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Open access

Fan-Hsuan Yang, Lisa W. DeVetter, Bernadine C. Strik, and David R. Bryla

evaluate the relationship between fruit stomatal functioning and Ca accumulation during different stages of development in northern highbush blueberry. This information is necessary to develop feasible practices for increasing Ca levels in the fruit

Free access

Masooma Ali-Abmad and Harrison Hughes

Scanning electron microscopy was used to study stomatal function of grape (Vitis sp. `Valiant') plantlets grown in vitro, polyethylene glycoltreated (PEG) in vitro and greenhouse. Fully open stomata were observed in in vitro grown plants with large aperture (13.5μm) as compared to narrow stomatal opening and small aperture in PEG-treated (4.9pm) and greenhouse grown plants (3.2μm). Furthermore, stomates of persistent leaves initiated during in vitro culture remained fully open with large apertures (12.8μm) two weeks after transplanting in the greenhouse. In contrast, newly-formed leaves produced in the greenhouse from in vitro cultured plants showed narrow stomatal opening with small apertures (3.3μm). In vitro produced leaves exhibited rapid wilting followed by irreversible tissue damage and severe desiccation within three hours of transplantation into the greenhouse. However, PEG-treated plantlets showed a reduced stomatal opening with associated minimal stress when directly transferred into the greenhouse. Thus use of an osmotic agent, PEG, induced more normal stomata1 function as well as improved survival after transfer to the greenhouse.

Free access

K.A. Shackel, V. Novello, and E.G. Sutter

The relative contribution of stomatal and cuticular conductance to transpiration from whole tissue-cultured apple shoots of Malus pumila Mill. M.26 was determined with a modified steady state porometer. When shoots were exposed to 90% RH and high boundary layer conductance, large (73%) and, in some eases, rapid (2 to 3 hours) reductions in leaf conductance occurred, indicating functional stomata. Stomatal closure was also observed microscopically. A maximum estimate for the cuticular conductance of these apple leaves was 18 to 40 mmol·m-2·s-1, which is lower than previous estimates and close to the upper limit of naturally occurring leaf cuticular conductances. Hence, both stomatal and cuticular restrictions of water loss appear to be of importance in determining the water balance of tissue-cultured apple loots. The pathway of water transport in relation to water stress of tissue-cultured shoots is also discussed.

Free access

Kenneth R. Schroeder and Dennis P. Stimart

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.

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Dalong Zhang, Yuping Liu, Yang Li, Lijie Qin, Jun Li, and Fei Xu

weight. Growth analysis in combination with gas exchange parameters highlighted the significant role of VPD control in improving plant growth and productivity. Reducing excessive VPD enhanced photosynthesis by sustaining stomatal function and improving

Free access

Dharmalingam S. Pitchay, John Gray, Jonathan M. Frantz, Leona Horst, and Charles Krause

Geranium (Pelargonium ×hortorum) typically follows the C3 metabolic pathway. However, it switches to CAM metabolism under certain abiotic stress environments. This switch may affect the nutritional requirement and appearance of visible deficiency symptoms of these plants. Because potassium (K) plays a key role in stomatal function, K-deficiency was studied in geranium. Plants were grown hydroponically in a glass greenhouse. The treatments consisted of a complete, modified Hoagland's solution with millimolar concentrations of macronutrients, 15 NO3-N, 1.0 PO4-P, 6.0 K, 5.0 Ca, 2.0 Mg, and 2.0 SO4-S and micromolar concentrations of micronutrients, 72 Fe, 9.0 Mn, 1.5 Cu, 1.5 Zn, 45.0 B, and 0.1 Mo, and an additional solution devoid of K. It took longer to develop the classic K deficiency symptoms than other bedding plant species commonly require. The K-stress plants' dry weight was 10% and 37% of control at incipient and advanced stage, respectively. When portions of geranium leaves were covered, symptomology on leaves with K stress developed rapidly (within 2 days) compared to the uncovered portion of the leaf blade. Control plants contained an abundance of marble-shaped K crystals in the adaxial surface of leaf mesophyll, but were lacking in the K-deficient plants. Geranium is more prone to K stress during short days than long days and an additional supply of K would be needed for normal growth in short days.

Free access

S.R. Green, T.M. Mills, and B.E. Clothier

We recorded canopy development and stomatal function of a kiwifruit vine for the purpose of calculating the seasonal water use by the crop. Canopy development was described using an empirical “S-shaped” curve fitted to weekly measurements of the vine's leaf area. Stomatal conductance was described using a semi-empirical model based on the incident radiation, and the ambient vapor pressure deficit of the air. These two descriptors, leaf area and stomatal conductance, were combined with meteorological data to calculate vine transpiration via the Penman–Monteith model. Transpiration rates calculated at 30-min intervals were in good agreement with the instantaneous rates of sap flow measured by heat-pulse sensors located in the vine stem. The measured and calculated transpiration remained in concert throughout the experiment, thereby confirming the Penman-Monteith model as a robust and suitable model to describe the seasonal water use by kiwifruit vines. The model validation enables confident predictions of crop water use and thus aids irrigation allocation for kiwifruit crops.

Free access

Sissel Torre, Tove Fjeld, Hans Ragnar Gislerød, and Roar Moe

Single node cuttings with one mature leaf were taken from Rosa ×hybrida `Baroness' and rooted in water culture. The plants were subjected to either 90% (high) or 70% (moderate) relative humidity (RH) in climate chambers. Single stem roses with intact roots were transferred to 40% (low) RH to investigate the stomatal response to water stress. Moderate RH plants showed decreasing leaf conductance from day 1 to day 3 during both light and dark phases, in contrast to high RH roses, which showed almost similar leaf conductances during the 3 days. Leaf samples were studied with a light microscope (LM) and a scanning electron microscope (SEM) to quantify morphological and structural changes. Epidermal imprints showed a significantly higher number of stomata and longer stomata, as well as a wider stomatal apertures on roses grown at high RH. The high RH leaves showed a reduced density of vascular tissue and thinner leaves when compared to moderate RH leaves. Enlarged intercellular air-space (ICA) was found due to a reduced number of spongy and palisade mesophyll cells. No obvious difference in shape, size, undulation or the structure of the epicuticular wax was observed in SEM between high and moderate RH grown leaves. In conclusion, roses subjected to high RH showed differences in leaf anatomy, stomatal morphology and stomatal function, which may explain the loss of water control of these plants. Stomatal ontogenesis should occur at RH conditions below 85% to secure roses with a high postharvest quality potential.

Free access

Kourosh Vahdati, Zeinab Maleki Asayesh, Sasan Aliniaeifard, and Charles Leslie

significant change in chlorophyll content (SPAD) ( Table 5 ). In the present study, elevated CO 2 concentration in the vessel headspace altered stomatal functioning and improved ex vitro acclimatization of walnut plantlets. Similarly, stomatal conductance was

Open access

Xiaohui Lin, Hongbo Li, Shenggen He, Zhenpei Pang, Shuqin Lin, and Hongmei Li

al., 2016 ; Kitamura and Ueno, 2015 ). Previous studies on stomatal function in cut-flower transpiration focused mainly on the leaves ( Aliniaeifard and van Meeteren, 2016 ; Schroeder and Stimart, 2005 ). However, stomata may also be distributed on