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.     

Sulle cause determinanti la formazione di tumori in ibridi di Nicotiana. Prime ricerche sierologiche

Abstract

PRELIMINARY SEROLOGICAL RESEARCHES ON MECHANISM OF TUMOR INDUCTION IN NICOTIANA HYBRIDS. According to GOODSPEED'S phyletic scheme, based on a cytogenetic evidence, both Nicotiana rustica and N. paniculata should be assigned to the sub-genus Rustica, while N. langsdorffiii and N. sanderae fit with the sub-genus Petunioides. Indeed the fact that genetical tumors are produced by the hybrids of these species only when the parents belong to different sub-genera, seems to support GOODSPEED'S views, just as KOSTOFF'S hypothesis of tumor production as a consequence of uncongeniality and incompatibility of parent's protein set, receives by this scheme a valid support.

Immunological research work has been carried out to test the possible affinities of the protein sets of the four Nicotiana species. It was observed that the protein set of N. paniculata is more similar to the protein set of N. langsdorffiii — a species included in a different sub-genus and whose hybrids with. N. paniculata bear tumors — than to the one of N. rustica, a species included in the same sub-genus and whose hybrids with N. paniculata never bear tumors. These studies are still in progress.