Soil Mechanical Resistance and Root Growth and Function

Plant Roots ◽  
2013 ◽  
pp. 632-647 ◽  
1982 ◽  
Vol 30 (3) ◽  
pp. 179-192 ◽  
Author(s):  
F.R. Boone ◽  
B.W. Veen

In 3 pot experiments, maize cv. Avanti was grown on a marine sandy loam compacted to different pore vol. and supplied with different rates of P. Root wt. was not changed by different levels of mechanical resistance but root extension growth and cone resistance were curvilinearly related. At high mechanical resistance, root growth was more horizontal; vertical root growth was very limited at high cone resistances. Specific root length was also smaller, root diam. larger and fewer laterals/cm main root were developed although their av. length was not affected. The influence of mechanical resistance on root distribution and morphology reduced nutrient uptake and therefore shoot growth. With low P availability, P limited shoot growth more the higher the mechanical resistance. With sufficient P, K had the same effect. If an aboveground factor such as a low light intensity limited shoot growth, mechanical resistance had no effect on shoot growth. (Abstract retrieved from CAB Abstracts by CABI’s permission)


Development ◽  
1992 ◽  
Vol 116 (2) ◽  
pp. 397-403 ◽  
Author(s):  
H. M. Ottoline Leyser ◽  
I. J. Furner

The shoot apical meristem of dicotyledonous plants is highly regulated both structurally and functionally, but little is known about the mechanisms involved in this regulation. Here we describe the genetic and phenotypic characterisation of recessive mutations at three loci of Arabidopsis thaliana in which meristem structure and function are disrupted. The loci are Clavata1 (Clv1), Fasciata1 (Fas1) and Fasciata2 (Fas2). Plants mutant at these loci are fasciated having broad, flat stems and disrupted phyllotaxy. In all cases, the fasciations are associated with shoot apical meristem enlargement and altered floral development. While all the mutants share some phenotypic features they can be divided into two classes. The pleiotropic fas1 and fas2 mutants are unable to initiate wild- type organs, show major alterations in meristem structure and have reduced root growth. In contrast, clv1 mutant plants show near wild-type organ phenotypes, more subtle changes in shoot apical meristem structure and wild-type root growth.


2016 ◽  
Vol 5 (2) ◽  
pp. 37 ◽  
Author(s):  
Setiyo Hadi Waluyo ◽  
Tek An Lie ◽  
Leendert ’t Mannetje

To clarify whether P had a direct or indirect effect on the nodulation  process of soybean grown in acid soils from Sitiung, West Sumatra, Indonesia, a series of rhizotron experiments, with special attention given to formation of nodule primordia, was conducted at Laboratory of  Microbiology, Wageningen University in 1998-2000. It was shown that Ca and P were essential nutrients for root growth, nodule formation, and growth of soybean in the acid soils (Oxisols). Ca increased root growth, number of nodule primordia, nodules, and growth of the soybean plant. This positive effect of Ca was increased considerably by the application of P. Ca and P have a synergistic effect on biological nitrogen fixation (BNF) of soybean in acid soils. Ca is important for the establishment of nodules, whilst P is essential for the development and function of the formed nodules. P increased number of nodule primordia, thus it also has an important role in the initiation of nodule formation. From this study, it can be concluded that Ca and P are the most limiting nutrients for BNF of soybean in the acid soils of Sitiung, West Sumatra, Indonesia.


2004 ◽  
Vol 14 (2) ◽  
pp. 196-202 ◽  
Author(s):  
R.G. Linderman ◽  
E.A. Davis

Formation and function of arbuscular mycorrhizae (AM) are affected by levels of fertility in soil or fertilizers applied to soilless container mixes. For AM fungi, phosphorus (P) is the main element influencing colonization of host plant roots. The question addressed in this study was whether inorganic or organic fertilizers were more compatible with the formation and function of AM. Several controlled-release inorganic (CRI) fertilizers were compared with several organic (OR) fertilizers at different rates (½× to 4× the recommended rate) to determine (1) threshold levels of tolerance by the AM fungus Glomus intraradices in relation to root colonization, and (2) growth responses of `Guardsman' bunching onion (Allium cepa) and `Orange Cupido' miniature rose (Rosa spp.) plants grown in a soilless potting mix or sandy loam soil. AM colonization in soil was greatly decreased or totally inhibited by CRI fertilizers with high P content at the 2× rate or greater, whereas colonization was decreased but never eliminated by low-P OR fertilizers at the 3× rate or greater. Shoot growth of onions was similar with or without AM inoculation when fertilized with CRI, but in general was only enhanced by OR fertilizers if inoculated with AM fungi, compared to the noninoculated controls. Shoot and root growth of onions were significantly increased by AM inoculation when OR fertilizers were used at the 1× rate. In contrast, root growth was not increased by the combination of CRI fertilizers and AM fungal inoculation. Inoculation of miniature roses grown in sandy loam amended with 25% peat and perlite and fertilized with all the CRI or OR fertilizers resulted in high AM colonization, but without much AM-induced growth increase except where OR fertilizers or CRI fertilizers with low P were used. In a soilless potting mix, growth of miniature roses was less with OR fertilizers at the rates used than CRI fertilizers, but mycorrhiza formation was greater in the former unless P was low in the latter. These results indicate that release of nutrients from organic fertilizers, as a result of microbial activity, favors AM establishment and function more than most inorganic fertilizers unless P levels of the latter are low.


Author(s):  
Joseph G Dubrovsky ◽  
Kris Vissenberg

Abstract This special issue is dedicated to the 100th anniversary of the birth of Frederick Albert Lionel Clowes, who discovered the quiescent centre (QC) of the root apical meristem (RAM). His discovery was a foundation for contemporary studies of the QC and RAM function, maintenance, and organization. RAM function is fundamental for cell production and root growth. This special issue bundles reviews on the main tendencies, hypotheses, and future directions, and identifies unknowns in the field.


1988 ◽  
Vol 66 (4) ◽  
pp. 385-395 ◽  
Author(s):  
Bodh I. Jugdutt

The effect of nitroglycerin and ibuprofen, given between 2 and 7 days after left anterior descending coronary artery ligation, on the mechanical resistance of the infarcted left ventricle to rupture or the rupture threshold (balloon technique), and on topography (computerized planimetry) and function (two-dimensional echocardiography) at 7 days (n = 32) and 42 days (n = 34) postligation was studied in 66 dogs randomly allocated to sham (no infarction, n = 22) and infarction subgroups (15 controls; 15 received nitroglycerin, 30 mg oral isosorbide dinitrate b.i.d; 14 received ibuprofen, 200 mg t.i.d orally). Nitroglycerin decreased mean arterial and left atrial pressures, decreased diastolic cross-sectional area, and improved systolic function, while ibuprofen increased diastolic area. Infarction subgroups showed infarct shrinkage and more infarct hydroxyproline at 6 weeks. Compared with shams, all infarct subgroups showed early expansion and thinning, with further marked late thinning in controls. Nitroglycerin produced less expansion and thinning both at 1 and 6 weeks, while ibuprofen produced marked early thinning. Rupture threshold was less at 6 weeks than 1 week with controls and ibuprofen but remained unchanged with nitroglycerin. Passive prerupture stiffness was less at 6 weeks than at 1 week in controls but remained unchanged with nitroglycerin and ibuprofen. Thus, reduced expansion and thinning with nitroglycerin during the first week after infarction improved function, mechanical strength, and resistance to distension at 6 weeks.


2012 ◽  
Vol 63 (12) ◽  
pp. 4631-4645 ◽  
Author(s):  
Biljana M. Kukavica ◽  
Sonja D. Veljovicć-Jovanovicć ◽  
Ljiljana Menckhoff ◽  
Sabine Lüthje

2007 ◽  
Vol 17 (2) ◽  
pp. 151-162 ◽  
Author(s):  
H.M. Mathers ◽  
S.B. Lowe ◽  
C. Scagel ◽  
D.K. Struve ◽  
L.T. Case

Container production has many advantages over traditional in-ground (field) production, including less damage occurring to the root system when transplanted, better establishment after transplanting, decreased labor and land acquisition costs for production, and increased product availability and longevity in the retail market. Growing plants in containers, however, alters root growth and function and can change root morphology. Numerous factors influence root growth in containers. Roots of container-grown plants are subjected to temperature and moisture extremes not normally found in field production. The effects of substrate aeration (Ea) as well as water holding capacity (Pv) interact with different pot characteristics, resulting in changes to root morphology. Successful plant establishment after transplanting is often linked to root health. This review focuses on the roles of substrate physical and chemical properties, container characteristics, and temperature in altering root growth in container-grown woody nursery crops. Root circling, planting too deeply or “too-deep syndrome” (TDS), and the use of composts as container substrates will also be examined.


1988 ◽  
Vol 18 (6) ◽  
pp. 728-732 ◽  
Author(s):  
G. L. Simmons ◽  
P. E. Pope

A root growth model was developed to graphically simulate predicted root responses of yellow-poplar and sweetgum seedlings to changes in soil physical properties. Data for the model were collected in greenhouse and laboratory experiments. Newly germinated yellow-poplar (Liriodendrontulipifera L.) and sweetgum (Liquidambarstyraciflua L.) seedlings were transplanted into pots containing silt loam soil compacted to bulk densities of 1.25, 1.40, or 1.55 Mg m−3 and grown under greenhouse conditions for 3 months. Minimum water potentials were maintained at −10 or −300 kPa. At harvest, root systems were excavated, divided into orders of lateral roots, and length, number, and branching frequency of each order were determined. Air-filled porosity and mechanical resistance were determined for soil samples equilibrated at the same bulk densities and water potentials as those used in the greenhouse study. Based on root and soil parameters, the model ROOTSIM graphically depicts the root distribution of each tree species at different levels of bulk density, mechanical resistance, and air-filled porosity. The model accurately predicts lateral root length and distribution for the range of soil properties used in the greenhouse study but has not been validated for these or other soil conditions.


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