Dissecting how fine roots function

Improved cultural practices in grape require a better understanding of root growth and physiology. Seasonal root dynamics were examined in mature `Concord' vines with balanced or minimal-pruning, and with or without supplemental irrigation in Fredonia, N.Y. Fine roots were continuously produced during the growing season starting in mid-June around time of bloom. Roots began to die in September at verasion. Minimal-pruned vines produced more roots than balanced-pruned vines, with the minimal-pruned/unirrigated vines producing the most roots. Irrigation and pruning delayed fine root production at the beginning of the growing season. Peak fine root flush was 16 June to 21 July 1997 for the minimal-pruned/unirrigated treatment, while peak flush was 7 July to 2 Sept. 1997 for balanced-pruned/irrigated treatment. In minimal-pruned vines, many roots were observed down to depths of 120 cm. In contrast, balanced-pruned vines had very few fine roots deeper than 40 cm. From initial observations, median lifespan of fine roots was 5 to 9.5 weeks, depending on treatment and depth in soil. Fine roots lived longer in the top 15-cm than in the 16- to 30-cm layer of soil in all treatments. Both minimal pruning and irrigation increased root lifespan. Fine roots had the shortest lifespan in the balanced-pruned/unirrigated treatment and the longest lifespan in the minimal-pruned/irrigated treatment.

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Organic mulching promotes soil organic carbon accumulation to deep soil layer in an urban plantation forest

Forest Ecosystems ◽

10.1186/s40663-020-00278-5 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Xiaodan Sun ◽

Gang Wang ◽

Qingxu Ma ◽

Jiahui Liao ◽

Dong Wang ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Carbon Content ◽

Fine Roots ◽

Soil Layer ◽

Carbon Accumulation ◽

Bulk Soil ◽

Organic Mulch ◽

The Impact ◽

Soc Fractions

Abstract Background Soil organic carbon (SOC) is important for soil quality and fertility in forest ecosystems. Labile SOC fractions are sensitive to environmental changes, which reflect the impact of short-term internal and external management measures on the soil carbon pool. Organic mulching (OM) alters the soil environment and promotes plant growth. However, little is known about the responses of SOC fractions in rhizosphere or bulk soil to OM in urban forests and its correlation with carbon composition in plants. Methods A one-year field experiment with four treatments (OM at 0, 5, 10, and 20 cm thicknesses) was conducted in a 15-year-old Ligustrum lucidum plantation. Changes in the SOC fractions in the rhizosphere and bulk soil; the carbon content in the plant fine roots, leaves, and organic mulch; and several soil physicochemical properties were measured. The relationships between SOC fractions and the measured variables were analysed. Results The OM treatments had no significant effect on the SOC fractions, except for the dissolved organic carbon (DOC). OM promoted the movement of SOC to deeper soil because of the increased carbon content in fine roots of subsoil. There were significant correlations between DOC and microbial biomass carbon and SOC and easily oxidised organic carbon. The OM had a greater effect on organic carbon fractions in the bulk soil than in the rhizosphere. The thinnest (5 cm) mulching layers showed the most rapid carbon decomposition over time. The time after OM had the greatest effect on the SOC fractions, followed by soil layer. Conclusions The frequent addition of small amounts of organic mulch increased SOC accumulation in the present study. OM is a potential management model to enhance soil organic matter storage for maintaining urban forest productivity.

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Observations on early fungal infections with relevance for replant disease in fine roots of the rose rootstock Rosa corymbifera 'Laxa'

Scientific Reports ◽

10.1038/s41598-020-79878-8 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

G. Grunewaldt-Stöcker ◽

C. Popp ◽

A. Baumann ◽

S. Fricke ◽

M. Menssen ◽

...

Keyword(s):

Fine Roots ◽

Woody Plant ◽

Fine Root ◽

Fungal Infections ◽

Thin Sections ◽

Replant Disease ◽

Pot Trials ◽

Worldwide Phenomenon ◽

First Time ◽

The Rose

AbstractReplant disease is a worldwide phenomenon affecting various woody plant genera and species, especially within the Rosaceae. Compared to decades of intensive studies regarding replant disease of apple (ARD), the replant disease of roses (RRD) has hardly been investigated. The etiology of RRD is also still unclear and a remedy desperately needed. In greenhouse pot trials with seedlings of the RRD-sensitive rootstock Rosa corymbifera ‘Laxa’ cultured in replant disease affected soils from two different locations, early RRD symptom development was studied in fine roots. In microscopic analyses we found similarities to ARD symptoms with regards to structural damages, impairment in the root hair status, and necroses and blackening in the cortex tissue. Examinations of both whole mounts and thin sections of fine root segments revealed frequent conspicuous fungal infections in association with the cellular disorders. Particularly striking were fungal intracellular structures with pathogenic characteristics that are described for the first time. Isolated fungi from these tissue areas were identified by means of ITS primers, and many of them were members of the Nectriaceae. In a next step, 35 of these isolates were subjected to a multi-locus sequence analysis and the results revealed that several genera and species were involved in the development of RRD within a single rose plant. Inoculations with selected single isolates (Rugonectria rugulosa and Ilyonectria robusta) in a Perlite assay confirmed their pathogenic relationship to early necrotic host plant reactions, and symptoms were similar to those exhibited in ARD.

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Fruit yield and properties of Camellia oleifera Abel can be enhanced via fine roots promotion under mulch

Archives of Agronomy and Soil Science ◽

10.1080/03650340.2021.1872783 ◽

2021 ◽

Author(s):

Junping Liu ◽

Juan Liu ◽

Jiawei Wang ◽

Hankun Wang ◽

Jilin Zuo ◽

...

Keyword(s):

Fine Roots ◽

Fruit Yield ◽

Camellia Oleifera

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Nutrient supply modulates species interactions belowground: dynamics and traits of fine roots in mixed plantations of Eucalyptus and Acacia mangium

Plant and Soil ◽

10.1007/s11104-020-04755-2 ◽

2021 ◽

Author(s):

B. Bordron ◽

A. Germon ◽

J.-P. Laclau ◽

I. R. Oliveira ◽

A. Robin ◽

...

Keyword(s):

Species Interactions ◽

Fine Roots ◽

Acacia Mangium ◽

Nutrient Supply ◽

Mixed Plantations

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Carbon and nutrient physiology in shrubs at the upper limits: a multi-species study

Journal of Plant Ecology ◽

10.1093/jpe/rtaa097 ◽

2020 ◽

Author(s):

Xue Wang ◽

Fei-Hai Yu ◽

Yong Jiang ◽

Mai-He Li

Keyword(s):

Fine Roots ◽

Soluble Sugar ◽

Soluble Sugars ◽

Growing Season ◽

Interactive Effects ◽

Tree Line ◽

Shrub Species ◽

Nutrient Physiology ◽

Upper Limits ◽

Species Study

Abstract Aims Carbon and nutrient physiology of trees at their upper limits have been extensively studied, but those of shrubs at their upper limits have received much less attention. The aim of this study is to examine the general patterns of non-structural carbohydrates (NSCs), nitrogen (N) and phosphorous (P) in shrubs at the upper limits, and to assess whether such patterns are similar to those in trees at the upper limits. Methods Across Eurasia, we measured the concentrations of soluble sugars, starch, total NSCs, N and P in leaves, branches and fine roots (< 0.5 cm in diameter) of five shrub species growing at both the upper limits and lower elevations in both summer (peak growing season) and winter (dormancy season). Important Findings Neither elevation nor season had significant effects on tissue N and P concentrations, except for lower P concentrations in fine roots in winter than in summer. Total NSCs and soluble sugars in branches were significantly higher in winter than in summer. There were significant interactive effects between elevation and season for total NSCs, starch, soluble sugars and the ratio of soluble sugar to starch in fine roots, showing lower soluble sugars and starch in fine roots at the upper limits than at the lower elevations in winter but not in summer. These results suggest that the carbon physiology of roots in winter may play an important role in determining the upward distribution of shrubs, like that in the alpine tree-line trees.

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In-situ measurement of the effect of canopy tree fine roots on nitrogen availability in forest soil

Rhizosphere ◽

10.1016/j.rhisph.2021.100324 ◽

2021 ◽

Vol 18 ◽

pp. 100324

Author(s):

Masataka Nakayama ◽

Ryunosuke Tateno

Keyword(s):

Forest Soil ◽

Fine Roots ◽

Nitrogen Availability ◽

In Situ Measurement ◽

Canopy Tree

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Biochar induced improvement in root system architecture enhances nutrient assimilation by cotton plant seedlings

BMC Plant Biology ◽

10.1186/s12870-021-03026-1 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Lei Feng ◽

Wanli Xu ◽

Guangmu Tang ◽

Meiying Gu ◽

Zengchao Geng

Keyword(s):

Root System ◽

System Architecture ◽

Fine Roots ◽

Nitrogen Assimilation ◽

Surface Soil ◽

Soil Layer ◽

Root System Architecture ◽

Seedling Stage ◽

Agronomic Efficiency ◽

Surface Soil Layer

Abstract Background Raising nitrogen use efficiency of crops by improving root system architecture is highly essential not only to reduce costs of agricultural production but also to mitigate climate change. The physiological mechanisms of how biochar affects nitrogen assimilation by crop seedlings have not been well elucidated. Results Here, we report changes in root system architecture, activities of the key enzymes involved in nitrogen assimilation, and cytokinin (CTK) at the seedling stage of cotton with reduced urea usage and biochar application at different soil layers (0–10 cm and 10–20 cm). Active root absorption area, fresh weight, and nitrogen agronomic efficiency increased significantly when urea usage was reduced by 25% and biochar was applied in the surface soil layer. Glutamine oxoglutarate amino transferase (GOGAT) activity was closely related to the application depth of urea/biochar, and it increased when urea/biochar was applied in the 0–10 cm layer. Glutamic-pyruvic transaminase activity (GPT) increased significantly as well. Nitrate reductase (NR) activity was stimulated by CTK in the very fine roots but inhibited in the fine roots. In addition, AMT1;1, gdh3, and gdh2 were significantly up-regulated in the very fine roots when urea usage was reduced by 25% and biochar was applied. Conclusion Nitrogen assimilation efficiency was significantly affected when urea usage was reduced by 25% and biochar was applied in the surface soil layer at the seedling stage of cotton. The co-expression of gdh3 and gdh2 in the fine roots increased nitrogen agronomic efficiency. The synergistic expression of the ammonium transporter gene and gdh3 suggests that biochar may be beneficial to amino acid metabolism.

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