CO2-Assimilation, Wurzelatmung und Ertrag von Fichten- und Kiefernsämlingen bei unterschiedlicher Mineralstoffernährung

Birmensdorf

1963

S. 217-242

9 Abb., 6 Tab., 34 Lit. Ang.

Bandaufführung

157533

1. Seedlings of spruce (Picea Abies [L.] Karst.) and pine (Pinus silvestris L.) were grown in hydroponics with 6 different nutrient solutions (tbale 1). At the end of the growing season the following data were gathered: photosynthesis, root respiration, lenght and weight of roots, stems and needles, as well as contents of chlorophyll, N, P, K, Ca and Mg in the needles. 2. The experimental conditions yielded a statistically siginificant correlation between chlorophyll content and N content of needles (figure 3). An influence of other, more abundantly supplied nutrients upon chlorophyll synthesis was not detected. In needles rich in N 1.5% of total N was contained in chlorophyll, whereas in needles poor in N thi percentage dropped to 0.6-1.1. with decreasing N content increasingly less N becomes available for chlorophyll synthesis. 3. There ist a highly significant correlation between chlorophyll content an CO2 uptake (figure 5). Although needles with a low chlorophlyy content show a higher assimilatory number (mg CO2/mg chlorophyll/h, figure 6), the absolutamount at about 15 000 Lus, other needles at > 50 000 Lux (figure7). 4. Pines grow faster in youth than spurce due to: +) formation of a larger phtosynthesic apparatus with +) higher chlorophyll content and +) higher assimilatory number at intensive illumination (probably caused by needle structur); +) lower root respiration. 5. Root respiration amounts in well fed spruce to 34-51%, in pine to 27-33% of the CO2 taken up by the shoot under long day conditions (table 5). In N-deficient seedlings it rises to 80% (spurce) and above 90% (pine). 6. A close correlation was found to exist between yield in dry matter and both photosyntheses and CO2 gain (photosyntheses - root respiration). Photosynthetic intensity (mg CO2/g needle dry weight) may be useful as an indicator for the growth rate, too, although differences in totaal needle mass - if not determined - may lead to erroneous conclusions. The result of the photosynthtic measurement depends futhermore upon development stage of the plant (season).