Evaluation of Edge Injection Errors in the Floating Leaf Disk Method of Measuring Leaf Tissue Water Deficit

Red scale were reared in the laboratory on disks cut from lemon leaves floated on distilled water in plastic vials. Scales could be reared to maturity on the disks and females would produce crawlers. Rates of development measured at four temperatures using the leaf disk method were similar to data reported by earlier authors. Unfertilized females were found to remain alive and could be fertilized up to 16 weeks after the second moult. On the average, the longevity of unfertilized females was shown to be 3.5 weeks longer than that of fertilized females. The fecundity of females collected from the field was measured at a series of constant temperatures. Estimates of the capacity for increase (rc) and the innate capacity for increase (rm were obtained at four temperatures. Both these statistics were shown to be greatly influenced by temperature; rc was found to be an underestimate of rm at higher temperatures.

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Leaf tissue water relations and hydraulic properties of sclerophyllous vegetation on white sands of the upper Rio Negro in the Amazon region

Journal of Tropical Ecology ◽

10.1017/s026646740900604x ◽

2009 ◽

Vol 25 (3) ◽

pp. 271-280 ◽

Cited By ~ 7

Author(s):

M. A. Sobrado

Keyword(s):

Water Relations ◽

Specific Conductivity ◽

Leaf Tissue ◽

Amazon Region ◽

Tissue Water ◽

Xylem Structure ◽

Sclerophyllous Vegetation ◽

And Function ◽

White Sands ◽

Leaf Survival

Abstract:The objective of this study was to explore the leaf tissue water relations in terminal branches, as well as the relations between xylem structure and function of five sclerophyllous species coexisting on white sands within the Amazon region. In these species, which possess costly leaves and thrive in an extremely nutrient-poor habitat, the preservation of leaf survival would be of comparable importance to the preservation of xylem vessels. Three trees per species were tagged in the field for all measurements. Minimum leaf water potential (Ψ) was −1.53 ± 0.61 and −0.94 ± 0.10 MPa during rainless and rainy days, respectively. The Ψ for turgor loss averaged −1.92 ± 0.05 MPa. Therefore, minimum Ψ was maintained within a safety range above the critical value for turgor loss. Xylem (Kx) and leaf (Kl) specific conductivity averaged 1.4 ± 0.22 and 0.00033 ± 0.000045 kg m−1 s−1 MPa−1, respectively. Water supply was favoured in species with higher vessel density, and all species depended on relatively less abundant larger vessels for water transport. This would be advantageous because leaves were unable to develop very negative water potentials in order to maintain transpiration. High transpiration rates may be restricted to a few hours daily so as to prevent cavitation of widest vessels.

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Sensitivity of Australian isolates of Plasmopara viticola to acylanaline fungicides

Australian Journal of Experimental Agriculture ◽

10.1071/ea9870601 ◽

1987 ◽

Vol 27 (4) ◽

pp. 601

Author(s):

T Wicks ◽

TC Lee ◽

J Overton

Keyword(s):

Phosphorous Acid ◽

Plasmopara Viticola ◽

Leaf Disk ◽

Sensitivity Testing ◽

Fungicide Sensitivity ◽

Floating Leaf

A floating leaf disk technique was used to test the sensitivity of Australian isolates of Plasmopara viticola to 4 acylanaline fungicides, phosethyl-A1 and phosphorous acid. Sporulation of all 15 isolates was completely inhibited by 1 mg/L of metalaxyl. Benalaxyl, oxadixyl and ofurace at 10 mg/L and phosethyl-A1 and phosphorous acid at 100 mg/L also completely inhibited sporulation of each of the isolates tested for each fungicide. These results indicate that acylanaline insensitive isolates of P. viticola are either not present or are not widely distributed in grape growing areas of Australia. Cultures of selected P. viticola isolates have been established on tissue-cultured grapevines. Sporangia from these cultures can be used as standards for future fungicide sensitivity testing.

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Genotypic differences in leaf area maintenance contribute to differences in recovery from water stress in soybean

Australian Journal of Agricultural Research ◽

10.1071/ar08177 ◽

2008 ◽

Vol 59 (12) ◽

pp. 1075 ◽

Cited By ~ 12

Author(s):

R. J. Lawn ◽

A. A. Likoswe

Keyword(s):

Leaf Area ◽

Water Deficit ◽

Leaf Tissue ◽

Water Deficit Stress ◽

Dead Leaf ◽

Genotypic Differences ◽

Leaf Stage ◽

Severe Water Deficit ◽

Soybean Plants ◽

Root Effects

Genotypic effects on leaf survival during water deficit stress and subsequent recovery were evaluated using soybean plants grown in tall cylinders in the glasshouse. An initial experiment sought to verify reported genotypic differences in leaf area maintenance under severe water deficit stress. A second experiment sought to test the hypothesis that these putative differences might affect recovery after stress was relieved. Two shoot genotypes, G2120 and cv. Valder, reported to have high and low leaf area retention, respectively, were used in both experiments. In order to preclude the possibility that the reported differences between G2120 and Valder were related to root rather than shoot traits, each shoot was grafted at the cotyledonary stage onto 2 non-self root genotypes, cv. Leichhardt and PI416937. Leichhardt has an apparently normal root, while PI416937 has been reported to be ‘extensively fibrous-rooted’. In the first experiment, water was withheld at the first trifoliolate leaf stage and the plants subjected to terminal water deficit stress. Consistent with the previous report, leaf area was maintained for longer into the stress by the G2120 shoots, with rapid loss of lower leaves not starting until c. 90% of plant-available water (PAW) had been depleted, compared with c. 80% for Valder. The Valder leaves also showed more ‘firing’ damage, with large patches of dead leaf tissue on the retained leaves. Also consistent with the previous report, leaf epidermal conductance to water vapour was lower in G2120 than in Valder. There were no apparent root effects. In the second experiment, water was again withheld at the first trifoliolate leaf stage, and treatments were re-watered when 80%, 85%, 90%, and 95% of the estimated PAW was extracted. Again, G2120 shoots showed better leaf area maintenance during the drying cycle, and less firing damage. When the plants were re-watered, the re-growth of G2120 generally exceeded that of Valder at all levels of PAW depletion. The differences in recovery between G2120 and Valder shoots were sufficient to have agronomic relevance, and confirmed the hypothesis that leaf area retention can affect recovery after severe water deficit stress. Root effects were relatively small. During the drying cycle, leaflet growth was marginally enhanced by Leichhardt relative to PI416937 roots. After re-watering, there was stronger recovery of plants with PI416937 roots, especially those with G2120 shoots. The basis of the differences between the root genotypes is not known but the stronger recovery of PI416937 may reflect its putative ‘extensively fibrous’ nature.

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Nitrogen levels via fertigation and irrigation depths in the arugula culture

Horticultura Brasileira ◽

10.1590/s0102-053620200401 ◽

2020 ◽

Vol 38 (4) ◽

pp. 343-349

Author(s):

Paulo Henrique Soares Silva ◽

Luiz Fabiano Palaretti ◽

Arthur Bernardes Cecílio Filho ◽

Yane Freitas da Silva

Keyword(s):

Block Design ◽

Irrigation Management ◽

Leaf Tissue ◽

High Yield ◽

Tissue Water ◽

Horticultural Crops ◽

Nitrogen Levels ◽

Leaf Chlorophyll ◽

Randomized Block Design ◽

Two Factors

ABSTRACT In vegetables, especially the leafy ones, nitrogen (N) and water are essential in its growth, being N the second most absorbed and identified nutrient in the arugula leaf tissue. Water is essential for horticultural crops, so its use must be rational in order to achieve high yield. The objective of this study was to evaluate the effect of nitrogen levels and irrigation depths on the productive characteristics, the total leaf chlorophyll index (ICF) and nitrogen contents in the arugula culture. The experiment was arranged in a randomized block design subdivided in plots, with two factors: A) nitrogen levels applied in coverage (25, 50, 100, 125 and 150 mg dm-3) and B) irrigation depths [(50 and 100% of the available water capacity (AWC)]. At harvest, 37 days after transplantation (DAT), we observed a significant effect of the treatments when individually analyzed, and also a significant interaction between factors of the analyzed variables. The nitrogen content in the plant showed no effect for irrigation depths. However, the highest content was found in the level of 129 mg dm-3 (27.8 g kg-1), corresponding to an increase of 26% in relation to the lowest level (25 mg dm-3; 22.07 g kg-1). In conclusion, the supply of 150 mg dm-3 nitrogen and full irrigation management (100% of AWC) provided substantial increase in height, leaf area and fresh mass of aerial part of the plant.

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Assessment of Severity of Powdery Mildew Infection of Sweet Cherry Leaves by Digital Image Analysis

HortScience ◽

10.21273/hortsci.36.1.107 ◽

2001 ◽

Vol 36 (1) ◽

pp. 107-111 ◽

Cited By ~ 22

Author(s):

James W. Olmstead ◽

Gregory A. Lang ◽

Gary G. Grove

Keyword(s):

Image Analysis ◽

Powdery Mildew ◽

Digital Image ◽

Digital Image Analysis ◽

Sweet Cherry ◽

Prunus Avium ◽

Leaf Tissue ◽

Visual Assessment ◽

Accurate Method ◽

Leaf Disk

A personal computer-based method was compared with standard visual assessment for quantifying colonization of sweet cherry (Prunus avium L.) leaves by powdery mildew (PM) caused by Podosphaera clandestina (Wallr.:Fr.) Lev. Leaf disks from 14 cultivars were rated for PM severity (percentage of leaf area colonized) by three methods: 1) visual assessment; 2) digital image analysis; and 3) digital image analysis after painting PM colonies on the leaf disk. The third technique, in which PM colonies on each leaf disk were observed using a dissecting microscope and subsequently covered with white enamel paint, provided a standard for comparison of the first two methods. A digital image file for each leaf disk was created using a digital flatbed scanner. Image analysis was performed with a commercially available software package, which did not adequately detect slight differences in color between PM and sweet cherry leaf tissue. Consequently, two replicated experiments revealed a low correlation between PM image analysis and painted PM image analysis (r2 = 0.66 and 0.46, P ≤ 0.0001), whereas visual assessment was highly correlated with painted PM image analysis (r2 = 0.88 and 0.95, P ≤ 0.0001). Rank orders of the 14 cultivars differed significantly (P ≤ 0.05) when PM image analysis and painted PM image analysis were compared; however, rankings by visual assessment were not significantly different (P > 0.05) from those by painted PM image analysis. Thus, standard visual assessment is an accurate method for estimating disease severity in a leaf disk resistance assay for sweet cherry PM.

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