Trajectories of principal directions of growth, natural coordinate system in growing plant organ

In symplasticly growing organs the principal directions of growth, which are indicated by the eigenvectors of the symmetric part of the growth tensor, can be associated with each positional point and joined up to form a network of orthogonal trajectories, uolcss the growth is isotropic. The trajectories represent a natura( coordinate system suitable for description of growing orgaos. These trajectories often can be recognized in patterns of nonrandom aligoments in the cell wali network: these alignmeots are norma\ to anticlinal and periclinal walls. Coordioate systems that fit the trajectories in different types of growiog organ are listed

Modeling of spatial variations of growth within apical domes by means of the growth tensor. Pt. 1. Growth specified on dome axis

By using the growth tensor and a natural curvilinear coordinate system for description of the distribution of growth in plant organs, three geometrie types of shoot apical domes (parabolic, clliptical and hyperbolic) were modcled. It was assumed that apical dome geometry remains unchanged during growth and that the natural coordinate systems are paraboloidal and prolate spheroidal. Two variants of the displacement yelocity fields V were considered. One yariant is specified by a constant relative elemental ratę of growth along the axis of the dome. The second is specified by a ratę inereasing proportionally with distance from the geometrie focus of the coordinate systems (and the apical dome). The growth tensor was used to calculate spatial yariations of growth rates for each yariant of each dome type. There is in both yariants a elear tendency toward lower growth rates in the distal region of the dome. A basie condition for the existence of a tunica is met

Perception of gravity expressed by production of cambial callus in ash (Fraxinus excelsior l.) internodes

In ash internodes isolated from vertical stems during winter dormancy, cambial activity was stimulated by applying an aqueous solution of auxin to the apical end and water to the basal end. The internodes maintained nearly horizontally produced cambial callus at the apical cut surface with more callus on the upper half although both halves were in contact with the same concentration of auxin. A differential response to auxin of the cambium in the upper and lower halves of the horizontally oriented internodes is postulated

Occurrence of circular vessels above axillary buds in stems of woody plants

The circular vcsscls gencrally occur in intact wood stems just above the axillary buds. In this region the cell arrangement with vortices occurs. We interprete the circular vessels as the result or circular polarity in the cambial zone or the region above the axillary bud. The stability or circular polarity in this region is based on the vorticity or the cambium cells arrangement

A remembrance of Professor Henryk Teleżyński (1908-1989)

Minęło 12 lat od śmierci Profesora Henryka Tele­żyńskiego. Miałem szczęście być Jego bliskim ucz­niem i pragnę utrwalić w tym wspomnieniu cząstkę wiedzy jaką o Nim posiadłem. Tuż po pogrzebie Profesora zobowiązałem się do napisania artykułu o Nim do Wiadomości Botanicznych. Po kilku próbach realizacji tego zobowiązania musiałem się wycofać, bo zwyczajna miarka przykła­dana do osiągnięć naukowca - publikowany dorobek. zawodziła w usiłowaniu przedstawienia wielkości Profesora. Choć można wymienić kilkanaście prac H. Teleżyńskiego, to należy stwierdzić. że dorobek Profesora to nie publikacje, ale przede wszystkim słu­żenie sprawie rozwoju botaniki w Polsce[...

Pulsations of domain lenght as support for the hypothesis of morphogenetic waves in the cambium

Wiadomo z poprzednich badań, że w kambium drzew występują domeny czyli obszary ukierunkowywania na prawo (Z) albo na lewo (S) takich zdarzeń komórkowych jak: skośne podziały antyklinalne, zachodzenie na siebie przeciwnie skierowanych końców komórkowych rosnących intruzywnie, rozszczepianie i łączenie promieni. Wzór domenowy przesuwa się względem komórek w związku z czym typ domeny w danym miejscu kambium zmienia się cyklicznie. Zaproponowano hipotezę, że w kambium występują fale ukierunkowywania zdarzeń, czyli fale morfogenetyczne. Hipoteza ta wyjaśnia wzór domenowy jako przestrzenny przejaw fali, zaś jego przesuwanie i zmianę typu domeny w danym miejscu kambium jako czasowy przejaw fali. Na podstawie tej hipotezy można przewidzieć pewien typ zachowania się wzoru domenowego w przypadku gdy kilka fal o różnej długości i prędkości współistnieje w tym samym kambium. W niniejszej pracy odtworzono wzór domenowy w kambium Fraxinus które produkowało podwójnie faliste drewno. Stwierdzono, że w kambium tym występują pulsacje długości domen, takie jakich można było oczekiwać na podstawie interferencji dwu fal morfogenetycznych o różnej długości i prędkości. Występowanie zjawiska interferencji wskazuje na słuszność hipotezy o istnieniu fal morfogenetycznych w kambium

An oscillatory component of propagated fluctuation electric potential in lupine shoot

Application of a drop of auxin solution to a cut surface on the petiole in lupine shoot elicits a travelling pulse of electric potentia) decrease. This pulse was simulta­neously recorded by means of a DC amplifier and band-pass amplifier 0.1-100 Hz, both connccted to the same exploring AgCI electrode driven into the stem. The DC record shows a pulse 20-80 mV in height of about 30 s duration at its height with smooth slopes. The band-pass amplifier shows one to a few pairs of spikes (negative and positive) whose amplitude is at least of an order lower than that of the DC pulse. Thcse spikcs are interpretcd as the action potentia) of certain excitable cclls rccorded in a --volume conductor"·. The pulse is interpreted as a wave of cooperative depolarization of excitable and a mass of inexcitable cells

Localized spontaneous fluctuations of electric potential in shoots of differentplants

Sharp short-lasting voltage nuctuation is one of the components of plant electric activity. Common appearance of such fast signals (FS) in the stems of severa) species has been found. Obscrved spatial distribution of its amplitude excludes the possibilit} of an artefact. deriving from the electrode surface --- plant tissue interaction. The hypothesis that FS are due to action potentia) of a single cell or a small group of cells observed in a volume conductor is considered

Modeling of spatial variations of growth within apical domes by means of the growth tensor. Pt. 2. Growth specified on dome axis

Variations of the elemental relative rate of growth are modeled for parabolic, elliptic and hyperbolic domes of shoot apices by using the growth tensor in a suitable curvilinear coordinate system when the mode of area growth on the dome surface is known. Variations of growth rates within the domes arc obtained in forms of computer-made maps for the following variants of growth on the dome surface: (I) constant meridional growth rate, (2) isotropic area growth, (3) anisotropy of area growth which becomes more intensive with increasing distance from the vertex. In variants I and 2 a maximum of volumetric growth rate appears in the center of the dome. Such a distribution of growth seems to be unrealistic, However, the corresponding growth tensors are interesting because they can be used in combination with other growth tensors to get the expected minimum volumetric growth rate in the dome center