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Guilherme Locatelli, Rafael Pio, Rayane Barcelos Bisi, Filipe Bittencourt Machado de Souza, Mariana Thereza Rodrigues Viana, Daniela da Hora Farias, Evaristo Mauro de Castro, and Carolina Ruiz Zambon

. (2018) compared the leaf anatomy of commercial and traditional almond cultivars ( Prunus dulcis ) under water deficit, and they observed great variation in the area occupied by transport vases within the same cultivars. However, they also found

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M.A. Shaheen

The present investigation was carried out to determine the effect of salinity on three grapevine leaf anatomy. The experiment was conducted in box culture with two mixed salts (NaCl and CaCl2) at five concentrations (0, 1000, 2000, 3000 and 4500 ppm) and three cultivars, namely, `Thompson seedless', `Flame seedless' and `Robby seedless'. Increasing salinity significantly reduced the total axes of the epidermis, assimilating, vascular and ground tissues of the leaf. It also changed the ratio of the upper to the lower epiderm tissue. The differences among the three cultivars were not significant. The area of the palisade tissue was larger than the area of the spongy tissue in case of the control or 1000 ppm salinity treatments, while higher concentration of salinity resulted reverse in a situation. The xylem area was larger than that of the phloem at all concentrations under study. The area of parenchyma tissue was consistantly larger than that of mechanical tissue.

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Imed Dami and Harrison Hughes

Grape cv. Valiant was micropropagated in an MS medium with and without 2% (W/V) of polyethylene glycol (PEG, MW 8000). Leaf anatomy of control (in vitro, no PEG), treated (in vitro, PEG), field grown and greenhouse grown plants were compared under light microscopy. Cell size, palisade layer formation, relative intercellular air space and apparent chloroplast number varied between the leaves of control and PEG treated (high osmoticum) plantlets. These leaf characteristics in the high osmoticum medium appeared more similar to the leaves of the greenhouse and field grown plants. Leaves from control plantlets contained cells of larger size, lacked normal palisade layer formation, greater intercellular pore spaces and fewer chloroplasts. Leaves of PEG treated plantlets had smaller cells, a more defined palisade layer, reduced intercellular pore spaces and greater number of chloroplasts. Leaves of greenhouse and field grown plants had small cells, a well-defined palisade layer, least intercellular pore space and greatest number of chloroplasts. These results demonstrate that a high osmoticum medium may be used to induce more normal leaf development.

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Greg Osterhaus and Alice Le Duc

An anatomical study was conducted to determine and compare the internal leaf surface to volume (S/V) ratio of the spongy mesophyll in selected cultivars of Acer saccharum. A low S/V ratio is one of several selectively advantageous characteristics associated with xerophytic plants. It has been proposed that a correlation exists between certain injuries produced by environmental stress and plant leaf anatomy. The taxa included in the study were Acer saccharum cvs. Green Mountain and Legacy, A. saccaharum Caddo and Wichita Mountain (seedlings of Caddo County and Wichita Mountains, Oklahoma relictual populations respectively), and A. saccharum ssp. nigrum (syn. Acer nigrum). Leaf samples were taken from five different representative trees for each of the five cultivars. The results showed that Caddo, which is highly stress tolerant, had a significantly lower internal S/V ratio than the other four cultivars. `Legacy' which is intermediate in stress tolerance had the next lowest S/V ratio. As expected the highly injury-susceptible selections A. saccharum `Green Mountain' and A. saccharum nigrum had high S/V ratios. However, the Wichita Mountain variety which exhibits a stress tolerance similar to Caddo, also had a high S/V ratio. These results suggest that other factors may be involved in determining environmental stress tolerance.

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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.

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Enoc Barrera-Aguilar, Luis A. Valdez-Aguilar, Ana M. Castillo-González, Andrew D. Cartmill, Donita L. Cartmill, Edilberto Avitia-García, and Luis Ibarra-Jímenez

research we also assessed the relationship of K nutrition with leaf water potential (ψ w ), photosynthetic rate, leaf anatomy, and plant nutritional status. Materials and Methods Cultural conditions and plant material. The study was conducted under

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Montree Issarakraisila and Ravie Sethpakdee

Leaf anatomy of young rambutan (Nephelium lappaceum Linn.), durian (Durio zibethinus Murray), mangosteen (Garcinia mangostana Linn.), and longkong (Aglaia dookoo Griff.) potted plants grown under different light intensity (100%, 55%, 40%, or 25% of full sun) were observed. The thickness of both palisade and spongy parenchyma decreased as the light intensity decreased. This resulted in a decrease of lamina thickness when the light was lower. An exception occurred in mangosteen when the thickness of both palisade and spongy parenchyma in leaf grown under full sunlight were lower than in leaves grown under 55% or 40% full sun. The thickness ratio of palisade and spongy tissue in rambutan and durian decreased as light intensity decreased. While the ratios in mangosteen and longkong leaves grown under full sunlight were lower than the ratios of leaves grown under 55% or 40% of full sun. The frequency of stomata also decreased as the light intensity decreased. The thickness of palisade tissue of leaves grown under 55% of full sun in rambutan, durian, mangosteen, and longkong were 70, 110, 110, and 55 μm, respectively. The thickness of spongy tissue of leaves grown under 55% of full sun in rambutan, durian, mangosteen, and longkong were 60, 30, 410, and 145 μm, respectively. The thickness of leaves grown under 55% of full sun in rambutan, durian, mangosteen, and longkong were 186, 230, 565, and 233 μm, respectively. The number of stomata per square millimeter of leaves grown under 55% of full sun in rambutan, durian, mangosteen, and longkong were 437, 221, 133, and 301, respectively. Photosynthesis efficiency and light adaptation were discussed.

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Xiang Wang, Rajeev Arora, Harry T. Horner, and Stephen L. Krebs

showing no leaf movement and thermonastic leaf movement (see arrows) in Rhododendron ponticum and R. catawbiense , respectively. The picture was taken on a sunny day while the ambient temperature was −5.5 °C in Dec. 2006. Leaf anatomy of R

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Madhulika Sagaram, Leonardo Lombardini, and L.J. Grauke

An assessment of leaf anatomic traits of pecan [Carya illinoinensis (Wangenh.) C. Koch] cultivars (Pawnee, Mohawk, and Starking Hardy Giant) collected from three locations (Tifton, GA; Chetopa, KS; and Stillwater, OK) was conducted to provide an understanding of patterns of ecogeographical variation within the natural range. Acetate casts of representative leaves were prepared for microscopic characterization of epidermal traits (stomatal density, stomatal index, and epidermal cell density). There were differences among the three pecan cultivars at the same location, but there were no differences in stomatal density within the same cultivar grown at three distinct locations. The stomatal density of ‘Pawnee’ leaves (404 stomata/mm2) was intermediate between that of ‘Mohawk’ (363 stomata/mm2) and ‘Starking Hardy Giant’ (463 stomata/mm2). ‘Pawnee’ had the greatest epidermal cell density (2511 cells/mm2) whereas ‘Starking Hardy Giant’ showed the least (1414 cells/mm2). Within a location, stomatal index differed significantly among cultivars, with ‘Starking Hardy Giant’ having a greater stomatal index than the other two cultivars. There were no differences in stomatal index across locations. ‘Mohawk’ had the greatest trichome density (18.92 trichomes/mm2) whereas ‘Starking Hardy Giant’ had the lowest (9.6 trichomes/mm2). The study suggests that differences in stomatal density and epidermal cell density in pecans are cultivar specific rather than being determined by environmental factors. The stability of certain leaf anatomic characteristics, such as stomatal and epidermal cell density, for pecan cultivars grown at different locations confirms that these traits can be used for screening provenances with desirable leaf anatomic characteristics for breeding and cultivar development.

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John L. Jifon, James P. Syvertsen, and Eric Whaley

Correlations between extractable leaf chlorophyll (Chl) concentration and portable, nondestructive leaf “greenness” meter readings imply that such estimates can be used as surrogate measurements of leaf nitrogen (N) status. However, few studies have actually found a direct relationship between Chl meter readings and leaf N. We evaluated the utility of two handheld transmittance-based Chl content meters (SPAD-502, Minolta Corp. and CCM-200, Opti-Sciences) and one reflectance-based meter (Observer, Spectrum Technologies), in estimating Chl and N concentrations in intact leaves of several citrus cultivars. Total Chl determined analytically, correlated well with nondestructive Chl meter readings (r 2: 0.72 to 0.97; P < 0.0001), but regression models differed among cultivars using the same meter and also among meters for a given cultivar. The relationships were generally more linear and stronger at low Chl concentrations (<0.5 mmol·m-2) than at higher Chl concentrations, reflecting increased variability in Chl meter readings with increasing leaf Chl. Significant relationships between Chl meter readings and measured leaf N concentrations were also found in all the cultivars tested (r 2: 0.23 to 0.69; P < 0.01), but the data were more variable than those for Chl. Field-grown leaves were significantly thicker and had higher Chl meter readings than greenhouse-grown leaves of similar Chl or N concentrations. The results suggest that nondestructive Chl content meters can overestimate Chl and N in thicker leaves and/or leaves with high Chl concentrations. A single prediction equation derived from a wide range of Chl or N concentrations could be applicable across the range of citrus cultivars when grown in the same environment. Potential limitations associated with leaf thickness as influenced by environmental factors may necessitate the development of more specific calibration equations.