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  • Author or Editor: R.C. Musselman x
  • Journal of the American Society for Horticultural Science x
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Abstract

Interior diffuse light readings were taken in trees of semi-dwarf ‘Wayne’ and ‘Golden Delicious’ apple (Malus domestica Borkh.) on days of varying cloudiness. Interior light to shaded spurs was found to be greatest when the total light outside the tree was 60 to 90% of maximum, due to higher diffuse light with haze or light cloudiness. Diffuse light available to a shaded site within the canopy is a function of exterior diffuse light levels and canopy density as affected by cultivar. Calculations of whole canopy photosynthetic potential from light data and photosynthetic light response, indicate that haze or cloudiness is needed to obtain maximum whole canopy rates.

Open Access

Abstract

Bean plants (Phaseolus vulgaris L. cv. Red Kidney) exposed to ozone with a simulated ambient concentration distribution showed significantly more injury, less growth, and lower yield than those exposed to an equivalent dose of ozone with a uniform concentration distribution. The concentration distribution did not alter the type of biological response of ‘Red Kidney’ beans to ozone, an indication that uniform concentration distribution fumigations are appropriate for investigations of mode of action of pollutants on plants. However, this study suggests that research using a uniform concentration distribution of pollutants may underestimate the magnitude of growth and yield responses to ambient pollutants.

Open Access

Abstract

Three cultivars of greenhouse-grown apple trees (Malus domestica, Borkh.) were fumigated for single, 4-hour exposures with ozone (O3) and/or sulfur dioxide (SO2) at 0.40 and 0.80 ppm. Fumigations were performed in a plexiglass chamber situated within a controlled environment walk-in growth chamber. All 3 cultivars responded to treatments in a similar manner. When applied separately both gases induced characteristic foliar injury. In general, apple trees were more sensitive to 0.40 ppm O3 than to 0.40 ppm SO2; but they responded similarly to 0.80 ppm O3 or SO2. Foliar injury, leaf abscission, and shoot growth reduction were greatest when 0.80 ppm O3 and 0.80 ppm SO2 were combined. The data showed a less-than additive response when the 2 pollutants were combined; a response due, in part, to the high amount of injury induced by single pollutants at these concentrations. All O3 and/or SO2 fumigations resulted in stomatal closure.

Open Access

Abstract

Three separate experiments were conducted in a mature Vitis labruscana Bailey ‘Concord’ vineyard in New York to determine the response of grapevines to daily, season-long sulfur dioxide (SO2) exposure, or to intermittent SO2 exposure simulating emissions from a 1700 MW coal-fired power plant. There was little SO2-induced necrosis on grape foliage from daily or power plant SO2. However, both treatments in ambient air increased susceptibility of leaves to oxidant stipple injury due to ambient ozone (O3). Daily SO2 increased leaf chlorosis. Power plant SO2 had no effect on vine growth, yield, or shoot maturation. Daily SO2 reduced soluble solids, growth, yield, and shoot maturation of grapevines. Damage to grapevines from SO2 seemed to be independent of SO2 induced leaf necrosis. SO2 reduced foliage tolerance to O3 injury in grapevines already stressed by ambient O3.

Open Access

Abstract

A 4-year study was conducted to compare vine growth and yield in ambient air with growth in air charcoal-filtered to remove ozone. Open top chambers, with and without charcoal filters, were placed over individual vines in a mature ‘Concord’ (Vitis labruscana, Bailey) vineyard. Vines growing in open top chambers, regardless of charcoal filtration, grew less, had delayed maturity of shoots, and delayed leaf senescence as compared to those not growing in chambers. Though chamber effect masked treatment effect on total vine productivity, charcoal filtration reduced oxidant stipple and increased fruit soluble solids. Year-to-year variability in severity of oxidant stipple may be related to seasonal rainfall and ambient ozone levels.

Open Access

Abstract

Performance of open-top chambers used for air pollutant effect studies on mature grapevines (Vitis labruscana Bailey cv. Concord) was evaluated. The chamber environment was characterized by somewhat higher air temperature and dew point and decreased light intensity and wind velocity compared with ambient conditions. Within the chambers, grapevines had slightly increased leaf temperature. No differences due to chambers were detected on vine stomatal resistance, leaf water potential, or the relationship between leaf temperature and incident radiation.

Open Access

Abstract

Response of Phaseolus vulgaris L. cv. California Dark Red Kidney to 2 different ozone concentration distributions was examined at 2 dose levels in controlled fumigations. When peak ozone concentrations were equal and total doses equivalent, there was no difference in injury, growth, or yield between a simulated ambient distribution with normal diurnal ozone fluctuations and a uniform distribution typical of laboratory fumigation at constant concentration. Plants fumigated with either ambient or uniform ozone distribution had oxidant stipple leaf necrosis and reduced growth and yield. There was significantly increased injury and reduced growth and yield at a high ozone dose for both types of distribution. The data indicate that with equal peak concentration and equivalent total dose, the constant square-wave, ozone concentration distributions in laboratory fumigations are adequate to describe mode of action and magnitude of response to ambient exposures.

Open Access

Abstract

Mature ‘McIntosh’, ‘Empire’, and ‘Golden Delicious’ apple trees (Malus domestica Borkh.) were sprayed with simulated acid rain solutions in the pH range of 2.5 to 5.5 at full bloom in 1980 and in 1981. In 1981, weekly sprays were applied at pH 2.75 and pH 3.25. Necrotic lesions developed on apple petals at pH 2.5 with slight injury appearing at pH 3.0 and pH 3.5. Apple foliage had no acid rain lesions at any of the pH levels tested. Pollen germination was reduced at pH 2.5 in ‘Empire’. Slight fruit set reduction at pH 2.5 was observed in ‘McIntosh’. The incidence of russetting on ‘Golden Delicious’ fruits was ameliorated by the presence of rain-exclusion chambers but was not affected by acid rain. With season-long sprays at pH 2.75, there was a slight delay in maturity and lower weight of ‘McIntosh’ apples. Even at the lowest pH levels no detrimental effects of simulated acid rain were found on apple tree productivity and fruit quality when measured as fruit set, seed number per fruit, and fruit size and appearance.

Open Access