Abstract
The effect of root applications of abscisic acid (ABA) on photosynthesis and transpiration in geranium (Pelargonium ×hortorum ‘Glacier Crimson’ Syn. Bruni) cuttings was evaluated using an open infrared CO2 gas exchange system. At concentrations above 3.8 μM ABA there was a reduction in relative growth rate (RGR), transpiration, and photosynthesis 2 days following treatment. Three hours following treatment with 76 μM ABA there was a maximum decrease in both photosynthetic and transpiration rates. Plants which were treated with 76 μM ABA for 6 or 9 hr showed an inhibition in photosynthesis and transpiration 4 days followiing treatment; however, after 6 days there was no difference between treated and control plants. The reduction in transpiration and photosynthesis reported in this paper may have practical value in the shipment and storage of geranium cuttings.
Evaluation of leaf stomatal numbers and postharvest water loss indicate these are important factors in Antirrhinum majus (snapdragon) cut flower postharvest longevity (PHL). Cut flowers with 9 days longer PHL had 53% fewer leaf stomata. Long PHL is associated with an early reduction in transpiration followed by low steady transpiration. Short-lived genotypes had a linear transpiration pattern over the period of PHL indicating poor stomatal control of water loss. Short-lived genotypes had 22% to 33% reductions in fourth quarter transpiration while long-lived genotypes had 2% to 8% reductions. In addition, short-lived genotypes had higher average fourth quarter cut flower weight losses compared to long-lived genotypes. Further investigation of stomatal numbers and functioning relative to PHL may provide breeders a rapid and nondestructive indirect selection method for PHL.
about the mechanisms and pathways of water loss by a cherry fruit’s pedicel ( Linke et al., 2010 ; Smith and Whiting, 2011 ). The role played by the fruit in pedicel transpiration is not clear. Water loss from plant surfaces (including of fruit and
transpire and affect the flow of substances through the xylem stream. In temperate deciduous trees, stomatal density correlates positively with transpiration and photosynthetic potential ( Aasamaa et al., 2001 ; Sack et al., 2003 , 2005 ). Moreover
drought tolerance. A high volumetric soil water content at which transpiration rate begins to decrease would be a possible mechanism to conserve soil water and maintain turf quality for a longer time as drought conditions persist. Identification of
control transpiration. At scales larger than the leaf, however, the boundary layer control on transpiration can become more important than genotype-specific stomata expressions. For example, it is commonly accepted that under ventilated conditions at the
Abstract
Young, actively growing, container-grown Malling Merton (MM) 106 apple trees (Malus domestica Borkh.), trained to a single shoot in a greenhouse, were oriented at vertical, 45° from vertical (45°), 90° from vertical (90°), or 90° from vertical and rotated at 1 rpm (90° rotated), and summer-pruned to remove none or 50% of 70.0-cm shoots. Orientation in a nonvertical position and summer pruning delayed a decline in net photosynthesis (Pn) exhibited by vertical unpruned trees. Pruning but not orientation increased total shoot growth, shoot number, and the number and total area of leaves of subsequent growth, but decreased average leaf size. Within 1 week after orientation, unpruned trees at 45° or 90° showed a decline of terminal shoot growth. However, 60 days after pruning a delayed growth of axillary shoots along the tree axis resulted in no difference in total shoot growth, leaf area, or leaf number on subsequent growth compared to vertical unpruned trees. Orientation at 45° and 90° increased the dry-weight root:shoot ratio and induced rootsuckers. Pruning decreased the root dry weight in all tree orientations. Rotation of unpruned trees increased apical growth, axillary shoot numbers, and dry weight of subsequent growth, and decreased root growth compared to unrotated trees.
Abbreviations: C I , internal CO 2 concentration (ppm CO 2 ); G 5 , stomatal conductance (mol·s -1 ·m -2 ); P N , net photosynthetic rate (μmol CO 2 /sec per square meter); T, transpiration rate (μmol H 2 O/sec per square meter). 1 Former Research
yield, postharvest transpiration, color, chemical composition, and antioxidant activity. Materials and Methods The study was conducted at the Horticulture Farm, University of Georgia (UGA), Tifton, GA, during the spring seasons of 2015 and 2016. The soil
to determine tree grass water use ratios and what this might mean in terms of water use trade-offs in the landscape. In addition, we quantified transpiration (T) using sap-flow sensors, allowing us to indirectly estimate evaporation (E) by difference