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1.
Root biomass, root nitrogen content, and root distribution down to 50 cm depth in winter wheat were determined by soil coring
on five dates in four different treatments: control (C), drought (D), daily irrigation (I), and daily irrigation and fertilization
(IF). The first three treatments received the N fertilizer application as a single dose in spring, whereas in IF daily doses
of N were supplied in the irrigation water using a drip-tube system, according to the estimated nutrient demand of the crop.
All treatments received 20 g N m−2 year−1.
The maximum root biomass (104 g m−2) was reached earliest in IF. On 6 June, root samples were taken down to a depth of 100 cm, and the proportion of deep roots
(50–100 cm) was least in I, indicating that it had the shaklowest root system. The root biomass as a fraction of the total
plant mass decreased during crop development in all treatments down to about 4% at harvest. The decrease was more rapid in
I and C than in D and IF. The higher proportion of roots during spring in D and IF coincided with a low nitrogen concentration
in the roots, which was attributed to the restricted water supply and to the relative shortage of nitrogen during early crop
development in D and IF, respectively. The dynamics of mass and nitrogen in macroscopic organic debris in the soil suggested
that root turnover rates were high. ei]{gnB E}{fnClothier} 相似文献
2.
Competition in tree row agroforestry systems. 1. Distribution and dynamics of fine root length and biomass 总被引:4,自引:0,他引:4
Complementarity in the distribution of tree and crop root systems is important to minimise competition for resources whilst
maximising resource use in agroforestry systems. A field study was conducted on a kaolinitic Oxisol in the sub-humid highlands
of western Kenya to compare the distribution and dynamics of root length and biomass of a 3-year-old Grevillea robusta A. Cunn. ex R. Br. (grevillea) tree row and a 3-year-old Senna spectabilis DC. (senna) hedgerow grown with Zea mays L. (maize). Tree roots were sampled to a 300 cm depth and 525 cm distance from the tree rows, both before and after maize
cropping. Maize roots were sampled at two distances from the tree rows (75–150 cm and 450–525 cm) to a maximum depth of 180
cm, at three developmental stages. The mean root length density (Lrv) of the trees in the upper 15 cm was 0.55 cm cm−3 for grevillea and 1.44 cm cm−3 for senna, at the start of the cropping season. The Lrv of senna decreased at every depth during the cropping season, whereas the Lrv of grevillea only decreased in the crop rooting zone. The fine root length of the trees decreased by about 35% for grevillea
and 65% for senna, because of maize competition, manual weeding, seasonal senescence or pruning regime (senna). At anthesis,
the Lrv of maize in the upper 15 cm was between 0.8 and 1.5 cm cm−3. Maize root length decreased with greater proximity to the tree rows, potentially reducing its ability to compete for soil
resources. However, the specific root length (m g−1) of maize was about twice that of the trees, so may have had a competitive uptake advantage even when tree root length was
greater. Differences in maize fine root length and biomass suggest that competition for soil resources and hence fine root
length may have been more important for maize grown with senna than grevillea.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
3.
Field experiments were performed in Southern Finland on fine sand and organic soil in 1990 and 1991 to study carrot roots. Fall ploughed land was loosened by rotary harrowing to a depth of 20 cm or compacted under moist conditions to a depth of 25–30 cm by three passes of adjacent wheel tracks with a tractor weighing 3 Mg, in April were contiguously applied across the plot before seed bed preparation. Sprinkler irrigation (30 mm) was applied to fine sand when moisture in the 0–15 cm range of soil depth was 50% of plant-available water capacity. For root sampling, polyvinyl chloride (PVC) cylinders (30 × 60 cm) were installed in the rows of experimental plots after sowing, and removed at harvest. Six carrot plants were grown in each of in these soil colums in situ in the field.Fine root length and width were quantified by image analysis. Root length density (RLD) per plant was 0.2–1.0 cm cm-3 in the 0–30 cm range. The fibrous root system of one carrot had total root lengths of 130–150 m in loose fine sand and 180–200 m in compacted fine sand. More roots were observed in irrigated than non-irrigated soils. In the 0–50 cm range of organic soil, 230–250 m of root length were removed from loosened organic soils and 240–300 m from compacted soils. Specific root surface area (surface area divided by dry root weight) of a carrot fibrous root system averaged 1500–2000 cm2 g-1. Root length to weight ratios of 250–350 m g-1 effectively compare with the ratios of other species.Fibrous root growth was stimulated by soil compaction or irrigation to a depth of 30 cm, in both the fine sand and organic soils, suggesting better soil water supply in compacted than in loosened soils. Soil compaction increased root diameters more in fine sand than it did in organic soil. Most of the root length in loosened soils (fine sand 90%, organic soil 80%) and compacted soils (fine sand 80%, organic soil 75%) was composed of roots with diameters of approximately 0.15 mm. With respect to dry weight, length, surface area and volume of the fibrous root system, all the measurements gave significant resposes to irrigation and soil compaction. Total root volumes in the 0–50 cm of soil were 4.3 cm3 and 9.8 cm3 in loosened fine sand and organic soils, respectively, and 6.7 cm3 and 13.4 cm3 in compacted sand and organic soils, respectively. In fine sand, irrigation increased the volume from 4.8 to 6.3 cm3. 相似文献
4.
Summary In 1982 and 1983 root samples were taken by auger from potato crops grown on marine clay in the Flevo-Polder. The roots increased
their penetration depth throughout the periods of measurement, and ultimately reached depths between 80 cm and 100 cm below
the hills. Between 50 and 60 days after emergence, decay of roots commenced, starting in the upper horizons. In the hill mean
root length densities varied between 1 and 2 cm cm−3. Below the hills root density rarely exceeded 1 cm cm−3. The random variation in root density was equivalent to a coefficient of variation of 50%. There were significant effects
of the position of sampling (relative to the centre of the plant) on root density; densities were usually lowest beneath the
furrow. Depending on season and sampling date, total root length varied between 3.4 and 7.1 km m−2, and root dry mass varied between 33 and 77 g m−2. Representative figures for specific root length were 100–120 m g−1 dry weight. About 90% of the root diameters were smaller than 0.44 mm; the most frequent class (35%) were roots with diameters
between 0.12 and 0.20 mm. 相似文献
5.
Seasonal dynamics of fine root biomass, root length density, specific root length, and soil resource availability in a Larix gmelinii plantation 总被引:1,自引:0,他引:1
Cheng Yunhuan Han Youzhi Wang Qingcheng Wang Zhengquan 《Frontiers of Biology in China》2006,1(3):310-317
Fine root turnover is a major pathway for carbon and nutrient cycling in terrestrial ecosystems and is most likely sensitive
to many global change factors. Despite the importance of fine root turnover in plant C allocation and nutrient cycling dynamics
and the tremendous research efforts in the past, our understanding of it remains limited. This is because the dynamics processes
associated with soil resources availability are still poorly understood. Soil moisture, temperature, and available nitrogen
are the most important soil characteristics that impact fine root growth and mortality at both the individual root branch
and at the ecosystem level. In temperate forest ecosystems, seasonal changes of soil resource availability will alter the
pattern of carbon allocation to belowground. Therefore, fine root biomass, root length density (RLD) and specific root length
(SRL) vary during the growing season. Studying seasonal changes of fine root biomass, RLD, and SRL associated with soil resource
availability will help us understand the mechanistic controls of carbon to fine root longevity and turnover. The objective
of this study was to understand whether seasonal variations of fine root biomass, RLD and SRL were associated with soil resource
availability, such as moisture, temperature, and nitrogen, and to understand how these soil components impact fine root dynamics
in Larix gmelinii plantation. We used a soil coring method to obtain fine root samples (⩽2 mm in diameter) every month from May to October
in 2002 from a 17-year-old L. gmelinii plantation in Maoershan Experiment Station, Northeast Forestry University, China. Seventy-two soil cores (inside diameter
60 mm; depth intervals: 0–10 cm, 10–20 cm, 20–30 cm) were sampled randomly from three replicates 25 m × 30 m plots to estimate
fine root biomass (live and dead), and calculate RLD and SRL. Soil moisture, temperature, and nitrogen (ammonia and nitrates)
at three depth intervals were also analyzed in these plots. Results showed that the average standing fine root biomass (live
and dead) was 189.1 g·m−2·a−1, 50% (95.4 g·m−2·a−1) in the surface soil layer (0–10 cm), 33% (61.5 g·m−2·a−1), 17% (32.2 g·m−2·a−1) in the middle (10–20 cm) and deep layer (20–30cm), respectively. Live and dead fine root biomass was the highest from May
to July and in September, but lower in August and October. The live fine root biomass decreased and dead biomass increased
during the growing season. Mean RLD (7,411.56 m·m−3·a−1) and SRL (10.83 m·g−1·a−1) in the surface layer were higher than RLD (1 474.68 m·m−3·a−1) and SRL (8.56 m·g−1·a−1) in the deep soil layer. RLD and SRL in May were the highest (10 621.45 m·m−3 and 14.83m·g−1) compared with those in the other months, and RLD was the lowest in September (2 198.20 m·m−3) and SRL in October (3.77 m·g−1). Seasonal dynamics of fine root biomass, RLD, and SRL showed a close relationship with changes in soil moisture, temperature,
and nitrogen availability. To a lesser extent, the temperature could be determined by regression analysis. Fine roots in the
upper soil layer have a function of absorbing moisture and nutrients, while the main function of deeper soil may be moisture
uptake rather than nutrient acquisition. Therefore, carbon allocation to roots in the upper soil layer and deeper soil layer
was different. Multiple regression analysis showed that variation in soil resource availability could explain 71–73% of the
seasonal variation of RLD and SRL and 58% of the variation in fine root biomass. These results suggested a greater metabolic
activity of fine roots living in soil with higher resource availability, which resulted in an increased allocation of carbohydrate
to these roots, but a lower allocation of carbohydrate to those in soil with lower resource availability.
__________
Translated from Acta Phytoecologica Sinica, 2005, 29(3): 403–410 [译自: 植物生态学报, 2005, 29(3): 403–410] 相似文献
6.
Root distribution of soybean was determined under wet soil culture on two Red-Brown earths in S.E. Australia. In general there
was a parabolic distribution of roots with low root length densities in the furrow (saturated soil zone) and centre of the
bed (dry zone). Maximum root length density (20 cm cm−3) occurred at the base of the plants, approximately 300 mm from the furrow under wet soil culture. Roots were confined to
the wet aerated zone which was determined by the permeability of the soil. 相似文献
7.
The change of soil carbon stocks and fine root dynamics after land use change from a native pasture to a pine plantation 总被引:3,自引:0,他引:3
A published meta-analysis of worldwide data showed soil carbon decreasing following land use change from pasture to conifer
plantation. A paired site (a native pasture with Themeda triandra dominant, and an adjacent Pinus radiata plantation planted onto the pasture 16 years ago) was set up as a case study to assess the soil carbon reduction and the
possible reason for the reduction under pine, including the change in fine root (diameter <2 mm) dynamics (production and
mortality). Soil analysis confirmed that soil carbon and nitrogen stocks to 100 cm under the plantation were significantly
less than under the pasture by 20 and 15%, respectively. A 36% greater mass of fine root was found in the soil under the pasture
than under the plantation and the length of fine root was about nine times greater in the pasture. Much less fine root length
was produced and roots died more slowly under the plantation than under the pasture based on observations of fine root dynamics
in minirhizotrons. The annual inputs of fine root litter to the top 100 cm soil, estimated from soil coring and minirhizotron
observations, were 6.3 Mg dry matter ha−1 year−1 (containing 2.7 Mg C and 38.9 kg N) under the plantation, and 9.7 Mg ha−1 year−1 (containing 3.6 Mg C and 81.4 kg N) under the pasture. The reduced amount of carbon, following afforestation of the pasture,
in each depth-layer of the soil profile correlated with the lower length of dead fine roots in the layer under the plantation
compared with the pasture. This correlation was consistent with the hypothesis that the soil carbon reduction after land use
change from pasture to conifer plantation might be related to change of fine root dynamics, at least in part. 相似文献
8.
Edward Castañeda-Moya Robert R. Twilley Victor H. Rivera-Monroy Brian D. Marx Carlos Coronado-Molina Sharon M. L. Ewe 《Ecosystems》2011,14(7):1178-1195
Patterns of mangrove vegetation in two distinct basins of Florida Coastal Everglades (FCE), Shark River estuary and Taylor
River Slough, represent unique opportunities to test hypotheses that root dynamics respond to gradients of resources, regulators,
and hydroperiod. We propose that soil total phosphorus (P) gradients in these two coastal basins of FCE cause specific patterns
in belowground biomass allocation and net primary productivity that facilitate nutrient acquisition, but also minimize stress
from regulators and hydroperiod in flooded soil conditions. Shark River basin has higher P and tidal hydrology with riverine
mangroves, in contrast to scrub mangroves of Taylor basin with more permanent flooding and lower P across the coastal landscape.
Belowground biomass (0–90 cm) of mangrove sites in Shark River and Taylor River basins ranged from 2317 to 4673 g m−2, with the highest contribution (62–85%) of roots in the shallow root zone (0–45 cm) compared to the deeper root zone (45–90 cm).
Total root productivity did not vary significantly among sites and ranged from 407 to 643 g m−2 y−1. Root production in the shallow root zone accounted for 57–78% of total production. Root turnover rates ranged from 0.04
to 0.60 y−1 and consistently decreased as the root size class distribution increased from fine to coarse roots, indicating differences
in root longevity. Fine root biomass was negatively correlated with soil P density and frequency of inundation, whereas fine
root turnover decreased with increasing soil N:P ratios. Lower P availability in Taylor River basin relative to Shark River
basin, along with higher regulator and hydroperiod stress, confirms our hypothesis that interactions of stress from resource
limitation and long duration of hydroperiod account for higher fine root biomass along with lower fine root production and
turnover. Because fine root production and organic matter accumulation are the primary processes controlling soil formation
and accretion in scrub mangrove forests, root dynamics in the P-limited carbonate ecosystem of south Florida have a major
controlling role as to how mangroves respond to future impacts of sea-level rise. 相似文献
9.
W. H. Van der Putten J. T. Van Der Werf-Klein Breteler C. Van Dijk 《Plant and Soil》1989,120(2):213-223
The role of harmful soil organisms in the degeneration ofAmmophila arenaria at coastal foredunes was examined by the growing of seedlings ofA. arenaria in soil samples collected from its root zone. Three sites, each representing a successive stage in foredune succession were
examined: (1) a highly mobile dune (sand accretion of 80 cm year−1) with vigorousA. arenaria, colonizing only the upper 30-cm of the annually deposited layer of sand, (2) a mobile dune with vigorousA. arenaria (sand accretion of 22 cm year−1) and a 1-metre soil profile completely colonized by roots and (3) a stable dune (no sand accretion) with degeneratedA. arenaria and young roots mainly present in the upper 0–10 cm.
In the upper part of the highly mobile site, the presence of harmful soil organisms was confined to the root layers and at
the mobile site for all depth layers a significant growth reduction ofA. arenaria was observed due to the activity of harmful soil organisms. At the stable site, however, growth had only been reduced in
some of the depth layers. At all sites newly formed roots ofA. arenaria had been colonized by harmful soil organisms within one year.
If present in sand prior to root growth harmful soil organisms reduced root length and root hair formation severely and they
enhanced branching of the roots. It is concluded that harmful soil organisms initiate degeneration ofA. arenaria in stable dunes by attack of the root system, which makes the plants suffer from abiotic stress. 相似文献
10.
Differences between growth forms in root responses to experimentally created heterogeneity have been documented in many greenhouse and plot studies, but not in natural vegetation. Here we examined the response of roots to experimental nutrient patches in undisturbed grassland and forest at the northern edge of the North American Great Plains. Forest vegetation increases the spatial heterogeneity of soil resources, and we tested for differences between forest and grassland roots in response to patches. Ten minirhizotrons (clear tubes, 5 cm diameter, 180 cm long) were installed in both grassland and forest 3 years before the experiment. Minirhizotrons ran horizontally 10 cm beneath the soil surface. Patches of available nitrogen (N) were created over the tubes, using three concentrations (0, 3, 15 g N m−2 yr−1) and two patch sizes (1␣and 10 cm2). Root images were collected beneath patches over the course of a growing season. Root length was significantly greater in grassland than forest at the start and end of the growing season, but did not respond to N patches. Root production was also significantly greater in grassland than forest, and was significantly greater (about 20%) in high-N patches than in unfertilized patches. This increase, however, did not differ between vegetation types. Turnover did not vary with any treatment, and patch size had no effect on any response variable. Overall, differences caused by experimental patches were much smaller than differences between habitats, and did not vary between habitats. Realistic levels of experimentally imposed hetereogeneity in established vegetation may not be much greater than background levels, and field vegetation has extant root systems which respond to patches via uptake instead of growth. Both mechanisms should contribute to less root proliferation in field experiments than in greenhouse experiments. 相似文献
11.
The role of roots penetrating various undisturbed soil horizons beneath loose layer in water use and shoot growth of maize
was evaluated in greenhouse experiment. 18 undisturbed soil columns 20 cm in diameter and 20 cm in height were taken from
the depths 30–50 cm and 50–70 cm from a Brown Lowland soil, a Pseudogley and a Brown Andosol (3 columns from each depth and
soil). Initial resistance to penetration in undisturbed soil horizons varied from 2.5 to 8.9 MPa while that in the loose layer
was 0.01 MPa. The undisturbed horizons had a major effect on vertical arrangement of roots. Root length density in loose layer
varied from 96 to 126 km m-3 while in adjacent stronger top layers of undisturbed horizons from 1.6 to 20.0 km m-3 with higher values in upper horizons of each soil. For specific root length, the corresponding ranges were 79.4–107.7 m g-1 (on dry basis) and 38.2–63.7 m g-1, respectively. Ratios of root dry weight per unit volume of soil between loose and adjacent undisturbed layers were much
lower than those of root length density indicating that roots in undisturbed horizons were produced with considerably higher
partition of assimilates. Root size in undisturbed horizons relative to total roots was from 1.1 to 38.1% while water use
from the horizons was from 54.1 to 74.0%. Total water use and shoot growth were positively correlated with root length in
undisturbed soil horizons. There was no correlation between shoot growth and water use from the loose layers. 相似文献
12.
Through use of a recently developed technique that can measure CO2 exchange by individual attached roots, the influences of soil O2 and CO2 concentrations on root respiration were determined for two species of shallow-rooted cacti that typically occur in porous,
well-drained soils. Although soil O2 concentrations in the rooting zone in the field were indistinguishable from that in the ambient air (21% by volume), the
CO2 concentrations 10 cm below the soil surface averaged 540 μLL−1 for the barrel cactusFerocactus acanthodes under dry conditions and 2400 μLL−1 under wet conditions in a loamy sand. For the widely cultivated platyopuntiaOpuntia ficus-indica in a sandy clay loam, the CO2 concentration at 10 cm averaged 1080 μLL−1 under dry conditions and 4170 μLL−1 under wet conditions. For both species, the respiration rate in the laboratory was zero at 0% O2 and increased to its maximum value at 5% O2 for rain roots (roots induced by watering) and 16% O2 for established roots. Established roots ofO. ficus-indica were slightly more tolerant of elevated CO2 than were those ofF. acanthodes, 5000 μLL−1 inhibiting respiration by 35% and 46%, respectively. For both species, root respiration was reduced to zero at 20,000 μLL−1 (2%) CO2. In contrast to the reversible effects of 0% O2, inhibition by 2% CO2 was irreversible and led to the death of cortical cells in established roots in 6 h. Although the restriction of various
cacti and other CAM plants to porous soils has generally been attributed to their requirement for high O2 concentrations, the present results indicate that susceptibility of root respiration to elevated soil CO2 concentrations may be more important. 相似文献
13.
Root Morphology and Anchorage of Six Native Tree Species from a Tropical Montane Forest and an Elfin Forest in Ecuador 总被引:1,自引:1,他引:0
Root architecture of tree species was investigated at two different altitudes in tropical forests in Ecuador. Increasing altitude
was accompanied by higher wind speeds and more shallow soils, while slope angles of both sites were comparable (20–50°). Three
tree species typical for the montane forest at 1900 m (Graffenrieda emarginata (Ruiz & Pav.) Triana (Melastomataceae), Clethra revoluta (Ruiz & Pav.) Spreng. (Clethraceae), Vismia tomentosa Ruiz & Pav. (Clusiaceae)) and for the elfin forest at 3000 m (Weinmannia loxensis Harling (Cunoniaceae), Clusia spec. (Clusiacaea) Styrax foveolaria Perkins (Styraceae)) were examined. At 1900 m, 92% of the trees grew upright, in comparison to 52% at 3000 m. At 3000 m,
48% of the trees were inclined, lying or even partly uprooted. At this altitude, all trees with tap roots or with shoots connected
by coarse rhizomes, 83% of the trees with stilt roots, and 50% of the trees in which stems or roots were supported by other
trees grew upright, suggesting that these characteristics were relevant for tree stability. Root system morphology differed
markedly between altitudes. In contrast to 1900 m, where 20% of structural roots originated in the deeper mineral soil, root
origin at 3000 m was restricted to the forest floor. The mean ratio of root cross sectional area to tree height decreased
significantly from 6.1 × 10−3 m2 m−1 at 1900 m to 3.2 × 10−3 m2 m−1 at 3000 m. The extent of root asymmetry increased significantly from 0.29 at 1900 m to 0.62 at 3000 m. This was accompanied
by a significantly lower number of dominant roots at 3000 m (2.3 compared to 3.8 at 1900 m). In conclusion, native tree species
growing in tropical montane and elfin forests show a variety of root traits that improve tree stability. Root system asymmetry
is less important for tree stability where anchorage is provided by a deep and solid root–soil plate. When deep rooting is
impeded, root traits improving the horizontal extension of the root–soil plate are more pronounced or occur more frequently.
Furthermore, mutual mechanical support of roots and stems of neighboring trees seems to be an appropriate mechanism to provide
anchorage in soils with low bulk density and in environments with high wind speeds. 相似文献
14.
Lars Rytter 《Plant and Soil》1989,119(1):71-79
Development of below-ground biomass and biomass allocation were studied in two different stands of young grey alder stands
growing on a peat bog. Both stands were given the same fertilization and irrigation treatment. The roots were investigated
from 1) open plastic tubes enclosing the complete root systems in 1982, and 2) root cores 1984–86. Coarse roots (diameter>1
mm) were mainly found close to the trunk of the trees while fine roots (≤1 mm) were more evenly distributed in the stands.
Root nodules were intermediate in distribution. The root systems were shallow, with more than 90% of the biomass in the uppermost
9–10 cm of the soil, probably because of low oxygen availability in the peat soil. The biomass allocation to the above-ground
parts increased during the study period. 相似文献
15.
Root growth and water uptake in winter wheat under deficit irrigation 总被引:20,自引:0,他引:20
Root growth is critical for crops to use soil water under water-limited conditions. A field study was conducted to investigate the effect of available soil water on root and shoot growth, and root water uptake in winter wheat (Triticum aestivum L.) under deficit irrigation in a semi-arid environment. Treatments consisted of rainfed, deficit irrigation at different developmental stages, and adequate irrigation. The rainfed plots had the lowest shoot dry weight because available soil water decreased rapidly from booting to late grain filling. For the deficit-irrigation treatments, crops that received irrigation at jointing and booting had higher shoot dry weight than those that received irrigation at anthesis and middle grain filling. Rapid root growth occurred in both rainfed and irrigated crops from floral initiation to anthesis, and maximum rooting depth occurred by booting. Root length density and dry weight decreased after anthesis. From floral initiation to booting, root length density and growth rate were higher in rainfed than in irrigated crops. However, root length density and growth rate were lower in rainfed than in irrigated crops from booting to anthesis. As a result, the difference in root length density between rainfed and irrigated treatments was small during grain filling. The root growth and water use below 1.4 m were limited by a caliche (45% CaCO3) layer at about 1.4 m profile. The mean water uptake rate decreased as available soil water decreased. During grain filling, root water uptake was higher from the irrigated crops than from the rainfed. Irrigation from jointing to anthesis increased seasonal evapotranspiration, grain yield, harvest index and water-use efficiency based on yield (WUE), but did not affect water-use efficiency based on aboveground biomass. There was no significant difference in WUE among irrigation treatments except one-irrigation at middle grain filling. Due to a relatively deep root system in rainfed crops, the higher grain yield and WUE in irrigated crops compared to rainfed crops was not a result of rooting depth or root length density, but increased harvest index, and higher water uptake rate during grain filling. 相似文献
16.
Summary Screening large populations of plant species for Al tolerance requires simple and rapid tests. In this study, root characteristics
of 12 cultivars of triticale (X Triticosecale, Witt Mack), wheat (Triticum aestivum L.), and rye (Secale cereale L.) were measured in nutrient solution with 0 or 6 ppm Al added.
Aluminum injury to roots of triticale and wheat was characterized by decreases in root length, increases in the number of
roots, and in Al-sensitive Redcoat and Arthur wheats by decrease in root weight. Root length and number of roots were correlated
in triticale (r=−0.73*) and in wheat (r=−0.85*). Root length was also correlated with root weight in wheat (r=0.65*); there was no relationship between the number of roots and weight. Differences in Al tolerance of cultivars of the three
species were greater when the solution was adjusted to pH 4.8 only on the first day of the experiment than when pH was maintained
at pH 4.8 throughout the growing period. Triticale and rye cultivars low in ability to increase solution pH gradually overcame
Al toxicity by increasing the nutrient solution pH between 12 and 22 days.
Aluminum sensitive triticale and wheat accumulated more Al in roots than tolerant cultivars when the solution pH was not adjusted
daily; but no differences in Al accumulation were obtained between wheat cultivars at constant pH value. This study indicated
that root length and number of roots can be reliably used for screening triticales for Al tolerance within 12 days of exposure
to Al. Root length, Al concentration, and dry weight after 22 days of Al treatment were also reliable criteria for evaluating
differential Al tolerances among triticale cultivars. 相似文献
17.
Fine root vertical distribution and temporal dynamics in mature stands of two enset (Enset ventricosum Welw Cheesman) clones 总被引:2,自引:0,他引:2
Quantification of the role of fine roots in the biological cycle of nutrients necessitates understanding root distribution,
estimating root biomass, turnover rate and nutrient concentrations, and the dynamics of these parameters in perennial systems.
Temporal dynamics, vertical distribution, annual production and turnover, and nitrogen use of fine roots (≤2 mm in diameter)
were studied in mature (5-year-old) stands of two enset (Ensete ventricosum) clones using the in-growth bag technique. Live fine root mass generally decreased with increasing depth across all seasons
except the dry period. Except for the dry period, more than 70% of the fine root mass was in the above 0-20 cm depth, and
the fine root mass in the upper 0–10 cm depth was significantly higher than in the lowest depth (20–30 cm). Live fine root
mass showed a seasonal peak at the end of the major rainy season but fell to its lowest value during the dry or short rainy
season. The difference between the peak and low periods were significant (p ≤ 0.05). Fine root nitrogen (N) use showed significant seasonal variation where the mean monthly fine root N use was highest
during the major rainy season. There were significant effects on N use due to depths and in-growth periods, but not due to
clones. Enset fine root production and turnover ranged from 2,339 to 2,451 kg ha−1 year−1 and from 1.55 to 1.80 year−1, respectively. Root N return, calculated from fine root turnover, was estimated at 64–65 kg ha−1 year−1. Fine root production, vertical distribution and temporal dynamics may be related to moisture variations and nutrient (N)
fluxes among seasons and along the soil depth. The study showed that fine root production and turnover can contribute considerably
to the carbon and nitrogen economy of mature enset plots. 相似文献
18.
Summary Few studies have focused on the effect of a broad range of phytohormones on growth and secondary metabolism of a single hairy
root species. We measured growth, development, and production of the antimalarial drug, artemisinin, in Artemisia annua hairy roots in response to the five main hormones: auxins, cytokinins, ethylene, gibberellins (GA), and abscisic acid (ABA).
Single roots grown in six-well plates in medium B5 with 0.01 mgl−1 (0.029 μM) GA3 produced the highest values overall in terms of the number of lateral roots, length of the primary root, lateral root tip
density, total lateral root length, and total root length. When the total root lengths are compared, the best conditions for
stimulating elongation appear to be: GA 0.01 mgl−1 (0.029μM)> ABA 1.0 mgl−1 (3.78μM)=GA 0.02 mgl−1 (0.058μM). Bulk yields of biomass were inversely proportional to the concentration of each hormone tested. All cultures provided with
ABA yielded the highest amount of biomass. Both 6-benzylaminopurine and 2-isopentenyladenine inhibited root growth, however,
only 2-isopentenyladenine stimulated artemisinin production, more than twice that of the B5 controls, and more than any other
hormone studied. These results will prove useful in increasing hairy root growth and artemisinin production. 相似文献
19.
Rui M.A. Machado Maria do Rosário G. Oliveira Carlos A. M. Portas 《Plant and Soil》2003,255(1):333-341
Tomato rooting patterns were evaluated in a 2-year field trial where surface drip irrigation (R0) was compared with subsurface drip irrigation at 20 cm (RI) and 40 cm (RII) depths. Pot-transplanted plants of two processing tomato, `Brigade' (C1) and `H3044' (C2), were used. The behaviour of the root system in response to different irrigation treatments was evaluated through minirhizotrons installed between two plants, in proximity of the plant row. Root length intensity (L
a), length of root per unit of minirhizotron surface area (cm cm–2) was measured at blooming stage and at harvest. For all sampling dates the depth of the drip irrigation tube, the cultivar and the interaction between treatments did not significantly influence L
a. However differences between irrigation treatments were observed as root distribution along the soil profile and a large concentration of roots at the depth of the irrigation tubes was found. For both surface and subsurface drip irrigation and for both cultivars most of the root system was concentrated in the top 40 cm of the soil profile, where root length density ranged between 0.5 and 1.5 cm cm–3. Commercial yields (t ha–1) were 87.6 and 114.2 (R0), 107.5 and 128.1 (RI), 105.0 and 124.8 (RII), for 1997 and 1998, respectively. Differences between the 2 years may be attributed to different climatic conditions. In the second year, although no significant differences were found among treatments, slightly higher values were observed with irrigation tubes at 20 cm depth. Fruit quality was not significantly affected by treatments or by the interaction between irrigation tube depth and cultivar. 相似文献
20.
Summary Callus induction and later plant regeneration were studied in four widely grown garlic (Allium sativum L.) cultivars from Europe. Root segments from in vitro plantlets were used as starting material. In addition to cultivar effects, the effects of auxin and cytokinin levels and
the position of the segments on the root were studied. There were no statistically significant differences among cultivars
for the number of root segments that induced callus in the two series of experiments. The average induction frequency was
34.7% in the first series of experiments. Callus induction on apical root segments was significantly higher compared to callus
induction on non-apical root segments in the second series of experiments. Two months after callus induction, callus lines
were transferred to a regeneration medium consisting of Murashige and Skoog basal medium supplemented with 30gl−1 sucrose and 1 mgl−1 (4.6μM) kinetin. Calluses derived from different experiments were quite uniform with respect to their regeneration potential. Also
it was found that our regeneration system was cultivar-independent. The average shoot regeneration frequency was 17.9% in
the first series of experiments. Highly significant differences were found in the frequency of shoot regeneration among different
callus induction treatments. When the cytokinin 6-(γ,γ-dimethylallylamino)purine (0.1mgl−1∶0.5 μM) was present during callus induction, shoot regeneration ranged from 30.10 to 47.60%. Shoot regeneration from callus induced
on non-apical segments was higher, although not significant, compared to callus induction from apical root segments in the
second series of experiments. All in all, an efficient callus induction and plant regeneration system was developed from both
apical and non-apical segments taken along the entire length of the roots. This system has potential to be used for garlic
transformation. 相似文献