Application of Kaolin-based Particle Film on Pecan Trees: Consequences on Leaf Gas Exchange, Stem Water Potential, Nut Quality, and Insect Populations

Trials were established in Summer 2002 and 2003 to test the consequences of the application of a kaolin-based particle film (Surround WP, Engelhard Corp.) on gas exchange, nut quality, casebearer density and population of natural predators (insects and arachnids) on pecan (Carya illinoinensis, cv. `Pawnee') trees. Film application started immediately after bud break and was repeated every 7-10 days for seven (2002) or nine (2003) times during the season. On both years, treated trees frequently showed lower leaf temperature (up to 4 °C) than untreated trees. Leaf net assimilation rate, stomatal conductance and stem water potential were not affected by film application. Nut size and quality did not differ between the two treatments. In 2003, shellout (percentage of nut consisting of kernel) was in fact 54.2% and 55.5% for treated and control trees, respectively. Moreover, the two treatments yielded similar percentage of kernel crop grading as fancy, choice, standard and damaged. Similar were also the percentages of kernels that showed damage caused by stink bugs. Only on one date the number of adult yellow pecan aphids (Monelliopsis pecanis) counted on film-treated leaves was lower than in control leaves. In general, the density of common natural predators (lady beetles, green lacewings, spiders) of pecan pests did not differ between the two treatments; however, the number of green lacewing eggs was frequently lower on film-treated leaves. In film-treated trees the number of nutlets damaged by pecan nut casebearer (Acrobasis nuxvorella) was significantly higher than that observed on trees treated with conventional insecticide (24.2% infested nutlets vs. 9.3%, respectively) and did not differ from trees that did not receive either product (29.9%).

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Effects of Particle Film Application on Leaf Gas Exchange, Water Relations, Nut Yield, and Insect Populations in Mature Pecan Trees

HortScience ◽

10.21273/hortsci.40.5.1376 ◽

2005 ◽

Vol 40 (5) ◽

pp. 1376-1380 ◽

Cited By ~ 12

Author(s):

Leonardo Lombardini ◽

Marvin K. Harris ◽

D. Michael Glenn

Keyword(s):

Gas Exchange ◽

Water Relations ◽

Natural Enemies ◽

Leaf Gas Exchange ◽

Carbon Assimilation ◽

Stem Water Potential ◽

Air Temperatures ◽

Insect Populations ◽

Stem Water ◽

Net Assimilation

Trials were conducted during summer months of 2002 and 2003 to evaluate the effects of a kaolin-based particle film (Surround WP, Engelhard Corp.) on gas exchange, nut quality, casebearer density and population of natural enemies (insects and arachnids) on pecan (Carya illinoinensis `Pawnee') trees. Film application was repeated for seven (2002) or nine (2003) times during the growing season. In both years, treated trees showed lower leaf temperature (up to 4 °C) than untreated trees. During the warmest hours of the day, kaolin-treated leaves were generally 0 to 2 °C cooler than air temperatures, compared to 4 to 6 °C for control leaves. Leaf net assimilation rate, stomatal conductance and stem water potential were not affected by film application. Nut size and quality did not differ between the two treatments. Shellout (percentage of nut consisting of kernel) was not affected by treatment and averaged about 55%. Crop grade distribution (fancy, choice, standard, and damaged) was also similar among treatments in both years. In both years, numbers of green lacewing eggs was less on kaolin-treated compared to control leaves. The density of common natural enemies (lady beetles, green lacewings, spiders) of pecan pests did not differ between treatments. The average number of developing nuts damaged by pecan nut casebearer (Acrobasis nuxvorella Neunzig) was significantly higher in kaolin-sprayed trees (24.2%) compared to control trees sprayed with conventional insecticides (9.3%). The results suggest that kaolin-based particle film may not be a viable alternative to conventional methods of controlling pecan pests. Also, under adequate irrigation conditions, carbon assimilation, water relations and productivity may not benefit from kaolin particle film application.

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Partial rootzone drying improves almond tree leaf-level water use efficiency and afternoon water status compared with regulated deficit irrigation

Functional Plant Biology ◽

10.1071/fp10247 ◽

2011 ◽

Vol 38 (5) ◽

pp. 372 ◽

Cited By ~ 24

Author(s):

Gregorio Egea ◽

Ian C. Dodd ◽

María M. González-Real ◽

Rafael Domingo ◽

Alain Baille

Keyword(s):

Gas Exchange ◽

Water Potential ◽

Leaf Gas Exchange ◽

Water Status ◽

Stem Water Potential ◽

Regulated Deficit Irrigation ◽

Leaf Level ◽

Use Efficiency ◽

Stem Water ◽

Partial Rootzone Drying

To determine whether partial rootzone drying (PRD) optimised leaf gas exchange and soil–plant water relations in almond (Prunus dulcis (Mill.) D.A. Webb) compared with regulated deficit irrigation (RDI), a 2 year trial was conducted on field-grown trees in a semiarid climate. Five irrigation treatments were established: full irrigation (FI) where the trees were irrigated at 100% of the standard crop evapotranspiration (ETc); three PRD treatments (PRD70, PRD50 and PRD30) that applied 70, 50 and 30% ETc, respectively; and a commercially practiced RDI treatment that applied 50% ETc during the kernel-filling stage and 100% ETc during the remainder of the growth season. Measurements of volumetric soil moisture content in the soil profile (0–100 cm), predawn leaf water potential (Ψpd), midday stem water potential (Ψms), midday leaf gas exchange and trunk diameter fluctuations (TDF) were made during two growing seasons. The diurnal patterns of leaf gas exchange and stem water potential (Ψs) were appraised during the kernel-filling stage in all irrigation regimes. When tree water relations were assessed at solar noon, PRD did not show differences in either leaf gas exchange or tree water status compared with RDI. At similar average soil moisture status (adjudged by similar Ψpd), PRD50 trees had higher water status than RDI trees in the afternoon, as confirmed by Ψs and TDF. Although irrigation placement showed no effects on diurnal stomatal regulation, diurnal leaf net photosynthesis (Al) was substantially less limited in PRD50 than in RDI trees, indicating that PRD improved leaf-level water use efficiency.

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Physiological Response of Carambola Trees to Soil Water Depletion in Krome Soils

HortScience ◽

10.21273/hortsci.39.4.857b ◽

2004 ◽

Vol 39 (4) ◽

pp. 857B-857

Author(s):

Rashid Al-Yahyai* ◽

Bruce Schaffer ◽

Frederick S. Davies

Keyword(s):

Stomatal Conductance ◽

Gas Exchange ◽

Water Potential ◽

Soil Water ◽

Leaf Gas Exchange ◽

Stem Water Potential ◽

Soil Water Depletion ◽

Water Depletion ◽

Loam Soil ◽

Stem Water

The effect of soil water depletion on plant water potential and leaf gas exchange of carambola (Averrhoa carambola L. cv. Arkin) in Krome very gravelly loam soil was studied in an orchard and in containers in the field and in a greenhouse. The rate of soil water depletion was determined by continuously monitoring soil water content with multi-sensor capacitance probes. Stem water potential and leaf gas exchange of carambola in containers were reduced when the soil water depletion level fell below 50% (where field capacity = 100%). Although there was a decrease in the rate of soil water depletion in the orchard as the soil dried, soil water depletion did not go below an average of 70%. This was presumably due to sufficient rainfall and capillary movement of water in the soil. Therefore, soil water content did not decline sufficiently to affect leaf gas exchange and leaf and stem water potential of orchard trees. A decline in soil water depletion below 40% resulted in a concomitant decline in stem water potential of the container trees in the field and greenhouse to below -1.0 MPa. Stomatal conductance, net CO2 assimilation, and transpiration declined significantly when stem water potential was below -1.0 MPa. The reduction of net CO2 assimilation and transpiration was proportional to the decline in stomatal conductance of container trees in the field and greenhouse. Thus, soil water depletion in Krome very gravelly loam soil must be less than 50% before water potential or leaf gas exchange of carambola is affected. Based on these results, irrigation scheduling should be based on physiological variables such as stem water potential and stomatal conductance or the amount rather than the rate of soil water depletion.

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Tolerance of lowbush blueberries (Vaccinium angustifolium Ait.) to drought stress. II. Leaf gas exchange, stem water potential and dry matter partitioning

Canadian Journal of Plant Science ◽

10.4141/p03-028 ◽

2005 ◽

Vol 85 (4) ◽

pp. 919-927 ◽

Cited By ~ 3

Author(s):

V. M. Glass ◽

D. C. Percival ◽

J. T.A. Proctor

Keyword(s):

Soil Moisture ◽

Drought Stress ◽

Gas Exchange ◽

Water Potential ◽

Stomatal Density ◽

Leaf Gas Exchange ◽

Water Status ◽

Stem Water Potential ◽

Vaccinium Angustifolium ◽

Stem Water

A 2-yr field study examining the effect of soil moisture on plant water status, photosynthesis and gas exchange parameters in lowbush blueberry (Vaccinium angustifolium Ait.) was conducted at the Nova Scotia Wild Blueberry Institute (NSWBI), Debert, NS. Drought and irrigation treatments were applied over two years in either or both the vegetative and cropping years of production. Midday stem water potential values indicated that all treatments resulted in drought stress. Mean stem water potential values ranged from -1.41 to -1.45 MPa. Predawn stem water potentials in the vegetative growth season indicated that although some recharging and recovery of water loss occurred overnight, the drought-stressed plants did not fully return to pre-stress levels under the moisture-limiting conditions. Higher chlorophyll a and b levels were observed in the single-season drought treatment. Leaves of irrigated plants in both sprout and crop years had the highest stomatal density. There were no differences in photosynthetic rate (Pn) among treatments despite the lower stomatal conductance resulting from limited soil moisture. Key words: Photosynthesis, stomate, stem water potential

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Physiological Effects of Mechanical Harvesting in Citrus Trees

HortScience ◽

10.21273/hortsci.39.4.885c ◽

2004 ◽

Vol 39 (4) ◽

pp. 885C-885

Author(s):

Kuo-Tan Li* ◽

James P. Syvertsen

Keyword(s):

Gas Exchange ◽

Water Potential ◽

Leaf Gas Exchange ◽

Fluorescence Emission ◽

Stem Water Potential ◽

Long Term Effects ◽

Significant Treatment ◽

Linear Type ◽

Stem Water ◽

Citrus Trees

Mechanical harvesting of citrus trees by trunk or canopy shakers can cause leaf and twig removal, bark injury and root exposure. Such problems have restricted the adoption of mechanical harvesting in Florida citrus. We assessed physiological responses of citrus trees that were mechanically harvested with a linear-type trunk shaker, operating at 4 Hz, 70.8 kg mass weight, and 6.5 cm displacement, for 10 or 20 seconds. We measured fruit recovery efficiency, leaf and shoot removal, mid-day stem water potential, leaf gas exchange, and leaf fluorescence emission of mature `Hamlin' and `Valencia' orange trees under restricted or normal irrigation. Shaking treatments effectively removed 90% to 94% of fruit without bark damage. Compared to harvesting by hand, trunk shaking removed 10% more leaf area and twigs, and caused some visible exposure of fibrous roots at the soil surface. There were no significant treatment differences on mid-day stem water potential, leaf gas exchange, and leaf photosystem efficiency. Excessively shaken trees for 20-30 seconds can temporary induce stress symptoms resembling that in trees without irrigation. Trees may have benefited from the low levels of leaf and twig loss after trunk shaking that compensated for any root loss. Long-term effects of trunk shaking will be assessed by tree growth, return bloom, subsequent yield, and carbohydrate reserves.

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Rootstocks induce functional differences that affect carbon isotope discrimination and water relations in the apple scion

10.22541/au.162578061.13443316/v1 ◽

2021 ◽

Author(s):

Erica Casagrande Biasuz ◽

Lee Kalcsits

Keyword(s):

Gas Exchange ◽

Water Potential ◽

Carbon Isotope ◽

Hydraulic Resistance ◽

Water Relations ◽

Water Movement ◽

Isotope Composition ◽

Leaf Gas Exchange ◽

Stem Water Potential ◽

Stem Water

Composite trees combine traits from both the rootstock and scion. Dwarfing rootstocks are used to reduce shoot vigor and improve fruit quality and productivity. Although differences in rootstock vigour have been clearly described, the underlying physiological mechanisms regulating scion vigor are not well understood. Plant water status is strongly influenced by stem hydraulic resistance to water movement. In the scion, stomata regulate transpiration rates and are essential to prevent hydraulic failure. Lower stomatal conductance contributes to enriched leaf carbon isotope composition (δ13C). Combined, the effects of increased hydraulic resistance, limited stomatal control, and subsequently, limited gas exchange can affect tree growth. These differences may also correspond to differences in scion vigor. Here, vegetative growth, gas exchange, stem water potential, and leaf δ13C were compared to determine how rootstocks affect scion water relations. B.9 had the lowest shoot vigor compared to the more vigorous rootstock, G.890. Similarly, photosynthetic rates were also lower. Rootstock vigor was closely associated with leaf gas exchange and stem water potential in the scion and were reflected in leaf δ13C signatures. Dwarfing was strongly related to hydraulic limitations induced by rootstock genotype and these changes are distinguishable when measuring leaf and stem δ13C composition.

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Interactive effects of biostimulants and water stress on potted Pinot noir grapevines

BIO Web of Conferences ◽

10.1051/bioconf/20191303006 ◽

2019 ◽

Vol 13 ◽

pp. 03006

Author(s):

Sofia Sbraci ◽

Linda Salvi ◽

Francesca Paoli ◽

Eleonora Cataldo ◽

Alessandra Zombardo ◽

...

Keyword(s):

Drought Stress ◽

Gas Exchange ◽

Water Potential ◽

Leaf Gas Exchange ◽

Pinot Noir ◽

Interactive Effects ◽

Stem Water Potential ◽

Full Irrigation ◽

Positive Effects ◽

Stem Water

Seaweeds extracts (SWE) are innovative and non-polluting tools that have become popular as biostimulants. Their effects on Pinot noir water potential, gas exchanges and fruit quality under drought stress and full irrigation were evaluated during the 2017 growing season. Differential irrigations were applied and Pinot Noir grapevines have been sprayed two times at label doses (3 g/L) during the vegetative growth, with the Ascophyllum nodosum exract, starting from veraison. During the season, measurements of single leaf gas exchange and stem water potential were made; moreover parameters of technological maturity (°Brix, acidity, pH) and phenological one were analyzed. The inhibition of gas exchange and increase of stomatal limitation induced by drought stress were not reduced by SWE where A.nodosum had positive effects on midday stem water potential. Under full irrigation SWE increased leaf gas exchange. No particular effect was observed on the technological parameters after the treatment. The application of the seaweed extract improved polyphenols accumulation in stressed theses, increasing wine grapes quality. A.nodosum can be useful to reduce negative effects of abiotic stress such lack of water and to improve polyphenols content in grapes, especially in genotypes with a limited phenolic profile like Pinot Noir variety.

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Gas Exchange, Stem Water Potential, and Leaf Orientation of Rubus idaeus L. Are Influenced by Drought Stress

HortScience ◽

10.21273/hortsci.31.4.648b ◽

1996 ◽

Vol 31 (4) ◽

pp. 648b-648

Author(s):

David C. Percival ◽

John T.A. Proctor ◽

J.P. Privé

Keyword(s):

Drought Stress ◽

Gas Exchange ◽

Water Potential ◽

Leaf Gas Exchange ◽

Rubus Idaeus ◽

Stem Water Potential ◽

Spatial Differences ◽

Leaf Movements ◽

Stem Water ◽

Effects Of Drought

Rubus idaeus L. cv. Heritage raspberries were placed in controlled environment chambers (25°C, 14-hour photoperiod, 2.0 kPa vapor pressure deficit, CO2 concentration of 380 mol·m-2·s-1) to study the effects of drought stress on leaf gas exchange and stem water potential. Whole-plant photosynthesis (Pn) and transpiration were sensitive to drought stress and gradually decreased from the second day of the study until rehydration. Stomatal aperture feed-back regulation was present during the initial 48 hours of the study with transpiration rates dropping in response to a decrease in stem water potential. Spatial differences were also present with leaf Pn, and stomatal and CO2 conductance values of the younger, distal (i.e., closer to the apex) leaves decreasing at a faster rate than the older, proximal leaves (i.e., close to crown). Evidence of increased mesophyll resistance to drought stress was apparent with ci either remaining constant or increasing, while Pn and carboxylation efficiency simultaneously decreased. Protection of the underlying photochemistry was evident with parahelionastic leaf movements which resulted in a reduction in the effective leaf area and subsequent heat load. Therefore, an optimum balance between water loss and ci existed, and an alteration in these rates represented a stomatal conductance adjustment to match the intrinsic photosynthetic capacity rather than just a causal relationship.

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Midday Stem Water Potential Values Needed to Maintain Photosynthesis and Leaf Gas Exchange Established for Pecan

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.139.5.537 ◽

2014 ◽

Vol 139 (5) ◽

pp. 537-546 ◽

Cited By ~ 7

Author(s):

Yahia Othman ◽

Dawn VanLeeuwen ◽

Richard Heerema ◽

Rolston St. Hilaire

Keyword(s):

Gas Exchange ◽

Water Potential ◽

Leaf Gas Exchange ◽

Water Status ◽

Irrigation Scheduling ◽

Stem Water Potential ◽

Flood Irrigation ◽

Dry Down ◽

Stem Water ◽

The Impact

Demand for New Mexico’s limited water resources coupled with periodic drought has increased the necessity for tree water status monitoring to guide irrigation scheduling of pecan (Carya illinoinensis) orchards. The objectives of this study were to assess the impact of water status developed during the flood irrigation dry-down cycles on photosynthesis (Pn), and gas exchange [stomatal conductance (gS) to H2O (gH2O), transpiration (E), and intercellular CO2 (ci)] and to establish values of midday stem water potential (Ψsmd) that are needed to maintain Pn and gas exchange of pecan. We conducted the study simultaneously on two southern New Mexico mature pecan orchards from 2011 through 2013. Flood irrigation as determined by grower practice was used on both orchards and Pn, gH2O, E, and ci were assessed at Ψsmd of –0.4 to –2.0 MPa. Photosynthesis and gas exchange were higher in pecan trees shortly after irrigation than trees exhibiting water deficit near the end of a flood irrigation dry-down cycle. The decline in Pn was markedly noticeable when Ψsmd dropped below –0.9 MPa. We attributed the reduction in Pn mostly to stomatal limitation. The decline in Pn and gH2O exceeded 50% when Ψsmd ranged from –1.5 to –2.0 MPa. For those reasons, we recommended that pecan orchards be maintained at Ψsmd higher than –0.90 MPa to prevent significant reductions in carbon assimilation and gas exchange.

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Microtensiometers Accurately Measure Stem Water Potential in Woody Perennials

Plants ◽

10.3390/plants10122780 ◽

2021 ◽

Vol 10 (12) ◽

pp. 2780

Author(s):

Victor Blanco ◽

Lee Kalcsits

Keyword(s):

Water Potential ◽

Leaf Gas Exchange ◽

Water Status ◽

Full Range ◽

Canopy Temperature ◽

Plant Water ◽

Stem Water Potential ◽

Woody Tissue ◽

Woody Perennials ◽

Stem Water

Stem water potential (Ψstem) is considered to be the standard measure of plant water status. However, it is measured with the pressure chamber (PC), an equipment that can neither provide continuous information nor be automated, limiting its use. Recent developments of microtensiometers (MT; FloraPulse sensors), which can continuously measure water tension in woody tissue of the trunk of the tree, can potentially highlight the dynamic nature of plant water relations. Thus, this study aimed to validate and assess the usefulness of the MT by comparing the Ψstem provided by MT with those same measurements from the PC. Here, two irrigation treatments (a control and a deficit treatment) were applied in a pear (Pyrus communis L.) orchard in Washington State (USA) to capture the full range of water potentials in this environment. Discrete measurements of leaf gas exchange, canopy temperature and Ψstem measured with PC and MT were made every two hours for four days from dawn to sunset. There were strong linear relationships between the Ψstem-MT and Ψstem-PC (R2 > 0.8) and with vapor pressure deficit (R2 > 0.7). However, Ψstem-MT was more variable and lower than Ψstem-PC when Ψstem-MT was below −1.5 MPa, especially during the evening. Minimum Ψstem-MT occurred later in the afternoon compared to Ψstem-PC. Ψstem showed similar sensitivity and coefficients of variation for both PC and MT acquired data. Overall, the promising results achieved indicated the potential for MT to be used to continuously assess tree water status.

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