Pub Date : 1997-10-01DOI: 10.1080/02571862.1997.10635102
C. Reinhardt, R. Meissner, L. V. Wyk
Chenopodium album L. and Chenopodium polyspermum L. are cosmopolitan weeds that often cause serious crop yield losses. Although it is well known that both species compete strongly with crops, nothing has been published on their relative allelopathic potentials. Experiments for assessing the allelopathic effects of C. album and C. polyspermum on three indicator species were conducted under controlled conditions. The indicator species were sunflower (Helianthus annuus L. cv. SO 222), tomato (Lycopersicon esculentum Mill cv. Heinz 1370) and the cosmopolitan weed Indian goosegrass (Eleusine indica subsp. indica (L.) Gaertn.). Top growth of mature C. album and C. polyspermum plants was freeze-dried, milled to a coarse powder and gamma-irradiated. Steam-sterilized soil was mixed with the powdered material to reach a concentration of 1% for each donor species. The control treatments consisted of an untreated soil and the same soil containing 1% extracted material of the donor species. Only sunflower and tomato s...
Chenopodium album L.和Chenopodium polyspermum L.是世界性杂草，经常造成严重的作物产量损失。虽然众所周知，这两个物种都与作物有很强的竞争，但没有关于它们的相对化感作用潜力的报道。在一定条件下，对三种指示种进行了化感作用试验。指示种为向日葵(Helianthus annuus L. cv)。so222)，番茄(Lycopersicon esculentum Mill cv.;海因茨1370)和世界各地的杂草印度鹅草(Eleusine indica subsp。籼稻(l)Gaertn)。采用冻干、碾磨成粗粉、伽玛射线辐照的方法，将成熟的香椿和多精香椿植株的顶部生长进行处理。将蒸汽灭菌的土壤与粉末状材料混合，使每个供体的浓度达到1%。对照处理为未经处理的土壤和含有1%供体植物提取物的土壤。只有向日葵和西红柿……
{"title":"Allelopathic effects of Chenopodium album L. and Chenopodium polyspermum L. on another weed and two crop species","authors":"C. Reinhardt, R. Meissner, L. V. Wyk","doi":"10.1080/02571862.1997.10635102","DOIUrl":"https://doi.org/10.1080/02571862.1997.10635102","url":null,"abstract":"Chenopodium album L. and Chenopodium polyspermum L. are cosmopolitan weeds that often cause serious crop yield losses. Although it is well known that both species compete strongly with crops, nothing has been published on their relative allelopathic potentials. Experiments for assessing the allelopathic effects of C. album and C. polyspermum on three indicator species were conducted under controlled conditions. The indicator species were sunflower (Helianthus annuus L. cv. SO 222), tomato (Lycopersicon esculentum Mill cv. Heinz 1370) and the cosmopolitan weed Indian goosegrass (Eleusine indica subsp. indica (L.) Gaertn.). Top growth of mature C. album and C. polyspermum plants was freeze-dried, milled to a coarse powder and gamma-irradiated. Steam-sterilized soil was mixed with the powdered material to reach a concentration of 1% for each donor species. The control treatments consisted of an untreated soil and the same soil containing 1% extracted material of the donor species. Only sunflower and tomato s...","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"1 1","pages":"165-168"},"PeriodicalIF":0.0,"publicationDate":"1997-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82828656","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 : 1997-08-01DOI: 10.1080/02571862.1997.10635095
O. T. Villiers, M. Bosman
Acid Polyacrylamide gel electrophoresis (A-PAGE) of proteins was used to identify different spring wheat cultivare, barley cultivars and Cyclopia species. Experimental conditions for the extraction of the proteins from single kernels as well as corresponding flour samples are described. Different solvents for extracting the proteins are mentioned. An electrophoretic formula was prepared for each cultivar and species using relative band mobility and staining intensities of protein bands. Distinctive band patterns were obtained. Cultivars and species collected on different locations were subsequently analysed.
{"title":"The use of acid polyacrylamide gel electrophoresis to determine the effect of locality of growth on the protein profiles of barley, wheat and honeybush tea","authors":"O. T. Villiers, M. Bosman","doi":"10.1080/02571862.1997.10635095","DOIUrl":"https://doi.org/10.1080/02571862.1997.10635095","url":null,"abstract":"Acid Polyacrylamide gel electrophoresis (A-PAGE) of proteins was used to identify different spring wheat cultivare, barley cultivars and Cyclopia species. Experimental conditions for the extraction of the proteins from single kernels as well as corresponding flour samples are described. Different solvents for extracting the proteins are mentioned. An electrophoretic formula was prepared for each cultivar and species using relative band mobility and staining intensities of protein bands. Distinctive band patterns were obtained. Cultivars and species collected on different locations were subsequently analysed.","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"120 1","pages":"131-136"},"PeriodicalIF":0.0,"publicationDate":"1997-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75788587","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 : 1997-08-01DOI: 10.1080/02571862.1997.10635094
E. Smit, G. V. Rensburg, F. Rijkenberg
The effect of monoculture maize and rotation with soybeans, sunflower and groundnuts on the incidence of maize root rot were studied in a long-term rotation trial for three seasons. The number of isolates of the common root colonizing fungi was also determined. Seasonal variables (i.e. moisture) had a significant effect on root discolouration arid results suggested that some environmental conditions, in the presence of certain fungi, contributed more to root discolouration. The spectrum of isolated fungi differed between Seasons and may be ascribed to the effect of variable environmental conditions, particularly rainfall. The highest number of isolates was obtained for Phoma spp. and Fusarium spp .. A significant interaction was observed between rotation treatments and seasons on number of isolates of Fusarium equiseti (Corda) Sacc., Fusarium oxysporum Schlecht. emend. Snyd. & Hans. and Macrophomina phaseolina (Tassi) Goid .. The effect of crop rotation on the number of isolates of these fungi were, however, inconsistent and appears to be complex. Fungi were affected differently by various rotation systems, indicating that no single cropping system favoured all fungi. A Significant seasonal effect was found with regard to crop rotation treatments and grain yield. Although this trial was sampled for three successive seasons, crop rotation may have a long-term effect on soil fungus populations which may only be evident after a longer period of time.
{"title":"Number of isolates of maize root fungi in different crop rotation systems","authors":"E. Smit, G. V. Rensburg, F. Rijkenberg","doi":"10.1080/02571862.1997.10635094","DOIUrl":"https://doi.org/10.1080/02571862.1997.10635094","url":null,"abstract":"The effect of monoculture maize and rotation with soybeans, sunflower and groundnuts on the incidence of maize root rot were studied in a long-term rotation trial for three seasons. The number of isolates of the common root colonizing fungi was also determined. Seasonal variables (i.e. moisture) had a significant effect on root discolouration arid results suggested that some environmental conditions, in the presence of certain fungi, contributed more to root discolouration. The spectrum of isolated fungi differed between Seasons and may be ascribed to the effect of variable environmental conditions, particularly rainfall. The highest number of isolates was obtained for Phoma spp. and Fusarium spp .. A significant interaction was observed between rotation treatments and seasons on number of isolates of Fusarium equiseti (Corda) Sacc., Fusarium oxysporum Schlecht. emend. Snyd. & Hans. and Macrophomina phaseolina (Tassi) Goid .. The effect of crop rotation on the number of isolates of these fungi were, however, inconsistent and appears to be complex. Fungi were affected differently by various rotation systems, indicating that no single cropping system favoured all fungi. A Significant seasonal effect was found with regard to crop rotation treatments and grain yield. Although this trial was sampled for three successive seasons, crop rotation may have a long-term effect on soil fungus populations which may only be evident after a longer period of time.","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"13 1","pages":"127-130"},"PeriodicalIF":0.0,"publicationDate":"1997-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81860690","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 : 1997-05-01DOI: 10.1080/02571862.1997.10635085
C. Bender, Z. Pretorius, J. J. Spies
Monogenic resistance in wheat (Triticum aestivum L.) to leaf rust, caused by Puccinia recondita Rob. ex. Desm. f. sp. tritici, has generally not been durable. Durable resistance, as well as an improved expression of resistance, have been associated with Lr gene combinations. In this study, the assumption that Lr12 and Lr13 may interact to condition improved resistance to leaf rust, was investigated. Four Thatcher (Tc) x RL6011 F3 lines (13/12–3, 13/12–9, 13/12- 19 and 13/12–40), homozygous for both Lr13 and Lr12, were selected and their leaf rust resistance compared with the parents (CT263 [=TcLr13] and RL6011 [=TcLr12]), the single gene lines Tc/13–22 and TC/12–16, and Thatcher. In addition to infection type studies in seedlings and adult plants, lines were compared according to macroscopic components of resistance, as well as disease ratings in the field. Flag leaf infection type studies showed that Lr12 is effective against most pathotypes of P. recondita f. sp. tritici occurring in South Africa. Conve...
{"title":"Assessment of macroscopic components of leaf rust resistance in wheat genotypes containing Lr12 and Lr13","authors":"C. Bender, Z. Pretorius, J. J. Spies","doi":"10.1080/02571862.1997.10635085","DOIUrl":"https://doi.org/10.1080/02571862.1997.10635085","url":null,"abstract":"Monogenic resistance in wheat (Triticum aestivum L.) to leaf rust, caused by Puccinia recondita Rob. ex. Desm. f. sp. tritici, has generally not been durable. Durable resistance, as well as an improved expression of resistance, have been associated with Lr gene combinations. In this study, the assumption that Lr12 and Lr13 may interact to condition improved resistance to leaf rust, was investigated. Four Thatcher (Tc) x RL6011 F3 lines (13/12–3, 13/12–9, 13/12- 19 and 13/12–40), homozygous for both Lr13 and Lr12, were selected and their leaf rust resistance compared with the parents (CT263 [=TcLr13] and RL6011 [=TcLr12]), the single gene lines Tc/13–22 and TC/12–16, and Thatcher. In addition to infection type studies in seedlings and adult plants, lines were compared according to macroscopic components of resistance, as well as disease ratings in the field. Flag leaf infection type studies showed that Lr12 is effective against most pathotypes of P. recondita f. sp. tritici occurring in South Africa. Conve...","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"100 1","pages":"71-80"},"PeriodicalIF":0.0,"publicationDate":"1997-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76658082","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 : 1997-05-01DOI: 10.1080/02571862.1997.10635083
O. Yerokun
Urea fertilizers may lose N by ammonia volatilization when applied in the field. In order to reduce this loss, modified urea compounds are being used. Not all of them reduce ammonia loss and improve crop yields. A field study was conducted to evaluate the comparative advantage of cogranulated urea-urea phosphate (340 g N kg−1, 73 g P kg−1) over urea (460 g N kg−1) and ammonium nitrate (350 g N kg−1) when supplied as nitrogen fertilizers to maize. The fertilizer granules were applied at rates of 67, 134 and 202 kg N ha−1, as surface-broadcast or soil-incorporated treatments. Fertilizer application increased crop yields and nitrogen uptake, but the sources were not significantly different from each other. Increasing nitrogen supply up to 134 kg N ha−1 improved maize yield and nitrogen uptake. Incorporating the fertilizer with the soil was not better than surface application. The data available suggest that maize responded to cogranulated urea-urea phosphate, urea and ammonium nitrate similarly.
氮肥在田间施用时可能因氨挥发而损失氮素。为了减少这种损失，正在使用改性尿素化合物。并不是所有的方法都能减少氨损失和提高作物产量。通过田间研究，评价了尿素-尿素磷酸酯颗粒剂(340 g N kg - 1, 73 g P kg - 1)作为玉米氮肥比尿素(460 g N kg - 1)和硝酸铵(350 g N kg - 1)的相对优势。施氮量分别为67、134和202 kg N ha - 1，施氮量分别为地表撒施和土壤掺入。施肥对作物产量和氮素吸收量均有促进作用，但各来源间差异不显著。增加氮供应至134 kg N ha - 1可提高玉米产量和氮吸收。土壤中掺入化肥的效果并不比地表施用好。现有资料表明，玉米对聚粒化尿素-磷酸脲、尿素和硝酸铵的反应相似。
{"title":"Response of maize to ammonium nitrate, urea and cogranulated urea-urea phosphate","authors":"O. Yerokun","doi":"10.1080/02571862.1997.10635083","DOIUrl":"https://doi.org/10.1080/02571862.1997.10635083","url":null,"abstract":"Urea fertilizers may lose N by ammonia volatilization when applied in the field. In order to reduce this loss, modified urea compounds are being used. Not all of them reduce ammonia loss and improve crop yields. A field study was conducted to evaluate the comparative advantage of cogranulated urea-urea phosphate (340 g N kg−1, 73 g P kg−1) over urea (460 g N kg−1) and ammonium nitrate (350 g N kg−1) when supplied as nitrogen fertilizers to maize. The fertilizer granules were applied at rates of 67, 134 and 202 kg N ha−1, as surface-broadcast or soil-incorporated treatments. Fertilizer application increased crop yields and nitrogen uptake, but the sources were not significantly different from each other. Increasing nitrogen supply up to 134 kg N ha−1 improved maize yield and nitrogen uptake. Incorporating the fertilizer with the soil was not better than surface application. The data available suggest that maize responded to cogranulated urea-urea phosphate, urea and ammonium nitrate similarly.","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"84 1","pages":"63-66"},"PeriodicalIF":0.0,"publicationDate":"1997-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79988781","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 : 1997-05-01DOI: 10.1080/02571862.1997.10635086
A. Mcbain, M. Salkinoja-Salonen, E. Senior, C. Plessis, A. Paterson, I. Watson-Craik
Survival and efficacy of monoculture inoculants of Flavobacterium sp. and Rhodococcus chlorophenolicus to bioremediate PCP-contaminated soil were examined under sterile and non-sterile conditions. Both species effected > 40% catabolism in four weeks although inoculant survival was significantly higher with R. chlorophenolicus. Supplements of bark chips or distillery waste with the inoculant did not, initially, promote bioremediation. PCP addition per se effected enrichment of indigenous catabolic populations and this was promoted by the presence of wood chips. Both aerobic and anaerobic enrichments were successful and PCP mineralization under both conditions was recorded. Under anoxic conditions, dehalogenation of o-substituents was dominant although some meta-chlorines were removed. Provisional evidence of two separate isomer-specific dehalogenating populations was obtained.
{"title":"Pentachlorophenol-contaminated soil bioremediation: survival and efficacy of monoculture inoculants and enrichment of indigenous catabolic populations","authors":"A. Mcbain, M. Salkinoja-Salonen, E. Senior, C. Plessis, A. Paterson, I. Watson-Craik","doi":"10.1080/02571862.1997.10635086","DOIUrl":"https://doi.org/10.1080/02571862.1997.10635086","url":null,"abstract":"Survival and efficacy of monoculture inoculants of Flavobacterium sp. and Rhodococcus chlorophenolicus to bioremediate PCP-contaminated soil were examined under sterile and non-sterile conditions. Both species effected > 40% catabolism in four weeks although inoculant survival was significantly higher with R. chlorophenolicus. Supplements of bark chips or distillery waste with the inoculant did not, initially, promote bioremediation. PCP addition per se effected enrichment of indigenous catabolic populations and this was promoted by the presence of wood chips. Both aerobic and anaerobic enrichments were successful and PCP mineralization under both conditions was recorded. Under anoxic conditions, dehalogenation of o-substituents was dominant although some meta-chlorines were removed. Provisional evidence of two separate isomer-specific dehalogenating populations was obtained.","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"20 1","pages":"81-88"},"PeriodicalIF":0.0,"publicationDate":"1997-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82529743","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 : 1997-05-01DOI: 10.1080/02571862.1997.10635084
O. Yerokun
The volatilization of ammonia following applications of urea fertilizers to soils may release significant amounts of N into the atmosphere and reduce the plant available N. This study compared ammonia loss from urea phosphate (170 g N kg−1, 190 g N kg−1), cogranulated urea-urea phosphate (340 g N kg−1, 73 g P kg−1), urea (460 g N kg−1) and ammonium nitrate (350 g N kg−1) granular fertilizers applied to the soil surface at 60, 120 and 200 mg N kg−1 soil. Soil moisture contents were adjusted to 100% and 25% of field moisture capacity at the beginning of the experiment. Ammonia losses from cogranulated urea-urea phosphate and urea were similar, being as much as 7.8% of applied nitrogen in 14 days. Urea phosphate and ammonium nitrate exhibited significantly lower ammonia losses. As the amount of N applied increased, corresponding ammonia loss increased. An initial soil moisture at 25% field moisture capacity caused the fertilizers to lose more ammonia than when the soils were initially at 100% field moisture ...
氨的挥发后土壤尿素肥料的应用可能释放大量的N到大气中,减少植物可用N .本研究氨损失相比尿素磷酸盐(N公斤−1 170克、190克N公斤−1),cogranulated urea-urea磷酸(N公斤−1 340克、73 g P公斤−1)、尿素(460 g N公斤−1)和硝酸铵(350 g N公斤−1)颗粒肥料应用于土壤表面在60,120 N和200毫克公斤−1土壤。试验开始时，将土壤含水量调整为田间水分容量的100%和25%。聚粒化磷酸脲-尿素和尿素的氨损失量相似，14 d内均为施氮量的7.8%。磷酸脲和硝酸铵的氨损失显著降低。随着施氮量的增加，相应的氨损失增加。土壤初始含水量为25%时，与土壤初始含水量为100%时相比，肥料的氨损失更多。
{"title":"Ammonia volatilization from ammonium nitrate, urea and urea phosphate fertilizers applied to alkaline soils","authors":"O. Yerokun","doi":"10.1080/02571862.1997.10635084","DOIUrl":"https://doi.org/10.1080/02571862.1997.10635084","url":null,"abstract":"The volatilization of ammonia following applications of urea fertilizers to soils may release significant amounts of N into the atmosphere and reduce the plant available N. This study compared ammonia loss from urea phosphate (170 g N kg−1, 190 g N kg−1), cogranulated urea-urea phosphate (340 g N kg−1, 73 g P kg−1), urea (460 g N kg−1) and ammonium nitrate (350 g N kg−1) granular fertilizers applied to the soil surface at 60, 120 and 200 mg N kg−1 soil. Soil moisture contents were adjusted to 100% and 25% of field moisture capacity at the beginning of the experiment. Ammonia losses from cogranulated urea-urea phosphate and urea were similar, being as much as 7.8% of applied nitrogen in 14 days. Urea phosphate and ammonium nitrate exhibited significantly lower ammonia losses. As the amount of N applied increased, corresponding ammonia loss increased. An initial soil moisture at 25% field moisture capacity caused the fertilizers to lose more ammonia than when the soils were initially at 100% field moisture ...","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"114 1","pages":"67-70"},"PeriodicalIF":0.0,"publicationDate":"1997-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77766436","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 : 1997-05-01DOI: 10.1080/02571862.1997.10635082
C. Reinhardt, K. J. Hugo
Leaching of atrazine [6-chloro-N-ethyf-N′-(methylethyl)-1,3,5-triazine-2,4-dlamine] and terbuthylazine [6-chloro- N-(1,1-dirnelhylethyt)-N′-ethyl-1,3,5-triazlne-2,4-diamine] was studied in 23 soils by means of the soil thick-layer leaching method. The equivalent of 4 kg ai ha−1 of both herbicides was leached with water equivalent to 129 mm rain Distances leached were measured qualitatively in bioassays with the test plant Tnfolium repens L. Leaching distances in different soils varied from 6–20 cm for atrazine, and from 2–16 cm for terbuthylazine. Atrazine leached at least 10 cm in 13 soils, while terbuthylazine did not move from the zone of application in 12 soils. Of the five soil properties assessed by means of simple regression, organic matter content (%C) and P-reversion were significantly correlated with the leaching distance of atrazine, and %C with the mobility of terbuthylazine. Relationships between herbicide leaching and either total clay content or soil pH were relatively weak. The combination...
采用土壤厚层淋滤法，研究了阿特拉津[6-氯-N-乙基-N′-(甲乙基)-1,3,5-三嗪-2,4-二胺]和特丁基嗪[6-氯-N- (1,1- dirnelhy乙基)-N′-乙基-1,3,5-三嗪-2,4-二胺]在23种土壤中的淋滤效果。两种除草剂的浸出量均为4kg / ha - 1，浸出量为129mm雨水。在生物测定中，对浸出距离进行了定性测量，试验植物为三叶草(Tnfolium repens L.)。阿特拉津在13种土壤中至少浸出10 cm，而特丁甲嗪在12种土壤中没有从施用区移动。在简单回归评价的5种土壤性质中，有机质含量(%C)和磷还原与阿特拉津的浸出距离显著相关，%C与特丁拉西嗪的迁移率显著相关。除草剂淋溶与土壤总粘粒含量和pH值的关系相对较弱。结合……
{"title":"Simple regression models for the qualitative prediction of atrazine and terbuthylazine leaching","authors":"C. Reinhardt, K. J. Hugo","doi":"10.1080/02571862.1997.10635082","DOIUrl":"https://doi.org/10.1080/02571862.1997.10635082","url":null,"abstract":"Leaching of atrazine [6-chloro-N-ethyf-N′-(methylethyl)-1,3,5-triazine-2,4-dlamine] and terbuthylazine [6-chloro- N-(1,1-dirnelhylethyt)-N′-ethyl-1,3,5-triazlne-2,4-diamine] was studied in 23 soils by means of the soil thick-layer leaching method. The equivalent of 4 kg ai ha−1 of both herbicides was leached with water equivalent to 129 mm rain Distances leached were measured qualitatively in bioassays with the test plant Tnfolium repens L. Leaching distances in different soils varied from 6–20 cm for atrazine, and from 2–16 cm for terbuthylazine. Atrazine leached at least 10 cm in 13 soils, while terbuthylazine did not move from the zone of application in 12 soils. Of the five soil properties assessed by means of simple regression, organic matter content (%C) and P-reversion were significantly correlated with the leaching distance of atrazine, and %C with the mobility of terbuthylazine. Relationships between herbicide leaching and either total clay content or soil pH were relatively weak. The combination...","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"32 1","pages":"58-62"},"PeriodicalIF":0.0,"publicationDate":"1997-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74131514","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 : 1997-05-01DOI: 10.1080/02571862.1997.10635080
C. D. Preez, G. Wiltshire
Cultivation caused, without exception, a decline in the organic matter content of dryland soils in the central regions of South Africa. The question arose as to how cultivation affects the organic matter content of irrigated soils from these regions. The main aim, therefore, was to quantify the effect of cultivation on the organic matter content of soils from three irrigation schemes with virgin soils serving as reference. Virgin and cultivated topsoils (0–200 mm) were sampled from seven sites at Riet River, eight sites at Ramah and six sites at Vaalharts. The sites at each irrigation scheme represented varying periods of cultivation. Soil samples were analysed for particle size distribution, pH, exchangeable Na, K, Mg and Ca, extractable P and Zn, CEC, organic C and total N. The K, P and Zn contents differed significantly between virgin and cultivated soils: K decreased, while P and Zn increased with cultivation and irrigation. Organic C and total N significantly increased at seven sites and decreased at...
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Pub Date : 1997-03-26DOI: 10.1080/02571862.1997.10635091
V. Tolmay, D. Lill, Marie F. Smith
Russian wheat aphid, (Diuraphis noxia) causes severe damage to wheat in South Africa and producers have been forced to use insecticides for control. Plant resistance to Russian wheat aphid has been successfully transferred into bread wheat cultivars. A split plot field trial was undertaken firstly to compare the yield of susceptible wheat to that of a near-isogenic resistant wheat cultivar in combination with insecticide treatments and secondly to determine whether the inclusion of Russian wheat aphid resistance influences the bread- making quality of the cultivar. Resistant wheat yielded higher indicating that the resistance is effective under field conditions. Seed treatment with Imidacloprid increased yield of wheat in both years. Significant two and three-way interactions were found in both years. No negative effects on dough quality characteristics were associated with Russian wheat aphid resistance.
{"title":"The influence of Demeton-S-Methyl/Parathion and Imidacloprid on the yield and quality of Russian wheat aphid resistant and susceptible wheat cultivars","authors":"V. Tolmay, D. Lill, Marie F. Smith","doi":"10.1080/02571862.1997.10635091","DOIUrl":"https://doi.org/10.1080/02571862.1997.10635091","url":null,"abstract":"Russian wheat aphid, (Diuraphis noxia) causes severe damage to wheat in South Africa and producers have been forced to use insecticides for control. Plant resistance to Russian wheat aphid has been successfully transferred into bread wheat cultivars. A split plot field trial was undertaken firstly to compare the yield of susceptible wheat to that of a near-isogenic resistant wheat cultivar in combination with insecticide treatments and secondly to determine whether the inclusion of Russian wheat aphid resistance influences the bread- making quality of the cultivar. Resistant wheat yielded higher indicating that the resistance is effective under field conditions. Seed treatment with Imidacloprid increased yield of wheat in both years. Significant two and three-way interactions were found in both years. No negative effects on dough quality characteristics were associated with Russian wheat aphid resistance.","PeriodicalId":22913,"journal":{"name":"The South African Journal of Plant and Soil","volume":"3 1","pages":"107-111"},"PeriodicalIF":0.0,"publicationDate":"1997-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88769408","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}
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