Epicuticular Wax on Johnsongrass (Sorghum halepense) Leaves

Weed Science ◽  
1993 ◽  
Vol 41 (3) ◽  
pp. 475-482 ◽  
Author(s):  
Chester G. Mcwhorter
Keyword(s):  
Drought Stress ◽  
Relative Humidity ◽  
Leaf Blade ◽  
Unit Area ◽  
Grain Sorghum ◽  
Epicuticular Wax ◽  
Sorghum Halepense ◽  
Wax Deposition ◽  
Narrow Side ◽  
Leaf Surfaces

Studies were conducted to investigate the uniformity of epicuticular wax deposition on leaf blades of johnsongrass. Johnsongrass leaves grown under drought stress had greatly increased epicuticular wax weights compared to leaves from plants with adequate moisture, but relative humidity (95% vs. 40 ± 5%) had little effect on wax deposition. Wax weights decreased as leaves matured. Sections of lower leaf surfaces of young johnsongrass leaves tended to have more wax than sections of upper leaf surfaces, but weights were nearly equal on upper vs. lower leaf surfaces of older leaves. The narrow side of asymmetrical johnsongrass leaf blades often had more wax per unit area than the wide side. The area over the midvein contained more wax per unit area than either the narrow or wide side of the leaf blade. Greatest wax concentrations on individual leaves were over the midvein area near the leaf apex. Leaf blades of johnsongrass had more wax per unit area than leaves of corn or grain sorghum.

Environmental Effects on Velvetleaf (Abutilon theophrasti) Epicuticular Wax Deposition and Herbicide Absorption

Weed Science ◽  
2011 ◽  
Vol 59 (1) ◽  
pp. 14-21 ◽  
Author(s):  
H. Hatterman-Valenti ◽  
A. Pitty ◽  
M. Owen
Keyword(s):  
Drought Stress ◽  
Light Intensity ◽  
Secondary Alcohol ◽  
Field Capacity ◽  
High Light Intensity ◽  
Epicuticular Wax ◽  
High Light ◽  
Wax Deposition ◽  
Low Light ◽  
Stress Regime

Controlled environment experiments showed that velvetleaf plants grown under drought stress or low temperature (LT) treatments had greater leaf epicuticular wax (ECW) deposition compared to plants grown in soil with moisture at field capacity (FC) or a high temperature (HT) regime. Light intensity did not affect ECW deposition; however, increasing light intensity decreased the leaf ECW ester content and increased the secondary alcohol content. Plants grown at an LT regime or under FC had leaf ECW with fewer hydrocarbons and more esters than those grown at an HT or drought stress regime. Velvetleaf absorption of acifluorfen increased as light intensity decreased for plants grown in adequate soil water content, while the opposite was true for drought-stressed plants. Velvetleaf absorption of acifluorfen was approximately 3 and 10 times greater, respectively, with the addition of 28% urea ammonium nitrate (UAN) in comparison to crop oil concentrate (COC) or no adjuvant, regardless of the environmental treatments. Plants absorbed more acifluorfen when subjected to the LT regime in comparison to the HT regime when UAN was the adjuvant, while the opposite was true when COC was the adjuvant. Velvetleaf absorption of acifluorfen was not affected by drought stress when COC or no adjuvant was used and varied between studies when UAN was used. Velvetleaf absorption of bentazon was greatest for plants grown under HT/FC or high light/FC treatments and least with plants grown under HT/drought stress or low light/drought stress treatments, regardless of the adjuvant. However, bentazon absorption was higher with the addition of an adjuvant and for plants grown at a high light intensity or FC condition compared with medium to low light intensity or drought stress treatments.

Bicellular Trichomes of Johnsongrass (Sorghum halepense) Leaves: Morphology, Histochemistry, and Function

Weed Science ◽  
1995 ◽  
Vol 43 (2) ◽  
pp. 201-208 ◽  
Author(s):  
Chester G. McWhorter ◽  
Rex N. Paul ◽  
J. Clark Ouzts
Keyword(s):  
Leaf Surface ◽  
Unit Area ◽  
Grain Sorghum ◽  
Sorghum Halepense ◽  
Structural Factors ◽  
Soil Mixture ◽  
Low Concentrations ◽  
And Function ◽  
Wax Crystals ◽  
Surface Microroughness

Studies were conducted of one of the structural factors that influences microroughness on johnsongrass leaves. Bicellular trichomes, 47 ± 5 μm long, represented 4 to 5% of all epidermal cells. They secreted a mucilagenous material that covered 8 ± 4% of the leaf surface. Bicellular trichomes occurred in longitudinal rows, intermixed with intercostal cork-silica cells, between rows of stomata. Numbers of bicellular trichomes present per unit area were inversely related to numbers of intercostal cork-silica cells. The trichomes were the panicoid type that are reported not to secrete salts. Johnsongrass trichomes, however, could be induced to discharge salt in the mucilage-type secretions when plants were grown in a soil mixture that was high in lime. Not all secretory constituents were identified, but carbohydrates and callose were found in addition to possible low concentrations of protein. The apical or cap cell of the trichomes stained positively for lipid, protein, and polysaccharide and negatively for pectin, polyphenols, steroids, and alkaloids. The presence of trichomes increases leaf surface microroughness, but the secretion covers wax crystals, decreasing leaf microroughness and likely providing another barrier to herbicide entry through the cuticle. Bicellular trichomes on grain sorghum were similar to those on johnsongrass and also discharged secretions on the leaf surface.

Leaf epicuticular wax and glaucousness in Altai wildrye grass: which trait is most important to water status?

2008 ◽  
Vol 88 (3) ◽  
pp. 447-455 ◽  
Author(s):  
Paul G Jefferson
Keyword(s):  
Drought Stress ◽  
Water Potential ◽  
Water Relations ◽  
Water Status ◽  
Epicuticular Wax ◽  
Forage Yield ◽  
Leaf Surfaces ◽  
The Mean ◽  
Selection For ◽  
Leaf Epicuticular Wax

Epicuticular wax (EW) concentration on the outermost layer of the plant cuticle increases in response to drought stress for many xeric plant species. Glaucousness, or the visible (blue) waxiness of leaf surfaces, is associated with greater EW concentration compared with nonglaucous (green) plants of Altai wildrye grass [Elymus angustus (Trin.) Pilger] (AWR). The contributions of EW concentration and glaucousness to drought stress response have been confounded in previous research. The objective of this study was to determine the effects of EW concentration and glaucousness on water relations of AWR. Water loss rate (WLR) of excised leaves was determined for 180 half-sib AWR lines in 1988, 1989 and 1990 at Swift Current, Saskatchewan, Canada. The mean WLR of blue half-sib lines was 36% less than green half-sib lines (P < 0.05). Among blue (n = 60) or among green (n = 60) half-sib lines, however, there was no significant correlation between WLR and EW concentration. Leaf water potential (Ψ) was determined for 10 blue and 10 green half-sib lines in 1988, 1989 and 1990. Predawn leaf Ψ was 18% higher for blue half-sib lines than for green half-sib lines (P < 0.01), but there was no correlation between Ψ and EW concentration within either group of half-sib lines. Four contrasting synthetics were generated by inter-crossing parent plants that had high or low EW production within either phenotype. The EW concentration, forage yield, predawn Ψ, and midday Ψ were determined for these four synthetics for three sampling dates per year from 1996 to 2001. Selection for high and low EW concentration shifted this trait (P < 0.01) by 0.19 g m-2 between glaucous synthetics and by 0.07 g m-2 between nonglaucous synthetics. Glaucous synthetics exhibited improved predawn Ψ by 0.05 MPa and predawn turgor potential (P) by 0.08 MPa (P < 0.05) compared with nonglaucous synthetics. However, selection for high and low EW concentration did not affect predawn Ψ nor predawn P in either glaucous or nonglaucous synthetics. Selection for blue glaucousness in AWR altered water relations, but selection for EW concentration did not. Key words: Forage breeding, range improvement, forage yield, drought stress, water potential, turgor potential, epicuticular wax

Morphology, Development, and Recrystallization of Epicuticular Waxes of Johnsongrass (Sorghum halepense)

Weed Science ◽  
1990 ◽  
Vol 38 (1) ◽  
pp. 22-33 ◽  
Author(s):  
Chester G. McWhorter ◽  
Rex N. Paul ◽  
William L. Barrentine
Keyword(s):  
Physical Properties ◽  
Epicuticular Wax ◽  
Sorghum Halepense ◽  
Epicuticular Waxes ◽  
Tubular Structures ◽  
Cuticular Membrane ◽  
Crystalline Structures ◽  
Capillary Method ◽  
Leaf Surfaces ◽  
Morphology Development

Johnsongrass leaves were covered with epicuticular wax that varied from 16 to 25 μg/cm2on leaf blades and 56 to 206 μg/cm2on leaf sheaths. At emergence, leaves were covered with a layer of smooth amorphous wax, but crystalline wax (wax plates) began to form on the amorphous wax within 1 or 2 days. This continued until all leaf surfaces were covered with wax plates. At 3 to 4 weeks of age, a smooth layer of coalescence wax was deposited over the wax plates. Formation of coalescence wax continued until nearly all leaf surfaces were covered with a smooth wax layer. Production of wax filaments began when plants were 3 to 4 weeks old and these tubular structures extended 100 to 200 μm above all other wax formations. Deposition of amorphous wax continued after stomata closed in the darkness, sealing over stomata, but the wax layer was broken when stomata opened again in the light. A capillary method was devised that was used to evaporate chloroform containing leaf waxes through 0.1- to 1.2-μm pores in inert filters to recrystallize amorphous wax and wax plates similar to that produced on johnsongrass leaves. Recrystallization of wax from wax filaments dissolved in chloroform produced the same structures of amorphous wax and wax plates as when only wax from leaves with amorphous wax and wax plates was used. Wax washed from leaves also produced wax plates and a variety of crystalline structures on the walls of glass vials after chloroform solutions were evaporated. This result indicated that the morphology of epicuticular waxes is influenced more by their inherent chemical and physical properties than by underlying cells or the cuticular membrane.

Basis for Increased Activity from Herbicide Combinations with Ethofumesate Applied on Sugarbeet (Beta vulgaris)

Weed Science ◽  
1982 ◽  
Vol 30 (2) ◽  
pp. 195-200 ◽  
Author(s):  
David N. Duncan ◽  
William F. Meggitt ◽  
Donald Penner
Keyword(s):  
Beta Vulgaris ◽  
Trichloroacetic Acid ◽  
Epicuticular Wax ◽  
Gas Liquid Chromatography ◽  
Wax Deposition ◽  
Foliar Absorption ◽  
Combination Treatments ◽  
Leaf Surfaces ◽  
Increased Activity ◽  
Long Chain

Differences in susceptibility of sugarbeet (Beta vulgarisL.) to preemergence application of ethofumesate [(±)-2-ethoxy-2,3-dihydro-3,3-dimethyl-5-benzofuranyl methanesulfonate], pyrazon [5-amino-4-chloro-2-phenyl-3(2H)-pyridazinone], and TCA (trichloroacetic acid) were evaluated in several combination treatments. Exposure of plants to ethofumesate severely decreased epicuticular wax deposition on leaf surfaces. Separation of epicuticular wax into major components by gas-liquid chromatography indicated that ethofumesate decreased deposition of alkanes andsec-ketones, but increased the percentage of long-chain waxy esters. TCA also decreased deposition of alkane and ketone components, but not of waxy esters. Waxes were unaffected by pyrazon. Greater foliar absorption of14C-ethofumesate,14C-desmedipham [ethylm-hydroxycarbanilate carbanilate (ester)], and14C-ethofumesate +14C-desmedipham was observed in plants that received preemergence treatments of ethofumesate plus TCA compared to pyrazon or a control.

A method of estimating stomatal density in Paspalum notatum (Poaceae)

2001 ◽  
Vol 49 (5) ◽  
pp. 579 ◽  
Author(s):  
Marisa Santos ◽  
Paulo Luiz de Oliveira ◽  
Flávio Costa Miguens
Keyword(s):  
Cross Section ◽  
Leaf Blade ◽  
Morphological Character ◽  
Unit Area ◽  
Stomatal Density ◽  
Paspalum Notatum ◽  
Frontal View ◽  
Adaxial Surface ◽  
Leaf Surfaces ◽  
Stomatal Number

Stomatal density was recorded on adaxial and abaxial leaf surfaces of Paspalum notatum var. notatum FlÜgge. As in other Poaceae, stomata observation and counting were very difficult from a frontal view because of the morphology of the P. notatum (bahiagrass) leaves: the leaf blade is extremely sinuous on its adaxial surface and trichomes or papillae can hide the stomata. The stomatal number per unit area was determined on both adaxial and abaxial leaf surfaces by using two methods: frontal view and leaf blade cross-section. From these results, we concluded that the use of a cross-section to determine the stomatal density in these plants is the most suitable. Such a method can be used for any plants with stomata organised in longitudinal rows and having a morphological character that makes observation of the stomata difficult.

Weed Control in a Conservation Tillage Rotation in the Texas Blacklands

Weed Science ◽  
1987 ◽  
Vol 35 (5) ◽  
pp. 695-699 ◽  
Author(s):  
Steven M. Brown ◽  
James M. Chandler ◽  
John E. Morrison
Keyword(s):  
Control Systems ◽  
Weed Control ◽  
Conservation Tillage ◽  
Grain Sorghum ◽  
Control Measures ◽  
Sorghum Halepense ◽  
Low Intensity ◽  
No Till ◽  
Primary Tillage ◽  
And Control

A field experiment was conducted to evaluate weed control systems in a conservation tillage rotation of grain sorghum [Sorghum bicolor(L.) Moench.] – cotton (Gossypium hirsutumL.) – wheat (Triticum aestivumL.). Herbicide systems included fall and spring/summer inputs of high and low intensity. Tillage regimes were no-till (NT) and reduced-till (RT) systems; the latter included fall primary tillage followed by spring stale seedbed planting. Both tillage systems utilized controlled traffic lanes and wide, raised beds. Effective johnsongrass [Sorghum halepense(L.) Pers. # SORHA] control required intense herbicide inputs at one or both application periods, i.e., in the fall and/or spring/summer. Grain sorghum and cotton yields for the most intense weed control system, which included high inputs in both the fall and spring/summer, were not superior to systems that included high inputs in only one of the two application periods. Seedling johnsongrass emergence occurred before spring planting in RT (but not in NT) in 2 of 3 yr, and control measures were ineffective. After 3 yr, the predominant weeds were johnsongrass and browntop panicum (Panicum fasciculatumSw. # PANFA).

Grain Sorghum Water Requirement and Responses to Drought Stress: A Review

2010 ◽  
Vol 9 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Yared Assefa ◽  
Scott A. Staggenborg ◽  
Vara P. V. Prasad
Keyword(s):  
Drought Stress ◽  
Grain Sorghum ◽  
Water Requirement

Wheat flag leaf epicuticular wax morphology and composition in response to moderate drought stress are revealed by SEM, FTIR-ATR and synchrotron X-ray spectroscopy

2017 ◽  
Vol 162 (3) ◽  
pp. 316-332 ◽  
Author(s):  
Ian R. Willick ◽  
Rachid Lahlali ◽  
Perumal Vijayan ◽  
David Muir ◽  
Chithra Karunakaran ◽  
...  
Keyword(s):  
Drought Stress ◽  
Flag Leaf ◽  
Epicuticular Wax ◽  
X Ray ◽  
Moderate Drought ◽  
Leaf Epicuticular Wax

Early spring and late autumn response to applied nitrogen in four grasses

1980 ◽  
Vol 94 (2) ◽  
pp. 443-453 ◽  
Author(s):  
D. Wilman ◽  
A. A. Mohamed
Keyword(s):  
Perennial Ryegrass ◽  
Leaf Blade ◽  
Unit Area ◽  
Total Yield ◽  
Early Spring ◽  
Late Winter ◽  
Number Of Leaves ◽  
Four Levels ◽  
Leaf Extension ◽  
Applied Nitrogen

SummaryThe regrowth of Aberystwyth S. 23 perennial ryegrass, S. 24 perennial ryegrass, S. 59 red fescue and S. 170 tall fescue was studied in field swards, comparing four levels of applied nitrogen, for 8 weeks following a clearing cut. The clearing cuts were in mid-October, mid-February and mid-March in each of 3 years, different plots being used on each occasion.The application of N increased the number of leaf primordia, the number of un-emerged leaves, the rate of leaf emergence and death, leaf blade length, width and weight, sheath length, number of leaves per unit area of ground and proportion of green tissue in total yield. The application of N had little effect on the number of leaves per tiller and tended to reduce weight per unit area of leaf blade. The increase in size, weight and number of leaf blades appeared to be major reasons for the positive effect of applied N on yield, previously reported; and the increase in sheath length contributed to the increase in proportion of yield above 4 cm. Rate of leaf extension was not closely related to yield and was more sensitive to temperature than was yield. Changes during regrowth in blade and sheath length helped to explain changes in weight per tiller, previously reported. The effects of improving weather conditions in late winter/early spring were similar to the effects of applied N: larger, heavier leaf blades, longer sheaths, a taller canopy, a lower proportion of dead material, younger leaves. The length of shoot apex per leaf primordium was relatively constant. Leaves continued to emerge, at a slow rate, in the period December–February. S. 170 had the biggest leaves, particularly in May, and the slowest rate of leaf turnover. Rate of leaf extension was increased by applied N more, on average, in the ryegrasses than in the fescues.

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