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Nursery stock of plum (Prunus salicina Lindel., `Casselman') was planted 1 Apr. 1988 in an experimental orchard at the Kearney Agricultural Center, Univ. of California, near Fresno. The trees were enclosed in open-top fumigation chambers on 1 May 1989 and exposed to three atmospheric ozone partial pressures (charcoal-filtered air, ambient air, and ambient air + ozone) from 8 May to 15 Nov. 1989 and from 9 Apr. to 9 Nov. 1990. Trees grown outside of chambers were used to assess chamber effects on tree performance. The mean 12-hour (0800-2000 hr Pacific Daylight Time) ozone partial pressures during the 2-year experimental period in the charcoal-filtered, ambient, ambient + ozone, and nonchamber treatments were 0.044, 0.059, 0.111, and 0.064 μPa·Pa-1 in 1989 and 0.038, 0.050, 0.090, and 0.050 pPa·Pa-1 in 1990, respectively. Leaf net CO2 assimilation rate of `Casselman' plum decreased with increasing atmospheric ozone partial pressure from the charcoal-filtered to ambient + ozone treatment. There was no difference in plum leaf net CO2 assimilation rate between the ambient chamber and nonchamber plots. Trees in the ambient + ozone treatment had greater leaf fall earlier in the growing season than those of the other treatments. Cross-sectional area growth of the trunk decreased with increasing atmospheric ozone partial pressures from the charcoal-filtered to ambient + ozone treatment. Yield of plum trees in 1990 was 8.8, 6.3, 5.5, and 5.5 kg/tree in the charcoal-filtered, ambient, ambient + ozone, and nonchamber treatments, respectively. Average fruit weight (grams/fruit) was not affected by atmospheric ozone partial pressure. Fruit count per tree decreased as atmospheric ozone partial pressure increased from the charcoal-filtered to ambient + ozone treatment. Decreases in leaf gas exchange and loss of leaf surface area were probable contributors to decreases in trunk cross-sectional area growth and yield of young `Casselman' plum trees during orchard establishment.
Abstract
The level of succinic acid-2,2-dimethylhydrazide (SADH) in ‘Spartan’ apples treated according to commercial practice with Alar-854 was higher in fruits treated in July or August than in fruits sprayed in late May, when measured at harvest and after storage. SADH was very persistent in apples stored at 0°C. Fruit from trees treated at comparable times in 2 seasons did not have higher SADH residues than those treated only in the second season, but fruit size reduction was more severe following some treatments applied in both years. Adding the wetting agent Tween 20 to the spray solutions increased uptake of SADH in most experiments as evidenced by increased fruit residue levels.
Abstract
Pecan-halves available to consumers in retail stores frequently failed to meet high quality standards. Excessive small pieces was the most common defect. When all USDA grading criteria were considered, 50.6% of pecan-half samples failed to meet U. S. No. 1 standards.
On a hedonic scale of 1 to 10, the average panel rating score of pecan halves was 6.42 based on flavor, appearance, aroma, color, and texture. The score of samples purchased in the Southeast and Northeast was significantly higher than that of samples purchased in the Midwest. Over all geographic regions, there was no significant difference in the ratings of ‘Stuart’ and seedlings. ‘Stuart’ rated higher than mixed cultivars at the 0.1% level of probability. Seedlings rated significantly higher than mixed cultivars. There were no significant relationships between ratings and the time of year samples were purchased or the brand of pecans.
The moisture content, a factor influencing the quality of pecan halves, varied from 6.4% to 2.3%.
Japanese plum (Prunus salicina Lindel., `Casselman') trees were enclosed in open-top chambers on 1 May 1989 and exposed to three atmospheric ozone partial pressures (charcoal-filtered air [CF], ambient air [AA], and ambient air+ozone [AO]) during the growing season in 1989, 1990, 1991, and 1992. The mean 12-h (0800-1900 HR PDT) ozone partial pressures during 1992 were 0.027, 0.045, and 0.087 μPa Pa-1 in the CF, AA, and AO treatments, respectively. Both stem and leaf water potential (Ψ) decreased from 0700 to 1600 HR PDT and were lowest at midday (1200-1400 HR PDT) in all ozone treatments. Leaf and stem were equivalent at predawn, but leaf Ψ was lower than stem Ψ during the diurnal period. Midday stem Ψ was greater in the AA and AO treatments compared to the CF treatment. Before 1 Aug., stomatal conductance of trees in the AO treatment was reduced compared to the CF treatment, but diurnal fluctuations were similar between the two treatments. Following 1 Aug., stomatal conductance of trees in the AO treatment was reduced compared to the CF treatment, but stomatal conductance of the AO treatment remained the same throughout the day. Trees in the AO treatment had greater leaf fall earlier in the growing season than those of the other treatments. Changes in plum tree stem Ψ under chronic ozone stress are probably due to a loss (early senescence) of transpiring leaf area as well as declines in stomatal conductance.
The effect of increasing temperatures on the duration of postharvest flower development was determined for three specialty crop species: marguerite (Argyranthemum frutescens Webb ex Schultz-Bip.) `Butterfly' and `Sugar Baby'; swan river daisy (Brachycome hybrid Cass.) `Ultra'; and bacopa (Sutera cordata Roth.) `Snowflake'. Plants were grown in a greenhouse at 18 °C (65 °F) until flowering, and then transferred into a phytotron to determine heat tolerance. Plants were stored for 8 weeks at constant temperatures of 18, 23, 28, and 33 °C (65, 73, 82, and 91 °F) for 2-week intervals. Flower bud and flower number were recorded weekly. Sutera cordata `Snowflake' and B. hybrid `Ultra' had the greatest flower number at the 23 °C temperature, decreasing in the 28 °C environment. Argyranthemum frutescens `Butterfly' and `Sugar Baby' had greatest flower number at 28 °C, but flowers were of lower quality thanat 23 °C. Flower development of all cultivars ceased at 33 °C, at the end of 8 weeks at increasing temperatures, but when plants were returned to the 18 °C production greenhouse, flower development resumed. High temperatures (28 °C) reduce the postharvest performance of S. cordata, B. hybrid, and A. frutescens plants grown in hanging baskets; therefore, these species should be marketed as spring-flowering products since summer performance may be unsatisfactory in warm climates.
Abstract
In cucumber (Cucumis sativus L.) a recessive gene designated sc (stunted cotyledon) produces small, dark green, concavely curved cotyledons with chlorotic tips with pleiotropic effects of plant weakness and stunting, cupped leaves, and abnormally shaped flowers.
A greenhouse experiment was conducted to determine the effects of shade treatments (0, 30, 47 and 63%) on photosynthetic and growth responses of `Redchief' strawberries. Net photosynthesis (Pn) measured on plants under shade decreased as % shade increased. Pn of plants grown under shade but measured under saturating light intensities decreased after 30% shade. Light saturation curves of leaves allowed to expand in full sun and then placed under shade indicated a decrease in the saturation rate and point under 63% shade. Leaves which expanded under shade had decreased saturation rates and points at all levels. Specific leaf weight and total plant dry weight decreased linearly as % shade increased.
A field study in which plants were either shaded in the fall or in the fall and spring demonstrated a decreasing trend in berry number for plots which were shaded in the fall and spring. Berry number decreased in fall-shaded plants after 30% shade. In both cases, berry weight decreased with increasing shade.
Uniform nursery stock of five almond cultivars (Prunus dulcis Mill., cv Nonpareil, Mission, Carmel, Butte, and Sonora) propagated on peach (P. domestica L. Batsch.) rootstock were planted in open-top fumigation chambers on 19 April 1989 at the University of California's Kearney Ag Center located in the San Joaquin Valley of California. The trees were exposed to three atmospheric ozone partial pressures (charcoal filtered air, ambient air, or ambient air+ozone) from 1 June to 2 November 1989. The mean 12-h (0800-2000 h) ozone partial pressure measured in the open-top chambers during the experimental period averaged 0.038, 0.060, and 0.112 μPa Pa-1 ozone in the charcoal filtered, ambient, and ambient+ ozone treatments, respectively. Leaf net CO2 assimilation and cross-sectional area growth of Nonpareil trees were reduced by increasing atmospheric ozone partial pressures, but Mission trees were unaffected. Foliage of Nonpareil almond abscised prematurely in the ambient and ambient+ozone treatments. The susceptibility of the Butte, Carmel, and Sonora almond cultivars to ozone was intermediate between the Nonpareil and Mission cultivars.
It is generally accepted that ethylene production is centrally located in petal senescence, however, non-climacteric flowers senesce irrespective of the presence of ethylene. The regulation of flower senescence may well be linked to protein synthesis. Our objective was to develop a simple tool which can be used in breeding programmes and\or the market place to determine potential longevity of a flower. Here, SDS-PAGE protein profiles of both potted and cut chrysanthemum flowers were determined from flowering to senescence. Generally, only minor changes in both protein content and the proportion of the major polypeptides were observed in the potted flowers. However, polypeptides at 40, 45 and 65 kDa increased during flower senescence and are of particular interest because they could be linked to flower longevity. The apparent stability of the proteins may contribute to the long postharvest life of the potted chrysanthemum.
Abstract
Black spine color of fruit in cucumber is controlled by either of two dominant genes B and C. The double recessive (bbcc) is white. No linkage was observed between fruit spine color and cotyledon bitterness.