摘要:

Morphogenesis in caulinar fragments of Aucuba japonica Thunb. in vitro. — Caulinar fragments ofAucuba japonicaThunb. are grownin vitroin different media. They show an obvious polarity; in fact only the basal section surface shows a vigorous proliferation and is able to form roots. When this surface emerges it gives rise to a green luxuriant callus; when the same surface is immersed it forms a protuberance in the shape of crateriform invaginations. Our histological studies indicate not only the connection between new proliferations and the pre-existent vascular tissues, but also the areas where the pseudothalli originate. The changes in the cortex and the central cylinder which are caused by thein vitrocultures were observed.

ISSN:0017-0070    

DOI:10.1080/11263507209426548

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Observations on vegetative growth and leghemoglobin contents of root nodules of pea and bean plants after flower bud removal. — These studies found their origin in the papers by MATTIROLO(1899) on the effect of the removal of flowers as they formed in bean plants; he observed that deflowering resulted in extraordinary plant growth, stem branching and flower buds formation as well as in a delayed root nodule senescence. In the light of modern knowledge of the leghemoglobin role in symbiotic nitrogen fixation, the aim of the present research was to ascertain any possible relation between flower bud removal and haeme pigment contents in the root nodules. The experiments were carried out during two growing seasons (1966 and 1970) usingVicia fabaL. cv.ReginaandPisum sativumL. cv.Senatoreduring 1966 and cv.Vittoriain 1970. In both control and test plants the seasonal trends of average plant height, fresh and dry weight of vegetative portions, fresh and dry weight of root system, fresh weight of nodules, root nodule leghemoglobin concentration and total leghemoglobin content per plant, were determined. The data obtained are quoted in Table 2 and reported in Figures 1, 2, and 3. The removal of flower buds caused in both species: an increased plant growth, a marked stem branching, a longer blooming period, an increased flower number, an increased root nodule number and a certain delay in root nodule reabsorption. Deflowering did not significantly extend — at least in the species studied — life span (senescence was delayed only of one week). On the basis of these and of other Authors' results, we conclude that deflowering may actually delay senescence; the size of this delay, however, depends on the plant species considered and is fairly negligible both in pea and bean. The different effects of deflowering and of preventing floral induction on life span extension, are discussed, and these facts lead to consider floral induction as the onset of a chain of processes leading annual plants toward senescence in a more or less delayable, but definitive way. After having stressed the generally accepted importance of leghemoglobin concentration as an index of nodule nitrogen fixing ability, a correlation between biomass increase of test plants and number and total weight increase of root nodules, is put in evidence. No correlation between test plant biomass and the leghemoglobin concentration in root nodules, was however observed. Leghemoglobin concentration in root nodules is known to change in connection with various factors depending either on host plants and onRhizobiumstrains and also in connection with several environmental conditions. Any prevented flower onset (ROPONENand VIRTANEN, 1968) and deflowering (our data) however exerted no significant influence. The effects of flower bud removal were therefore the following: increased stem, leaf and root weights and increased root nodule number; no difference between control and test plants was however observed as regards size and leghemoglobin concentration of root nodules and hence probably no difference as regards their nitrogen fixing ability.

ISSN:0017-0070    

DOI:10.1080/11263507209426549

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Preliminary studies on the marine phythobenthic communities in the Straits of Sicily and adjacent islands. — The results of algological researches carried out by the Gruppo di Algologia of the S.B.I. in the Straits of Sicily and adjacent islands are reported. 288 species have been collected, 275 of which have been identified: 160 wereRhodophyta, 62 Phaeophyta, 32 Chlorophyta, 16 Cyanophytaand2 Angiospermae. The vegetational research leads to the following conclusions: 1 - the harbour areas (Pantelleria, Malta: loc. 1 and 11) show a nitrophile vegetation, particulary near La Valletta where an almost pure population ofPterocladia pinnatais found; 2 - there are important biogeographical differences between Pelagie islands (Lampedusa, Linosa) and Pantelleria. In fact the former ones have an algal flora composed mostly of eastern mediterranean species, whilst the latter shows strong affinities with the north-african basin, as is demonstrated by the rich well developed belt ofCystoseira sedoides; 3 - several species of atlantic origin, such asCallophyllis laciniata, Peyssonnelia coriacea, P. inamoenaandCastagnea chordariaeformis, have been found on the banks (loc. 3, 6, 7).

ISSN:0017-0070    

DOI:10.1080/11263507209426550

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue

ISSN:0017-0070    

DOI:10.1080/11263507209426547

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor