Graviresponsiveness and cap dimensions of primary and secondary roots of Ricinus communis (Euphorbiaceae)

After branching from the primary root, secondary roots of castor bean (Ricinus communis) grow laterally for 15–20 mm, after which they bend downward (i.e., become positively gravitropic). During the first 10 mm of growth, the lengths of caps of secondary roots increase from 120 ± 26 to 220 ± 28 μm. Although this increase is statistically significant (P < 0.1%), the resulting secondary roots are only minimally graviresponsive. A subsequent doubling of the lengths and widths of the root caps (i.e., to 420 ± 34 and 450 ± 41 μm, respectively) is positively correlated with the onset of gravicurvature. The graviresponsiveness and dimensions of caps of positively gravitropic secondary roots are not significantly different from those of positively gravitropic primary roots. These results indicate that (i) a statistically significant increase in the length and length:width ratio of a root cap does not necessarily result in the root becoming positively gravitropic, (ii) there may be a minimum cap length and (or) width necessary for graviresponsiveness, and (iii) the degree of graviresponsiveness exhibited by a particular root may be related to the size of its root cap.

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The cap size and shape of Arabidopsis thaliana primary roots impact the root responses to an increase in medium strength

10.1101/378828 ◽

2018 ◽

Author(s):

J. Roué ◽

H. Chauvet ◽

N. Brunel-Michac ◽

F. Bizet ◽

B. Moulia ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Primary Root ◽

Root Cap ◽

Size And Shape ◽

Primary Roots ◽

Medium Strength ◽

Cell Layers ◽

Root Responses ◽

Mutant Lines

AbstractDuring root progression in soil, root cap cells are the first to encounter obstacles. The root cap is known to sense environmental cues, making it a relevant candidate for a mechanosensing site. An original two-layer medium was developed in order to study root responses to growth medium strength and the importance of the root cap in the establishment of these responses. Root growth and trajectory of primary roots of Arabidopsis thaliana seedlings were investigated using in vivo image analysis. After contact with the harder layer, the root either penetrated it or underwent rapid curvature, enabling reorientation of the root primary growth. The role of the root cap in tip reorientation was investigated by analyzing the responses of Arabidopsis mutant roots with altered caps. The primary root of fez-2 mutant lines, which has fewer root cap cell layers than wild-type roots, showed impaired penetration ability. Conversely, smb-3 roots of mutant lines, which display a higher number of root cap cells, showed enhanced penetration abilities. This work highlights that alterations in root cap shape and size affect the root responses to medium strength.HighlightThe analysis of the growth and orientation of Arabidopsis thaliana mutant roots affected in root cap size and shape showed that properly formed root cap is required to trigger the root responses to medium strength.AbbreviationsCOLcolumella;LRCLateral Root Cap;SISharpness Index;SMBSOMBRERO.

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Screening of exotic and indigenous apple rootstocks for different horticultural traits

SAARC Journal of Agriculture ◽

10.3329/sja.v14i2.31250 ◽

2017 ◽

Vol 14 (2) ◽

pp. 117-125

Author(s):

KK Srivastava ◽

DB Singh ◽

Dinesh Kumar ◽

JI Mir

Keyword(s):

Root Length ◽

Primary Root ◽

Apple Rootstock ◽

Apple Rootstocks ◽

Leaf Petiole ◽

Secondary Root ◽

Root Numbers ◽

Horticultural Traits ◽

Primary Roots ◽

Secondary Roots

An experiment was carried out to find the suitable exotic as well as indigenous apple rootstocks for temperate zone of India. The rootstocks were screened on the basis of 11 important pomological traits. The data revealed that maximum numbers of primary and secondary roots were noted of 93.40, 92.76 in MM.106 and USA 106 and 92.0 noted in CITHrootstock- 01, respectively. Maximum length of primary roots (19.83cm) was recorded of EMLA 106 whereas shortest primary roots (6.47 cm) were recorded of ALNARP. The longest secondary roots (11.83cm) were found in M.27 and shortest secondary roots (2.10 cm) in ALNARP rootstock. Most of the indigenous apple rootstocks were having short to medium length of secondary roots. Leaf area was recorded highest (3.80cm2) in CITH-Apple rootstock-04 and smallest (1.96 cm2) of USA- 106. All the evaluated rootstocks have pink colored petiole except B-9, which has dark red color. Highest collar rot incidence was observed in M- 27 and M-26 and least in indigenous root stocks (CITH-Apple rootstocks). Highest wooly aphid infection was found in M-9, B-9, M-27, EMLA-106 and ALNARP whereas least infestation noted in M-26 and indigenous apple rootstock (CITH-ARS-01, CITH-ARS-02, CITH-ARS-03, CITH-ARS-04, CITH-ARS-, CITH-ARS-09 and CITH-ARS-10). Primary root length has positive correlation with secondary root numbers, secondary root length and leaf petiole length but negative correlation with leaf area.SAARC J. Agri., 14(2): 117-125 (2016)

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Efeito da salinidade na germinação e desenvolvimento inicial da mamona ‘BRS energia’

Revista Verde de Agroecologia e Desenvolvimento Sustentável ◽

10.18378/rvads.v10i4.3344 ◽

2015 ◽

Vol 10 (4) ◽

pp. 17 ◽

Cited By ~ 2

Author(s):

K. Q. D. Brito ◽

F. G. Souza ◽

G. J. Dantas Junior ◽

K. S. A. Brito

Keyword(s):

Salt Stress ◽

Castor Bean ◽

Root Zone ◽

Ricinus Communis ◽

Primary Root ◽

Germination Percentage ◽

Raw Material ◽

Initial Development ◽

Average Speed ◽

Castor Seeds

A mamoneira possui destacável importância no mundo, tem como principal produto derivado do seu óleo que pode ser utilizado como matéria prima para o biodiesel. Objetivou-se com este trabalho avaliar os níveis de tolerância das sementes de mamona ao estresse salino simulados por NaCl. A pesquisa foi desenvolvida no Laboratório de Irrigação e Salinidade na Universidade Federal de Campina Grande. Em cada tratamento foram utilizadas 100 sementes, dispostas em quatro repetições de 25 sementes. O delineamento experimental utilizado foi o inteiramente casualizado. Para a avaliação da germinação sob estresse salino utilizou-se soluções de NaCl com as seguintes condutividade elétrica: 0,4; 1,2; 2,2; 3,2 e 4,2dSm-1. Realizou-se avaliações de porcentagem de germinação, tempo médio de germinação, velocidade média de germinação, índice de velocidade de germinação e aos 15 dias realizaram o comprimento da raiz primaria, da parte aérea, e pesou a massa seca e fresca das plântulas. As sementes de mamoneira BRS Energia apresentaram tolerância às águas com níveis de salinidade de até 4,2 dS m-1 em relação ao índice de velocidade de germinação, tempo médio de germinação, velocidade média de germinação e porcentagem de germinação e o aumento da salinidade afetou o comprimento da parte aérea e da zona radicular.Effect of salinity on germination and initial development of castor bean ‘BRS energia’Abrstact: The castor bean (Ricinus communis L.) is an oilseed that has detachable importance in Brazil and worldwide, its main product derived from its oil that can be used as raw material for biodiesel, therefore the aim of this study was to evaluate the tolerance levels of castor seeds to salt stress simulated by NaCl. In each treatment, 100 seeds, in four replicates of 25 seeds. For the evaluation of germination under salt stress was used NaCl solutions with the following electric conductivity: 0.4dSm-1 1.2dSm-1, 2.2dSm-1, 3.2dSm-1 and 4.2dSm-1. Was evaluated germination percentage, average time of germination, average speed of germination, GRI and 15 days held the length of the primary root, of shoots, and weighed dry and fresh weight of seedlings. The experimental design was completely randomized. The seeds of castor bean BRS Energia showed tolerance to water with salinity levels up to 4.2dSm-1 in relation to the germination speed index, average time of germination, average speed of germination and germination percentage and the high salinity affected the length of shoot and root zone.

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Chemotaxis of zoospores of Phytophthora megasperma to primary roots of alfalfa seedlings

Canadian Journal of Botany ◽

10.1139/b78-091 ◽

1978 ◽

Vol 56 (7) ◽

pp. 795-800 ◽

Cited By ~ 12

Author(s):

C. C. Chi ◽

F. E. Sabo

Keyword(s):

Trifolium Pratense ◽

Primary Root ◽

Root Hairs ◽

Red Clover ◽

Root Surface ◽

Root Cap ◽

Root Tips ◽

Phytophthora Megasperma ◽

Root Area ◽

Primary Roots

Chemotaxis of the zoospores of Phytophthora megasperma was studied on freshly excised primary root tips of 2-day-old seedlings of nine alfalfa (Medicago sativa L.) cultivars and four other legume species. The highly susceptible cultivars Saranac, Algonquin, and Vernal attracted masses of zoospores within minutes after being placed into fresh zoospore suspensions. The moderately susceptible cultivars Iroquois, Angus, and Thor displayed less severe en masse zoospore accumulation. Resistant cultivars Apollo, Agate, and to a lesser degree WL-318 exhibited minor chemotaxis.Zoospores were strongly attracted to the region of elongation, immediately above the root cap area. Relatively few zoospores, if any, were attracted to the root cap and older regions of the roots. Zoospores were not attracted to root hairs. Within 0.5-1 h, zoospores attracted to the roots began to encyst and germinate. Germ tubes always originated from the side of cysts closest to the root surface, and all showed unidirectional growth towards the root.Very weak or no chemotactic responses of zoospores to nonhost legume plants of white sweet clover (Melilotus alba Desr.), red clover (Trifolium pratense L.), bird's-foot trefoil (Lotus corniculatus L.), and soybean (Glycine max (L.) Merr. cv. Vansoy) were observed. Roots of susceptible alfalfa seedlings pretreated in boiling water did not attract zoospores.Injured, susceptible alfalfa roots displayed a strong preferential attraction around a wounded root area. Varying zoospore densities occurred at different distances from the wound. Wounded, resistant alfalfa roots showed slightly more zoospore accumulation than the uninjured resistant roots.The magnitude of chemotaxis and response time appear to be related to the susceptibility or resistance of the young, primary roots of alfalfa seedlings.

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Effect of Preconditioning Treatments and Auxins on the Rooting of Semi-Hardwood Cuttings of Olive Planted During Winter Under Mist Condition

Current World Environment ◽

10.12944/cwe.11.2.26 ◽

2016 ◽

Vol 11 (2) ◽

pp. 560-566

Author(s):

Manish Thakur ◽

D. D Sharma ◽

Pramod Verma ◽

Babita

Keyword(s):

Leaf Area ◽

Plant Height ◽

Root Length ◽

Primary Root ◽

Rooted Cuttings ◽

Secondary Root ◽

Survival Percentage ◽

Primary Roots ◽

Primary Root Length ◽

Secondary Roots

An experiment was conducted during winter to find the effect of girdling, etiolation and auxins i.e. IBA and NAA on rooting of semi- hardwood cuttings of olive cv. Leccino under mist. The experiment comprised of 13 treatments and was combinations of girdling, etiolation and auxins. The results indicated that the best rooting characteristics viz; highest percent rooted cuttings (53.33), number of primary roots (6.58) and secondary roots (8.53) and diameter (0.46 mm) were maximum with cuttings treated with IBA at 5000 ppm, where as the maximum primary root length (5.30 cm) and secondary root length (2.42) was recorded with the treatment girdling + IBA 4000 ppm + NAA 1000 ppm and IBA 4000 ppm, respectively. Regarding the shoot characteristics viz; plant height (14.59 cm) was recorded highest for the treatment IBA@ 4000 ppm which was at par with the treatment IBA @ 5000 ppm (14.26 cm). Highest plant diameter (2.40 mm), numbers of leaves (16.26) and leaf area (36.42 cm2) were highest for the treatment IBA @ 5000 ppm. Survival percentage of cuttings (71.57 %) was also highest in cuttings treated with IBA @ 5000 ppm. It is concluded that IBA at 5000 ppm was found to be the best treatment for propagation of olive through semi- hardwood cuttings during winter.

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Early Pinus caribaea var. hondurensis root development. 2. Influence of soil strength

Australian Journal of Experimental Agriculture ◽

10.1071/ea9960847 ◽

1996 ◽

Vol 36 (7) ◽

pp. 847 ◽

Cited By ~ 8

Author(s):

A Costantini ◽

D Doley ◽

HB So

Keyword(s):

Root Development ◽

Soil Type ◽

Root Elongation ◽

Primary Root ◽

High Strength ◽

Soil Strength ◽

Shoot Development ◽

Pinus Caribaea ◽

Primary Shoot ◽

Primary Roots

The influence of penetration resistance (PR), an easily measured indicator of soil strength, on the growth of Pinus caribaea var. hondurensis radicles and seedlings was investigated. Negative exponential relationships between PR and both radicle and primary root elongation were observed. All root elongation ceased at PR levels of 3.25 MPa. Tip diameters of radicles and primary roots were positively correlated with PR values up to 2.4 MPa, whilst numbers of primary roots, total root lengths and lengths of longest roots were all negatively correlated with PR. Hypocotyl elongation was also reduced by increasing PR, although the reductions occurred at higher PRs than those which inhibited root development. In contrast, primary shoot development was unaffected by PR levels which were sufficient to stop root elongation, but was reduced in soil with a PR of 4.8 MPa. There were significant family x soil type and family x PR interactions for radicle, hypocotyl, primary root and primary shoot development. 1f these interactions are correlated with performance in the field, then they may serve as useful indicators of family suitability to both soil type and high strength soils.

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