Ciclo Di Accrescimento E Differenziazione Delle Gemme in Piante Perenni Nel Territorio Di Bari

Abstract

The secondary wood of the fig tree is characterized by a remarcable degree of dimorphism and the concentric rings d o not correspond to yearly recurring growth periods. These false rings are formed by alternating tangential strips of fibers and wood parenchima. During each vegetative season three or four of these strips arc laid down by the cambium.

During the year the cambium undergoes a period of activity and a period of rest, but there is no histological difference between the early wood and the late one, differentiated just before the restring period. In consequence the so-called annual wood rings do not exist in the fig tree stem.     

Ciclo Di Accrescimento e Differenziazione Delle Gemme in Piante Perenni Nel Territorio Di Bari

Summary

Growth CYCLE AND BUDS DIFFERENTIATION IN PERENNIAL PLANTS GROWING IN Bari AREA. 1) Observations ON Ficus Carica DURING THE YEAR 1946.

The fig tree under observation in Bari started its growth (during the year 1946) in the second week of March and stopped in June second half. The growth period lasted about three months (tab. 1 e 2; diagr. 1).

The most rapid growth occurred during the second week of May (tab. 2; diagr. 1).

From the diagr. 3 it appears that in the fig tree the growth end corresponds at the beginning of the rainless weather; in the meantime the temperature rises gradually (diagr. 4). The atmospheric humidity subsists high also during the summer rainless period (diagr. 5).

Among the four shoots examinated, only one showed a further slow lengthening (13 mm.) from 2nd. August to 6th September. The three others did not grow anymore from June 15 (tab 2; diagr. 1).

The young shoot internodes have different lengths. The basal ones are shorther than the middle ones, which appeared during this speedly growing period (diagr. 2); the last two internodes are very short, so that the nodes are rather contiguous. At each node one leaf unfolds, with two large stipules, which soon fall; on the very last node the stipules do not fall, sheltering the young apical bud, which they completely close in. The corresponding leaflet scarsely grows, falling soon. Neverthless the protection of the two stipules, the first leaflet of the apical bud withers and falls frequently as soon as the bud unfolds at the beginning of spring (fig. 1).

Each leaf axil bears two or three buds (fig. 7). When two buds are present, one is a fruit bud and the second a vegetative one (figg. 11 e 13), when three buds are present, the two lateral ones develop into flowers, while the middle one grows into a vegetative shoot (fig. 12).

The very first sign of the fruit character of a bud is the flattening of the apical bud meristem (fig. 7); successively it deeps into a cuplike body (figg. 8 and 9); on the bottom and along the walls of the cup the female floscules are developing (fig. 10).

The first sign of the vegetative character of a bud is, after the formation of the leaf meristem outline, its evolution with the caratteristically lobed leaves and stipules.

As far as a given height along the shoot (as far as the sixth node in our shoots) the syconia prolong their growth after the shoot lengthening has stopped and ripen completely during August-September (forniti or September-figs). From a certain level ahead, as far as the apical bud (from the seventh to the tenth node in our shoots) the syconia cease their development about contemporarly the vegetative shoot. They are three or four mm. wide and the little flowers are clearly distinguishible inside. So they hang from the nodes as late as next spring time, when they begin to grow again, ripening in June (fioroni or June-figs).

September and June figs then represent a continous acropetal fruit series differentiating at each leaf axil, as soon as the leaflets unfold during the shoot development. We must point out that while the September figs reach the ripe condition through a stopless development in the same year, the June figs stop their growth at a given time, standing a resting period and begin to grow again, ripening the next vegetative season.

As to explain such a behaviour, the presence of an inhibitory stuff is prospected, produced from the more developed figs, which attain a given stadium of development. This stuff would act on those figs, which have not yet reached this particular development stage.

The summer drought checkes the shoot growth and the bud differentiation. The flower buds, which have been too early stopped in their development, are not able to grow again the next season and fall during the apical bud unfolding. Such a condition occurs in the last leaf bud (fig. 4) and in the first leaflet bud inside the vegetative tip (apical bud) (fig. 5). At the beginning of the new vegetation season the shoot awakes with the differentiation of those buds, which did not yet differentiate at the axil of the leaflets inside the apical bud (fig. 6). (See fig. I, where the phenomenon is schematically reproduced).     

Ciclo di Accrescimento E Differenziazione Delle Gemme in Piante Perenni Nel Territorio di Bari

Summary

Growth cycle and buds differentiation in perennial plants growing in Bari's area. — V. The evolution of the wood ring in Rhammus Alaternus L. from December 1946 to March 1949.

In Rhamnus Alaternus L. the cambium awackens in March with the production of an early wood, characterized by large vessels and loose fibers. It keeps on dividing the following months, producing intermediary wood, whose vessels become narrower and narrower. In June the wood ring is almost complete and the cambial activity slows down. In July late wood is formed, with narrow tracheae and highly lignified fibers. From August to February cambial activity is very scarce and irregular, in the wood produced fibers being tangentially compressed.

In a young branch of R. A. cambium becomes suddenly active in February, that is one month before than in the stem, it goes on during the month of March-June, with an evident diminution in the size of the wood elements. This diminution of size instead of being regular, shows some oscillations, expecially during the month of May. In Sept. the cambium starts again dividing, but rather poorly and irregularly, forming some vessels a little wider than the preceeding ones, so that an incomplete false ring is formed only in some points of the branch. As a rule the autumn wood is a typical late wood. This scarce and irregular cambial activity goes on also during Oct.-Dec. In January is more active and forms rather wide vessels in comparison with those formed in the preceeding month. This new formed wood however does not show the characteristics of the early wood of a new ring.

Concluding, the characteristics of the cambial activity of A. R. are

In the stem: 1) March: early wood. 2) March-June: intermediary wood. 3) July: late wood, resting period. 4) At the end of Autumn a scarce production of late wood is sometimes possible.

In the young branch: 1) February: early wood. 2) March-June: intermediary wood, with positive and negative oscillations in the vessels width. 3) At the end of June the late wood is already differentiated. 4) July-August: resting period. 5) Spt.-Juan.: the cambium starts again dividing very scarcely and producing a transition wood between the two rings. This wood can be regarded neither as a true ring nor a false one, it represents rather the last phase of the late wood formation. 6) In the young branch of the female specimen the cambium starts dividing somewhat later than in the male one. 7) The wood ring width does not vary much in relation to the yearly amount of rainfall. The lack of relation between rainfall and ring width is particularly evident in 1948 (a rainy year). The, «Compleasance» of R. A. could show that this species is, in Puglia, in its own habitat. On the other hand it is rather peculiar that R. A. forms only one wood ring during one year, with production of early wood during the spring, and of late wood in the autumn, instead of producing a second autumn ring following a distint summer rest, as could be expected.     

Proposta Di Una Scala Di Differenziazione Delle Gemme Fogliari Del Pioppo Utile Per Gli Interventi Antiparas Sitari

Abstract

A poplar leaf-bud differentiation scale suggested for the pest control treatments. – After having pointed out that also in Poplars the severity of the transplanting crisis and of several pest attacks is in relation to the development stage the leaves are in, the Authors suggest a differentiation scale of the leaf-buds particularly useful for the pest control treatments.     

Naturalizzazione E Riproduzione Spontanea Di Piante Ornamentali Nella Liguria Occidentale

Abstract

Effects of the growth-retarding compounds «CCC» and «AMAB» on the growth and alkaloidal content of Datura Stramonium L. — Datura Stramonium L. was administered two fortnightly-doses of 200 cc 10 ^-2 M solutions of (2-cloroethyl)-trimethylammonium chloride (CCC) or (allyl)-trimethylammonium bromide (AMAB), poured on the soil of every pot. In the treated plants were noted shorter and thicher stems and petioles and leaves larger in size and darker green than in the controls. Yields of leaves in CCC and AMAB-treated plants were not significantly changed while root fresh and dry weights were decreased. The per-cent concentration of total alkaloids in the leaves and roots of both CCC and AMAB-treated plants was not significantly different in comparison with that of normal plants. Therefore the A. assumes that the growth-retarding chemicals must not interfere with alkaloidal synthesis.     

L'amido E L'endosperma Delle Cariossidi Dure E Tenerizzate Di Triticum Durum Desf

Abstract

Starch and endosperm of vitreous and starchy (yellow-berries) kernels of Triticum durum Desf. — Starch and endosperm in kernels of T. durum Desf. have been examined in relation with the problem of the origin and nature of the vitreous or starchy texture which this tissue shows in the ripe fruits. This research has demonstrated that the starch of the vitreous differs from that of the starchy kernels in the shape, respectively irregular and regular; in the distribution of the frequencies y versus the length of the diameter x which is exponential and of the type log y = log a — x log b, in the vitreous kernels the value of log b is generally lower than in the starchy kernels; in the submicroscopical texture, because the irregular grains of the vitreous kernels do not show either birefringence or polarisation cross and are coloured with Congo red: starchy kernels behave quite differently. The starchy kernels are also more swollen and regular, their apparent specific weight and their nitrogen content being less than in the vitreous; the process of starchiness is always in close contact with fibro-vascular bundle of the row; in the starchy cells the cytoplasm shows some interruptions of continuity which leave partly uncovered the starch grains; the endosperm and the starch of the hard kernels wetted with water or placed in moist atmosphere become micro- and macroscopically similar to the starchy ones; in the starch the process of trasformation of the orderly into the amorphous texture is reversible, but for this to happen the only contact with water is insufficient; according to the treatments the vitreous kernels might show a decrease in their nitrogen content. Both starch types are connected with the presence orabsence of slightly bound water; the hypothesis which considers the nitrogen supply of the fruit as immediate cause of the endosperm texture is criticised and it is considered more plausible that such cause might be the different structure and texture of the cytoplasmatic gels during, in function of temperature and moisture.     

Quinta Serie Di Rinvenimenti Floristici Marchigiani E Di Osservazioni Diverse Sulla Flora Delle Marche

Abstract

The A. refers about the most interesting discoveries and observations performed during the year 1958 in the limits of the flora of Marche.     

Appunti Sulla Flora Stradale E Ruderale Dei Dintor Ni Di Molfetta (Bari)

Summary

The author has studied the flora of a few country lanes in the surroundings of Molfetta (Apulia). The various stations are described and the plants collected are listed.     

Variazioni Di Composizione in Piante Di Vicia Faba L. Trattate Con Acido Gibberellico (Nota preliminare)

Abstract

The effects of gibberellic acid on the composition of VICIA FABA. — The A. takes into consideration fresh weight, dry weight, total ash and chlorophyll, carotene, mineral content variations in Vicia Faba L. plants as affected by pure and practical gibberellic acid treatments.     

Effetto Del Dinitrofenolo Sulla Conversione Del Glicerolo A Glucidi in Fettine Di Carote E in Internodi Di Pisello

Abstract

On the effect of dinitrophenol on carbohydrate activation in higher plant tissues. — Previous investigations on the effects of 2,4 dinitrophenol (DNP) on carbohydrate metabolism in isolated pea internodes and in yeast showed that the increased rate of glycolysis induced by the uncoupler corresponds to an increased rate of the conversion of free hexoses and polysaccarides to hexose phosphates. In yeast about 30% of the radioactivity supplied and taken up as ¹⁴C labelled glucose, and 20% of that supplied and taken up as glycerol is recovered as soluble sugar and glycogen; this phenomenon is almost completely suppressed by 10^-4M DNP.

This suggested that a mechanism involving kinase enzymes, on one hand, and phosphatases, on the other, is mediating the interconversion of phosphorylathed and free sugars, and that the apparent increase of hexose phosphorylation observed in the presence of DNP might depend on a decreased rate of phosphatase mediate reactions, consequent to the decrease of phosphorylated sugars level in the cell.

The experiments here reported were planned to test the validity of this hypothesis in the case of higher plant tissues.

Material used in these experiments were segments from the growing part of the third internode isolated from 7 day old, etiolated pea seedlings, and carrot root diks (0,7 mm thick, 7 mm diameter) preincubated for 24 hours in aerated distilled water. Both of these materials show an active, steady respiration and some growth activity, so that they may be taken as representing a condition close enough to that of the generally physiologically active higher plant tissues.

The reversibility of the hexose phosphate-free sugar interconversion process was tested by feeding 10^-3M 1-C¹⁴ labeled glycerol, and measuring after 150 minutes the amount of radioactivity incorporated into CO₂, soluble sugars, organic acids and proteins. The results of these experiments are summarized in table I and II.

Glycerol metabolism as well as its response to DNP appears very similar in the two material used. In both cases, glycerol uptake and incorporation into organic acids and amino acids is almost insensitive to DNP. In contrast large differences are observed for the free sugar fraction. In the absence of the uncoupler, a consistent amount of the radioactivity fed as glycerol is found in this fraction. It appears reasonable to assume that the glycerol-sugar interconversion comprehends, as intermediate steps, glycerol-P, fructose di-P (or sedoeptulose di-P) and hexose-6-P. If this is true, the observed data implicate that a continuous interconversion occurs, in the cell, between sugar phosphates and free sugars and vice-versa, one reaction direction involving the activity of phosphatases, and the other one that of kinases. The true rate of this interconversion process is probably much larger than indicated by the radioactivity found in free sugars: as a considerable part of the triose-P transormed into sugars must immediately re-enter the descending flux of glycolysis.

This view finds some support in the fact that DNP almost completely inhibits the incorporation of radioactivity in the free sugar fraction. It has been previously observed that DNP very markedly decreases the level of hexose mono- and di-phosphates and of triose-phosphates in the pea stem tissues. If phosphatases acting on fructose di-phosphate and on hexose-6-P are not saturated by their substrates, a decrease of the rate of free hexose synthesis from sugar phosphates should be expected.

The present results are thus consistent with the hypothesis that hexose phosphates and free sugars in the cell are continuously interconverted by the simultaneous action of phosphatases and kinases; and that the effect of DNP, and thus of any physiological conditions decreasing the ATP/ADP ratio in accelerating free hexose utilizations is at least in part due to a decreased rate of the reactions catalized by fructose diphosphate and hexose-6-P phosphatases. The reversibility of the kinase-phosphatase system would thus represent a crucial link in the mechanism by which the rate of carbohydrate activation and breackdown is controlled by the rate of utilization of high-energy phosphate bonds.     

Sviluppo Vegetativo E Riproduttivo Di Alcune Longidiurne in Rapporto All'Azione Dell'Acido Gibberellico

Summary

Continuing the experiments on the action of Gibberellic acid on growth and development of herbaceous plants, the Authors have examined once more several species which require “long day” for espletion of some phases of their reproductive development.

The principal aim was to bring into evidence whether Gibberellic acid can really substitute for some manifestations of the reproductive development itself, or whether some apparent manifestations of reproductive development provoked by this substance are due primarily to modifications of vegetative processes determinated by it.

The experiments were carried out on Papaver somniferum L., Centaurea calcitrapa L., Oenothera acaulis L., Aethusa Cynapium L. and Myosurus minimus L.

Results obtained on Papaver somniferum demonstrate that Gibberellic acid accelerates the macroscopic flowering manifestations under short day conditions of plants already induced to flowering, substituting in this for the effect of “long day” factor in so far as concerns the lengthening of the floral axis. No experiments which can establish whether Gibberellic acid may have an action on specific processes involved in the transition to the reproductive stage, have so far been conducted on Papaver.

Experiments on Centaurea calcitrapa have revealed that Gibberellic acid, treatment though promoting in plants manteined in short-day conditions a “bolting” effect simulating that obtained usually only at long-day, does not succeed in flowering this is true in our experimental conditions (experiments limit: 10 weeks; (photo-phase at light intensity inferior to 2000 lux). Experiments on Centaurea were also supplemented with histological observation of esperimental material.

In the experiments on Oenothera acaulis, a long-day plant only for the macroscopic development phase of floral apparatus, and indeterminate for the formation of floral primordia, has been noted that Gibb. acid can, in the long run, partly substitute for the long-day effect. However, development of floral structures at shortday, is more easily obtained if the plants are supplied, besides with Gibberellic acid, also with other stimulating and trophic substances. This and others observations may indicate that Gibberellic acid represent only one of the substances involved in the metabolism of plants under long-day conditions.

Aethusa Cynapium has furnished results similar to those obtained with Centaurea, even if within very long experimental limits some apparently indirect action of Gibberellic acid towards flowering may occurs.

Preliminary experimental data on logday Myosurus minimus L. show that Gibberellic acid can substitute sooner or later for longday requirements in flowering. In fact, two months old plants flower when Gibberellic acid is supplied under 9 hr. shortday conditions while the controls in shorday remain vegetative. We must note that Myosurus flowers better when light extension is prevalently constituted by far red radiation the effect of which is apparently substituted more easily by Gibberellic acid even if its action appears less afficient and rapid than that of supplementary illumination.