Showing papers in "Plant Biosystems in 1948"
TL;DR: No relation has been found between degree of macroscopical growth responses and intensity of lateral root formation: treatments inducing the most intense growth reactions may show very poor « root-forming » effects.
Abstract: Summary The authors have studied growth responses and induction of laterals in onion roots subjected to various experimental treatments. The following reactions have been observed: C-tumours, coiling and bending responses, basal thickening, root hair formation and browning of roots. Fasciation, sometimes present in onion roots, is brought to greater evidence by many chemical treatments; none of these seems, however, to enhance its frequency. A more or less complete inhibition of growth and induction of lateral roots are generally concomitant phenomena; an exception to this rule are sulfathiazole and the threshold concentrations of 2,4-D (2,4-dichlorophenoxyacetic acid) and its sodium salt (see Table I). No relation has been found between degree of macroscopical growth responses and intensity of lateral root formation: treatments inducing the most intense growth reactions may show very poor « root-forming » effects (for ex., nicotinic acid and moist air). For most of the chemicals tested the threshold valu...
79 citations
TL;DR: The present study deals with the anatomical characters of the wood-ring in the Aleppo pine, in a grown-up specimen and in a young one (20–25 years); in both the specimens the wood of the stem and of the young branch has been investigated.
Abstract: Summary The evolution of the wood ring in Pinus halepensis M'ill in B'ari (from july ′46 to july ′47) The present study deals with the anatomical characters of the wood-ring in the Aleppo pine, in a grown-up specimen (80–100 years) and in a young one (20–25 years); in both the specimens the wood of the stem and of the young branch has been investigated The wood elements forming the ring are more highly differentiated, respectively in early and late wood in the stem of the grown-up specimen in comparison with those of the stem of the young one, and respectively the wood ring of the young branch shows a lower stage of differentiation in comparison with that of the stem of the same specimen; so that the older a specimen or a part of a specimen, the higher the degree of differentiation of the parts of its wood ring; namely the early tracheids are more different from the late ones Conclusively, the final histological aspect in the secondary wood of the Aleppo Pine seems to be attained rather late A parall
18 citations
TL;DR: Dioecism in idesia polycarpa maxim is a dioecious species, native of Japan and China, which bears occasionaly some flowers with ovaries, which exceptionally develop into fruits.
Abstract: Summary On the dioecism in idesia polycarpa maxim. Idesia polycarpa Maxim. is a dioecious species, native of Japan and China. Two specimens have been studied for this research, a ♀ and a ♂ one, growing in the Botanical garden of Siena. The female plant does not present anomalies in the sex behaviour; the male plant, on the contrary, bears occasionaly some flowers with ovaries, which exceptionally develop into fruits. In the Botanical Garden of Pisa a case of complete sex inversion has been observed (male into female). In both the ♀ and the ♂ the first development stage is identical and hermaphrodyte. The flower is tendentially proterandrous, unisexuality being attained only successively. In the male flowers the pystil degenerates while the pollen mother cells undergo meiosis. The ovary ceases developing farther, at the ovule forming stage from the placentae. The only cellular line which degenerates is the epithelium, which lines the ovary inner surface and extends as far the upper surface of the stygma. T...
8 citations
7 citations
TL;DR: Piante cratiche delle Alpi Venete as mentioned in this paper, Piante et al. (1948), p. 68-81, Vol. 55, No. 1, pp.
Abstract: (1948). Piante cratiche delle Alpi Venete. Giornale botanico italiano: Vol. 55, No. 1, pp. 68-81.
6 citations
TL;DR: Growth Cycle and Buds Differentiation in Perennial Plants Growing in Bari's area and the evolution of the wood ring in Prunus Amygdalus Stokes, From December 1946 to December 1947.
Abstract: Growth Cycle and Buds Differentiation in Perennial Plants Growing in Bari's area. - III. The evolution of the wood ring in Prunus Amygdalus Stokes, From December 1946 to December 1947. The cambial ...
5 citations
TL;DR: The author describes the embryo-sac of Pepsremia maculosa Hook, providing his study with drawings which illustrate its various stages, and notes the polarization is most irregular and does not develop after any regular schema but follows the most different proceedings.
Abstract: Summary The author describes the embryo-sac of Pepsremia maculosa Hook, providing his study with drawings which illustrate its various stages. During the megasporogenesis which, owing to the lack of divisory walls, closes with the building of a tetrade of megaspores, the author notices the delay of the chromosones in reaching their respective poles which however has no irflaence on the genesis of the embryo-sac. The vacuolization begins before the end of the omeotypic division which deviates from the normal course, as the vacuolization always follows the omcotypic division. The somatogenic division is abolished and at its place the tetrade of megaspores undergoes a long rest which however does not result in any increase of the volume of the tetrade. The polarization is most irregular and does not develop after any regular schema but follows the most different proceedings. An uncertain polarization determines alterations which if they do not appear during the quite regular gametogenical divisions are to be...
5 citations
TL;DR: The present work is introductory to a series of special papers dealing with Italian farm-land weeds and ruderal plants, and attempts to lay down the general criteria for the study, of the antropic communities of the earth's vegetation.
Abstract: Summary Introduction to the Study of Plant Cover of Anthropic Stations in Italy. The present work is introductory to a series of special papers dealing with Italian farm-land weeds and ruderal plants. The Author attempts to lay down the general criteria for the study, of the antropic communities of the earth's vegetation. He points out the great ecological and phytogeographical interest of those plant communities which are directly conditioned by man, seen as a widespread experiment in soil occupation by plants and in the “settling-down” process of mature vegetal cover, in such peculiar stations as the anthropic ones. This natural experiment is going on all the time and has in itself the possibility of leading towards characteristic oecological settlements of plants, biological competition, and — possibly · specific mutations.
4 citations
TL;DR: The evolution of cambial activity during one year in Viburnum Tinus L. in Bari has been studied, with an irregular step, and the relations between ring evolution and climatic factors are discussed.
Abstract: Summary The evolution of cambial activity during one year in Viburnum Tinus L. in Bari has been studied. The research seems to be particularly difficult in this evergreen shrub. The wood is of the porous diffused type with scarse evidence of wood rings. The vessel diameter varies rather irregularly in the wood ring; on the other side the fibers show wide variations and may be assumed as a good index of the wood ring evolution. Both in the branch and in the stem only one wood ring each year is formed. Cambial activity prosecutes during the whole year, with an irregular step. During the period July-beginning of September the cambium devides very slowly, or possibly stops deviding. The early wood is produced earlier in the branch than in the stem; namely in February-end of May in the branch and in March-beginning of June in the stem. The stimulating growth stuffs evidently proceeds downwards from the top to the base of the plant. The relations between ring evolution and climatic factors are discussed. The pe...
3 citations
TL;DR: The Author has studied the vegetation of the Ossero pools (the large and the small one) analising especially the formation which are characteristic of them, and identified the Salicornia herbacea formation and the Hordeun marinum Huds.
Abstract: Summary The Author has studied the vegetation of the Ossero pools (the large and the small one) analising especially the formation which are characteristic of them. In the level partion of the large pool the following formations — starting from the beach — are to be noted: Salicornia herbacea L., Hordeum marinum Huds., Inula viscosa All. and Artemisia coerulescens L. The Salicornia herbacea L. formation is sensibly homogencus in that portion of its area in which, owing to the high saline concentration of the soil, no other pecies is able to grow. In the remaining portion with a lower saline concentration, other species accompagny Salicornia herbacea. The Hordeun marinum Huds. formation comprises that portion of the pool which, being but little above the sea level, is invaded by high tides during the winter time. The saline concentation of the soil is here lower than in the area of the Salicornia herbacea formation. On the sea side Hordeum marinum is mixed to Salicornia herbacea; on the opposite side it ac...
3 citations
TL;DR: The white Narcissus grows on the lime areas of the Eastern Alps, in the valleys, wet prairies and flat moors: it can be found also in some high stations where it probably represents a relict from a late warm post-glacial period.
Abstract: Summary The Author refers on the distribution of «Narciso bianco» (white Narcissus) on the Eastern Alps and on the plant associations among which the white daffodil grows, by means of statistical reliefs. The white Narcissus grows on the lime areas of the Eastern Alps, in the valleys, wet prairies and flat moors: it can be found also in some high stations where it probably represents a relict from a late warm post-glacial period. The Author deals also with the devices to keep the plant alive.
TL;DR: It is opportune that Seed Testing Stations execute series of 4 parallel tests of 100 or 50 seeds each, and the writer suggests, in these cases, the following criterions of validity.
Abstract: Summary The tests to determinate the germination power of seeds are necessarily carried out on a small part of the lot of which we wish to know the germinative capacity. The results of the tests are ever susceptible to systematic and accidental errors so that it is necessary: 1st) to carry out the tests on such a number of seeds that allow a sufficient accuracy, without making them too difficult; 2nd) to determinate the germinative faculty through a series of parallel tests, in order to judge the validity of the obtained results. It is opportune that Seed Testing Stations execute series of 4 parallel tests of 100 or 50 seeds each. The writer suggests, in these cases, the following criterions of validity. For series of 4 × 100: For series of 4 × 50: where (x—M)2 is the sum of the squares of the deviations of the single results (x) from their mean (M). For scientific trials is better to use more sensitive means, like Pearson's test of goodness of fit, but it is necessary to increase the number of parallel t...
TL;DR: Les inspections de Toscane ont ete faites dans d'autres localites tres importantes pour the culture des cerisiers: Forli, Cesena, Modena, Verona etc.
Abstract: Resume On a continue les etudes sur le deperissement des cerisiers qui avait ete commencees au moi d'avril 1945 et dont les premiers resultats avaint ete publies dans un travail deja paru. Les inspections de Toscane ont ete faites dans d'autres localites tres importantes pour la culture des cerisiers: Forli, Cesena, Modena, Verona etc. Ona fait d'abord pathographie des arbres en deperissement qui montrent les secheresses seulement d'une partie; la production de gomme des rameaux, la presence sur le portegreffe de crevasses d'ecorce ou de depressions qui sont toujours placees sur la direction Sud-Ouest. Toutes les plantes qui deperissent ne presentent pas ces crevasses de l'ecorce. Apres onta fait l'anatomie des differents organes des plantes malades: des fcuilles, des petioles, des petits rameaux, des branches en les comparant avec les měmes organes de plantes saines. Il n'y a pas presqu'aucune difference; seulement le livre des rameaux et des petites branches des arbres deperissants presente d'alteration...
TL;DR: It is shown that the lethal action of nitrogen mustard on spores of Aspergillus niger can be described in terms of the target theory, if one assumes that the intensity of this action varies with time.
Abstract: Summary It is shown that the lethal action of nitrogen mustard on spores of Aspergillus niger can be described in terms of the target theory, if one assumes that the intensity of this action varies with time. A two-hit curve can be fitted on the experimental data, on the assumption that a decrease of lethality depends on the inactivation of the substance with time. By diluting the suspension containing the spores with a solution of glycine and sodium bicarbonate, the action of nitrogen mustard is stopped. The lethal action of nitrogen mustard is much weaker at 0° C than at 27° C. Even though exact mutation rates have not been evaluated, an outstanding number of morphological and physiological mutants among the colonies developing from irradiated spores have been observed.
TL;DR: Results concerning the influence of ultra-violet light upon both germinating energy and power: ultra-Violet light stimulates the germinates power of grains, born from subjects treated no longer than 240 hours at a distance of 1 m from the lamp; longer treatments abate germinate power.
Abstract: Summary In order to study a side of the influence of ultra-violet light on plants, the A. has harvested, 10 days after fertilisation, 1040 plants of Triticum vulgare Vill. and made many groups of them; then he sheared differently the ears and screened them partially from light so as to obtain, from the same subject, treated and untreated grains. Such ears he treated for different times of exposure with the light of a quarzlamp giving almost only ultra-violet rays. For the present, are here reported only results concerning the influence of ultra-violet light upon both germinating energy and power: ultra-violet light stimulates the germinating power of grains, born from subjects treated no longer than 240 hours at a distance of 1 m from the lamp; longer treatments abate germinating power; ultra-violet light stimulates, the germinating energy of grains born from subjects treated no longer than 120 hours; treatments during 120–240 hours don't notably modify it; treatments of over 240 hours reduce it very much...
TL;DR: The anatomical and histological structure of Mimosa pudica during the differentiation of secondary structures is described, which gives the whole characters of a tree to this plant, where the missing differentiation of phellogen only determines the external look of a grass.
Abstract: Summary The Author describes the anatomical and histological structure of Mimosa pudica during the differentiation of secondary structures. She discusses the meaning of this annual species within the genus Mimosa where only woody and perennial species are represented. The type of vascolarization of the plantula from the initial stage of development, the early appearance of the cambium and the histological characteristics of the secondary wood give the whole characters of a tree to this plant, where the missing differentiation of phellogen only determines the external look of a grass.