Measurements of ultrastructural characteristics of chloroplast thylakoids are important for studies of ontogenic or ecological limitations of leaf photosynthetic functions. Most frequently, volumetric proportion of thylakoids in the chloroplast is measured; however, such measurement does not provide a direct information about the surface area of thylakoids which is most important from the functional point of view. Therefore, we adapted the stereological method using "local vertical windows" for estimating thylakoid surface area in the chloroplast volume and compared thus obtained surface density results with results of conventional volume density measurements. The methods were tested in the study of chloroplast ultrastructure in the leaves of plants of two maize (Zea mays L.) hybrid combinations, 2013×CE810 and CE704×CE810, developing in control and chilling conditions. Correlation analysis revealed a tight relationship between the granal/intergranal thylakoid surface density and volume density results, both indicating that under chilling conditions the development of the system of thylakoids in maize leaves is suppressed, while the difference is more pronounced in CE704 than in CE810 genotype, known to have a better photosynthetic performance. and L. Kubínová, J. Kutík.
The practicality of the portable, non-destructive type nitrogen meter (Agriexpert PPW-3000) was tested on ten forest species. Also investigated was the potential relationship between leaf nitrogen and chlorophyll (Chl) contents and the readings taken with the PPW-3000 and a Chl meter (SPAD-502). There was a significantly positive correlation between the readings of PPW-3000 and N content in the same leaves, whereas the correlation between leaf Chl content and the PPW-3000 values was less positive. Similarly there was a significant positive correlation between actual Chl content and the SPAD-502 readings and the less positive correlation between actual N content and the SPAD-502 readings. Thus using both the PPW-3000 and SPAD-502 enables to determine leaf N and Chl contents simply and non-destructively in the field. and T. Ichie ... [et al.].