摘要:

Summary.The effects of 2,4‐D, 2,4,5‐T, IAA and GA on the germination behaviour of one‐seeded pods ofPsoralea corylifoliaL. were studied. For each chemical, inhibition of germination of acid‐scarified pods increased with increase in concentration. The inhibition was irreversible and led to death of the seed in the pod. Morality, expressed as percentage of dead pods, was highest for 2,4,5‐T and IAA and lowest for GA. Impermeable or ‘hard’ pods were unaffected by the treatments. Though acid‐scarified pods were significantly damaged by an 8 h chemical treatment, weathered pods were unaffected by treatments of less than 30 h duration. After scarification, dry pods were more susceptible than pre‐imbibed ones. Rates of water uptake were determined for pods of both categories.Effets de quelgues produits chimiques sur la germination dePsor

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1972.tb01223.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Summary.The selective action of triazine herbicides for control of wild canarygrass (Phalarisspp.) in wheat was studied in four field experiments. Canarygrass was controlled by pre‐ and post‐emergence applications of methoprotryne and terbutryne. The phytotoxicity of methoprotryne to wheat was higher than that of terbutryne. Addition of small amounts of simazine to either one of the methylthiotriazines considerably increased damage to wheat. The most resistant stage of wheat after emergence was that of spike initiation, whereas the most sensitive stage was that of earing. Increase of yield as a result of control of canarygrass was higher in semi‐dwarf wheat than in normal‐height cultivars. Application of 625 g/ha of terbutryne to a semi‐dwarf cultivar pre‐ and post‐emergence increased grain yield by 56% and 29%, respectively.Action selective des triazines pour la lutte contre lesPhala

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1972.tb01224.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Summary.Trifluralin (2,6‐dinitro‐NN‐dipropyl‐4‐trifluoromethylaniline) pre‐sowing, and carbetamide (d‐N‐ethyl‐2‐(phenylcarbamoyloxy)propionamide) and asulam (N‐(4‐aminobenzenesulphonyl)methylcarbamate) pre‐sowing or post‐emergence were evaluated for the control ofRumex obtusifoliusL. in autumn‐sown red clover (Trifolium pratenseL.). All herbicides gave good control of if.obtusifoliusfrom seed. Asulam at 2 or 4 kg/ha gave the best control ofR. obtusifoliusfrom rootstocks, followed by trifluralin at 1 kg/ha and carbetamide at 2 kg/ha.Poa annuaL. was controlled by trifluralin and carbetamide but not by asulam. The results are interpreted in terms of the mode of action and method of application of the herbicides.La lutte contre la Patience sauvage(Rumex obtusifoliusL.) dans un semis récent de trèfle rouge(Trifolium pratenseL.) avec la triflural

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1972.tb01225.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Summary.Freshly‐collected seeds of twenty species of annual weeds were uniformly mixed with 2.5, 7.5 or 15 cm of soil confined in cylinders sunk in the ground outdoors. The soil was either cultivated four times a year or left undisturbed, seedling emergence was recorded, and after 5 years the numbers of viable seeds remaining were determined.Total seedling emergence from seeds incorporated to 2·5, 7·5 and 15 cm amounted to 75, 65 and 54% respectively of those added when the soil was cultivated, and 58, 36 and 21% where it was left undisturbed. The corresponding numbers of viable seeds remaining after 5 years were 2·3, 4·0 and 7·7% respectively for cultivated soil, and 6·8, 16·5 and 31·6% of the seeds initially added and then not disturbed. Individual species varied in their responses to increasing depth of incorporation and to cultivation; these differences are discussed in relation to the dormancy characteritics of the seeds.Devenir des semences de quelques mauvaises herbes annuelles à différentes profondeur dans un sol cultivé e

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1972.tb01226.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Summary.Chlorfenprop‐methyl, the active ingredient of the selective herbicide BIDISIN®, induces autolysis in the leaves ofAvena fatuaL. During this process the cellular hydrolytic enzynnes, normally inactive, degrade the polymeric proteins, starch and nucleic acids, leading to breakdown of the plant. The basic metabolic processes of respiration, photosynthesis, protein synthesis and RNA synthesis are not inhibited by chlorfenprop‐methyl but become inactivated during autolysis.Méemisme d'action de l'herbicide sélectif chlorfenprop

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1972.tb01227.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Summary.Evidence is presented that blackcurrants show a considerable tolerance to simazine when the entire root system is exposed to a uniform concentration of the herbicide in sand and water culture. The tolerance of this species under field conditions does not therefore seem to be primarily due to root development being limited in the surface soil to which simazine is applied. Accordingly, experiments were carried out using simazine, labelled in the ring with14C, to determine whether there were restrictions to the uptake of the herbicide by the roots and its translocation to the xylem sap and leaves, and whether there was extensive breakdown of simazine in the plant. The results of these experiments are compared with those on two susceptible species, barley and marrow.Although simazine appeared to be metabolized to a greater extent in blackcurrants, and was less readily translocated from the roots, than in the susceptible species, a substantial proportion of the labelled material in the leaves was present as unchanged simazine. Studies on the effects of simazine on the rate of transpiration of detached leaves of the three species suggested that in blackcurrants there was a restriction to movement of the herbicide from the conducting tissue in the leaves to the mesophyll; this was confirmed by autoradiographs. It is suggested that this restriction, combined with partial breakdown of the herbicide in the leaves, may be responsible for the tolerance of blackcurrants to simazine.Résistance du cassissier à la simazi

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1972.tb01228.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Summary.Single tubers ofCyperus rotundusL. were planted at intervals over the year. Plant growth was slow and sprouting of tubers was inhibited at temperatures below 20°C, but tubers overwintered at temperatures above freezing point. In the warm season, plant growth and tuber formation rate closely followed air temperature and tubers were forming within 1 month from planting. No inflorescence appeared during the cool season.In autumn‐plantedC. rotundusgrown in containers, the ratio of aerial to subterranean weight decreased from 1·1 in December to 0·2–0·4 in summer. The weight of tubers in mid‐summer was about 10 times more than that present in December.Tubers formed at ail times of year and at various locations on plants sprouted readily in laboratory tests (76–100% sprouting).C. rotundusplanted in March at wide spacings was grown in field conditions free of other plant competition for 20 months. Within 2 months the plants had spread to 90 cm. At the end of the first and the second summer of growth, the mean area of one plant was 7·6 m2and 56·7 m2, respectively, and patches had expanded then by 2·8 m and 5·4 m, respectively, from the initial shoot. After 20 months of growth all tubers were present within the 0–40 cm soil depth, 60–70% of them in the 0–20 cm layer. About 30% of the tubers were within 1 m and 60% within 2 m of the plant centre.Under the patch centre there were about 1000 tubers per m2with 0·3 kg dry weight; in the upper 20 cm more than 3500 tubers weighing 0·9 kg were present per m3of soil.Croissance, formation de tubercules et propagation deCyperus rotundusL. is

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1972.tb01229.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Summary.The hydrolysis of the iso‐propyl, n‐butyl and iso‐octyl esters of 2,4‐dichloro‐phenoxyacetic acid to the free acid was studied in aqueous solutions and on three prairie soils. The esters were analysed using electron‐capture gas chromatography following extraction from solution with benzene, and from soils, using either 10% aqueous aceto‐nitrile or a 2:1 mixture of benzene and iso‐propanol.Ester hydrolysis in 0·1nsodium hydroxide solution was very rapid, more than 50% of all the esters being hydrolysed in less than 1 min. In 0·1nsodium carbonate solution the times for 50% hydrolysis at 25°C were<5, 5 and 30 min for the n‐butyl, iso‐propyl and iso‐octyl esters respectively. In distilled water negligible hydrolysis occurred over a 5 h period.The iso‐propyl and n‐butyl esters underwent a very facile hydrolysis on soils. Shaking the treated soils with 0·1 M calcium chloride solution for 30 min at 25°C resulted in extensive hydrolysis to the acid as determined spectrophotometrically. Under similar conditions negligible hydrolysis of the iso‐octyl ester occurred.After 1·5 h at 25±1°C on soils at their wilting point moisture levels, and greater, less than 15% of the applied iso‐propyl or n‐butyl esters could be recovered using either extraction procedure, indicating rapid hydrolysis to the acid. After 24 h no iso‐propyl or n‐butyl ester residues could be detected in any of the soils. Loss of the iso‐octyl ester was slower under these conditions with approximately 20–30% of the ester remaining after 24 h, and 10% after 48 h.L'hydrolyse des esters de2,4dichlorophénoxyacétates en acide2,4dich

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1972.tb01230.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Summary.Small sprigs ofCynodon dactylon(L.) Pers., were planted and grown without competition from weeds and crops for 2 1/2 years. The plant spread by means of above‐ground creeping stolons and subterranean rhizomes which could also emerge as aerial shoots, producing in their turn new stolons and rhizomes. Initially there was linear extension of stolons and rhizomes, following which gaps in the sod were filled by stolon branching and new shoots. There was no preferential direction of stolon elongation and established sods developed an approximately circular shape and expanded concentrically. The rate of increase in sod area was similar in both years of observation but radial extension was smaller in the second year than in young plants.The mean sod area was 25 m2after 2½ years of growth, and mean monthly area increment was 0·9 m2. Growth almost stopped in the cold season and exceeded 2 m2per month in the summer. The plants had extended up to 3·9 m from the plant centre after 2 1/2 years. The number of flowering culms per sod, produced only in the warm season, was directly proportional to sod area; seeds were infertile in the Newe Ya'ar area.After 2½ years of growth about 70% of the rhizome dry weight was present in the upper 20 cm of soil. Few rhizomes penetrated deeper than 40 cm. More than 60% of the rhizomes were present within 1 m radius of the plant centre and 90% were present within 2 m radius.Croissance spatiale deCynodon dactylon (L.

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1972.tb01231.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1972.tb01232.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY