摘要:

Summary:Studies were made at Kairi on the Atherton Tableland of Queensland, Australia, on the effects of varying lemperature regimes, both controlled and natural, on the germination of seed ofSetaria antceptStapf. cv. Nandi andEleusine indica(L.) Gaertn. The germination ofE. indicaseed was found to be much more temperature labile than that ofS. ancepts.The temperature required for peak germination was higher forE. indicaseed than forS. anceptsseed.The effects of temperature on competition betweenE. indicaandS. anceptswere studied in the field by varying the time of planting. It was shown that at mean screen temperatures measured throughout the growth period of23° CE. indicawas dominant. There was a tendancy forS. awepsyields to decline with increase inE. indicaplant density but there was a much closer negative correlation betweenE indicatop dry weight andS. aanceptsyield.From the meteorological data for Kairi for the past 25 years predictions were made on the best times to plantS. anceptsto avoid serious competition fromE indic

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1979.tb01539.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Summary:Thlaspi perfoliatumL. is an introduced winter annual that grows in waste places, but it is not a troublesome agricultural weed. Seeds are dormant at maturity in spring, afterripen during summer and germinate in autumn. Non‐dormant seeds that fail to germinate in autumn are induced into secondary dormancy by low winter temperatures and cannot germinate the following spring. These seeds afterripen during summer and germinate in autumn if conditions are suitable. Vernalization is not an absolute requirement for flowering. However, it shortens the time to flowering, and vernalized plants produce many more flowers and seeds than non‐vernalized plants. Results from studies on seed germination and flowering ofT. perfoliatumare compared to published studies on the life cycle ofThlaspi arvenseL., an introduced species that is a serious agricultural weed which behaves both as a winter and a summer ann

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1979.tb01540.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Summary:Wild oat (Avena fatua L.) plants sprayed at the 2‐or 3‐leaf stages of growth with diclotop‐methyl developed chlorosis over the entire leaf blade of all leaves. The leaves became necfrotic7days after spraying Shool growth was inhibited. In wheat (Triticum aesicumL cv.Waldron) discrete chlorotic areas developed only where the herbicide convicted the 2nd or 3rd leaf with no visible injury so new growth uf'ter treutment. Growth inhibition of susceptible oat (Avena sativaL. cv. Garry) was sensitive to placement of diclutop‐methyl near the upica and meristematic sites of the plant. Chlorosis and necrosis were independent of herbicide placement. Selective herbicide placement induced chlorosis only or both chlorosis and growth inhibition Root growth in wild oat and barley (Hordeum rulgareL. cv. Dickson) was strongly inhibited by 1–0 μM diclofop‐methyl. Wild oat shoots were killed when seedlings were root‐treated with 10 μM diclofop‐melhyl. The 100 μM rool treatment killed barley shoots but only stunted the growth of wheat shoots by approximately 50%. In root‐ireated wheat plants the shoots were turgid and developed a light purple colour, whereas in foliar‐treated plants the shoots developed di

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1979.tb01541.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Summary:Soil incorporated. pre‐sowing application of trifiuralin in cotton or of benfluralin in gruundnut, each at 1–68 kg a.i., ha, cut labour requirement for handweeding to levels where the tenant could he largely independent of hired labour, Economic returns from a combination of these herbicides plus supportive hand‐ weeding for herbicide‐resistant species compared favourably with those from hand‐ weeding only as presently recommended.Application and incorporation of trifluralin and benfluralin fited well into existing practices for seedbed preparation and any likely modifications of these. There was no evidence of crop phytoxicity and crop maturity was not affected. Residue analysis indicated no soil residue problems for crops in rotations and no residues were detected in crop seed. Trifluralin applied many months in advance of cotton planting in the dry season, did not start to disappear until the soils were wetted just before couon

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1979.tb01542.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Summary:Examination of the fine structure ofRubus procerusleaves following application of 2.4.5‐trichlorophenoxyacetic acid a field does shows that the chloroplast is a side of herbicide action and that by 1 week after spraying the leaves show changes indicative of accelerated senescence. Both aqueous and non‐aqueous methods were used to isolate chloroplasts following treatment of leaves with radioactive 2.4.5‐T. Chloroplast isolation using the non‐aqueous method indicated an accmulation of radioactivity in that or

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1979.tb01543.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Summary:The persistence of dichlobenil following the application of dichlobenil granules was studied in a replicated plot experiment including both surface and incorporated treatments of 8·3 and 16·6 kg/ha ai. Soil analyses showed an initial half‐life of about 4 weeks but the persistence increased with time and a year after application the half‐life was about 1 year. Incorporation of the granules into the soil markedly increased the persistence of dichlobenil and its metabolite dichlorobenzamide. The most sensitive crop was carrot which was damaged by residues of only 1–2% of the recommended dose. Residues phytotoxic to carrots persisted for 2 years from the 8·3 kg/ha surface application and 5 years from the 18·6 kg/ha incorporated application. Lettuce was also highly sensitive to

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1979.tb01544.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Summary:Imperata cylindricaandCyperus rotunduswere grown under three different light regimes; unshaded, 50% shade, and 75% shade and no shade plus 75% shade before and after spraying, (temporary shade) in a heated greenhouse. Six weeks after the start of the experimenis, glyphosate was applied to the plants at 0·2, 0·4 and 0·8 kg/ha (forImperata) or 0·3, 0·6 and 1·2 kg/ha (forCyperus). Glyphosate toxicity was enhanced as shade increased. InImperata, all shade regimes at all rates of glyphosate eaused greater damage to the plants than the unshaded regime. The reduction in shoot dry weight, rhizome dry weight and total carbohydrate content ofImperaterhizotties at 75% continuous and temporary shaiie conditions, with the lowest rate of glyphosate, was almost twice as much as the reduction in the same features m the unshaded plants caused by the highest rate of glyphosate. InCyperus.glyphosate at the intermediate and highest rates decreased the shoot dry weight at 75% continuous shade by 79% and 98% respectively. Plants in 50% shade were significantly affected only at the highest rate of glyphosate. Sprouting ability of the tubers al 75% continuous shade was inhibited when the tubers were replanted for recovery. Enhanced toxicity of glyphosate in reduced light intensity was attributed to the morphological changes in the nature of the leaves caused by

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1979.tb01545.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1979.tb01546.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY