Leaf nitrogen assimilation and partitioning differ among subtropical forest plants in response to canopy addition of nitrogen treatments

Abstract Aims The functions of global forests are threatened by the increasing frequency of severe drought. Due to drought inducing reductions in soil nutrient availability, efficiencies of nutrient use and resorption of trees become crucial for forest functions and biogeochemical cycles. However, understanding the dynamics of responses of foliar nutrient use and resorption efficiencies to drought, especially in tropical or subtropical forests, is still limited. Our goal was to detect whether and how the importance of leaf nutrient use and resorption changes across different species in the hot and wet forests when suffering drought stress in different months. Methods Based on a 70% throughfall exclusion experiment in a subtropical forest, we collected green and senesced leaves of Schima superba and Lithocarpus glaber in different months from October 2016 to May 2019, to estimate the effects of drought on leaf nitrogen (N) and phosphorus (P) use and resorption efficiencies (i.e. NUE and PUE, NRE and PRE). Important Findings The effects of drought on nutrient use and resorption efficiencies varied between species and months. Based on a 2-year observation, drought had no effect on S. superba, but significantly decreased NUE, NRE and PRE of L. glaber by 3.4%, 20.2% and 7.1%, respectively. Furthermore, the negative drought effects were aggravated by the natural summer drying in 2017. As a result, NUE and PUE of L. glaber were significantly depressed by 17.2% and 58.1%, while NRE and PRE were significantly reduced by 56.5% and 53.8% in August 2017. Moreover, the responses of NRE, PRE and NUE to drought were related with soil moisture (SM) for L. glaber, and when SM decreased to a threshold near 9 v/v%, drought effects were shifted from unresponsive to negative. Our results highlight a species-specific threshold response of nutrient use under drought in a subtropical forest.

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Alterations in leaf nitrogen metabolism indicated the structural changes of subtropical forest by canopy addition of nitrogen

Ecotoxicology and Environmental Safety ◽

10.1016/j.ecoenv.2018.05.037 ◽

2018 ◽

Vol 160 ◽

pp. 134-143 ◽

Cited By ~ 4

Author(s):

Nan Liu ◽

Jiaxin Wang ◽

Qinfeng Guo ◽

Shuhua Wu ◽

Xingquan Rao ◽

...

Keyword(s):

Nitrogen Metabolism ◽

Structural Changes ◽

Leaf Nitrogen ◽

Subtropical Forest

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Influence of Light Regime and Leaf Nitrogen Concentration on 77k Fluorescence in Leaves of Four Tropical Grasses: No Evidence for Photoinhibition

Functional Plant Biology ◽

10.1071/pp9880669 ◽

1988 ◽

Vol 15 (5) ◽

pp. 669 ◽

Cited By ~ 8

Author(s):

MM Ludlow ◽

SP Samarakoon ◽

JR Wilson

Keyword(s):

Nitrogen Content ◽

Nitrogen Availability ◽

Nitrogen Concentration ◽

Chlorophyll Concentration ◽

Leaf Nitrogen ◽

Nitrogen Supply ◽

Poor Growth ◽

Full Sunlight ◽

Nitrogen Treatments ◽

Low Nitrogen

This work was undertaken to determine if the stimulation of growth associated with shading of some tropical C4 grasses growing on soils with low to moderate nitrogen availability is partly due to overcoming photoinhibition (i. e. damage caused by excessive light). Four grasses (green panic, carpet grass, buffalo grass and kikuyu) were grown in full sunlight and at 37% of full sunlight, and given a low or high nitrogen supply. Despite differences of up to twofold in leaf nitrogen and chlorophyll concentration between high and low nitrogen treatments in all four grasses, photoinhibition measured by reduction in chlorophyll fluorescence was less than 3% in leaves of low nitrogen content that developed in full sunlight. Therefore, photoinhibition is not a contributor to the poor growth of nitrogen-limited grasses in full sunlight. A second objective was to determine if low nitrogen content predisposed shade-grown leaves to photoinhibition when they were subsequently exposed to full sunlight. Green panic plants that had been given either high or low nitrogen supply and grown in 37% of full sunlight were transferred to full sunlight and the extent of photoinhibition was followed over 8 days. The amount of photoinhibition that occurred was small (<6%) compared with plants grown at either nitrogen level in full sunlight. Therefore, shade and low nitrogen content separately or in combination did not cause any appreciable photoinhibition in green panic.

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Effects of Ethylene-Chlormequat-Potassium on Leaf Nitrogen Assimilation after Anthesis and Early Senescence under Dif-ferent Planting Densities

ACTA AGRONOMICA SINICA ◽

10.3724/sp.j.1006.2015.01870 ◽

2015 ◽

Vol 41 (12) ◽

pp. 1870

Author(s):

Lin LU ◽

Zhi-Qiang DONG ◽

Xue-Rui DONG ◽

Liu JIAO ◽

Guang-Yan LI ◽

...

Keyword(s):

Nitrogen Assimilation ◽

Leaf Nitrogen

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Functional Traits Are Good Predictors of Tree Species Abundance Across 101 Subtropical Forest Species in China

Frontiers in Plant Science ◽

10.3389/fpls.2021.541577 ◽

2021 ◽

Vol 12 ◽

Author(s):

Ronghua Li ◽

Shidan Zhu ◽

Juyu Lian ◽

Hui Zhang ◽

Hui Liu ◽

...

Keyword(s):

Nitrogen Content ◽

Functional Traits ◽

Phosphorus Content ◽

Species Abundance ◽

Leaf Nitrogen ◽

Subtropical Forest ◽

Evergreen Forest ◽

Forest Plot ◽

Stem Density ◽

Leaf Nitrogen Content

What causes variation in species abundance for a given site remains a central question in community ecology. Foundational to trait-based ecology is the expectation that functional traits determine species abundance. However, the relative success of using functional traits to predict relative abundance is questionable. One reason is that the diversity in plant function is greater than that characterized by the few most commonly and easily measurable traits. Here, we measured 10 functional traits and the stem density of 101 woody plant species in a 200,000 m2 permanent, mature, subtropical forest plot (high precipitation and high nitrogen, but generally light- and phosphorus-limited) in southern China to determine how well relative species abundance could be predicted by functional traits. We found that: (1) leaf phosphorus content, specific leaf area, maximum CO2 assimilation rate, maximum stomata conductance, and stem hydraulic conductivity were significantly and negatively associated with species abundance, (2) the ratio of leaf nitrogen content to leaf phosphorus content (N:P) and wood density were significantly positively correlated with species abundance; (3) neither leaf nitrogen content nor leaf turgor loss point were related to species abundance; (4) a combination of N:P and maximum stomata conductance accounted for 44% of the variation in species’ abundances. Taken together, our findings suggested that the combination of these functional traits are powerful predictors of species abundance. Species with a resource-conservative strategy that invest more in their tissues are dominant in the mature, subtropical, evergreen forest.

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Shade Avoidance 3 Mediates Crosstalk Between Shade and Nitrogen in Arabidopsis Leaf Development

Frontiers in Plant Science ◽

10.3389/fpls.2021.800913 ◽

2022 ◽

Vol 12 ◽

Author(s):

Xin-Yue Yang ◽

Zhong-Wei Zhang ◽

Yu-Fan Fu ◽

Ling-Yang Feng ◽

Meng-Xia Li ◽

...

Keyword(s):

Leaf Development ◽

Nitrogen Assimilation ◽

Molecular Mechanisms ◽

Shade Avoidance ◽

Plant Leaves ◽

Shade Treatment ◽

Chlorophyll Accumulation ◽

N Treatment ◽

Nitrogen Treatments ◽

Auxin Accumulation

After nitrogen treatments, plant leaves become narrower and thicker, and the chlorophyll content increases. However, the molecular mechanisms behind these regulations remain unknown. Here, we found that the changes in leaf width and thickness were largely compromised in the shade avoidance 3 (sav3) mutant. The SAV3 gene encodes an amino-transferase in the auxin biosynthesis pathway. Thus, the crosstalk between shade and nitrogen in Arabidopsis leaf development was investigated. Both hypocotyl elongation and leaf expansion promoted by the shade treatment were reduced by the high-N treatment; high-N-induced leaf narrowing and thickening were reduced by the shade treatment; and all of these developmental changes were largely compromised in the sav3 mutant. Shade treatment promoted SAV3 expression, while high-N treatment repressed SAV3 expression, which then increased or decreased auxin accumulation in cotyledons/leaves, respectively. SAV3 also regulates chlorophyll accumulation and nitrogen assimilation and thus may function as a master switch responsive to multiple environmental stimuli.

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The effect of application of genistein to Bradyrhizobium japonicum culture and its rooting medium on soyabean growth nodulation and nitrogen assimilation in the presence of nitrate

The Journal of Agricultural Science ◽

10.1017/s0021859699007959 ◽

2000 ◽

Vol 135 (1) ◽

pp. 19-25

Author(s):

B. PAN ◽

D. L. SMITH

Keyword(s):

Nitrogen Assimilation ◽

Nitrogen Concentration ◽

Dry Weight ◽

Leaf Nitrogen ◽

Root Extracts ◽

Randomized Design ◽

Rooting Medium ◽

Nitrogen Concentrations ◽

Completely Randomized Design ◽

Nitrogen Contents

In the soyabean [Glycine max (L.) Merr.]–B. japonicum symbiosis, genistein has been identified as one of the major compounds in soyabean seed and root extracts responsible for inducing the expression of the B. japonicum nod genes. High combined nitrogen in the growth medium inhibits nodulation and nitrogen assimilation. Two experiments were conducted to test the possibility of overcoming this inhibition by adding genistein to the rooting medium and by incubation of B. japonicum cells with genistein. One soyabean cultivar was used in the first experiment, and two in the second experiment. The experiments were conducted in a glasshouse using a completely randomized design with three rooting medium nitrate concentrations (0, 5 and 10 mM) and four genistein treatments. The genistein treatments were 0 (control), incubation of B. japonicum cells with 5 μM genistein, and regular watering with 5 μM or 20 μM genistein. A two way interaction existed in the first experiment, and two and three way interactions existed in the second experiment. Root growth was inhibited by repeated watering with 20 μM genistein. Weight per nodule was greater at 5 mM than at 0 mM nitrate. At 10 mM nitrate watering with genistein resulted in significant increases in nodule dry weight per plant. Shoot nitrogen contents were significantly increased at 5 mM nitrate by genistein incubation and watering with 20 μM genistein. Watering with 5 μM genistein significantly increased nodule nitrogen concentrations at both 5 and 10 mM nitrate. The two soyabean cultivars responded differently to the genistein and nitrate treatments in terms of nodule number, nodule weight, leaf nitrogen concentration and nodule nitrogen content. Genistein could, at least partially, overcome the inhibition of soyabean nodulation and nitrogen assimilation by nitrate.

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