Hydraulic Properties of Pine and Bean Roots With Varying Degrees of Suberization, Vascular Differentiation and Mycorrhizal Infection.

1982 ◽  
Vol 9 (5) ◽  
pp. 559 ◽  
Author(s):  
R Sands ◽  
EL Fiscus ◽  
CPP Reid
Keyword(s):  
Loblolly Pine ◽  
Root Systems ◽  
Hydraulic Conductance ◽  
Root Surface ◽  
Root Surface Area ◽  
Mycorrhizal Infection ◽  
Vascular Differentiation ◽  
Hydraulic Behaviour ◽  
Pine Seedlings ◽  
Axial Conductance

The hydraulic behaviour of root systems of loblolly pine seedlings conformed to the model of Fiscus (1975) and Dalton et al. (1975). The average hydraulic conductance per unit of root surface area was 1.4 × 10-6 cm s-1 bar-1. The hydraulic conductance of various parts of pine root systems was determined using root severing experiments. The average hydraulic conductance of brown (older suberized) roots was 7.55 × 10-7 cm s-1 bar-1, and that of white (newly regenerated unsuberized) roots was 1.95 x 10-6 cm s-1 bar-1. Hydraulic conductance was independent of the amount of mycorrhizal infection. The mean maximum exudation rate from detopped seedlings at zero hydrostatic pressure difference was 1.31 × 10-7 cm s-1. Axial conductance of nutrient solution by roots of bean plants and loblolly pine seedlings was measured at 25°C. Bean vessels and pine tracheids conducted at 0.4 and 0.55 times idealized Poiseuille conductance. Bean roots with differentiated vessels had 8 times more axial conductance per unit area of stele than pine roots, and 6.5 times more axial conductance than bean roots with undifferentiated vessels. Change in axial conductance of bean roots with temperature was completely explained by change in viscosity of the solution. Axial resistance was negligible in the experiments where the hydraulic conductance of whole root systems was measured.

scholarly journals Comparison of Root System Morphology of Cucurbit Rootstocks for Use in Watermelon Grafting

2018 ◽  
Vol 28 (5) ◽  
pp. 629-636 ◽  
Author(s):  
Matthew B. Bertucci ◽  
David H. Suchoff ◽  
Katherine M. Jennings ◽  
David W. Monks ◽  
Christopher C. Gunter ◽  
...  
Keyword(s):  
Root System ◽  
Surface Area ◽  
Root Length ◽  
Dry Weight ◽  
Root Systems ◽  
Root Surface ◽  
Root Diameter ◽  
Root Surface Area ◽  
Diameter Class ◽  
Main Effect

Grafting of watermelon (Citrullus lanatus) is an established production practice that provides resistance to soilborne diseases or tolerance to abiotic stresses. Watermelon may be grafted on several cucurbit species (interspecific grafting); however, little research exists to describe root systems of these diverse rootstocks. A greenhouse study was conducted to compare root system morphology of nine commercially available cucurbit rootstocks, representing four species: pumpkin (Cucurbita maxima), squash (Cucurbita pepo), bottle gourd (Lagenaria siceraria), and an interspecific hybrid squash (C. maxima × C. moschata). Rootstocks were grafted with a triploid watermelon scion (‘Exclamation’), and root systems were compared with nongrafted (NG) and self-grafted (SG) ‘Exclamation’. Plants were harvested destructively at 1, 2, and 3 weeks after transplant (WAT), and data were collected on scion dry weight, total root length (TRL), average root diameter, root surface area, root:shoot dry-weight ratio, root diameter class proportions, and specific root length. For all response variables, the main effect of rootstock and rootstock species was significant (P < 0.05). The main effect of harvest was significant (P < 0.05) for all response variables, with the exception of TRL proportion in diameter class 2. ‘Ferro’ rootstock produced the largest TRL and root surface area, with observed values 122% and 120% greater than the smallest root system (‘Exclamation’ SG), respectively. Among rootstock species, pumpkin produced the largest TRL and root surface area, with observed values 100% and 82% greater than those of watermelon, respectively. These results demonstrate that substantial differences exist during the initial 3 WAT in root system morphology of rootstocks and rootstock species available for watermelon grafting and that morphologic differences of root systems can be characterized using image analysis.

Influence of Tylenchorhynchus ewingi on growth of loblolly pine seedlings, and host suitability of legumes and small grains

Nematology ◽  
2012 ◽  
Vol 14 (4) ◽  
pp. 417-425 ◽  
Author(s):  
Stephen W. Fraedrich ◽  
Michelle M. Cram ◽  
Zafar A. Handoo ◽  
Stanley J. Zarnoch
Keyword(s):  
Pearl Millet ◽  
Loblolly Pine ◽  
Cover Crops ◽  
Root Systems ◽  
Forest Tree ◽  
Initial Population ◽  
Severe Damage ◽  
Pine Seedlings ◽  
Small Grains ◽  
Production Losses

Tylenchorhynchus ewingi, a stunt nematode, causes severe injury to slash pine seedlings and has been recently associated with stunting and chlorosis of loblolly pine seedlings at some forest tree nurseries in southern USA. Experiments confirmed that loblolly pine is a host for T. ewingi, and that the nematode is capable of causing severe damage to root systems. Initial population densities as low as 60 nematodes (100 cm3 soil)−1 were sufficient to damage the root systems of loblolly pine seedlings. Populations of T. ewingi increased on pine from two- to 16-fold, depending on the initial population density. Evaluations of various cover crops used in southern forest tree nurseries indicated that legumes, rye and several varieties of sorghum were excellent hosts for T. ewingi. Other small grains such as ryegrass, oats and wheat were poorer hosts. A cultivar of pearl millet was a non-host for T. ewingi, and a cultivar of brown top millet appeared to be either a very poor host or a non-host. Nurseries that have seedling production losses caused by T. ewingi should consider rotating with non-host cover crops such as pearl millet or leaving fields fallow as part of their pest management programme.

scholarly journals 470 Narrow-sense Heritability Estimates for Melon Root Traits

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 475A-475
Author(s):  
Kevin M. Crosby
Keyword(s):  
Genetic Variation ◽  
Root System ◽  
Block Design ◽  
Root Systems ◽  
Root Surface ◽  
Root Tip ◽  
Root Surface Area ◽  
Narrow Sense ◽  
Narrow Sense Heritability ◽  
Heritability Estimates

Improving melon root systems by traditional breeding is one component of the program to develop multiple-stress-resistant melons at the Texas Agricultural Experiment Station, Weslaco. Ten diverse melon lines representing four horticultural groups were intercrossed utilizing a Design II mating scheme. The male parents were: `PI 403994,' `Perlita,' `Doublon,' `Caravelle', and `PI 525106.' The female parents were: `Créme de Menthe,' `Magnum 45,' `BSK,' `PI 124111 × TDI', and `Deltex.' F1 progeny were grown in pasteurized sand in the greenhouse using a randomized complete-block design with four reps. After 4 weeks, root systems from all plants were carefully washed to remove the sand. Each root system was then placed onto a glass, plated, and scanned into the computer software Rhizo Pro 3.8 (Regent Instruments, Quebec). This software calculated root lengths of various diameter classes, root area, and root tip number. All data was input into Agrobase software for calculation of genetic variances based on Design II analysis. Significant differences of contributions by male parents to progeny variation were few. Only length of roots with 1.0- to 1.5-mm-diameter and vine length were significantly different. Differences in contributions by female parents to all traits except root tip number were highly significant. No significant interaction effects were observed for any trait. Narrow-sense heritability estimates were moderate to high for all traits. The range was from 0.56 for root tip number by males to 0.81 for both length of 0.5- to 1.0-mm-diameter roots and vine length for females. Estimates for total root length (0.76) and root surface area (0.77) were high. The lack of male by female interaction suggests very low dominance genetic variation and contributed to high heritability estimates, which represent predominantly additive gene action. Additive genetic variation allows more-efficient progress by selection, making the potential for root system improvement favorable.

Absorption of Water and 32P through Suberized and Unsuberized Roots of Loblolly Pine

1975 ◽  
Vol 5 (2) ◽  
pp. 229-235 ◽  
Author(s):  
Hsu-Ho Chung ◽  
Paul J. Kramer
Keyword(s):  
Nutrient Solution ◽  
Loblolly Pine ◽  
Mineral Nutrition ◽  
Woody Plants ◽  
Root Systems ◽  
Root Surface ◽  
P Uptake ◽  
Mineral Nutrients ◽  
Vacuum Pump ◽  
Root Segments

Measurements were made of the rate of intake of water and 32P through suberized and unsuberized roots and root segments from seedlings of Pinustaeda L. under a pressure gradient of 31 cm Hg (41 kPa), produced by use of a vacuum pump. Water and 32P intake through suberized root segments from seedlings in storage was only 11% of the intake through unsuberized segments from roots grown in nutrient solution. Water intake through entirely suberized root systems grown in nutrient solution was about 71% and 32P uptake about 58% of those through root systems grown in nutrient solution but with 40–50% of their surface unsuberized. Uptake of water and 32P through root segments and root systems grown in vermiculite was intermediate between that for seedlings grown in nutrient solution and that for dormant root systems. Removal of all unsuberized root surface reduced the total root surface by 42%, water uptake by 54%, and 32P uptake by 70% per seedling. These results indicate that absorption of water and mineral nutrients through suberized roots may play an important role in the water economy and mineral nutrition of woody plants.

Loblolly pine seedling growth after inoculation with plant growth-promoting rhizobacteria and ozone exposure

2004 ◽  
Vol 34 (7) ◽  
pp. 1410-1416 ◽  
Author(s):  
B L Estes ◽  
S A Enebak ◽  
A H Chappelka
Keyword(s):  
Plant Growth ◽  
Loblolly Pine ◽  
Plant Growth Promoting Rhizobacteria ◽  
Field Trials ◽  
Root Surface ◽  
Ozone Exposure ◽  
Root Surface Area ◽  
Foliar Injury ◽  
Plant Growth Promoting ◽  
Growth Promoting

Plant growth-promoting rhizobacteria promote plant growth and induce biocontrol, but are affected by soil type, water stress, microbial competition, and environmental conditions. One unexplored factor is the interaction of rhizobacteria-inoculated plants exposed to ozone. Loblolly pine (Pinus taeda L.) seeds were inoculated with either Bacillus subtilis (Ehrenberg) Cohn or Paenibacillus macerans (Schardinger) Ash. In field trials, 4-week-old seedlings were exposed for 12 weeks to carbon-filtered (CF ≈ 12 ppb), 1× (≈46 ppb), or 2× (≈97 ppb) ozone for 12 h·d–1 in open-top chambers (OTC) in 1998 and 1999. In three greenhouse trials, 5-week-old seedlings were exposed to ozone at 0× (≈8 ppb), 1× (≈105 ppb), 2× (≈199 ppb), and 3× (≈298 ppb) for 4 h·d–1, 5 d·week–1 for 8 weeks in continuously stirred tank reactors (CSTR). In both the CSTRs and the OTCs, ozone-exposed seedlings exhibited 20%–50% less biomass and more foliar injury as compared with nonexposed seedlings. In CSTRs, at the 3× exposure, B. subtilis-inoculated seedlings had 12% less foliar injury than noninoculated seedlings. Foliar injury was 65% less for B. subtilis-treated seedlings in 1998, and root surface area, total root length, and root diameter was 25%–35% greater when seedlings were exposed to 2× ozone in the OTCs. This is the first report of rhizobacteria protecting seedlings against the negative effects of ozone exposure.

Effects of ozone and simulated acidic precipitation on above- and below-ground growth of loblolly pine (Pinustaeda)

1992 ◽  
Vol 22 (4) ◽  
pp. 582-587 ◽  
Author(s):  
Z. Qiu ◽  
A.H. Chappelka ◽  
G.L. Somers ◽  
B.G. Lockaby ◽  
R.S. Meldahl
Keyword(s):  
Surface Area ◽  
Loblolly Pine ◽  
Ozone Concentration ◽  
Final Height ◽  
Root Surface ◽  
Root Surface Area ◽  
Ph Effects ◽  
Acidic Precipitation ◽  
Ozone Concentrations ◽  
Ozone Sensitivity

Loblolly pine (Pinustaeda L.) seedlings from two families differing in ozone sensitivity were exposed to four ozone concentrations (charcoal-filtered (subambient ozone concentration), nonfiltered (ambient ozone concentration), non-filtered × 1.7, and nonfiltered × 2.5) and three levels of acidic precipitation (pH = 3.3, 4.3, and 5.3) in modified open-top chambers for one growing season at Auburn, Alabama. Seedlings were planted in the ground in root-exclusion tubes that isolated root systems of individual seedlings. Foliage, stem, and root biomass, three-dimensional root surface area (root surface area × π; in cm3), final height, and groundline diameter were recorded and analyzed. Foliage dry matter and root surface area decreased and root to shoot ratio significantly increased with increasing ozone concentrations for the ozone-sensitive family. There were no significant pH effects for this family. No significant differences in either ozone or pH treatments occurred for the ozone-tolerant family. The possible implications on long-term effects of ozone and acidic precipitation on loblolly pine growth are discussed.

scholarly journals Effects of Ridge Tillage and Straw Mulching on Cultivation the Fresh Faba Beans

Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1054
Author(s):  
Bo Li ◽  
Xinyu Chen ◽  
Xiaoxu Shi ◽  
Jian Liu ◽  
Yafeng Wei ◽  
...  
Keyword(s):  
Rice Straw ◽  
Precision Agriculture ◽  
Field Experiments ◽  
Root Length Density ◽  
Root Surface ◽  
High Yield ◽  
Root Surface Area ◽  
Straw Mulching ◽  
Faba Beans ◽  
Ridge Tillage

Ridge tillage is an effective agronomic practice and a miniature precision agriculture; however, its effects on the growth of faba beans (Vicia faba L.) are poorly understood. This study aimed to determine the effect of ridge tillage and straw mulching on the root growth, nutrient accumulation and yield of faba beans. Field experiments were conducted during 2016 and 2017 cropping seasons and comprised four treatments: ridge tillage without any mulching (RT), flat tillage without any mulch (FT), flat tillage with rice straw mulched on the ridge tillage (FTRSM) and ridge tillage with rice straw mulched on the ridge tillage (RTRSM). The RT and RTRSM increased soil temperature and decreased soil humidity and improved soil total nitrogen, total phosphorus, available potassium and organic matter. RT and RTRSM increased the root length density, root surface area, root diameter and root activity of faba beans at flowering and harvest periods. The RT and RTRSM also increased the nitrogen, phosphorus, potassium absorption and the yield of faba beans. These results indicated that ridge tillage and straw mulching affect faba bean growth by improving soil moisture conditions and providing good air permeability and effective soil nutrition supply. This study provides a theoretical basis for the high yield cultivation improvement of faba beans.

scholarly journals Biological nitrification inhibition in maize—isolation and identification of hydrophobic inhibitors from root exudates

2021 ◽  
Author(s):  
Junnosuke Otaka ◽  
Guntur Venkata Subbarao ◽  
Hiroshi Ono ◽  
Tadashi Yoshihashi
Keyword(s):  
Root Exudation ◽  
Root Systems ◽  
Root Surface ◽  
Maize Root ◽  
Nitrification Inhibition ◽  
Isolation And Identification ◽  
N Losses ◽  
Chemical Structures ◽  
Maize Roots ◽  
Biological Nitrification

AbstractTo control agronomic N losses and reduce environmental pollution, biological nitrification inhibition (BNI) is a promising strategy. BNI is an ecological phenomenon by which certain plants release bioactive compounds that can suppress nitrifying soil microbes. Herein, we report on two hydrophobic BNI compounds released from maize root exudation (1 and 2), together with two BNI compounds inside maize roots (3 and 4). On the basis of a bioassay-guided fractionation method using a recombinant nitrifying bacterium Nitrosomonas europaea, 2,7-dimethoxy-1,4-naphthoquinone (1, ED50 = 2 μM) was identified for the first time from dichloromethane (DCM) wash concentrate of maize root surface and named “zeanone.” The benzoxazinoid 2-hydroxy-4,7-dimethoxy-2H-1,4-benzoxazin-3(4H)-one (HDMBOA, 2, ED50 = 13 μM) was isolated from DCM extract of maize roots, and two analogs of compound 2, 2-hydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (HMBOA, 3, ED50 = 91 μM) and HDMBOA-β-glucoside (4, ED50 = 94 μM), were isolated from methanol extract of maize roots. Their chemical structures (1–4) were determined by extensive spectroscopic methods. The contributions of these four isolated BNI compounds (1–4) to the hydrophobic BNI activity in maize roots were 19%, 20%, 2%, and 4%, respectively. A possible biosynthetic pathway for zeanone (1) is proposed. These results provide insights into the strength of hydrophobic BNI activity released from maize root systems, the chemical identities of the isolated BNIs, and their relative contribution to the BNI activity from maize root systems.

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