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721.
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Further evidence is presented to show that the systems of orientationof cellulose fibrils in the cell-walls of Valonia and Dictyosphaeriamay be described by reference to two poles uponwhich these orientation systems converge. The polesare real structural features of the wall. 相似文献
724.
One effect of the removal of cotyledons of soya-beans 24 h afterimbibition was to reduce subsequent growth, especially in thefirst 10 weeks after planting. The longevity of treated plantswas increased by 30 days and the onset of leaf senescence delayed,as judged by the time-course of leaf chlorophyll and solubleprotein content, and also by the time-course of net photosynthesisand respiration rates. These effects are similar to those reportedto result from partial defoliation of more mature plants. 相似文献
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726.
A study of the dry weights and ages of 57 Salix arctica plantsgrowing in a higharctic region shows that their annual relativegrowth-rate, which decreases with age, is about one-fifth ofthe annual relative growth-rate of comparable plants under temperateconditions. Data on the thickness of annual rings indicate thatthere is a large and progressive increase in annual growth fromhigh-arctic to sub-arctic regions. 相似文献
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Abstract. A treated-surface test was used in a bioassay to detect insecticide resistance to the organophosphorus compounds diazinon and propetamphos, in larvae of field strains of Lucilia cuprina in New Zealand during 1990/91 and 1991/92 (December-April). Mean LC50 s for both diazinon and propetamphos showed a significant increase between seasons although this is not necessarily indicative of a trend. Mean LC50 s for diazinon increased from 1.16 to 1.60 mg/1 (P< 0.001) and for propetamphos from 0.49 to 0.59 mg/1 (P< 0.005) in pooled populations. Diazinon and propetamphos resistance was significantly correlated in both seasons, suggesting side-resistance between the two insecticides. 相似文献
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730.