摘要:

RésuméLes auteurs présentent l'état actuel de l'infestation des cultures parSolanum elaeagnifoliumCav. dans l'ensemble de la région agricole du Tadla (Maroc Central). En utilisant la méthode des profils écologiques, il apparaît d'une part, que le périmètre des Béni Amir (Nord du Tadla) est beaucoup plus infesté que celui des Béni Moussa (Sud du Tadla) et d'autre part, que les cultures les plus envahies sont celles de printemps (coton, maïs, sésame). Une carte adjointe au texte permet de préciser la répartition de l'espèce au nivea

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00610.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

RásumáA partir des échantillons de sol, prélevés dans quatre champs du périmètre irrigué du Tadla (Maroc Central) et choisis dans la zone la plus infestée parSolanum elaeagnifolium, des estimations de semences de cette adventice vivace, révèlent que la valeur moyenne du stock en semences dénombrées (semences mortes + semences viables) deS. elaeagnifoliumest de 375 semences au m2sur 60 cm de profondeur. Tandis que la valeur moyenne du stock en semences viables est de 163 semences au m2sur 60 cm de profondeur, ceci représente en moyenne 43, 5% du stock total en semences dénombrées.Le profil moyen de répartition des semences deS. elaeagnifoliumdans le sol est le suivant: 71,7, 25,1 et 3,2% respectivement, dans les horizons 0–20, 20–40 et 40–60 cm. De même, la répartition verticale des semences viables suit le même profil que le stock total, ainsi nous trouvons que 73 et 27% des semences viables sont localisées respectivement dans les

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00611.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryIn an effort to determine the physical basis of the maternal inheritance of triazine resistance inAmaranthus hybridusL. the fate of plastids and other organelles in developing pollen was investigated in triazine‐resistant and susceptible biotypes. In both types, immediately after microspore mitosis, the newly formed generative cells contained an array of organelles (golgi bodies, endoplasmic reticulum, plastids and mitochondria) similar to that in the larger vegetative cells. No selective exclusion of organelles from the generative cell was noted although only small plastids were present. The immature generative cells contained small vacuoles, within which degenerate organelles were frequently observed, and no ultrastucturally recognizable plastids were found in mature cells. Maternal transmission of the triazine resistance factor thus appears to be due to a selective destruction of paternal plastid

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00612.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryField and laboratory studies of the South African grassEhrharta erectaLam. are presented. Seasonal growth and the soil seed bank were monitored at Mornington, Victoria, whereE. erectais naturalized beneath nativeLeptospermum laevigatumF. Muell. scrub. Adult plant growth commenced in late autumn, following a severe reduction in green shoot material resulting from drought damage. Seedlings emerged in autumn and winter and coincided with a significant decline in the soil seed bank.Germination trials indicated dormancy in fresh seed, which could readily be broken by a period of after‐ripening. Germination was also found to be inhibited by the presence of seed covering structures, but this effect diminished with time.A growth experiment conducted at different light intensities demonstrated a high level of shade tolerance inE. erectawith the compensation point ranging from 0·82 to 0·98% of full daylight. In view of the speciese’ shade tolerance and other evidence, it is hypothesized that the availability of water restricts the ability ofE. erectato grow under very dense canopies and controls its seasonal growth and regeneration pattern in the

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00613.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryThe metabolism of atrazine was studied in resistant and susceptible biotypes ofChenopodium albumL.,Chenopodium strictumRoth., andAmaranthus powelliiS. Wats. Both biotypes metabolized atrazine byN‐dealkylation, hydroxy lation at the 2‐position and conjugation. In addition, binding of mono‐N‐dealkylated atrazine with plant constituents to form nonextractable (bound) residues was also observed. Although parent atrazine levels were similar in the shoots and roots of both biotypes of the three weed species, the resistant biotype in each case contained a higher level of polar conjugates and bound residues in the plant tissues. In contrast, presence of a phytotoxic metabolite, namely 2‐chloro‐4‐amino‐6‐isopropylamino‐s‐triazine, was only observed in the susceptible biotype of t

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00614.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryStumps of birches (Betulaspp.) and aspens (Populus tremulaL.) in thinning stands and on clear‐felled areas were injected with herbicides by a modified bolt gun. Herbicides were formed into tablets and placed in a wedge of nylon. The wedge was fixed in the stem with the tablet placed close to the cambium. The tablets dissolved inside the tree. Injection doses were one tablet per 2·5 or 5 cm stump diameter and were done about 5 cm below the cut surface of the stump. The injector worked adequately. Injected stumps of both species produced few and shorter suckers than untreated stum

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00615.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryThe allelopathic effect ofSalvia syriacaL. (Syrian sage) was examined against wheat in glasshouse and laboratory experiments. The germination of wheat grains was delayed, and the development of wheat seedlings was decreased in laboratory experiments by both shoot and rhizome extract. The inhibitory effect of both extracts was most pronounced at 20°C compared with 10 or 15°C. Shoot extracts had more drastic effects than the rhizome extract on germination percentage, shoot and root lengths. In glasshouse experiments fresh and dried shoot ofS. syriacaadded to soil drastically decreased germination and development of whea

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00616.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryA machine was built to kill reproductive plants (‘bolters’) in sugar beet by high‐voltage electricity. A generating system producing 10, 13 or 17 kV each at 54 kW was connected to a set of guarded electrodes spanning twelve rows, suspended 5–15 cm above the top of a sugar‐beet crop. With 13 kV the system travelling at 5 km h−1could clear a light‐to‐moderate infestation of bolters at a rate of 2·4 ha h−1with the tractor's diesel‐fuel consumption at 3·51 ha−1. In 1979, the electrothermal machine, used twice, reduced viable seed returns by 83%; the flail mower used once or twice by 44 and 76–84%; the wire reel mower used once or twice by 45 and 80–87%; and the roller chemical applicator used once by only 13%. Further trials were made in 1981 with an improved electrothermal machine, a rope wick applicator and a flail mower when all gave over 90% control of viable seeds. The electrothermal machine killed between 38 and 41% of bolters compared with 65% for the chemical applicator. The flail mower did not kill any plants.Although possessing many advantages, the electrothermal machines are heavy and more expensive than alternative methods. Development has ceased in the U.K. on electrical weed control but one company in the U.S.A

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00617.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryCultures ofChlorella pyrenoidosaPringsheim were grown photoautotrophically in the presence of two concentrations (0·25 and 0·50 μm) of atrazine and methabenzthiazuron. The cell density and chlorophyll content were greatly reduced in presence of both herbicides. These herbicides affected net photsynthesis equally without affecting oxygen uptake. However, cell division was more inhibited by atrazine than by methabenzthiazuron, but chlorophyll content per cell was more inhibited by methabenzthiazuron than by atrazi

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00618.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryA study was made of the caryopsis weights ofAvena fatuagrown in the field and in pots and of the competitive ability ofA. fatuafrom heavy seed (≥18 mg) and light reed (≤11 mg) grown at a depth of either 25 or 75 mm with spring barley sown at 25 mm.The weight of field‐ and pot‐grown caryopses ofA. fatuatypes fA, fB and fC ranged from 3 to 25, 5 to 23, and 5 to 25 mg respectively. With one exception, both the field‐ and pot‐grown samples showed a double normal distribution pattern. The mean weights of pot‐grown primary and secondary caryopses of fA, fB and fC were 15 and 9, 19 and 11, and 18 and 11 mg respectively.In a competition experiment,A. fatuagrown from heavy seeds sown at 75 mm depth with an equal number of barley produced 47% more panicles, 54% more seed and 56% more dry weight per plant than plants from light seeds. When barley and both seed weights ofA. fatuawere sown at 25 mm depth these differences were smaller, being 21, 28 and 34% respectively.When the barley was at Zadoks stage 87, and when the barley andA. fatuawere grown at equal densities at 25 mm depth, the dry weight of barley was reduced from 10·4 to 7·7, and to 5·8 g per plant by light‐ and heavy‐seededA. fatua, respectively. When the barley was grown at 25 mm and theA. fatuaat 75 mm, the weight per barley plant was reduced to 9·5 and 7·2 g byA. fatuaplants grown from light and heavy seeds respectively. Reductions in numbers of grain were caused mainly by a reduction in the n

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00619.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY