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ŠUMARSKI LIST 5-6/1968 str. 51     <-- 51 -->        PDF

Tek pošto se odgovori na ova pitanja moći će se za ovu specifičnu pojavu
naći adekvatan termin. Do tog momenta, a pošto se ova pojava ne može izjednačiti
sa mrazopucom predlažemo da se u svim radovima koji se odnose na
ovaj vid pucanja stabala govori ne o mrazopucu već jednostavno o »pucanju
stabala«. Da bi se istaklo da su u pitanju zasadi osnovani sa dvogodišnjim
sadnicama može se napisati: pucanje stabala (2/3, 2/2).


INJURIES FROM LOW TEMPERATURES TO POPLAR PLANTS


(Comments on the article by Dr. M. Vasić)


Summary


From 1962 on the Poplar plantations in Yugoslavia have been established with
2-year-old plants. Most represented in these plantations is the Italian clone »1-214«,
and less the acclimatized cultivars Populus robusta, P. marilandica, and P. serotina.


In the spring of 1964 in many of these plantations was noticed that individual
trees have been cracked during the winter. A relatively high percentage of cracked
stems was found in the plantations of the Baranja province (over 25|:|/»). In winter
1963/1964 were cracked by frost not only stems of Italian clones but also stems of
acclimatized cultivars raised by 2-year plants. The phenomenon was studied in de^
tail by Dr. M. Vasić, and he came to the conclusion that specific temperature conditions
which prevailed in the Baranja province outside the growing period 1963/
1964 were the main agencies to cause cracking of one-year-old stems. This phenomenon
has been described by Dr. M. Vasić as frost crack. Stems of the same clones
and cultivars — which had been raised earlier in plantings in the Baranja province
from one-year plants — had not been cracking either earlier or outside the growing
period 1963/1964.


The authors of this work refer the conclusions of M. Vasić and present their observations
about this phenomenon.


The conclusions about this phenomenon are based on observations carried out
during the 1963/1964—1967 period in I-124-clone plantations on a greater number of
localities in Yugoslavia.


Stems of the I-214-clone in plantations established by 2/3 plants were cracking
in all the mentioned intervals outside the growing period and in all areas of Yugoslavia.
A special comment upon the cracking of trees within the mentioned periods
has been given for the Experimental Estate of the Poplar Institute, Novi Sad.


Stems of this clone in the Experimental Estate of the Poplar Institute were
cracking even in November, 1967, when the lowest temperature was —7° C.


In Yugoslavia, the I-214-clone has been cultivated since 1956, and the authors
state that the stems of this clone (issued from one-year plants) were not cracking
in any interval outside the growing period until 1967.


These plantings behave in the same manner also in the Experimental Estate of
the Poplar Institute, Novi Sad.


There has not been noticed so far the cracking of those I-214-clone stems which
were raised from 2/3 plants if the latter were deeply planted (in the sand) with the
vegetative storey in the soil (above the ground remains the one-year-old sprout of
the 2/3 plant).


The phenomenon of stem cracking in Baranja (1963/1964) and in Yugoslavia is
interpreted with the use of 2/3 plant as the primary consequence.
By this phenomenon are involved those plantings established by vigorous 2/3
plants on soils of poor hydrological-physical properties.


Cracking is preceded by a discoloration and change of consistency of the interoir
(central) part of the stem. Bö a discoloration are especially characterized the
cross-sections within the zone of numerous occlusions of branch scars. These wounds
are formed during the process of producing 2/3 planting stock and through these