摘要:

AbstractAn experimental study of growth and reproduction inPleurozium schreberiwas undertaken to obtain information on the species seasonal pattern of growth and the previously reported irregular distribution of perigonia and sporophytes in the field in Great Britain. Humid conditions and the regular application of water and mineral nutrients in solution directly to the leafy shoots were found necessary for the sustained growth of mature gametophores. Under these conditions the rate of growth increased with increase in temperature independently of photoperiod over the range 5–20°C. No consistent differences in growth rate between male and felnale plants were recorded.Most tetrads in immediately post-meiotic capsules were shown to contain at least three and often four developing spores. Mature capsules contained normal and aborted spores, the frequency of the latter normally being 0–40%. Over 95% germination of normal spores was consistently achieved on agar. The rate of germination increased with temperature, day-length having only a slight effect. Regeneration by detached leaves occurred only in the case of young leaves, particularly those from close to the stem apex and on the uppermost branches where the stem and branch axes remained green in colour. Over 80% of such leaves normally gave rise to secondary protonemal filaments, which arose from enlarged cells in the basal angles, and many subsequently produced leafy buds. Bud formation was more frequent in male leaves (58%) than females (28%) on moist filter paper but little difference between males and females was recorded on peat-sand mixture.The explanation of a predominance of female plants in most British populations remains obscure but it is suggested that it may have its origin in events between meiosis and the protonemal stage.

ISSN:0373-6687    

DOI:10.1179/jbr.1979.10.3.321

出版商:Taylor&Francis    

年代:1979

数据来源: Taylor

摘要:

AbstractPhotosynthesis, respiration, net assimilation, chlorophyll b concentration, and levels of potassium, calcium, magnesium and iron were measured in 2 cm shoot segments ofPleurozium schreberiin order to examine patterns of physiological decline with ageing in a continuously growing species. Photosynthesis and chlorophyll b levels declined rapidly after the apical shoot segment and were undetectable after a distance of 8 cm from the shoot apex. Respiration rate also fell rapidly at first but then declined more gradually and some respiration was detected in all shoot segment samples. Potassium and magnesium levels declined approximately linearly in relation to segment number. Calcium levels, expressed on a concentration per unit weight basis, became progressively higher in older segments but the calcium content per segment may actually decline with age. The disparity may be due to a decline in the proportion of cytoplasm compared with cell wall material in older segments.No clear division could be made between living and dead shoot segments. Different physiological processes decline at different rates as ageing occurs and the importance of the age structure of shoot samples is discussed in relation to design of physiological experiments.

ISSN:0373-6687    

DOI:10.1179/jbr.1979.10.3.339

出版商:Taylor&Francis    

年代:1979

数据来源: Taylor

ISSN:0373-6687    

DOI:10.1179/jbr.1979.10.3.353

出版商:Taylor&Francis    

年代:1979

数据来源: Taylor

ISSN:0373-6687    

DOI:10.1179/jbr.1979.10.3.355

出版商:Taylor&Francis    

年代:1979

数据来源: Taylor

ISSN:0373-6687    

DOI:10.1179/jbr.1979.10.3.357

出版商:Taylor&Francis    

年代:1979

数据来源: Taylor

ISSN:0373-6687    

DOI:10.1179/jbr.1979.10.3.ii

出版商:Taylor&Francis    

年代:1979

数据来源: Taylor