摘要:

Summary.Studies were conducted to determine the influence of pyrazon (5‐amino‐4‐chloio‐2‐phenyl‐3(2H)‐pyridazinone) on photosynthesis. A strong inhibiting effect on O2evolution from leaf discs of several species was recorded. For most species a concentration of 5 × 10−5M caused a reduction of about 50% in the rate of photosynthesis. Photosynthesis of sugar beet, highly resbtant to pyrazon, was reduced to 50% by a concentration of 7–5 × 10−5M. Since these differences cannot account for the great divergence in susceptibility to pyrazon, it is suggested that the selectivity of this herbicide results from degradation and differential accumulation in the foliage.Pyrazon was phytotoxic to plants of tomato and pigweed (Amaranthus retrofiexus L.) kept in the light but not when kept in the dark, after foliage application. The conclusion that pyrazon inhibits the mechanism of photosynthesis and causes starvation for carbohydrates, was strengthened by the fact that external feeding of glucose overcame the toxicity of the compound in tomato plants. These results and a possible mode of sele

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1969.tb01470.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

Summary.Under dry field conditions, vernolate (S‐propyl dipropylthiocarbamate) incorporated by conventional methods controlled less yellow nutsedge (Cyperusesculentus L.) and injuied peanuts (Arachis hypogaea L., groundnuts) more than when injected in lines under the soil or subsurface‐applied through sweep applicators. In glasshouse studies, vernolate eliminated production of new nutsedge tubers if it was applied below the soil surface either 1 in. above or 1 in. below the parent tuber. Method of placement was less critical in determining control of most annual weeds.When averaged over two soil types and 2 years, peanuts yielded 14% more after subsurface applications than after incorporated treatments of vernolate. In comparison with the optimum subsurface placement, the yield from incorporation was significantly lower in three of four field studies, the reduced yields probably resulting from a combination of herbicide injury and poor weed control. Factors affecting the distribution of vernolate vapours (such as method of placement, soil type and amount of rainfall after treatment) apparently determine the differential toxicity of this herbicide. Neither market quality nor germination of peanut seed was adversely affected by vernolate treatm

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1969.tb01471.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

Summary.A method of exposing seedlings of Norway spruce (Picea abies (L.) Karst.) to14CO2is described. Within the 1st hr alter14CO2exposure, no translocation of the14C out of the treated branch could be observed. After a 24‐hr period, however, the14C in dormant seedlings had been translocated basipetally to part of the root system only, with no lateral diffusion of the14C‐compounds in the stem. About a week after exposure, both symplastic and apoplastic patterns of translocation had caused a more uniform distribution of14C. In seedlings at active internode elongation, the translocation patterns were fundamentally identical to those in dormant seedlings, but the active shoot growth had led to a more uniform distribution of the14C.Simazine at 20 ppm had apparently stimulated both the photofixation of14CO2and the rate of translocation of the14C‐assimilates. At 30 ppm, however, simazine had blocked the translocation of nutrients to the roots. On the other hand, the14CO2uptake was not influenced. The simazine incubation had apparently no influence on the synthesis of cationic photosyn

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1969.tb01472.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

Summary.Undisturbed natural infestations of annual weeds, mainly Digitaria sanguinalis (L.) Scop, andRichardia scabraL., reduced the yield of harvestable peanuts [groundnuts) by an average of 20% over an 8‐year period. Yield reductions in individual years ranged from I to 50%, depending mainly on the density of the weed population. From one to 5%‘non‐dirting’ cultivations generally did not reduce yield as compared with hand weeding, unless environmental conditions favoured development of the disease southern blight (Sclerotium rolfsii Sacc.) on uncultivated

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1969.tb01473.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

Summary.Dry seeds of oat (Avena sativa L.) were placed in various concentrations of bromacil for 4 hr and then placed either on glasscloth which dipped into the herbicide solution, or with the roots in aerated herbicide solution. Root elongation was measured by two methods. Alter various exposure periods, selected portions of the plants were prepared by classical methods for examination with the light or electron microscope.Total root elongation was inhibited by the concentrations used (10−6to 10−3M), and the degree of inhibition increased with increasing concentration. The inhibition was almost entirely restricted to the terminal 0.5 mm, the region of greatest elongation in untreated roots. Treated roots were swollen or necrotic and collapsed, with neerotic cells in the meristem, procambium and epidermis. There was also precocious vacuolation of cells in most tissues of the root tip, and inhibition of cell wall formation resulted in cells with multiple nuclei. The development of the chloroplast grana and fret system was inhibited by bromacil. The loculi of the grana and fret vesicles progressively swelled, and there was modification of the chloroplast envelope. These effects appear to be associated with loss of integrity of membranes.Résumé.Des semences sèches d'avoine (Avena sativa L.) furent placées dans diverses concentrations de bromacile pendant 4 heures puis placées ensuite soit sur de la laine de verre qui trenipait dans la solutjon herbicide, soit avec les racincs plongées dans une solution herhieide aérée. L'élongation des racines fut mesuree par detix methodes. Aprèa des periodes variees d'exposition, des portions choisies des plantes furent preparees par les methodes classiques pour cxamen au microscope ordinaire ou au microscope electronique. L'elongation totale des racines fut inhibde par les concentrations utilisees (10−6à 10−3M), et le degré d'inhibition s'accrut avec l'augmentation des concentrations. L'inhibition fut presque entièrement localisée sur 0,5 mm á l'extrémité de la racine, région où se manifeste la eroissance la plus importante dans les racines non traitées. Les racines traitées apparuient gonflées, ou nécrosées et flasques, avec des cellules nécrosées dans le méristéme, le procambium et l'épiderme. Il apparut également une formation précoce de vacuoles dans les cellules dans la plupart des tissus de l'extrémité cs racines; de plus, l'inhibition de la formation de la paroi cellulaire provoqua la formation de cellules à noyaux multiples. Le développement des grana chloroplastes et du systéme lamellaire inter‐grana fut inhibé par le bromacile. Les cavités des grana et les vésicules du système lamellaire inter‐grana grossirent progressi vement et l'enveloppe des chloroplastes fut modifiée. Ces effets semblent ê

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1969.tb01474.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

Summary.Tracer studies using single drops of solutions containing 3–amino‐1,2,4–triazole‐5–14C (aminotriazole‐14C) or 2,2–dichloropropionic acid‐2–14C (datapon‐14C) revealed that in couch plants (Agropyron repens (L.) Beauv.) growing under field conditions in the autumn and at the stage where the aerial shoots were 40–50 cm long, both compounds moved in both symplast and apoplast. Dalapon was less mobile in the symplast than aminotriazole and only negligible amounts of dalapon were translocated to the rhizomes. The nodes of the treated shoots appeared to act as barriers to translocation, a phenomenon more pronounced for dalapon than for aminotriazole.Application to a basal green leaf led to a more uniform distribution of the compounds within plants and rhizomes than when the application was made to the youngest fully‐expanded leaf.In couch plants with aerial shoots 10–15 cm long treated in the stubble, the distribution of both aminotriazole and dalapon was mainly restricted to the treated shoots. Even 15 days after application only trace amounts of radioactivity could be found in the rhiz

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1969.tb01475.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

Summary.3,4,3′,4′‐Tetrachloroazobenzene (TCAB) and TCAB‐14C were supplied to the roots of rice (Oryza sativaL.) plants in nutrient solution. An analysis of the shoots indicated that the TCAB was absorbed and translocated to the shoots. The translocated material was characterized by gas‐liquid chromatography and mass spectrometry. Roots were exposed to saturation concentrations of TCAB‐14C in liquid culture to determine the translocation and distribution of the compound. Only 5′6% of the total azobenzene present in the nutrient solution was absorbed by the intact rice plants and only 3′2% of the absorbed TCAB‐14C was translocated to the shoots after 12 days of treatment. No TGAB was isolated from plants treated with propanil or 3,4‐dichloroaniline after 1

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1969.tb01476.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

Summary.Identification of 3, 4‐dichloroaniline in a hydrolysate of rice grain obtained from experimental plots treated with N‐(3, 4‐dichlorophenyl) propionamide (propanil) and in rice grain purchased on the consumer's market is reported. Rice grain harvested before the introduction of pesticides that contain 3, 4‐dichloroaniline but treated with isopropyl N‐(3‐chlorophenyl)carbamate (chlorpropham) yielded rice cereal from which, after caustic hydrolysis of the rice grain, 3‐chloroaniline was isolated. The presence of chloroaniline or chloroaniline‐containing compounds raises the question as to the source of t

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1969.tb01477.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1969.tb01478.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

Summary.Spring wheat, sown at three different times, and Agropyron repens, defoliated at the same three times, were grown separately or together in pots kept in an open‐sided cage. The pots were widely spaced and adequately watered. Early sowing of wheat gave a greater grain yield than late sowing, and lessened the loss from competition with Agropyron. Early defoliation ofAgropyronslowed its subsequent early growth more than did late defoliation, and plants defoliated early suffered more from competition with wheat. Competition, probably mainly for nitrogen, decreased tillering and the number of ears produced by wheat, more when sowing was late than early, but grain dry weight per ear was decreased equally at the three times of sowing. The rate at which wheat produced leaves was affected by competition only at the last date of sowing. In competition with wheat, Agropyron produced fewer shoots and ears, had lighter shoots and rhizomes, and ear emergence was slightly delaye

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1969.tb01479.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY