Effects of leaf age and psyllid damage on the spectral reflectance properties of Eucalyptus saligna foliage

Stone, Christine; Chisholm, Laurie; McDonald, Simon

doi:10.1071/bt04062

Cited by 47 publications

(8 citation statements)

References 52 publications

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“…Reflectance spectra of Eucalyptus spp. leaves for a wide range of species have been found to be the least sensitive to differences in pigment content around 672 nm (Datt, ), and without much difference between old and young leaves at this wavelength (Stone, Chisholm, & McDonald, ).…”

Section: Resultsmentioning

confidence: 99%

Plumage coloration follows Gloger's rule in a ring species

Ribot

Berg

Schubert

et al. 2019

Journal of Biogeography

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Aim: Animal coloration is expected to differ between populations in different habitats according to Gloger's rule, with darker animals found in more humid, vegetated or warmer environments. Yet despite considerable support across the globe, the mechanisms behind this biogeographical rule are currently still unclear. Exploiting a ring species with plumage coloration from crimson to pale yellow, we test Gloger's rule and the mechanisms behind phenotypic divergence.Location: South-eastern Australia.Major taxa studied: Crimson rosellas (Platycercus elegans). Methods:We combined three modelling approaches (spatial regression; random decision forest species distribution and conditional inference tree) to test the association between 10 environmental variables (based on long-term climate data and remotely sensed reflectance of the land) and plumage coloration across the distribution of P. elegans. We also took in-situ measurements of background coloration of dominant vegetation to examine the relationship between (a) background coloration measured locally and remotely, (b) P. elegans coloration and (c) known differences in visual sensitivity of the subspecies using species-specific visual models.Results: On both a continental and a local scale, the distribution of yellow-red plumage coloration was strongly predicted by average rainfall, summer temperature and the Earth's reflectance between 620-670 nm. Remotely sensed radiance measures correlated strongly and positively with reflectance of the leaves of the dominant tree species at sites across the P. elegans distribution. Visual modelling indicated that differences in background colour could affect signalling efficacy in dim-light conditions.Main conclusions: Our study shows that the highly variable plumage coloration conforms to Gloger's rule, and indicates that background coloration of the vegetation and thermoregulation are likely to be important mechanisms. Our results also show that Gloger's rule can explain variation in pigmentary systems other than melanin, and highlight that selection from environmental variation could be an important force behind the geographic diversity found in ring species.

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Section: Resultsmentioning

confidence: 99%

Plumage coloration follows Gloger's rule in a ring species

Ribot

Berg

Schubert

et al. 2019

Journal of Biogeography

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“…We also observed leaf discolouration in the plants damaged by the carrot psyllids. Discolouration is a common symptom of plants damaged by homopterans: leafhoppers (Backus et al., 2005), aphids (Miller & Porter, 1997; Gonzáles et al., 2002), whiteflies (Costa et al., 1993), and psyllids (Cranshaw, 1993; Crawford & Wilkens, 1996; Stone et al., 2005; Liu et al., 2006). However, the mechanism is not known; there is a current debate over whether it is caused by a phytoplasma or a toxin excreted in the saliva of the psyllids, for example, B. cockerelli (Liu et al., 2006).…”

Section: Discussionmentioning

confidence: 99%

Short feeding period of carrot psyllid (Trioza apicalis) females at early growth stages of carrot reduces yield and causes leaf discolouration

Nissinen¹,

Vanhala²,

Holopainen³

et al. 2007

Entomologia Exp Applicata

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Overwintered adult carrot psyllids [Trioza apicalis Förster (Homoptera: Psylloidea: Triozidae)] damage carrot [(Daucus carota ssp. sativum L.) (Apiaceae)] seedlings by phloem feeding on the leaves. The aim of this study was to investigate the carrot root and shoot growth in relation to carrot psyllid density during early growth stages. One, two, or three carrot psyllids were allowed to feed on carrot seedlings for 3 days. Leaf damage was measured at the 8‐leaf stage, and root, leaf fresh weight, and number of true leaves were measured at harvest. Both the age of the carrot seedling at infestation and the psyllid density had a significant effect on leaf damage at the 8‐leaf stage: seedlings damaged at the cotyledon stage exhibited more leaf damage than seedlings damaged at the 1‐leaf stage. A higher psyllid density significantly reduced the carrot root weight at harvest. The significant interaction of psyllid density with seedling age indicates that differently aged carrot seedlings responded differently to feeding: one psyllid feeding for 3 days at the cotyledon stage caused a significant yield loss, whereas three psyllids were needed to cause the same impact at the 1‐leaf stage. Carrot leaf weight at harvest was not reduced by carrot psyllid feeding: leaves recovered from the damage but roots did not. Our results confirm the farmers’ observations that a trap replacement period of 1 week for carrot psyllid monitoring is too long, especially at the cotyledon stage. Severe leaf discolouration on damaged carrots was observed at harvest. The possible reasons for this discolouration, such as toxin excreted in psyllid saliva or plant pathogenic mycoplasma infection, are discussed.

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“…These technological advantages can provide a great assistance to farmers, provided that the variability within a plant's canopy – originating from spatial and phenological differences [5] – is understood. Physiologically, leaves of various ages and positions in a single plant were previously documented to have distinct levels of water content [6] – [8] , water use efficiency [9] , [10] , stomatal conductance [11] , [12] , nitrogen content and allocation [13] – [15] , photosynthesis [16] – [19] , chlorophyll content [19] – [21] , assimilation rates [12] , [22] , [23] , and cellular structures and processes [24] . These within-canopy variations highlight the difficulty of representing an entire plant and, more so, comparing between different plants using a single leaf – normally chosen on the basis of the ‘age’ and ‘position’ concepts, which many studies refer to as equals (e.g., [25] – [28] ).…”

Section: Introductionmentioning

confidence: 99%

The Effect of Differential Growth Rates across Plants on Spectral Predictions of Physiological Parameters

et al. 2014

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Leaves of various ages and positions in a plant's canopy can present distinct physiological, morphological and anatomical characteristics, leading to complexities in selecting a single leaf for spectral representation of an entire plant. A fortiori, as growth rates between canopies differ, spectral-based comparisons across multiple plants – often based on leaves' position but not age – becomes an even more challenging mission. This study explores the effect of differential growth rates on the reflectance variability between leaves of different canopies, and its implication on physiological predictions made by widely-used spectral indices. Two distinct irrigation treatments were applied for one month, in order to trigger the formation of different growth rates between two groups of grapevines. Throughout the experiment, the plants were physiologically and morphologically monitored, while leaves from every part of their canopies were spectrally and histologically sampled. As the control vines were constantly developing new leaves, the water deficit plants were experiencing growth inhibition, resulting in leaves of different age at similar nodal position across the treatments. This modification of the age-position correlation was characterized by a near infrared reflectance difference between younger and older leaves, which was found to be exponentially correlated (R2 = 0.98) to the age-dependent area of intercellular air spaces within the spongy parenchyma. Overall, the foliage of the control plant became more spectrally variable, creating complications for intra- and inter-treatment leaf-based comparisons. Of the derived indices, the Structure-Insensitive Pigment Index (SIPI) was found indifferent to the age-position effect, allowing the treatments to be compared at any nodal position, while a Normalized Difference Vegetation Index (NDVI)-based stomatal conductance prediction was substantially affected by differential growth rates. As various biotic and abiotic factors may form distinctions in growth, future precision agriculture studies should consider its spectral effect on physiological predictions.

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Effects of leaf age and psyllid damage on the spectral reflectance properties of Eucalyptus saligna foliage

Cited by 47 publications

References 52 publications

Plumage coloration follows Gloger's rule in a ring species

Plumage coloration follows Gloger's rule in a ring species

Short feeding period of carrot psyllid (Trioza apicalis) females at early growth stages of carrot reduces yield and causes leaf discolouration

The Effect of Differential Growth Rates across Plants on Spectral Predictions of Physiological Parameters

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