Search Results
The effects of atmospheric CO2 enrichment and root restriction on net CO2 assimilation (A), dry mass partitioning, and leaf mineral element concentrations in `Kensington' and `Tommy Atkins' mango (Mangifera indica L.) were investigated. Trees were grown in controlled-environment glasshouse rooms at ambient CO2 concentrations of 350 or 700 μmol·mol-1. At each CO2 concentration, trees were grown in 8-L containers, which restricted root growth, or grown aeroponically in 200-L root mist chambers, which did not restrict root growth. Trees grown in 350 μmol·mol-1 CO2 were more efficient at assimilating CO2 than trees grown in 700 μmol·mol-1 CO2. However, total plant and organ dry mass was generally higher for plants grown at 700 μmol·mol-1 CO2 due to increased A as a result of a greater internal partial pressure of CO2 (Ci) in leaves of plants in the CO2 enriched environment. Root restriction reduced A resulting in decreased organ and plant dry mass. In root-restricted plants, reduced A and dry matter accumulation offset the increases in these variables resulting from atmospheric CO2 enrichment. Atmospheric CO2 enrichment and root restriction did not affect dry mass partitioning. Leaf mineral element concentrations were generally lower for trees grown at the higher ambient CO2 concentration, presumably due to a dilution effect from an increased growth rate.
Diploid (2x) and autotetraploid (4x) Citrus L. rootstock cultivars were grown at elevated CO2 to obtain insights into limitations on growth and net gas exchange that have been associated with tetraploidy. Well-nourished 2x and 4x seedlings of `Volkamer' lemon (Volk, C. volkameriana Ten & Pasq.), `Troyer' citrange [Troy, C. sinensis (L.) Osbeck × Poncirus trifoliata (L.) Raf.] and `Cleopatra' mandarin (Cleo, C. reticulata Blanco.), were grown in greenhouses at either ambient or twice ambient CO2 for 4 months. Plant growth, water relations, mineral nutrition, and net gas exchange characteristics of leaves were measured. Most 4x plants were smaller and had lower rates of whole plant transpiration but shorter fibrous roots than 2x plants. Fibrous roots of 4x were thicker than 2x roots as indicated by a lower specific root length (SRL) in 4x than in 2x roots. Root hydraulic conductivity was correlated to total plant growth but there were no effects of CO2 or ploidy on root conductivity. Tetraploid leaves had lower N concentrations than 2x leaves when expressed on a dry weight basis but these differences disappeared when N concentration was expressed on an leaf area basis because 4x leaves had more leaf dry weight per area (LDW/a) than 2x leaves. Plant growth was greater and SRL was lower at elevated CO2 than at ambient CO2. LDW concentrations of N, P, and K were lower at elevated CO2 than at ambient apparently due to a growth dilution effect. LDW/a, net CO2 assimilation (ACO2), and leaf water use efficiency were greater at elevated CO2 than at ambient. Overall, there was no effect of ploidy on ACO2 but 4x Volk and Troy had lower rates of ACO2 than their 2x at elevated CO2. Net gas exchange of tetraploid leaves was less responsive to elevated CO2 than 2x leaves. The low SRL of tetraploids was correlated with low whole plant transpiration rates and low leaf area-based N concentrations, which may be operative in determining the growth characteristics associated with tetraploidy.
higher plants ( Demmig-Adams et al., 1996 ). However, Lefsrud et al. (2006) suggested that high light intensities may lead to the photodegradation of pigment molecules. In addition, it was suggested that a dilution effect with higher light intensities
cases except for root P concentrations, shade vines had greater nutrient concentrations compared with full sun vines (dilution effect with growth) and similar or greater concentrations as compared with shade/full sun vines. Root P concentrations, however
Abstract
Purees were prepared from green (G, immature and mature green 1:1) and ripe (R, firm ripe and processing ripe 1:1) fruits of ‘Cardinal’ and A-5344 strawberries (Fragaria × ananassa Duch.). Blends of 25%R + 75%G, 50%R + 50%G, 75%R + 25%G, and 100% R were prepared before and after holding purees at 10, 30 and 50°C for 0, 12, 24 and 36 hours. The decrease in puree color caused by the addition of puree of green fruit to puree of ripe fruit was a dilution effect rather than a synergistic effect, since pures of green and ripe fruits combined after holding were equal in color to purees of comparable proportions of purees of G and R fruits combined before holding. Holding strawberry puree for up to 36 hours at 30° and 50°C increased discoloration and reduced total anthocyanins, pelargonidin-3-monoglucoside content, COM “a”, and visual color. Holding at 50° resulted in the greatest reductions in color.
dilution effect as more dry weight was accumulated. However, in mature leaves, the likely cause was the translocation of N out of the mature leaves, because there was no significant change in the dry weight of mature leaves ( Fig. 4A ). Our finding thus