Dalapon resistance at an early seedling stage in Lolium perenne

The inhibitory effect of the herbicide dalapon on germination and shoot elongation was evaluated in two perennial ryegrass cultivars, Melino RvP and Cropper. These cultivars had been shown to be dalapon resistant and susceptible, respectively, in a previous comparison of 14-week-old plants. Dalapon (10^-2 and 10^-3 m) significantly reduced rates of germination and shoot elongation to the same extent in both cultivars. It is suggested that the effects of dalapon on germination and shoot elongation during the first 9 days of development are not indicative of levels of resistance in more mature plants.     

The influence of the herbicide methabenzthiazuron on the synthesis of plastidic lipids in Hordeum vulgare seedlings

The herbicide methabenzthiazuron, and inhibitor of the Hill reaction, was applied to Hordeum seeds at the time of sowing, and the greening process under continuous Fluora light was investigated to the age of 13 days. Chlorophyll and xanthophyll contents were increased by methabenzthiazuron relative to the controls, with degrading ratios of chlorophyll a/chlorophyll b and rising xanthophyll/carotene values. The enhanced ratios of chlorophyll a to lipoquinones, like the absolute values, indicate an inhibition of the lipoquinones. These metabolic alterations are similar to those found in shade-adapted leaves. It is suggested, therefore, that inhibition of the photosynthetic electron transport, like deficiency in light of shade leaves, is compensated by metabolic reactions leading to a greater amount of photosystem II with an enhanced accumulation of the light-trapping chlorophylls and carotenoids.     

Tolerance of Cattle to DDT

GRADE cows fed a commercial 50 per cent wettable DDT powder developed symptoms of DDT poisoning following a minimum dose of 514 mgm/kg actual DDT and recovered from maximum of 1100 mgm/kg. Each cow received a total of 720 grams (25 oz) of the wettable powder which is far in excess of the quantity which is likely to be ingested following the spraying of barns.     

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Nieuwe Inzichten In Den Aard Der Voor Planten Pathogene Viren

Ohne Zusammenfassung Voordracht gehouden ter gelegenheid van het tienjarig bestaan van den biologenkring te Wageningen op 14 Februari 1939.