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  • Author or Editor: R.J. Oshima x
  • Journal of the American Society for Horticultural Science x
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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

Parsley (Petroselinum crispum (Mill.) Nym. cv. Banquet) incurred leaf injury, reduced growth, and altered assimilate partitioning after exposures to 20 pphm ozone. Total plant dry weight and root dry weight were decreased 23% and 43% respectively, with little effect on leaves. The relative growth rate of fumigated plants was reduced after the initial ozone exposure but leveled off at a steady state above that of the control plants when plant dry weights reached about 4.5 g. Ozone appeared to have its greatest effect on growth during initial exposures.

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

Foliar ozone sensitivity evaluations of 5 fresh market tomato (Lycopersicon esculentum Mill.) cultivars from fumigation experiments were contrasted with field trial yields at Riverside, California, a high ambient dose location (3798 pphm-hour > 10 pphm). Foliar injury was not an accurate indicator of yield response as a correlation of foliar susceptibility and yield rankings was insignificant. Cultivar production characteristics at the South Coast Field Station (222 pphm-hour > 10 pphm) and at Riverside were identical with standardized field plots of ‘6718 VF’ from a concurrent experiment. Reduced fruit size and depressed early season production, previously correlated with ozone dose, were characteristic of all cultivars planted at Riverside. Comparisons of cultivar production rankings revealed that ‘H-ll’ and ‘6718 VF’ yielded significantly more, in terms of weight and number of fruit harvested than ‘Ace’, ‘Polepak’, or ‘Earlypak 7’. All cultivars except ‘Ace’ produced equivalent yields in terms of weight at South Coast Field Station.

Open Access

Abstract

A multiple regression analysis of yields of ‘6718 VF’ tomato (Lycopersicon esculentum Mill.) from 11 field plots along an ambient ozone gradient in southern California indicated that ozone was responsible for a significant reduction in fruit size. Ozone dose accounted for 85% of the reduction in fruit size and was at least 3.3 times more important than any of the monitored meteorological variables in predicting the percentage of marketable fruit. High ambient ozone depressed production and caused a significant decrease in fruit size over time. A model describing the reduction in marketing container yield (% reduction = 0 + (.0232 x dose)) predicted a 50% reduction at a dose of 2000 pphm-hours > 10 pphm.

Open Access