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  • Author or Editor: J. S. Sanders x
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Abstract

Eight cultivars of azalea were tested for sensitivity to 0.25 ppm of nitrogen dioxide (NO2), sulfur dioxide (SO2) and ozone (O3), alone and in mixture. Sixty-eight days after pruning, the 1 yr-old liner plants were exposed to the pollutants for 6, 3-hr fumigations over a 4 week period. Cultivars demonstrated a range of sensitivity (tolerant to moderately sensitive) based on both visible injury and growth. Neither NO2 nor SO2 (alone and in combination) induced foliar injury on any of the cultivars. Ozone and mixtures of O3 with NO2 and/or SO2 induced small amounts of injury (10% or less) to foliage of ‘Pink Gumpo’, ‘Mme. Pericat’ and ‘Red Wing’. ‘Red Luann’, ‘Glacier’, and ‘Hershey Red’, sustained >10% foliar injury from mixture treatments containing O3. No significant interactions among NO2, SO2, and O3 were detected by measurements of plant weight. The pollutants did not change the weight of leaves or stems of ‘Pink Gumpo’ and ‘Mme. Pericat’. Significant weight loss occurred in leaves or stems from exposure of ‘Hershey Red’, ‘Red Luann’, and ‘Red Wing’ to treatments containing O3 and from exposure of ’Mrs. G. G. Gerbing’, ‘Glacier’, and ‘Red Luann’ to treatments containing SO2.

Open Access

Abstract

Radish (Raphanus sativus L. cv. Cherry Belle) and marigold (Tagetes patula L. cv. King Tut) were exposed 3 times (every other day), for 3 hours each time to NO2, SO2, and O3, alone and in mixture at 0.3 ppm of each pollutant. Plants were exposed to the pollutant treatments at 3 ages. Radish was most sensitive to O3 at 19–23 days from seeding. The response of marigold to the individual pollutants was not dependent on plant age. Pollutant treatments containing O3 reduced radish root (hypocotyl) dry weight 48% per plant compared with plants exposed to treatments without O3. Interactions of NO2, SO2, and O3 on weight changes in marigold were significant. Sulfur dioxide, alone, reduced the dry weight of the marigold flower and roots, but the inhibitory effect of SO2 was reversed in the presence of NO2 or O3.

Open Access

A significant portion of harvested produce never reaches the consumer due to, postharvest diseases. Various chemicals have been used to reduce the incidence of postharvest diseases. Many of these materials have been removed from the market in recent years due to economic, environmental, or health concerns. Although somewhat limited in the range of diseases controlled, chlorination is effective when combined with proper postharvest handling practices. Additionally, it is a relatively inexpensive postharvest disease control method that poses little threat to health or the environment. The proper use of chlorination in the management of postharvest diseases in fresh fruits and vegetables is discussed.

Full access

A commercial mixture of 1-naphthaleneacetamide and 1-naphthaleneacetic acid (Amcotone) was applied to tomato (Lycopersicon esculentum Mill.) and pepper (Capsicum annuum L.) at various timings from early bloom through early fruit development to evaluate effects on fruit size and both early and total marketable yield. Amcotone was applied at rates from 10 to 40 mg·L-1, at three sites for each of the species studied. Measured yield response variables in tomato did not differ between the control and Amcotone treatments, regardless of location. Amcotone treatments did not affect yields or fruit size for pepper at the New Jersey or Texas sites. However, at Ft. Pierce, Fla., early marketable yield of pepper was increased in plots receiving three Amcotone applications at 10 mg·L-1, but total marketable yield was significantly reduced in all plots receiving more than two Amcotone sprays, and mean fruit weight was reduced by all Amcotone treatments. Early and total marketable yield of pepper at Ft. Pierce were markedly reduced in plots receiving four applications of 40 mg·L-1, which was a high rate used to assess potential phytotoxicity. While minimal benefit from auxin application was observed in this study, earlier studies suggest that these results may have been influenced by favorable environmental conditions for fruit development or negative effects on unopened flowers during all Amcotone spray applications.

Free access

The ability of two tomato cultivars, Lycopersicon esculentum cv. VFNTCherry (chill sensitive) and L. esculentum × L. pimpinellifollim cv. New York 280 (chill tolerant) to acclimate to low temperature storage at 2 °C were compared following prior temperature preconditioning. The activities of catalase, peroxidase, and superoxide dismutase and electrolyte leakage were monitored during a 15-day preconditioning period. Low temperature preconditioning reduced membrane damage in both fruit. In contrast, high temperature preconditioning accelerated the rate of leakage in VFNT, while fruit of NY 280 remained relatively undamaged. Low temperature preconditioning stimulated a 4-fold increase in catalase and peroxidase activities in fruit of NY280. High-temperature preconditioning appeared only to benefit fruit of NY280. Regardless of pretreatment, no significant change in superoxide dismutase activities were observed for either cultivar. These findings suggest that the ability to acclimate to low temperature stress may correlate with increased levels of catalase and peroxidase.

Free access

Abstract

Root length densities (cm·cm−3) of ‘VF145-B7879’ and ‘UC-82B’ tomatoes (Lycopersicon esculentum Mill.) were determined at three depths and four locations across the planting bed for traveling trickle irrigation treatments applied at 35%, 70%, and 105% of evapotranspiration (ET). Cultivars did not differ in root length densities or in their effect on soil moisture levels. Root length density and soil moisture decreased with soil depth. Although soil moisture was greater in the furrows, the zones of highest root concentration were between the rows of plants and along the edge of the beds. Greater root length density was found in the 35% ET than in the 70% or 105% ET irrigation rate. Chemical names used: 2-(α-naphthoxy)-N,N-diethylpropionamide (napropamide); S-propyl butylethylthiocarbamate (pebulate).

Open Access

Abstract

Field studies were conducted on a Typic Xerorthents Entiosols soil (Hanford sandy loam) to determine the response of two cultivars of processing tomatoes (Lycopersicon esculentum Mill.) to trickle irrigation applied at three percentages of evapotranspiration (ET) to either the top of the plant row or between the beds using a traveling irrigation system. Irrigation was terminated when fruits were either 30% or 70% red (14 or 7 days before harvest). Yields of red tomatoes and total tomatoes increased with increasing trickle irrigation water. The concentrations of soluble solids (SSC) and total solids (TS) and pH decreased with increasing trickle irrigation rates, while color, fruit size, and acidity increased, as did the yield of SSC and TS per hectare. Placement of trickle irrigation on the plant row was more favorable than placement in the furrow between the beds for yield and quality characteristics. Trickle irrigation to 70% ET terminated 7 days before harvest produced responses similar to conventional furrow irrigation. Although statistically these treatments could not be compared directly to conventional furrow, all traveling trickle irrigation rates were superior in water use efficiency to that of the conventional furrow irrigation. Trickle irrigation rates of 35% ET, 70% ET, and 105% ET did not differ in water use efficiency. Chemical names used: 2(a-naphthoxy)-N,N-diethyl propionamide (napropamide); S-propyl butylethiocarbamate (pebulate).

Open Access