Pub Date : 1999-01-01DOI: 10.1080/02571862.1999.10634851
W. Boshoff, Z. Pretorius, W. Swart
The objectives of this study were to compare the infection of wheat heads by Fusarium graminearum and F. crookwellense and to determine the effect of temperature on head blight development induced by these species. Scanning electron microscopy of spikes of the wheat cv. Palmiet revealed no differences in the infection process between F. graminearum and F. crookwellense. In glasshouse experiments, F. graminearumwas more pathogenic than F. crookwellense at constant ± 22°C and ± 24.6°C, whereas F. crookwellense was more pathogenic at ± 13.8X. Both species caused more severe head blight at 22°C and 24.6°C than at 13.8°C.
{"title":"A comparison of head infection and blight development caused by Fusarium graminearum and Fusarium crookwellense in wheat","authors":"W. Boshoff, Z. Pretorius, W. Swart","doi":"10.1080/02571862.1999.10634851","DOIUrl":"https://doi.org/10.1080/02571862.1999.10634851","url":null,"abstract":"The objectives of this study were to compare the infection of wheat heads by Fusarium graminearum and F. crookwellense and to determine the effect of temperature on head blight development induced by these species. Scanning electron microscopy of spikes of the wheat cv. Palmiet revealed no differences in the infection process between F. graminearum and F. crookwellense. In glasshouse experiments, F. graminearumwas more pathogenic than F. crookwellense at constant ± 22°C and ± 24.6°C, whereas F. crookwellense was more pathogenic at ± 13.8X. Both species caused more severe head blight at 22°C and 24.6°C than at 13.8°C.","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"117 1","pages":"79-84"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81002530","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-01-01DOI: 10.1080/02571862.1999.10634848
A. Nel, H. Loubser, P. Hammes
Die voginhoud van sonneblomsaad (Helianthus annuns L.) wat vir persing gebruik word, wissel tussen 5.5% (ongeveer die laagste inhoud waartoe saad natuurlik droog) en 10% (die hoogste toelaatbare inhoud vir berging). Die doel van die ondersoek was om vas te stel hoe die voginhoud van twee saadmonsters wat natuurlik droog die dopbaarheid beinvloed, met die spoed van die dopper gestel vir minimalisering van ongedopte saad plus fynmateriaal. Die saad van twee kultivars wat by Heilbron gedurende 1996/97 gekweek is, is gebruik. Die saad is gelaat om natuurlik te droog en ontdopping is met tussenposes met 'n laboratoriumdopper uitgevoer. Die resultate toon dat droer saad 'n laer dopperspoed as natter saad vereis. Dopbaarheid het van 88 tot 95% toegeneem met 'n saadvogafname van 9.5 tot 5.7%. Terselfdertyd het die produksie van fynmateriaal, wat 'n verlies aan olie en protei'en meebring, vir die twee monsters verskillend toegeneem. Indien die verlies van fynmateriaal voorkom kan word, sal ontdopping die hoogste w...
{"title":"Die invloed van die voginhoud op die dopbaarheid van sonneblomsaad","authors":"A. Nel, H. Loubser, P. Hammes","doi":"10.1080/02571862.1999.10634848","DOIUrl":"https://doi.org/10.1080/02571862.1999.10634848","url":null,"abstract":"Die voginhoud van sonneblomsaad (Helianthus annuns L.) wat vir persing gebruik word, wissel tussen 5.5% (ongeveer die laagste inhoud waartoe saad natuurlik droog) en 10% (die hoogste toelaatbare inhoud vir berging). Die doel van die ondersoek was om vas te stel hoe die voginhoud van twee saadmonsters wat natuurlik droog die dopbaarheid beinvloed, met die spoed van die dopper gestel vir minimalisering van ongedopte saad plus fynmateriaal. Die saad van twee kultivars wat by Heilbron gedurende 1996/97 gekweek is, is gebruik. Die saad is gelaat om natuurlik te droog en ontdopping is met tussenposes met 'n laboratoriumdopper uitgevoer. Die resultate toon dat droer saad 'n laer dopperspoed as natter saad vereis. Dopbaarheid het van 88 tot 95% toegeneem met 'n saadvogafname van 9.5 tot 5.7%. Terselfdertyd het die produksie van fynmateriaal, wat 'n verlies aan olie en protei'en meebring, vir die twee monsters verskillend toegeneem. Indien die verlies van fynmateriaal voorkom kan word, sal ontdopping die hoogste w...","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"372 1","pages":"64-68"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80494154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-01-01DOI: 10.1080/02571862.1999.10634997
V. Tolmay, C. S. Deventer, M. Westhuizen
The Russian wheat aphid, Diuraphis noxia, is a serious pest of wheat grown in the summer rainfall regions of South Africa. The use of D. noxia resistant cultivars may reduce the impact of this pest on cereal production, at the same time reducing environmental risks and minimizing control costs. The objective of the study was to determine the inheritance of D. noxia resistance present in the lines OSU ID 2808 (Triticum aestivum) and Aus 22498 (Triticum aestivum var. vavilovi) in order to ensure their judicious use in a backcross breeding programme. Resistant lines OSU ID 2808 and Aus 22498 were crossed with the susceptible cultivar Tugela after being screened with D. noxia. Resistance reactions of the F1, BC1 and F2 plants, and individual F2 plant derived F3 families indicated that the resistance in both genotypes is controlled by single dominant genes. It is unknown whether these genes are identical to any known, designated resistance genes or each other. In Suid-Afrika is die Russiese koringluis, Diuraph...
俄罗斯小麦蚜虫，Diuraphis noxia，是南非夏季降雨地区小麦的一种严重害虫。使用抗稻瘟病的品种可以减少稻瘟病对谷物生产的影响，同时降低环境风险并最大限度地降低防治成本。本研究的目的是确定OSU ID 2808(小麦)和Aus 22498(小麦)的抗赤霉病遗传，以确保它们在回交育种计划中的明智使用。将抗性品系OSU ID 2808和aus22498与感病品种土格拉进行杂交。F1、BC1和F2植株以及F2植株衍生F3家族的抗性反应表明，两种基因型的抗性均受单显性基因控制。目前尚不清楚这些基因是否与任何已知的指定抗性基因相同或彼此相同。在苏德-非洲，有俄罗斯人、俄罗斯人、俄罗斯人……
{"title":"Inheritance of resistance to Russian wheat aphid, Diuraphis noxia (Homoptera: Aphididae) in two wheat lines","authors":"V. Tolmay, C. S. Deventer, M. Westhuizen","doi":"10.1080/02571862.1999.10634997","DOIUrl":"https://doi.org/10.1080/02571862.1999.10634997","url":null,"abstract":"The Russian wheat aphid, Diuraphis noxia, is a serious pest of wheat grown in the summer rainfall regions of South Africa. The use of D. noxia resistant cultivars may reduce the impact of this pest on cereal production, at the same time reducing environmental risks and minimizing control costs. The objective of the study was to determine the inheritance of D. noxia resistance present in the lines OSU ID 2808 (Triticum aestivum) and Aus 22498 (Triticum aestivum var. vavilovi) in order to ensure their judicious use in a backcross breeding programme. Resistant lines OSU ID 2808 and Aus 22498 were crossed with the susceptible cultivar Tugela after being screened with D. noxia. Resistance reactions of the F1, BC1 and F2 plants, and individual F2 plant derived F3 families indicated that the resistance in both genotypes is controlled by single dominant genes. It is unknown whether these genes are identical to any known, designated resistance genes or each other. In Suid-Afrika is die Russiese koringluis, Diuraph...","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"20 1","pages":"127-130"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86476013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-01-01DOI: 10.1080/02571862.1999.10635004
M. I. Ferreira, C. Reinhardt
Information on the temperature requirements for germination of weed seeds can be used to predict the soil temperature required for weed emergence. The germination behaviour of the two types of mature C. benghalensis seeds, ie. subterranean and aerial, were studied to establish whether differences in seed germination provide these plants with an apparent competitive advantage over other weed species. Seeds of aerial and subterranean types were placed separately on germination towels and put inside plastic bags. The subterranean seeds germinated significantly faster than the aerial seeds, indicating greater thermal sensitivity of the former type of seed. The dormancy displayed by aerial seeds could inter alia be attributed to delayed germination and not to loss of viability. The optimum germination temperature for subterranean seeds was 21/28°C, and for aerial seeds 18/25°C. This broad adaptability may require continuous C. benghalensis management efforts and supports the need for an effective residual herb...
{"title":"The role of temperature in the germination of subterranean and aerial seeds of Commelina benghalensis L.","authors":"M. I. Ferreira, C. Reinhardt","doi":"10.1080/02571862.1999.10635004","DOIUrl":"https://doi.org/10.1080/02571862.1999.10635004","url":null,"abstract":"Information on the temperature requirements for germination of weed seeds can be used to predict the soil temperature required for weed emergence. The germination behaviour of the two types of mature C. benghalensis seeds, ie. subterranean and aerial, were studied to establish whether differences in seed germination provide these plants with an apparent competitive advantage over other weed species. Seeds of aerial and subterranean types were placed separately on germination towels and put inside plastic bags. The subterranean seeds germinated significantly faster than the aerial seeds, indicating greater thermal sensitivity of the former type of seed. The dormancy displayed by aerial seeds could inter alia be attributed to delayed germination and not to loss of viability. The optimum germination temperature for subterranean seeds was 21/28°C, and for aerial seeds 18/25°C. This broad adaptability may require continuous C. benghalensis management efforts and supports the need for an effective residual herb...","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"137 1","pages":"165-168"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86198206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-01-01DOI: 10.1080/02571862.1999.10634844
L. Rensburg, J. Peacock, G. Krüger
Although numerous studies, both phenomenological and mathematical, have related gaseous interchanges at the plant leaf surface and atmospheric interface specifically with regard to drought tolerance, the important role of trichomes and the boundary layer has not been recognized. In this investigation the focus was restricted to the role of the boundary layer along with stomatal geometry and -spacing in determining the diffusional resistance to CO2 and H2O in four Nicotiana tabacum L. cultivars of different, but known, drought tolerance. Resistances were expressed both in terms of resistance components on a unit leaf area basis and in terms of dimensionless quantities. The abaxial leaf surface had the highest trichome frequency, more so in the drought tolerant than in the drought sensitive cultivars, being 9.7% and 6.9% higher than on the adaxial surface for TL33 and CDL28, as opposed to being 21.2% and 26.8% higher for GS46 and Elsoma, respectively. The frequency of the long glandular trichomes of epiderm...
{"title":"Boundary layer, stomatal geometry and -spacing, in relation to drought tolerance in four Nicotiana tabacum L. cultivars","authors":"L. Rensburg, J. Peacock, G. Krüger","doi":"10.1080/02571862.1999.10634844","DOIUrl":"https://doi.org/10.1080/02571862.1999.10634844","url":null,"abstract":"Although numerous studies, both phenomenological and mathematical, have related gaseous interchanges at the plant leaf surface and atmospheric interface specifically with regard to drought tolerance, the important role of trichomes and the boundary layer has not been recognized. In this investigation the focus was restricted to the role of the boundary layer along with stomatal geometry and -spacing in determining the diffusional resistance to CO2 and H2O in four Nicotiana tabacum L. cultivars of different, but known, drought tolerance. Resistances were expressed both in terms of resistance components on a unit leaf area basis and in terms of dimensionless quantities. The abaxial leaf surface had the highest trichome frequency, more so in the drought tolerant than in the drought sensitive cultivars, being 9.7% and 6.9% higher than on the adaxial surface for TL33 and CDL28, as opposed to being 21.2% and 26.8% higher for GS46 and Elsoma, respectively. The frequency of the long glandular trichomes of epiderm...","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"11 6","pages":"44-49"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91499081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-01-01DOI: 10.1080/02571862.1999.10634843
J. V. Rensburg
The gene Cry1Ab derived from the entomopathogenic bacterium Bacillus thuringiensis is currently deployed commercially for control of Pyralid stem borers of maize in the USA. In this study various events of the Bt-gene were evaluated in maize inbred lines and hybrids for leaf feeding resistance to the local stem borers Busseola fusca and Chilo partellus, using artificially infested plants under greenhouse and field conditions. The event MON810 proved superior to all other events tested. C. partellus was more susceptible than B. fusca to the same events. Significant maternal effects were observed. Efficacy was not negatively affected by variations in the time of infestation. Hybrids did not respond equally to transformation with the same event, which was attributed to differences in adaptation to adverse environmental conditions.
{"title":"Evaluation of Bt.-Transgenic maize for resistance to the stem borers Busseola fusca (Fuller) and Chilo partellus (Swinhoe) in South Africa","authors":"J. V. Rensburg","doi":"10.1080/02571862.1999.10634843","DOIUrl":"https://doi.org/10.1080/02571862.1999.10634843","url":null,"abstract":"The gene Cry1Ab derived from the entomopathogenic bacterium Bacillus thuringiensis is currently deployed commercially for control of Pyralid stem borers of maize in the USA. In this study various events of the Bt-gene were evaluated in maize inbred lines and hybrids for leaf feeding resistance to the local stem borers Busseola fusca and Chilo partellus, using artificially infested plants under greenhouse and field conditions. The event MON810 proved superior to all other events tested. C. partellus was more susceptible than B. fusca to the same events. Significant maternal effects were observed. Efficacy was not negatively affected by variations in the time of infestation. Hybrids did not respond equally to transformation with the same event, which was attributed to differences in adaptation to adverse environmental conditions.","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"10 1","pages":"38-43"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78440363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-01-01DOI: 10.1080/02571862.1999.10634846
P. V. Merwe, L. J. Reddy, P. Subrahmanyam, R. Naidu
Short-duration groundnut cultivars were screened under high, medium and low rosette disease pressures and evaluated for rosette disease incidence, presence of groundnut rosette assister virus and other agronomic characteristics. Heritabili- ties of these characteristics and interaction plus variance components across the three disease pressures were calculated. Significant differences among the entries were observed for both agronomical parameters and disease resistance. Broad-based heritabilities for pod and kernel yields under high disease pressure were higher than the values for rosette resistance. It is expected from the results that the genetic improvement for rosette disease resistance will be higher using pod yields as a selection criterion. The interaction components between cultivars and disease pressures were significant, suggesting different responses of the cultivars across the three disease pressures. Yield stability may only be introduced when the cultivars are evaluated under different dise...
{"title":"Criteria for selecting groundout varieties in breeding for resistance to rosette disease","authors":"P. V. Merwe, L. J. Reddy, P. Subrahmanyam, R. Naidu","doi":"10.1080/02571862.1999.10634846","DOIUrl":"https://doi.org/10.1080/02571862.1999.10634846","url":null,"abstract":"Short-duration groundnut cultivars were screened under high, medium and low rosette disease pressures and evaluated for rosette disease incidence, presence of groundnut rosette assister virus and other agronomic characteristics. Heritabili- ties of these characteristics and interaction plus variance components across the three disease pressures were calculated. Significant differences among the entries were observed for both agronomical parameters and disease resistance. Broad-based heritabilities for pod and kernel yields under high disease pressure were higher than the values for rosette resistance. It is expected from the results that the genetic improvement for rosette disease resistance will be higher using pod yields as a selection criterion. The interaction components between cultivars and disease pressures were significant, suggesting different responses of the cultivars across the three disease pressures. Yield stability may only be introduced when the cultivars are evaluated under different dise...","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"25 1","pages":"56-58"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86585853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-01-01DOI: 10.1080/02571862.1999.10634850
A. J. Tarimo, F. Blarney
An experiment was conducted at the University of Queensland Redland bay Farm (27°37′ S, 153°17′ E) in southeast Queensland, Australia to study response of groundnut cultivars [Improved Virginia Bunch, NC-7, Q18801 (Virginia types), TMV-2, McCubbin and Red Spanish (Spanish types)] to different plant population densities (6.3, 11.1, 25.0 and 100.0) arranged in square spacings. The objective was to study plant physiological and morphological characteristics associated with the optimum plant population density among groundnut cul- tivars. Leaf area index (LAI), interception of photosynthetically active radiation (PAR), total dry mass (TDM), dry mass (DM) partitioning, economic yield and yield components were measured. The results show that TDM and economic yield were both maximized at 25 plants m−2 in all cultivars and so were the radiation use efficiency (Ec), crop growth rate (CGR) and DM partitioning'toTeproductive components (pods and kernels). Overall, variation in economic yield (kernel DM) was determin...
{"title":"Effects of plant population density and cultivar on growth, yield and yield components in groundnut (Arachis hypogaea 1.)","authors":"A. J. Tarimo, F. Blarney","doi":"10.1080/02571862.1999.10634850","DOIUrl":"https://doi.org/10.1080/02571862.1999.10634850","url":null,"abstract":"An experiment was conducted at the University of Queensland Redland bay Farm (27°37′ S, 153°17′ E) in southeast Queensland, Australia to study response of groundnut cultivars [Improved Virginia Bunch, NC-7, Q18801 (Virginia types), TMV-2, McCubbin and Red Spanish (Spanish types)] to different plant population densities (6.3, 11.1, 25.0 and 100.0) arranged in square spacings. The objective was to study plant physiological and morphological characteristics associated with the optimum plant population density among groundnut cul- tivars. Leaf area index (LAI), interception of photosynthetically active radiation (PAR), total dry mass (TDM), dry mass (DM) partitioning, economic yield and yield components were measured. The results show that TDM and economic yield were both maximized at 25 plants m−2 in all cultivars and so were the radiation use efficiency (Ec), crop growth rate (CGR) and DM partitioning'toTeproductive components (pods and kernels). Overall, variation in economic yield (kernel DM) was determin...","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"54 1","pages":"74-78"},"PeriodicalIF":0.0,"publicationDate":"1999-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86429938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-10-01DOI: 10.1080/02571862.1998.10635134
S. Materechera, O. T. Mandiringana, K. Nyamapfene
The study was undertaken to estimate surface cast production by microchaetid earthworms and to compare the physical and chemical properties of the casts with the surrounding non-cast soil. An average of 104 (range 64-132) and 192 (range 182-222) t ha-1 of surface casts were produced at Alice and Dimbaza sites in central Eastern Cape during the period September 1995 to August 1996. The casts had an average height of 6.8 cm and diameter of 5.6 cm and had higher silt and clay (66.2 vs 62.9%) but lower sand (33.8 vs 37.1 %) sized particles than the non-cast surface soil. The casts also had a higher proportion of water stable aggregates > 0.5 mm (76.7 vs 67.2%), mean weight diameter, bulk density (1.55 vs 1.37 Mg m-3) and retained more water than the non-cast soil. Earthworm casts had significantly higher available Bray 1-P, exchangeable K, Ca, Mg and Na than the non-cast soil. Levels of organic C and pH were also elevated in earthworm casting compared to surrounding soil. The large amounts of casts that are deposited on the surface can play an important role in modifying the hydraulic properties at the soil surface and help minimise runoff and erosion. Because of the high concentration of nutrients in casts compared to non-cast soil, potential may exist for using the casts to supply plants with nutrients.
本研究旨在估计微毛囊蚯蚓的表面铸件产量，并将铸件的物理和化学性质与周围非铸造土壤进行比较。1995年9月至1996年8月期间，在东开普省中部的Alice和Dimbaza场址平均生产了104(64-132吨)和192(182-222吨)吨/公顷的表面铸件。铸型的平均高度为6.8 cm，直径为5.6 cm，与非铸型表层土壤相比，粉砂和粘土(66.2 vs 62.9%)含量较高，而砂粒(33.8 vs 37.1%)含量较低。浇筑土的水稳性团聚体> 0.5 mm的比例(76.7 vs 67.2%)、平均重量直径、容重(1.55 vs 1.37 Mg m-3)也高于非浇筑土，并且保留了更多的水分。蚯蚓浇铸土的有效Bray - 1-P、交换态K、Ca、Mg和Na均显著高于非浇铸土。与周围土壤相比，蚯蚓粪中的有机碳和pH值也有所升高。沉积在地表的大量铸件在改变土壤表面的水力特性方面发挥着重要作用，并有助于减少径流和侵蚀。由于与未浇筑土壤相比，浇筑土壤中的养分浓度较高，因此可能存在利用浇筑土壤为植物提供养分的潜力。
{"title":"Production and physico-chemical properties of surface casts from microchaetid earthworms in central Eastern Cape","authors":"S. Materechera, O. T. Mandiringana, K. Nyamapfene","doi":"10.1080/02571862.1998.10635134","DOIUrl":"https://doi.org/10.1080/02571862.1998.10635134","url":null,"abstract":"The study was undertaken to estimate surface cast production by microchaetid earthworms and to compare the physical and chemical properties of the casts with the surrounding non-cast soil. An average of 104 (range 64-132) and 192 (range 182-222) t ha-1 of surface casts were produced at Alice and Dimbaza sites in central Eastern Cape during the period September 1995 to August 1996. The casts had an average height of 6.8 cm and diameter of 5.6 cm and had higher silt and clay (66.2 vs 62.9%) but lower sand (33.8 vs 37.1 %) sized particles than the non-cast surface soil. The casts also had a higher proportion of water stable aggregates > 0.5 mm (76.7 vs 67.2%), mean weight diameter, bulk density (1.55 vs 1.37 Mg m-3) and retained more water than the non-cast soil. Earthworm casts had significantly higher available Bray 1-P, exchangeable K, Ca, Mg and Na than the non-cast soil. Levels of organic C and pH were also elevated in earthworm casting compared to surrounding soil. The large amounts of casts that are deposited on the surface can play an important role in modifying the hydraulic properties at the soil surface and help minimise runoff and erosion. Because of the high concentration of nutrients in casts compared to non-cast soil, potential may exist for using the casts to supply plants with nutrients.","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"67 1","pages":"151-157"},"PeriodicalIF":0.0,"publicationDate":"1998-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90144427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1998-10-01DOI: 10.1080/02571862.1998.10635135
J. Smit, B. D. Villiers
Herbicide resistance raises the possibility that the agricultural industry and crop producers might loose a valuable chemical tool that is essential for the control of weeds in wheat (Triticum aestivum L.) production. The recognition of herbicide resistance occurred relatively recently (1960), despite the widespread use of selective herbicides worldwide. Resistant biotypes of Averta fatua L. to diclofop-methyl (±)2-[4-(2,4dichlorophenoxy)phenoxy]propanoic acid were confirmed in the western Cape. Recently, farmers and chemical companies reported resistance of Lolium spp. to several selective herbicides in small grains in the western Cape. The main objective of the present study was to assess resistance of Lolium spp. against ACC-ase inhibitors used in wheat production. Seed of Lolium spp. which were suspected to be resistant was sown in pots in a glasshouse at a temperature regime of 15°C/20°C (night/day). During the 2–4-leaf stage, the plants were sprayed with four herbicides viz. diclofop-methyl, clodina...
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