Light response curves for gas exchange characteristics were developed for spur leaves of `Stayman' and `Delicious' apple (Malus domestica Borkh.) from interior, intermediate, and exterior canopy positions throughout the season. At full bloom (FB), before full leaf expansion, exterior leaves had higher maximum rates of net photosynthesis (Pn), and a statistically different Pn light response curve than the interior leaves. Intermediate leaves had intermediate Pn rates and light response curves. Pn light response curves for all three `Delicious' canopy positions differed from each other from FB + 6 weeks until the end of the season. Interior leaves had maximum Pn rates of only 50% to 60% of those for the exterior leaves from FB + 10 weeks until the end of the season. Light saturation levels were higher for the exterior leaves than for interior or intermediate leaves. Exterior leaves had a tendency throughout the season for higher quantum efficiency of Pn at subsaturating light levels than interior or intermediate leaves. Stomatal conductance was higher for the exterior than the interior or intermediate leaves of `Delicious' on all dates. Water-use efficiency was equivalent among all leaves. Exterior leaves had higher specific leaf weight, dark respiration rates, and incident light levels on all dates than interior or intermediate leaves.
with low R:FR light (FL20S·FR·P; Panasonic Corp.) (FL L ), and then the photosynthetic light-response curve and growth characteristics of the seedlings were evaluated in the same way as Expt. 1. The spectrum of FL H was similar to that of FL L , except
·s −1 . A n of C. portenschlagiana on the other hand would be expected to increase by 1.6 to 6.1 μmol·m −2 ·s −1 ( Fig. 6 ). Fig. 6. Photosynthesis (A n )–light response curve for Heuchera americana ‘Dale’s Strain’ grown at an average daily
Abstract
Suitable conditions for determining net photosynthesis (Pn) of individual sun- and shade-grown leaves of weeping fig (Ficus benjamina L.) were 21°C dew point and an air flow rate between 1 and 3 liters/min. A diurnal trend in Pn occurred for sun leaves, with maximum rates between 0800 and 1200 hr; shade leaves did not decline in Pn until mid-afternoon. Leaves which originated from nodes 4 through 10 (from the shoot apex) did not differ in Pn, transpiration (Tr), specific leaf weight (SLW), or leaf water content. Shade-grown leaves had a photosynthetic advantage over sun-grown leaves at levels of photosynthetically active radiation (PAR) below 77 μE m−2s−1, whereas at PAR levels above 100 μE m−2s−1 the reverse was true. Sun-grown leaves had higher Tr rates than shade grown leaves at all PAR levels used.
parameters, and light response curves. The photosynthetic light responses of the four cultivars were determined between the months of May and July during three sampling periods: 1) BH, 2) during PH, and 3) when nearly all or all fruit had naturally fallen
pigments, chloroplast structure, and photosynthesis light-response curve in different phenotypes of variegated temple bamboo to understand the differences in leaf color and to explore the relationship among photosynthetic pigments, chloroplast structure
stage. The overall difference in g l between treatments was smaller during the reproductive growth stage than that during the vegetative growth stage. Photosynthetic light response. The photosynthetic light response curves during the vegetative growth
system with an integrated light source to maintain constant light, temperature, and CO 2 during measurements. Light response curves were generated using light levels between 100 and 2000 μmol·m −2 ·s −1 at 100-μmol·m −2 ·s −1 intervals. Single leaflet
concentration. In both Boldt et al. (2014) and Erwin and Gesick (2017) , CO 2 concentration was maintained at 400 µmol·mol −1 for the light response curves, and PPFD was maintained at 300 µmol·m −2 ·s −1 for the CO 2 response curves. Therefore, data
. Photosynthetic light response curves. Light response curves were performed on three leaves per leaf type and cultivar using a portable IR gas analyzer (LI-6400; LI-COR, Lincoln, NE) equipped with a standard LI-6400, 2 × 3-cm leaf chamber and a red/blue light