摘要:

SummarySome substituted urea herbicides (chlortoluron, diuron and methabenzthiazuron) were tested for possible use in the cultivation ofEuphorbia lathyrisL. Diuron showed high phytotoxicity for this species, which was tolerant to chlortoluron and methabenzthiazuron. In preliminary experiments two triazine herbicide (atrazine and simazine) were also used, but both were so toxic toE. lathyristhat their use was not continued beyond this stage.In glasshouse experiments, chlortoluron showed slight phytotoxicity toE. lathyrisbut this did not appear in field experiments. Both chlortoluron and methabenzthiazuron were very efficient against weeds which were present and significantly increased yield ofE. lathyrisin comparison with unweeded plots. The poor competitive ability ofE. lathyrisagainst weeds was confirmed.

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00651.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryThe unrestricted growth and clonal spread from individual tubers ofCyperus esculentusL. were studied in Zimbabwe. Clonal material, collected from the Trelawney area, was grown in a square arrangement in the field with a 5 m spacing between original tubers. Growth was recorded at approximately monthly intervals for 2 years. The natural logarithm of clonal spread (m per month) was positively correlated to temperature and rainfall. Most growth occurred from November to March, a period of optimal moisture and temperature conditions. There was little growth during the remainder of the year. The changes in clonal spread during the year are expressed mathematically and incorporate two parameters of growth; one describes the rate of growth and the other predicts the radius once growth ceasesTuber numbers increased exponentially from December‐April, the rate of tuber production being greater in the first than in the second year of growth. Tuber production was greatest during March, April and December, 1980. Dormancy of the tubers decreased during the cooler months from May to August. The value of describing unrestricted clonal growth, and conditions favouring tuber production, are discusse

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00652.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryThe sites of uptake of chlorsulfuron in maize (Zea maysL.) were investigated at three different growth stages. Exposure of seedling roots, or shoots separately, to herbicide‐treated sand over 4 days resulted in inhibition of both roots and shoots. Exposure of seedling roots to chlorsulfuron‐treated soil over 21 days severely inhibited both roots and foliage, while separate shoot exposure also reduced both foliage and root growth. After plant emergence, exposure of the crown root node, growing point and lower stem to treated soil reduced foliage and root growth, but exposure of the shoot above the growing point caused only slight inhibition of foliage and had no effect on roots.The herbicide safener 1,8‐naphthalic anhydride (NA) applied as a dust (10 g kg−1seed weight), or as a 50 mg 1−1suspension in water to maize seeds, reduced the root inhibition by chlorsulfuron in 4‐day‐old seedlings. NA completely prevented both foliage and root injury when chlorsulfuron was placed in soil in the shoot zone before emergence, or in the shoot zone below the soil surface after plant emergence. NA slightly decreased injury to foliage, but not to roots when chlorsulfuron was placed in soil in the root zone before emergence. NA seed treatment protected both roots and foliage against injury from foliarly applied chlorsulfuron. Plants were also protected when a suspension of NA in water was sprayed on the foliage seven days before chlorsulfuron. When a mixture of NA and chlorsulfuron was applied to foliage, root injury was reduced more than f

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00653.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryThe effect of chlorsulfuron on uptake of45Ca was studied in maize (Zea maysL. cv. Earliking) plants grown from seeds dusted with 1, 8 naphthalic anhydride (NA).45Ca absorption in sand‐grown maize was significantly decreased when chlorsulfuron was applied to the foliage but this was not so when seeds had been dusted with NA. Uptake of45Ca was also reduced when either root or shoot soil zones were separately exposed to chlorsulfuron. When seeds had been dusted with NA, uptake of45Ca from main roots was similar to that of untreated plants, but only when chlorsulfuron was localized in the shoot zone. NA did not counteract the severe reduction in45Ca absorption when chlorsulfuron was localized in the root zon

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00654.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryThe effect of chlorfenprop‐methyl, flampropisopropyl and benzoylprop‐ethyl on14CO2fixation was followed in wild oat (Avena fatuaL.), barley (Hordeum vulgareL., cv. Ametyst), and wheat (Triticum aestivumL., cv. Mironovská). Experimental plants were exposed to a14CO2‐enriched atmosphere in a special apparatus 2 h, 1, 3, and 9 days after the herbicide treatment.Chlorfenprop‐methyl already inhibited14CO2fixation in wild oat plants 2 h after the treatment.14C‐metabolite transport to the roots was strongly decreased. Both14CO2fixation and14C‐metabolite level in the roots were significantly depressed inA. fatuawhen compared with untreated plants at the last sampling time.14C incorporation into starch was inhibited from the first day after treatment, and on day 9 was lowered more than ten fold in treated plants.Flamprop‐isopropyl inhibited14CO2fixation in wild oat plants from day 3 after treatment, but benzoylprop‐ethyl not until day 9. Both herbicides also decreased14C incorporation into starch inA. fatua.Chlorfenprop‐methyl also slightly decreased14CO2fixation in barley on day 9. However, assimilate transport into the roots and14C incorporation into starch were not affected. Flamprop‐isopropyl inhibited14CO2fixation in barley plants only on the first day after treatment, and assimilate transport was also reduced. By contrast, no differences from untreated plants were found at the end of the experiment. Benzoylprop‐ethyl did not decrease either14CO2 fixation or assimilate transport to the roots in wheat, but it inhibited starch synthesis. Atrazine depressed14CO2fixation in wild oat plants by 91%, in wheat plants by 99% compared with untreated plants. Assimilate transport into the roots was also strongly inhibited. In contrast to atrazine, the effect of chlorfenprop‐methyl, flamprop‐isopropyl, and benzoylprop‐ethyl on CO2fi

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00655.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryWhenAchillea millefoliumL. (yarrow) seedlings were grown in the field in association with a pea (Pisum sativumL.) crop vegetative growth of yarrow was significantly reduced by 6 weeks after emergence. Flowering was totally suppressed while the pure stand of yarrow developed flower clusters at 13 weeks after seedling emergence. Rhizome development occurred at 8 weeks after seedling emergence in the pure stand, but not until 15 weeks when grown with pea.The early suppression of seedling yarrow in a glasshouse experiment was associated with root interference, although by 5 weeks shoot interference by pea plants was important in reducing yarrow growth. The greatest suppression of yarrow occurred when both roots and shoots of the two species were allowed to interfere. Yarrow had low aggressivity against pea when grown in various combinations in a replacement series experiment in the glasshouse.

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00656.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryExperiments were carried out on seeds ofAbutilon theophrasti(velvetleaf) to examine the germination behaviour of hard (impermeable) and soft (permeable) seeds and to test various physical and chemical treatments against hardseededness. There was no evidence, in fresh or in old seeds, of leachable germination inhibitors or of leachable compounds affecting hardseededness.Marked differences were found between hard and soft seeds in respiration and leakage. Oxygen uptake was negligible in hard seeds. A rapid efflux of K+ions from hard and soft seeds was detected during the first minutes of immersion. Subsequently, the rate of leakage of hard seeds decreased markedly. After 4 h of imbibition, conductivity measurements differentiated individual hard and soft seeds.Abrasion, percussion and immersion in sodium hypochlorite had no effect on hard seeds, but mechanical scarification and immersion in sulphuric acid reduced hardseededness. Gamma radiation did not affect the hard coat but damaged the embryo.A. theophrastiseeds were exposed to organic solvents such as acetone. ethanol and methanol, and to pesticides such as butylate, EPTC, metham‐sodium, vernolate and methyl bromide, in liquid or gaseous phase. Some of the treatments reduced germination of soft seeds, but none, even methyl bromide, had any significant effect on the number or viability of hard seeds, proving their complete impermeabilit

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00657.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryAtrazine, chlorpropham and diuron gave excellent control of volunteer perennial ryegrass seedlings and reduced vegetative tillers of perennial ryegrass grown in the glasshouse and for seed in the field. However, there was no compensation in terms of the fertile tillers or seed weight during the second year. The results suggest that the lack of positive effect on seed yield may be due to direct effects on the crop from the residual herbicides.

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00658.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryThe patterns of regeneration ofPteridium aquilinum(L.) Kuhn. (bracken) rhizome segments grown in pot culture are described. The overall capacity for regeneration was unaffected by the rhizome type planted, i.e., whether it consisted of only a length of frond‐bearing ‘short shoote’ or whether this was attached to part of the main storage and exploratory ‘long shoot’. In all cases rhizomes extended, produced new lateral buds and developed fronds during the first summer. Regenerative capacity was also similar for segments with or without apical buds. Different patterns of growth were observed in plants grown from different types of segment: in particular, more new lateral buds were produced on rhizome segments originally lacking an apex. As rhizomes extended, the distance between successive lateral buds increased. The results are discussed in relation to the possible roles of correlative inhibition and patterns of translocation between fronds and rhizomes and to information on field po

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00659.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryA rapid and sensitive technique, involving analysis of chlorophyllafluorescence induction kinetics, for the study of the penetration of photosynthetically active herbicides into leaves is described. A range of chlorophyll fluorescence parameters are examined for wheat leaves treated with diuron in order to determine the most appropriate parameter to use in herbicide penetration studies. The usefulness of the technique is demonstrated by examination of the effect of a range of commercially available additives on diuron penetration in wheat leaves.

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00660.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY