Développement et polymorphisme racinaires chez de jeunes semis d'hévéa (Hevea brasiliensis)

1994 ◽  
Vol 72 (7) ◽  
pp. 924-932 ◽  
Author(s):  
Yannick Le Roux ◽  
Loïc Pagès
Keyword(s):  
Root System ◽  
Hevea Brasiliensis ◽  
System Development ◽  
Lateral Roots ◽  
Rubber Tree ◽  
Morphological Plasticity ◽  
Daily Basis ◽  
External Diameter ◽  
First Order ◽  
Root Observation

The major problems (bad anchorage, water stress, and root disease) with the cropping of the rubber tree (Hevea brasiliensis) are related to the architecture of its root system. So, the morphogenetic properties of the various roots that emerge during the development of the young seedlings are described to improve our understanding of the dynamics of root system architecture. In this study, the development of the root system of 12 seedlings grown for 40 days in root observation boxes has been recorded on a daily basis and analysed. Additional observations were also made on plants grown in pots or in the field for a 60-day period. This analysis of the sequential differentiation of the root system allowed us to distinguish five different root types according to their spatial and temporal location at emergence: (i) taproot, (ii) early first-order lateral roots, (iii) acropetal first-order lateral roots, (iv) late first-order lateral roots, (v) second-order lateral roots. Large variations and close relationship were found within the growth and branching characteristics on one hand, and within anatomical characteristics on the other (number of xylem poles, external diameter, and stele diameter). These between-type variations were also observed, to a lesser extent, among roots from the same type. The continuity of these development characteristics, which were shown to be acquired early, led us to characterize a morphogenetic gradient. This gradient is a reference scale to understand the morphological plasticity of the root system growing in other mediums. Key words: root system, development, morphogenesis, anatomy, root observation box, Hevea brasiliensis.

scholarly journals Longleaf Pine Root System Development and Seedling Quality in Response to Copper Root Pruning and Cavity Size

2011 ◽  
Vol 35 (1) ◽  
pp. 5-11 ◽  
Author(s):  
Mary Anne Sword Sayer ◽  
Shi-Jean Susana Sung ◽  
James D. Haywood
Keyword(s):  
Root Growth ◽  
Root System ◽  
System Development ◽  
Longleaf Pine ◽  
Lateral Roots ◽  
Dry Weight ◽  
Root Pruning ◽  
Cavity Size ◽  
Root System Development ◽  
Primary Lateral

Abstract Cultural practices that modify root system structure in the plug of container-grown seedlings have the potential to improve root system function after planting. Our objective was to assess how copper root pruning affects the quality and root system development of longleaf pine seedlings grown in three cavity sizes in a greenhouse. Copper root pruning increased seedling size, the allocation of root system dry weight to the taproot, and the fraction of fibrous root mass allocated to secondary lateral roots compared with primary lateral roots. It decreased the allocation of root system dry weight to primary lateral roots and led to a distribution of root growth potential that more closely resembled the root growth of naturally sown seedlings. These effects of copper root pruning may benefit longleaf pine establishment. However, because copper root pruning increased competition for cavity growing space among the taproot and fibrous roots, we suggest that recommendations regarding cavity size and seedling quality parameters be tailored for copper-coated cavities.

Réaction géotropique des différents types de racines chez l'hévéa (Hevea brasiliensis)

1996 ◽  
Vol 74 (12) ◽  
pp. 1910-1918 ◽  
Author(s):  
Yannick Le Roux ◽  
Loïc Pagès
Keyword(s):  
Root System ◽  
Hevea Brasiliensis ◽  
Vertical Plane ◽  
Growth Direction ◽  
Vertical Position ◽  
Different Types ◽  
Original Direction ◽  
Growth Development ◽  
Secondary Roots ◽  
Root Observation

To describe the different types of geotropic reactions of hevea (Hevea brasiliensis), young seedlings were cultivated in root observation boxes and submitted to a double gravistimulation (90° rotation of the minirhizotrons in the vertical plane). It was demonstrated that the taproot is a strongly orthogeotropie organ since it resumed rapidly its prestimulation vertical position. Morphological and morphogenetic modifications were associated with the geotropic response: reduced speed of growth coupled with a reduction of the apical diameter as well as an alteration of ramification density in the curving zone and the following one. Early secondary roots showed a somewhat reduced orthogeotropism that was weaker as the growth direction before gravistimulation was more distant from the vertical. Secondary roots of the acropetal sequence were semiplagiotropic, that is only those roots oriented upward after the gravistimulation resumed, more or less, the original direction. Tertiary roots didn't respond to the gravistimulation and therefore were ageotropic. Complementary observations conducted in large laboratory rhizotrons showed that late forming secondary roots were plagiotropic in their younger stages, thereafter loosing most of their sensitivity to gravity. Quaternary roots were ageotropic. On the basis of these data, a geotropic gradient was defined within the hevea root system, where the strongly responding taproot and late secondary roots are opposed to the weakly or nonresponding tertiary and quaternary roots. Functional significations of these differential geotropic reactions in different hevea root types are discussed. Keywords: geotropism, gravistimulation, root system, growth, development, morphogenesis, root observation box, Hevea brasiliensis. [Journal translation]

Effects of root severing treatments on loblolly pine

1988 ◽  
Vol 18 (11) ◽  
pp. 1376-1385 ◽  
Author(s):  
William C. Carlson ◽  
Constance A. Harrington ◽  
Peter Farnum ◽  
Stephen W. Hallgren
Keyword(s):  
Soil Moisture ◽  
Water Potential ◽  
Root System ◽  
Loblolly Pine ◽  
Water Status ◽  
Lateral Roots ◽  
Second Order ◽  
Plant Water Status ◽  
Plant Water ◽  
First Order

Six-year-old loblolly pine seedlings were subjected to root severing treatments varying from 0 to 100% of first-order lateral roots. Separate treatments severed surface-oriented or deep-oriented roots. Plant water status was monitored periodically for several months. After all measurements were taken, gross root system structure was determined by excavation. Treatment responses were evident on all dates of measurement. Relationships between percentage of root system cut and leaf conductance or water potential were stronger when surface-oriented roots were cut than when deep-oriented roots were cut. Severing surface-oriented first-order lateral (SOFOL) roots probably resulted in greater impact on plant water status than severing deep-oriented first-order lateral (DOFOL) roots because (i) SOFOL roots had both surface-oriented and deep-oriented second-order lateral roots that could tap both surface and subsurface soil horizons for soil moisture, and (ii) the deep-oriented second-order roots (originating from the SOFOL roots) were spatially distributed over a much larger area than the DOFOL roots and thus would have access to soil water in a larger volume of soil. For SOFOL roots the relationship between percentage cut and leaf conductance or transpiration was strongly negative; for DOFOL roots, no relationship between these variables was observed. Initially water potential decreased with the percentage of roots cut in both groups; in later measurements, water potential was affected more by severing SOFOL than DOFOL roots. Calculation of soil moisture depletion by depth indicated that both surface- and deep-oriented second-order lateral roots were important for water uptake. Severing SOFOL roots significantly decreased nitrogen, phosphorus, and potassium levels in needles of the first growth flush of the year. Levels of these elements in terminal buds were not affected by severing SOFOL roots, but were significantly reduced by severing DOFOL roots. Secondary xylem production was reduced proportionately to the amount of root system cross-sectional area severed.

scholarly journals Co-fertilization of sulfur and struvite-phosphorus in a slow-release fertilizer improves soybean cultivation

2021 ◽  
Author(s):  
Stella F. Valle ◽  
Amanda S. Giroto ◽  
Gelton G. F. Guimarães ◽  
Kerstin A. Nagel ◽  
Anna Galinski ◽  
...  
Keyword(s):  
Controlled Release ◽  
Root System ◽  
System Development ◽  
Lateral Roots ◽  
Crop Productivity ◽  
World Population ◽  
Triple Superphosphate ◽  
Root System Development ◽  
Use Efficiency ◽  
Controlled Release Fertilizers

In face of the alarming world population growth predictions and its threat to food security, the development of sustainable fertilizer alternatives is urgent. Moreover, fertilizer performance should be assessed not only in terms of yield but also root system development, as it impacts soil fertility and crop productivity. Fertilizers containing a polysulfide matrix (PS) with dispersed struvite (St) were studied for S and P nutrition due to their controlled-release behavior. Soybean cultivation with St/PS composites provided superior biomass compared to a reference of triple superphosphate (TSP) with ammonium sulfate (AS), with up to 3 and 10 times higher mass of shoots and roots, respectively. Additionally, St/PS achieved a 22% sulfur use efficiency against only 8% from TSP/AS. Root system architectural changes may explain these results, with higher proliferation of second order lateral roots in response to struvite ongoing P delivery. Overall, the composites showed great potential as efficient controlled-release fertilizers for enhanced soybean productivity.

scholarly journals Disruption of CYCLOPHILIN 38 function reveals a photosynthesis-dependent systemic signal controlling lateral root emergence

2020 ◽  
Author(s):  
Lina Duan ◽  
Juan Manuel Pérez-Ruiz ◽  
Francisco Javier Cejudo ◽  
José R. Dinneny
Keyword(s):  
Root Growth ◽  
Root System ◽  
Lateral Root ◽  
System Development ◽  
Lateral Roots ◽  
Primary Root ◽  
Root System Architecture ◽  
Minor Effect ◽  
Low Light ◽  
Primary Root Growth

AbstractPhotosynthesis in leaves generates the fixed-carbon resources and essential metabolites that support sink tissues, such as roots [1]. One of these products, sucrose, is known to promote primary root growth, but it is not clear what other molecules may be involved and whether other stages of root system development are affected by photosynthate levels [2]. Through a mutant screen to identify pathways regulating root system architecture, we identified a mutation in the CYCLOPHILIN 38 (CYP38) gene, which causes an accumulation of pre-emergent stage lateral roots, with a minor effect on primary root growth. CYP38 was previously reported to maintain the stability of Photosystem II (PSII) in chloroplasts [3]. CYP38 expression is enriched in the shoot and grafting experiments show that the gene acts non-cell autonomously to promote lateral root emergence. Growth of wild-type plants under low light conditions phenocopied the cyp38 lateral root emergence phenotype as did the inhibition of PSII-dependent electron transport or NADPH production. Importantly, the cyp38 root phenotype is not rescued by exogenous sucrose, suggesting the involvement of another metabolite. Auxin (IAA) is an essential hormone promoting root growth and its biosynthesis from tryptophan is dependent on reductant generated during photosynthesis [4,5]. Both WT seedlings grown under low light and cyp38 mutants have highly diminished levels of IAA in root tissues. The cyp38 lateral root defect is rescued by IAA treatment, revealing that photosynthesis promotes lateral root emergence partly through IAA biosynthesis. Metabolomic profiling shows that the accumulation of several defense-related metabolites are also photosynthesis-dependent, suggesting that the regulation of a number of energy-intensive pathways are down-regulated when light becomes limiting.

Modifications expérimentales de la morphogenèse du système racinaire de jeunes semis d'hévéa (Hevea brasiliensis)

2000 ◽  
Vol 78 (11) ◽  
pp. 1460-1468
Author(s):  
Yannick Le Roux ◽  
Loïc Pagès
Keyword(s):  
Root System ◽  
Hevea Brasiliensis ◽  
High Plasticity ◽  
External Diameter ◽  
Active Growth ◽  
Experimental Block ◽  
Tap Root ◽  
Large Growth ◽  
Growth Correlations ◽  
Secondary Roots

Determining factors involved in root polymorphism were studied in young hevea seedlings (Hevea brasiliensis Mull. Arg.) following an experimental block of the tap root in the laboratory, using minirhizotron grown plants. The authors show that this block promotes different morphogenetic modifications in the root system: regrowth of the early secondary roots having the largest external apex, high density of the ramification zone in the taproot apical area, large growth (associated with an important external diameter at the apex), and orthogeotropism of the sequential secondary roots emerging after the treatment in the zone close to the blockage site. The evolution of morphogenetic potentialities of sequential secondary roots following an inhibition of the taproot growth was confirmed using other cultivation set ups, under controlled (aeropinic) or natural (underground observation windows) conditions. Overall results show that the expression of the early morphogenetic potential acquired by the roots can be modulated by the environmental conditions exerting their effect during their development. Notably, the active growth correlations existing between the taproot and the secondary axes confer a high plasticity to the root system which will permit its adaptation to heterogeneous or restricting environments. These correlative influences are discussed in the frame of an hormono-trophic model for the root morphogenetic determinism, essentially based on taproot dominancy.Key words: articial block, growth correlations, root system, morphogenesis, minirhizotron, Hevea brasiliensis.[Journal translation]

scholarly journals IBA endogenous auxin regulates Arabidopsis root system development in a glutathione-dependent way and is important for adaptation to phosphate deprivation

2019 ◽  
Author(s):  
José A. Trujillo-Hernandez ◽  
Laetitia Bariat ◽  
Lucia C. Strader ◽  
Jean-Philippe Reichheld ◽  
Christophe Belin
Keyword(s):  
Root System ◽  
Root Development ◽  
Developmental Process ◽  
System Development ◽  
Lateral Roots ◽  
Root System Architecture ◽  
Indole Butyric Acid ◽  
Phosphate Deprivation ◽  
Root System Development ◽  
Glutathione Deficiency

AbstractRoot system architecture results from a highly plastic developmental process to perfectly adapt to environmental conditions. In particular, the development of lateral roots (LR) and root hair (RH) growth are constantly optimized to the rhizosphere properties, including biotic and abiotic constraints. Every step of root system development is tightly controlled by auxin, the driving morphogenic hormone in plants. Glutathione, a major thiol redox regulator, is also critical for root system development but its interplay with auxin is still scarcely understood. Indeed, previous works showed that glutathione deficiency does not alter root responses to exogenous indole acetic acid (IAA), the main active auxin in plants. Because indole butyric acid (IBA), another endogenous auxinic compound, is an important source of IAA for the control of root development, we investigated the crosstalk between glutathione and IBA during root development. We show that glutathione deficiency alters LR and RH responses to exogenous IBA but not IAA. Although many efforts have been deployed, we could not identify the precise mechanism responsible for this control. However, we could show that both glutathione and IBA are required for the proper responses of RH to phosphate deprivation, suggesting an important role for this glutathione-dependent regulation of auxin pathway in plant developmental adaptation to its environment.

scholarly journals Salinity Stress Alters Root Morphology and Root Hair Traits in Brassica napus

Plants ◽  
2019 ◽  
Vol 8 (7) ◽  
pp. 192 ◽  
Author(s):  
Mohammad Rashid Arif ◽  
M. Thoihidul Islam ◽  
Arif Hasan Khan Robin
Keyword(s):  
Lateral Roots ◽  
Root Hairs ◽  
Root Traits ◽  
Morphological Plasticity ◽  
Root Surface ◽  
Root Surface Area ◽  
Third Order ◽  
Breeding Programs ◽  
First Order ◽  
Treated Condition

Plant roots show morphological plasticity and play a substantial role in tolerance to various edaphic stresses. The aim of this study was to explore salinity-induced morphogenic responses of root traits and root hairs of two rapeseed varieties, BARI Sarisha-8 and Binasarisha-5, at the reproductive stage and perceive the effects on their reproductive growth. The experiment was conducted in a hydroponic culture. Two treatments, 0 mM NaCl as control and 100 mM NaCl, were imposed 55 d after germination. Plants exposed to 100 mM NaCl for seven days displayed greater damage in the leaves, flowers, and siliquae compared to control. Length of root hairs on first-order and third-order lateral roots, density of root hairs on first-order lateral roots, and length of third-order lateral roots were significantly greater by 91%, 22%, 29%, and 48%, respectively, in the treated condition compared to the control. An increase in estimated root surface area by 20% under salt stress conditions indicated that the spontaneous responses of plants to uptake more water and nutrients allowed a plant to cope with stressful conditions. The results of this study suggest that any future stress breeding programs should consider plasticity of root traits intensively.

Relationships between lateral root order, arbuscular mycorrhiza development, and the physiological state of the symbiotic fungus in Platanus acerifolia

1996 ◽  
Vol 74 (12) ◽  
pp. 1947-1955 ◽  
Author(s):  
B. Tisserant ◽  
S. Gianinazzi ◽  
V. Gianinazzi-Pearson
Keyword(s):  
Alkaline Phosphatase ◽  
Arbuscular Mycorrhiza ◽  
Root System ◽  
Lateral Root ◽  
System Development ◽  
Lateral Roots ◽  
Physiological State ◽  
Arbuscular Mycorrhizal ◽  
Platanus Acerifolia ◽  
Root System Development

The rapid development of an efficient root system resulting from arbuscular mycorrhiza formation is essential to the successful establishment of many plant species. We have analysed root system development and used histochemical staining to define relationships between lateral root order dynamics, arbuscular mycorrhiza development, and the physiological state of the symbiotic fungus Glomus fasciculatum (Thaxter sensu Gerdeman) Gerd & Trappe amend. Walker and Koske, in a woody plant species Platanus acerifolia Willd. Arbuscular mycorrhiza induced modifications in root system development in P. acerifolia, compared with nonmycorrhizal root systems. Third-order lateral roots dominated in arbuscular mycorrhizal plants, while second-order laterals were most numerous in nonmycorrhizal systems. Arbuscular mycorrhiza colonization was closely related to the appearance of different root orders; the most active mycelium (characterized by fungal succinate dehydrogenase and alkaline phosphatase activities) was mainly localized in newly formed lateral roots. Nine weeks after inoculation with G. fasciculatum the proportion of alkaline phosphatase-active mycelium strongly decreased in all root orders, and this was related to an increased phosphorus content of the host plant. The dynamics of development of the arbuscular mycorrhizal fungus and the possible regulation of its activity by the host plant are discussed. Keywords: arbuscular mycorrhiza, fungal enzyme, root system morphology, Platanus acerifolia, Glomus fasciculatum.

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