Stress physiology of palm trees II. The effect of heavy metals and high irradiance on the photosynthesis of palm Trachycarpus fortunei84-88.Views:147
A study was carried out to analyse the individual and combined effects of heavy metal toxicity and high irradiance on the photosynthetic characteristics of young, fully expanded leaves of palm seedling Trachycarpus fortunei under laboratory conditions. Heavy metals were found to inhibit both the light and dark reactions of photosynthesis and the inhibition was more affected in the light than in the dark. Single photoinhibitory conditions caused a 60 % decrease in the electron transport activity after 120 min of light exposure which was completely reversible in the dark. In contrast, the combined effect of high light and heavy metal treatment resulted in a 90 % decrease in the activity, but no reversible recovery in the dark could be detected. This indicated that the simultaneous effect of these two stress factors led to irreversible damages of the photosynthetic machinery and as a consequence caused the general destruction of the plant.
Abbreviations and symbols: Fo: initial chlorophyll fluorescence; Fm: maximum total fluorescence; Fv: variable fluorescence; AFi: intermediate level of fluorescence induction; PSII: photosystem 2.
In vitro rooting and anatomical study of leaves and roots of in vitro and ex vitro plants of Prunus x davidopersica 'Piroska'42-46.Views:150
The process of in vitro rooting and the anatomical characters of in vitro and ex vitro leaves and roots of Prunus x davidopersica 'Piroska' were studied. Best rooting percentage (50%) and highest root number (5.0) was achieved in spring on a medium containing 0.1 mg/I NAA + 30 g/1 glucose. At the end of rooting the parenchyma of the in vitro leaves was more loose and spongy, than during the proliferation period. In the first newly developed leaf of an acclimatised plant, the parenchyma was much more developed, contained less row of cells and less air space too, compared to the leaves developed in the field. The in vitro developed root had a broad cortex and narrow vascular cylinder with less developed xylem elements, but at the end of the acclimatisation the vascular system became dominant in the root.
Influence of soaking periods and temperatures on germination and respiration of pea seeds69-71.Views:171
Samples of 50 wrinkled-seeded pea (Piston sativum cv. ‘Farida') were soaked for 0.5, 1, 4, 8, 24, 48 and 72 hours at temperature of 5, 10, 15 and 20 °C in distilled water before germination. Water absorption, percent of germination, vigorous seedlings and dry weight of normal seedlings were assessed after 8 days. Respiration of short and long seedlings were checked by IRGA, LI-COR 6200 photosynthesis system. Most plants had more or less respiration but some of them already had photosynthesis. Differences in the amount of water absorbed were evident after one hour, only. Water amount was increased by increasing soaking temperatures and times. The maximum was achieved after 24 hours. Normal germination percent was not improved at any soaking time and temperature combinations but it was significantly declined at 10 °C with soaking time combinations and at 20 °C for 72 hours. The seedling vigour values were not very different at the higher soaking temperatures, but the treatments at 20 °C temperature with 8 and 24 hour soaking periods are proved to be optimal for seedling vigour. At the low soaking temperature the increase of the soaking period influenced the seedling vigour. Reduction of dry weight percent was noticeable by any soaking time related to temperature and compared with the control.