N/ha per year were consistently below the maximum contamination level (MCL) of 10 mg·L–1. As the fern became established, leachate nitrate/nitrite-N concentrations from higher N application rate treatments also remained below the MCL. Leachate N concentrations decreased as rainfall increased. Fern growth increased with increasing N application rate. Stipe sap nitrate-N and frond TKN concentrations were not well-correlated during establishment.

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Robert H. Stamps

Six preemergence herbicides were applied twice a year at 1x and 2x rates for 2 years to leatherleaf fern [Rumohra adiantiformis (Forst.) Ching] starting from the time of rhizome planting. Predominant weeds present were Cardimine hirsuta, Erechrites hieracifolia, Oxalis stricta, and Phyllanthus tenellus. All herbicides, except pendimethalin and oxadiazon at the 1x rates, reduced weed biomass by 60% to 99% compared to the unweeded control during the fern bed establishment phase (year 1). During that period, hand-weeding times were reduced (51% to 95%) by prodiamine and dithiopyr at both rates, and oxadiazon and pendimethalin at 2x rates. During year 2, herbicides were of greatly reduced benefit due to reduced weed growth caused by the increasingly competitive fern. After 2 years, only 2x dithiopyr-treated plots had reduced yields compared to the hand-weeded controls. Herbicide treatments had no detrimental effects on frond postharvest longevity. In fact, fronds harvested from the 1x isoxaben-treated plots exhibited increased vase life compared to the controls.

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Robert H. Stamps

Four spunbonded crop covers were evaluated for use with and without irrigation for cold protection of leatherleaf fern [Rumohra adiantiformis (Forst.) Ching]. Heavier and less porous covers provided the most protection when used without over-the-crop irrigation. However, differences in cover weight and porosity did not affect temperatures under covers when over-the-crop irrigation was applied. Damage to immature fronds was decreased by 75% to 99% when the covers were used alone and by 98% to 99% when the covers were used with over-the-crop irrigation. Covers had no effect on frond vase life.

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Robert H. Stamps and Daniel W. McColley

Established ground beds of leatherleaf fern were sprayed repeatedly with water, a flowable formulation of thiophanate-methyl, or one of four formulations of chlorothalonil on a predominantly weekly schedule. None of the treatments produced visible phytotoxicity symptoms or had any effect on yield (frond number and total fresh mass). However, average masses of fronds from plots treated with a liquid formulation of chlorothalonil were 21% greater than those from control plots. All chlorothalonil formulations left visible residues on the fronds and reduced frond vase life compared to fronds treated with water or thiophanate-methyl. Reduced vase life was due to more rapid desiccation of chlorothalonil-treated fronds. During those months (July—Sept.) when postharvest desiccation is most common, chlorothalonil reduced vase life of fronds by 36% to 62%. Vase life of fronds was generally reduced more by dry chlorothalonil formulations than by liquid ones, probably due to slightly higher application rates of dry formulations. Determination of the mode of action could lead to an understanding of the causes of frond curl syndrome. Until a remedy is found, chlorothalonil should not be used repeatedly on leatherleaf fern. Chemical names used: tetrachlorisophthalonitrile (chlorothalonil); dimethyl [(1,2-phenylene)-bis(iminocarbonothioyl)]bis[carbamate]) (thiophanate-methyl).

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Matthew Donelan and Kenneth Corey

Crowns of ostrich fern (Matteuccia struthiopteris L. Todaro) were field-planted in June 1993 on a Hadley silt loam in South Deerfield, Mass. Shade cloth was used to alter light intensity to determine if light intensity effects growth and development of fronds and crowns. Light levels were 22% (low), 45% (intermediate), 72% (high), and 100% (full) of ambient conditions. Survival of crowns decreased with increasing light intensity with only 22% survival under full light. Low, intermediate, and high light levels resulted in 89%, 75%, and 56%, respectively, of crowns producing shoots. Light intensity did not effect the number or length of fronds produced. Frond length reached a maximum after 2 months growth. Development of secondary crowns was enhanced at intermediate and high light intensities. Final crown weight was significantly correlated with initial crown weight regardless of light intensity. Crowns will be vernalized and forced hydroponically to determine effects of light intensity and crown size on growth of croziers.

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Devi Prasad and S.D.P. Potluri

Scotch Bonnet pepper is a valuable commodity for Jamaica and the Caribbean, both for local consumption and for export because of its unique flavor and pungency. It is a valuable cash crop for small farmers who supply most of the fruit needed for processing and export. Azolla is a small water fern that grows on the surface of water bodies or on moist soil. Due to the presence of the nitrogen-fixing cyanobacterium Anabaena azollae, it fixes molecular nitrogen. This fern is used as biofertilizer for rice in millions of hectares in Asia. In the present work, experiments were carried out to determine the suitability and usefulness of both fresh and dried Azolla as biofertilizer for Scotch Bonnet pepper. A control without any fertilizer and a fertilizer control with 100 kg N/ha, supplied as ammonium sulfate, were used in 2-m2 plots, with three replicates for each treatment. Fertilizer was supplied in three split doses. Fresh Azolla was spread at the base of each plant and the soil was kept moist for the duration of the study. Dry Azolla was spread like a mulch around the base of the plant and used as a split treatment similar to inorganic fertilizer. Both the fresh and dry Azolla increased the marketable fruit yield over the control without fertilizer. Dry Azolla resulted in a similar yield as the fertilizer treatment [80%] while the fresh Azolla had a 60% increase in the yield over the control. In addition, dry Azolla resulted in early anthesis by 3 days over the fertilizer control. The dry weights of the whole shoot also showed increases similar to fruit yield. The dry Azolla also helped to improve the soil conditions and retained moisture for long periods. The results suggest that dry Azolla can be successfully substituted for chemical fertilizer for pepper. The cost of preparing Azolla to be used as fertilizer is calculated to be about 10% to 15% of the cost of chemical fertilizer for small farmers.

Open access

Jessica D. Lubell-Brand and Mark H. Brand

relatively few plants, was the only viable propagation method for sweet fern, because it is difficult to produce from seed and traditional stem cuttings. Griffith Gardner et al. (2019) made stem propagation feasible by reporting a method using young