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Abstract
Levels of incident photosynthetic photon flux density (PPFD), net photosynthetic rate (Pn), and stomatal conductance (g) were monitored on individual intact kiwifruit (Actinidia chinensis Planch.) leaves at well-exposed and densely shaded canopy positions. Diurnal fluctuations of Pn and g closely paralleled changes in PPFD for exposed leaves. PPFD reaching shaded leaves were extremely low throughout the day; Pn and g were correspondingly low. Pn ranged between 10 and 12 µmol CO2·m-2s-1 when exposed leaves were light-saturated at PPFD between 500 and 700 µmol·m-2s -1. Exposed and shaded leaves had similar chlorophyll concentrations, though the former had significantly higher chlorophyll a:b ratios. Implications relative to leaf canopy design and management are discussed.
Abstract
Levels of incident photosynthetic photon flux density (PPFD), net photosynthetic rate (Pn), and stomatal conductance (g) were monitored on individual intact kiwifruit (Actinidia chinensis Planch.) leaves at well-exposed and densely shaded canopy positions. Diurnal fluctuations of Pn and g closely paralleled changes in PPFD for exposed leaves. PPFD reaching shaded leaves were extremely low throughout the day; Pn and g were correspondingly low. Pn ranged between 10 and 12 µmol CO2·m-2s-1 when exposed leaves were light-saturated at PPFD between 500 and 700 µmol·m-2s -1. Exposed and shaded leaves had similar chlorophyll concentrations, though the former had significantly higher chlorophyll a:b ratios. Implications relative to leaf canopy design and management are discussed.
The sweetpotato [Ipomoea batatas (L.) Lam] breeding clone TU-82-155 was grown during Spring 1990 and Summer 1991 in standard Tuskegee Univ. (Alabama) growth channels (0.15 × 0.15 × 1.2 m) for 120 days in a greenhouse using a hydroponic (nutrient film) system with a modified half-strength Hoagland nutrient solution. The nutrient solution was changed every 2, 14, or 28 days. Total N, oil, ash, amino acid, vitamin, and mineral concentrations in storage roots generally were higher and dry weight and starch concentration were lower with 2-day solution changes than with those less frequent.
In continuing trials (1995-current), we have used a variety of treatments to overcome inadequate chilling, coordinate bloom, improve leaf out and cropping, and advance/coordinate maturity in sweet cherry, cv. Bing. Treatments have included hydrogen cyanamide (HCN, Dormex) and various surfactants or dormant oils combined with calcium ammonium nitrate (CAN17). Chill hour accumulation, (required chilling for `Bing' = 850 to 880 chill hours) has varied greatly in each dormant season from 392 (Hollister, 1995-1996) to adequate, depending both on the season and location (central valley vs. coastal valley). In 1998, 4% HCN advanced budbreak significantly compared to any other treatment, although other chemical treatments also were more advanced than the untreated control. Dormex advanced completion of bloom 11% to 40% more than other treatments, although other dormancy-replacing chemicals were at least 16% more advanced in petal fall than the untreated control. Dormex contributed to slightly elevated truss bud death, as did 2% Armobreak + 25% CAN17. In 1998, fruit set was improved by 2% Armobreak + 25% CAN17 (79%) compared to the untreated control (50%); all other treatments statistically equaled the control. Fruit set was not improved by Dormex, although bloom was advanced by a few days in this treatment. As fruit set was increased by treatments, rowsize decreased (as did fruit weight), as expected, but no treatment resulted in unacceptable size. In 1997, fruit set was also improved by 2% Armobreak + 25% CAN17; however, fruit set was so low overall in that year that no real impact was found. In 1997 and 1998, 4% HCN advanced fruit maturity compared to other treatments, with darker, softer, larger fruit at commercial harvest. These and additional results will be presented.
Breeding programs around the world continually collect data on large numbers of individuals. To be able to combine data collected across regions, years, and experiments, research communities develop standard operating procedures for data collection and measurement. One such method is a crop ontology, or a standardized vocabulary for collecting data on commonly measured traits. The ontology is also computer readable to facilitate the use of data management systems such as databases. Blueberry breeders and researchers across the United States have come together to develop the first standardized crop ontology in blueberry (Vaccinium spp.). We provide an overview and report on the construction of the first blueberry crop ontology and the 178 traits and methods included within. Researchers of Vaccinium species—such as other blueberry species, cranberry, lingonberry, and bilberry—can use the described crop ontology to collect phenotypic data of greater quality and consistency, interoperability, and computer readability. Crop ontologies, as a shared data language, benefit the entire worldwide research community by enabling collaborative meta-analyses that can be used with genomic data for quantitative trait loci, genome-wide association studies, and genomic selection analysis.