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The effect of differential growth rates across plants on spectral predictions of physiological parameters.

Rapaport T, Hochberg U, Rachmilevitch S, Karnieli A - PLoS ONE (2014)

Bottom Line: 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 (R(2) = 0.98) to the age-dependent area of intercellular air spaces within the spongy parenchyma.As various biotic and abiotic factors may form distinctions in growth, future precision agriculture studies should consider its spectral effect on physiological predictions.

View Article: PubMed Central - PubMed

Affiliation: The Remote Sensing Laboratory, The Jacob Blaustein Institutes for Desert Research, Ben Gurion University of the Negev, Beer-Sheva, Israel.

ABSTRACT
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 (R(2) = 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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Volumetric water content (A; VWC), stomatal conductance (B; gs) and net assimilation rate (C; AN) throughout the experiment.Excluding day 1, values of the two groups were significantly different for every measuring date. Vertical bars represent means ± standard deviations (n = 10).
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pone-0088930-g001: Volumetric water content (A; VWC), stomatal conductance (B; gs) and net assimilation rate (C; AN) throughout the experiment.Excluding day 1, values of the two groups were significantly different for every measuring date. Vertical bars represent means ± standard deviations (n = 10).

Mentions: The water range for the WD pots was achieved between the 5th and 6th DOE, and was maintained at an average of 8% until the end of the experiment (Figure 1A). This water level was significantly different from that of the control pots, which were continuously refilled to a VWC of 33% by day 30. Significant physiological distinctions between the irrigation groups were noticed on the 7th DOE, as the stomatal conductance (Figure 1B) and net assimilation rates (Figure 1C) of the WD vines were lower than those of the control vines by 0.23 mol H2O m−2 s−1 (a 75% reduction) and 5.35 µmol CO2 m−2 s−1 (a 37% reduction), respectively. Those gas exchange differences remained similar until the end of the experiment.


The effect of differential growth rates across plants on spectral predictions of physiological parameters.

Rapaport T, Hochberg U, Rachmilevitch S, Karnieli A - PLoS ONE (2014)

Volumetric water content (A; VWC), stomatal conductance (B; gs) and net assimilation rate (C; AN) throughout the experiment.Excluding day 1, values of the two groups were significantly different for every measuring date. Vertical bars represent means ± standard deviations (n = 10).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3921250&req=5

pone-0088930-g001: Volumetric water content (A; VWC), stomatal conductance (B; gs) and net assimilation rate (C; AN) throughout the experiment.Excluding day 1, values of the two groups were significantly different for every measuring date. Vertical bars represent means ± standard deviations (n = 10).
Mentions: The water range for the WD pots was achieved between the 5th and 6th DOE, and was maintained at an average of 8% until the end of the experiment (Figure 1A). This water level was significantly different from that of the control pots, which were continuously refilled to a VWC of 33% by day 30. Significant physiological distinctions between the irrigation groups were noticed on the 7th DOE, as the stomatal conductance (Figure 1B) and net assimilation rates (Figure 1C) of the WD vines were lower than those of the control vines by 0.23 mol H2O m−2 s−1 (a 75% reduction) and 5.35 µmol CO2 m−2 s−1 (a 37% reduction), respectively. Those gas exchange differences remained similar until the end of the experiment.

Bottom Line: 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 (R(2) = 0.98) to the age-dependent area of intercellular air spaces within the spongy parenchyma.As various biotic and abiotic factors may form distinctions in growth, future precision agriculture studies should consider its spectral effect on physiological predictions.

View Article: PubMed Central - PubMed

Affiliation: The Remote Sensing Laboratory, The Jacob Blaustein Institutes for Desert Research, Ben Gurion University of the Negev, Beer-Sheva, Israel.

ABSTRACT
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 (R(2) = 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.

Show MeSH
Related in: MedlinePlus