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1.
A significant proportion of arable land in south-western Australia is highly susceptible to subsoil compaction, which limits access of roots of wheat to water and nutrients at depth. Genotypic variation in the ability of roots to penetrate a hardpan has been reported for other cereals, using a pot technique, where a thin wax-layer of paraffin wax and petroleum jelly is placed in a soil column to simulate a hardpan. Previously we have modified and validated this technique for measuring root penetration ability of wheat seedlings under contrasting water regimes. Here we report on a series of five experiments (runs), two in well-watered and three in drought stress conditions, which evaluated seminal and nodal root penetration ability through thin wax layers among 24 Australian wheat cultivars and breeding lines (entries). These results were compared with observations on their rooting depths in two contrasting soil types in field trials, including a sandy duplex that contained a hardpan and a red clay that increased in soil strength with depth. Nodal roots ceased growth early under soil water deficit, and water uptake was instead dependant on seminal roots under conditions imposed in the pots. Plants were then reliant on the ability of seminal roots to penetrate the wax layer. Eight entries had superior root penetration ability in both well-watered and drought stressed conditions. Roots of three other entries, which failed to penetrate the wax layers, died under drought stress conditions. In field trials, there was a significant interaction between site and entry for maximum root depth. Our results from the pot studies and field trials indicate that there exists genotypic variation in root traits that are required to penetrate uniformly hard soil, dry soil or soil containing a hardpan. As four of the eight superior entries also showed superior root penetration ability at both sites in the field, there was an overall consistency, but there were exceptions at individual field sites. Factors likely to result in such exceptions were discussed, and topics for further research identified.  相似文献   

2.
Clark  L.J.  Aphalé  S.L.  Barraclough  P.B. 《Plant and Soil》2000,219(1-2):187-196
The development of a wax layer method for screening the ability of rice (Oryza sativa L.) roots to overcome mechanical impedance is described. Wax layers (3 mm thick) made of mixtures of white soft paraffin and paraffin wax were installed 50 mm deep in tubes of sand. The sand was watered with nutrient solution and planted with 3-d old rice seedlings. The numbers of root axes per plant that had penetrated the wax layers 24 d after planting were counted. The ratio of penetrated to total root axes per plant gave a misleading measure of root penetration ability, as rice varieties differed in the ratio of penetrated to total axes in a low impedance (3% wax) control. In non-flooded conditions, a 60% wax layer decreased root penetration (number of roots penetrating the wax layer per plant) to a mean of 74% of the low impedance control, whereas an 80% wax layer decreased mean root penetration to 31% of the control. The best measure of root penetration in non-flooded conditions was the number of axes penetrating an 80% wax layer. Flooding decreased root penetration of a 60% wax layer to a mean of 26% of the low impedance control. The best measure of root penetration in flooded conditions was the number of axes penetrating a 60% wax layer.  相似文献   

3.
Terry, P. H., Krizek, D. T. and Mirecki, R. M. 1988. Genotypic variation in coleus in the ability to accumulate abscisic acid in response to water deficit. - Physiol. Plant. 72: 441–449.
Abscisic acid (ABA) concentration and plant and soil water potentials were determined in leaves of three cultivars of Coleus blumei Benth. cvs. Marty, Buckley Supreme and PI354190, chosen for their differences in sensitivity to drought, SO2 and/or chilling stress. Plants were subjected to 'gradual' soil moisture stress (SMS) for 0–6 days, during which time the soil dried out slowly and to more 'rapid' SMS for 0–9 days where the soil dried out at a faster rate. Plants were propagated from clonal stock in the greenhouse and transferred to the growth chamber, where they were maintained for 1 week prior to beginning water stress treatment. ABA concentration was determined as the methyl ester using a gas chromatography - electron capture detector method. Samples for ABA determinations were taken from the third pair of leaves from the apex at the same time each day (1430 h). Measurements of stomatal conductance (C5) and leaf water potential (φl) were made on the fourth pair of leaves from the apex, using the same plants as those sampled for ABA. During the more rapid stress portion of the study soil matric potentials (φm) were monitored on a daily basis. Despite large cultivar differences in ABA concentration at 0–6 days, by 7–9 days these differences had largely disappeared. Except for drought-insensitive cv. Marty, there was generally little correlation between ABA levels and measurements of plant and soil water status at 7–9 days.  相似文献   

4.
The ability of two laboratory screening techniques to predict the abilities of roots of eight crop species to penetrate a compacted soil were evaluated and compared in a field experiment. A soil tilled to remove the effects of mechanical resistance was planted with the same species to serve as a control. Depth of root penetration, root density and the influence of the roots on the sorptivity of water were measured.Roots of all species penetrated deeper in the deep tilled than compacted soils. There were differences in the ability of roots of the species to penetrate the compacted soil. Generally dicotyledonous species had more roots penetrating to depth in both the compact and deep tilled soils. Within the main species classifications, lupin and safflower (dicotyledons) and oats and barley (monocotyledons) had the highest penetration into the compacted soil.Water sorptivities in the deep tilled soils were higher than those of the compact soil. Soil from planted treatments had higher sorptivities than soil which had not been planted. This is attributed to biopores left by the roots. Sorptivities of soils which had dicotyledonous species were generally higher than those of monocotyledons. The soil planted with safflower produced the highest sorptivity in the compacted layer (0.1–0.3 m).A comparison of the accuracy of the two laboratory screening methods in predicting the field penetration of roots suggest that the method involving mechanical stress was better than that involving osmotic stress. Relative root diameter was found to be a better indicator of the penetration ability of roots than relative root elongation.  相似文献   

5.
The response of anthers to in vitro culture and the effect of coculture of ovaries on anther culturability have been studied in responsive and recalcitrant cultivars of durum wheat (Triticum turgidum ssp. durum) from Morocco and ICARDA. A large genotypic-dependence of anther culture has been shown in 18 cultivars. Their response in term of callus and embryo induction varied from 0 to 13%. Coculture of ovaries with anthers enhanced the response of the most responsive genotype (cv. Sarif) and removed the recalcitrance in Cocorit and Isly cultivars. However, there was no effect of anther-ovary coculture on green plant regeneration. The implication of the genome and the media conditioning by the ovaries on anther response is discussed. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

6.
The penetration ability of four physical variables whose value in the undisturbed atmosphere is influenced by meteorological processes and which have repeatedly been mentioned in biometeorological studies has been investigated. Ion concentration, sferics, pressure fluctuations, and temperature fluctuations were simultaneously recorded outside and inside buildings. Measurements were made in a classical wood/brick house as well as in a fully airconditioned reinforced concrete/glass construction. It was found that pressure fluctuations with periods longer than one minute penetrate the buildings practically unchanged while sferics (measured at a frequency of 10 kHz) are attenuated. The attenuation depends strongly on the construction type. The concentration of ions and the temperature fluctuations inside buildings are independant of their respective values in the atmosphere. Their value is determined only by local activity such as smoking, open windows, heaters, or the presence of persons.  相似文献   

7.
8.
Bingham  I.J.  Bengough  A.G. 《Plant and Soil》2003,250(2):273-282
Root systems of individual crop plants may encounter large variations in mechanical impedance to root penetration. Split-root experiments were conducted to compare the effects of spatial variation in soil strength on the morphological plasticity of wheat and barley roots, and its relationship to shoot growth. Plants of spring barley (Hordeum vulgare cv Prisma) and spring wheat (Triticum aestivum cv Alexandria) were grown for 12 days with their seminal roots divided between two halves of a cylinder packed with sandy loam soil. Three treatment combinations were imposed: loose soil where both halves of the cylinder were packed to 1.1 g cm–3 (penetrometer resistance 0.3 MPa), dense soil where both halves were packed to 1.4 g cm–3 (penetrometer resistance 1 MPa), and a split-root treatment where one half was packed to 1.1 and the other to 1.4 g cm–3. In barley, uniform high soil strength restricted the extension of main seminal root axes more than laterals. In the split-root treatment, the length of laterals and the dry weight of main axes and laterals were increased in the loose soil half and reduced in the dense soil half compared with their respective loose and dense-soil controls. No such compensatory adjustments between main axis and laterals and between individual seminal roots were found in wheat. Variation in soil strength had no effect on the density of lateral roots (number per unit main axis length) in either barley or wheat. The nature and extent of wheat root plasticity in response to variation in soil strength was very different from that in response to changes in N-supply in previous experiments. In spite of the compensatory adjustments in growth between individual seminal roots of barley, the growth of barley shoots, as in wheat, was reduced when part of the root system was in compacted soil.  相似文献   

9.
n-Alkanes, esters, aldehydes, free alcohols, -diketones and hydroxy--diketones were found to be the lipid components of the cuticular waxes of common wheat Chinese Spring (Triticum aestivum L.). The ditelosomic lines 7A-L and 7D-S showed a dramatic decrease in the amount of -diketones and hydroxy -diketones which are reduced to traces. The homologue composition within each class of compounds has also been determined for all three of the lines of wheat. The effects of chromosomal deficiencies have been demonstrated. Chromatographic techniques and mass spectrometry have been used for the separation and identification of the substances which compose the waxes. This study has provided further evidence of the role of genes situated on well defined chromosomes in determining the nature of classes of compounds composing wax and governing the homologous composition within each class of substances.  相似文献   

10.
H Ozkan  M Feldman 《Génome》2001,44(6):1000-1006
The Ph1 gene has long been considered the main factor responsible for the diploid-like meiotic behavior of polyploid wheat. This dominant gene, located on the long arm of chromosome 5B (5BL), suppresses pairing of homoeologous chromosomes in polyploid wheat and in their hybrids with related species. Here we report on the discovery of genotypic variation among tetraploid wheats in the control of homoeologous pairing. Compared with the level of homoeologous pairing in hybrids between Aegilops peregrina and the bread wheat cultivar Chinese Spring (CS), significantly higher levels of homoeologous pairing were obtained in hybrids between Ae. peregrina and CS substitution lines in which chromosome 5B of CS was replaced by either 5B of Triticum turgidum ssp. dicoccoides line 09 (TTD09) or 5G of Triticum timopheevii ssp. timopheevii line 01 (TIMO1). Similarly, a higher level of homoeologous pairing was found in the hybrid between Ae. peregrina and a substitution line of CS in which chromosome arm 5BL of line TTD140 substituted for 5BL of CS. It appears that the observed effect on the level of pairing is exerted by chromosome arm 5BL of T turgidum ssp. dicoccoides, most probably by an allele of Ph1. Searching for variation in the control of homoeologous pairing among lines of wild tetraploid wheat, either T turgidum ssp. dicoccoides or T timopheevii ssp. armeniacum, showed that hybrids between Ae. peregrina and lines of these two wild wheats exhibited three different levels of homoeologous pairing: low, low intermediate, and high intermediate. The low-intermediate and high-intermediate genotypes may possess weak alleles of Ph1. The three different T turgidum ssp. dicoccoides pairing genotypes were collected from different geographical regions in Israel, indicating that this trait may have an adaptive value. The availability of allelic variation at the Ph1 locus may facilitate the mapping, tagging, and eventually the isolation of this important gene.  相似文献   

11.
12.
Genotypic variation in response of barley to boron deficiency   总被引:2,自引:0,他引:2  
Responses of a range of barley (Hordeum vulgare L.) genotypes to boron (B) deficiency were studied in two experiments carried out in sand culture and in the field at Chiang Mai, Thailand. In experiment 1, two barley genotypes, Stirling (two-row) and BRB 2 (six-row) and one wheat (Triticum aestivum L.) genotype, SW 41, were evaluated in sand culture with three levels of applied B (0, 0.1 and 1.0 μM B) to the nutrient solution. It was found that B deficiency depressed flag leaf B concentration at booting, grain number and grain yield of all genotypes. In barley Stirling, B deficiency also depressed number of spikes plant-1, spikelets spike-1 and straw yield. However, no significant difference between genotypes in flag leaf B concentration was found under low B treatments. Flag leaf B concentration below 4 mg kg-1 was associated with grain set reduction and could, therefore, be used as a general indicator for B status in barley. In experiment 2, nine barley and two wheat genotypes were evaluated in the field on a low B soil with three levels of B. Boron levels were varied by applying either 2 t of lime ha-1 (BL), no B (B0) or 10 kg Borax ha-1 (B+) to the soil prior to sowing. Genotypes differed in their B response for grain spike-1, grain spikelet-1 and grain set index (GSI). The GSI of the B efficient wheat, Fang 60, exceeded 90% in all B treatments. The B inefficient wheat SW 41 and most of the barley genotypes set grain normally (GSI >80%) only at the B+. In B0 GSI of the barley genotypes ranged from 23% to 84%, and in BL from 19% to 65%. Three of the barley with severely depressed GSI in B0 and BL also had a decreased number of spikelets spike-1. In experiment 3, 21 advanced barley lines from the Barley Thailand Yield Nursery 1997/98 (BTYN 1997/98) were screened for B response in sand culture with no added B. Grain Set Index of the Fang 60 and SW 41 checks were 98 and 65%, respectively, and GSI of barley lines ranged between 5 and 90%. One advanced line was identified as B efficient and two as moderately B efficient. The remaining lines ranked between moderately inefficient to inefficient. These experiments have established that there is a range of responses to B in barley genotypes. This variation in the B response was observed in vegetative as well as reproductive growth. Boron efficiency should be considered in breeding and selection of barley in low B soils. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

13.
14.
Genotypic variation in carboxylation of tomatoes   总被引:8,自引:6,他引:2       下载免费PDF全文
The gas exchange characteristics of 24 genotypes of Lycopersicon esculentum Mill. and one of L. minutum were measured with an infrared gas analyzer and dew point hygrometer in an open system. Net carbon exchange (NCE) and transpiration rate were measured at 50, 100, 150, and 300 μ1 1−1 CO2, and a regression of NCE versus internal lead [CO2] estimates was calculated. The slope of the regression curve at the CO2 compensation point was used as the measure of carboxylation efficiency (CE). Significant genotypic differences for CE were obtained. Differences in CE did not appear to be due to differences in diffusive resistance defined as the sum of the boundary layer resistance (ra) and the stomatal plus cuticular resistance (r1). There was no correlation (r = -0.07) between (ra + r1) and CE. Within groups with nonsignificantly different means for (ra + r1) there were genotypes with extremes for CE.  相似文献   

15.
Horst  W. J.  Abdou  M.  Wiesler  F. 《Plant and Soil》1993,155(1):293-296
In an attempt to evaluate whether breeding and selection for high yielding capacity did change the P requirements of modern wheat cultivars, the response of two wheat cultivars to different levels of P supply was investigated. A traditional cultivar ("Peragis") and a modern cultivar ("Cosir") were cultivated in a C-loess low in available P and high in CaCO3 in 120 cm high PVC pots. Shoot and root growth at different developmental stages was compared. The grain yield of the modern cultivar Cosir was higher at limiting and non-limiting P supply and, therefore, this cultivar can be considered as more P-efficient than the traditional cultivar. From the results it can be concluded that the main factors contributing to the higher P efficiency of the modern cultivar are (i) efficient use of assimilates for root growth characteristics which enhance P acquisition: smaller root diameter, and longer root hairs, (ii) efficient remobilization of P from vegetative plant organs to the grains, and (iii) lower P requirement for grain yield formation because of lower ear number per plant but higher grain number per ear.  相似文献   

16.
Genotypic variation of the response to cadmium toxicity in Pisum sativum L   总被引:13,自引:0,他引:13  
This work evaluates the (cor-)relations between selected biochemical responses to toxic Cd and the degree of Cd sensitivity in a set of pea genotypes. Ten genotypes were analysed that differ in their growth response to Cd when expressed as root or shoot tolerance indices (TIs). Concentrations of non-protein thiols (NPTs) and malondialdehyde (MDA), activity of chitinase, peroxidase (POX), and catalase significantly increased in all pea genotypes treated with Cd. Cd-sensitivity of genotypes was correlated with relative increases in MDA concentration as well as activities of chitinase and POX, suggesting similar Cd stress effects. Activities of ascorbate peroxidase (APX) decreased, but concentrations of glutathione (GSH) increased in the less Cd-sensitive genotypes. Differences in root and leaf contents of Cd revealed no correlation with TI, metabolic parameters, and enzyme activities in Cd-treated plants, respectively, except that shoot Cd concentration positively correlated with shoot chitinase activity. Toxic Cd levels inhibited uptake of nutrient elements such as P, K, S, Ca, Zn, Mn, and B by plants in an organ- and genotype-specific manner. Cd-sensitivity was significantly correlated with decreased root Zn concentrations. The results show both similarities, as well as distinct features, in Cd toxicity expression in genotypes of one species, suggesting that independent and multi-factorial reactions modulate Cd sensitivity on the low-tolerance level of plants. The study illustrates the biochemical basis of earlier detected genotypic variation in Cd response.  相似文献   

17.
Phenotypes respond to environments experienced directly by an individual, via phenotypic plasticity, or to the environment experienced by ancestors, via transgenerational environmental effects. The adaptive value of environmental effects depends not only on the strength and direction of the induced response but also on how long the response persists within and across generations, and how stably it is expressed across environments that are encountered subsequently. Little is known about the genetic basis of those distinct components, or even whether they exhibit genetic variation. We tested for genetic differences in the inducibility, temporal persistence, and environmental stability of transgenerational environmental effects in Arabidopsis thaliana. Genetic variation existed in the inducibility of transgenerational effects on traits expressed across the life cycle. Surprisingly, the persistence of transgenerational effects into the third generation was uncorrelated with their induction in the second generation. Although environmental effects for some traits in some genotypes weakened over successive generations, others were stronger or even in the opposite direction in more distant generations. Therefore, transgenerational effects in more distant generations are not merely caused by the retention or dissipation of those expressed in prior generations, but they may be genetically independent traits with the potential to evolve independently.  相似文献   

18.
Several methods of NA isolation and estimation were examined in order to determine RNA in the whole root systems of young wheat plants. It was found out that during the hydrolysis of roots with perchloric acid according toOgur andRosen (1950),Spirin (1958) andHeitefuss (1965) a considerable amount of orcine-positive compounds is released which cannot be adequate to the RNA content. Therefore the separate RNA determination in the presence of DNA was excluded even after the NA fractionation by hydrolysis at various temperature and perchloric acid concentration. Besides NA hydrolysates contained a high amount of other compounds absorbing in the UV-region. Compounds interfering with both these methods were present especially in the basal parts of roots. Using the method ofKern (1960) a nucleoprotein fraction was isolated containing about 75 per cent of the total NA content in the tissue. This fraction consisted of more than 90 per cent RNA combined with proteins, namely the ribosomal RNA. After the hydrolysis it could be estimated spectrophotometrically for the hydrolysate did not contain other compounds absorbing in the UV-region. In the root tips the content of this fraction was high in comparison with the basal parts of roots and it changed with the kind of nutrition.  相似文献   

19.
Genetic variation in the drought response of leaf and root tissue water relations of seedlings of eight sources of black walnut ( Juglans nigra L.) was investigated using the pressure-volume technique. Tissue water relations were characterized at three stages of a drying cycle during which well-watered plants were allowed to desiccate and then were reirrigated.
Sources varied both in the capacity for and degree of leaf and root osmotic adjustment, and in the mechanism by which it was achieved. A decrease in osmotic potential at the turgor loss point (ψπp) of 0.4 MPa was attributable to increased leaf tissue elasticity in seedlings of four sources, while seedlings of an Ontario source exhibited a 0.7–0.8 MPa decline in ψπp as a result of both increased solute content and increased leaf tissue elasticity. Seedlings of a New York source showed no detectable osmotic adjustment.
In roots, decreased ψπp (osmotic potential at full hydration) and ψπp were observed under drought. Sources that exhibited significant leaf osmotic adjustment also generally showed a similar response in roots. Tissue elasticity and ψπp of roots were higher than those of shoots, whereas ψπp of the two organs was similar for most sources. Because of greater elasticity, roots exhibited a more gradual decline in turgor and total water potential than did leaves as tissue relative water content decreased.  相似文献   

20.
《Theriogenology》2010,73(9):1171-1179
The penetration ability of boar (Sus scrofa domestica) spermatozoa exposed to viscous preparations under in vivo and in vitro fertilization conditions has been examined. Experiments involving induced ovulation in prepubertal animals and surgical insemination directly into the oviduct isthmus revealed an advantage of colloidal preparations. Based on within-animal comparisons, the incidence of penetration was 100% using both spermatozoa suspended in a viscous preparation of plant extracts and spermatozoa suspended in a control medium. However, percentages of monospermy were 22.2% in 54 oocytes inseminated with the control suspension compared with 62.5% in 48 oocytes inseminated with the colloidal preparation. An in vitro study involving 355 oocytes from slaughterhouse ovaries inseminated with in vitro–capacitated spermatozoa gave similar percentages of penetrated oocytes for both the control and colloidal suspensions. In this case, however, the percentage of monospermy was 32.7% in the control group compared with 10.6% for spermatozoa suspended in the colloidal preparation. Higher mean numbers of sperm inside the oocytes and higher numbers of sperm bound to the zona pellucida were also observed with the colloidal suspensions. In vitro motility and viability for spermatozoa in the colloidal suspensions were enhanced compared with that of the control group. Lower sperm membrane lipid disorder and reactive oxygen species generation were also observed in the viscous solution. These findings suggest that viscous fluids can enhance the ability of sperm to move, bind, and penetrate the oocyte in vitro, although this influence may be masked in vivo due to the already high viscosity in the oviductal fluid close to the time of ovulation.  相似文献   

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