Glede uočenih promjena u reakciji bukve (Fagus sylvaticaL.) u odnosu na ekološke promjene, odabrano je pet ploha mlade bukve jednake starosti na prirodnim staništima, koje su bile jednakomjerno ...raspoređene na svjetlosnom gradijentu od zastora odrasle sastojine, šumskog ruba do svjetlosnih uvjeta na otvorenome. Kriterij za grupiranje bio je neizravni stanišni čimbenik (ISF), dobiven analizom hemisfernih snimaka pomoću sustava Win-Scanopy: zastor krošanja (ISF<20), rub sastojine (20<25) i otvoreno, bez zastora krošanja (ISF>25), koji su bili jednaki na svim plohama. Za izmjere fotosintetskog kapaciteta, krivulje svjetlosnog zasićenja (0, 50, 250, 600 i 1200 µmol/m2s) i A-Ci krivulje (0, 100, 400, 700 i 1000 µmol CO2/l) dobivene su pomoću Li-Cor LI-6400 u kontroliranom okruženju (temperatura, protok i koncentracija CO2, zračna vlaga). Analize sadržaja dušika u lišću napravljene su Leco CNS-2000 analizatorom.
Potvrđene su signifikantne razlike u reakciji mladih bukava između odabranih kategorija, kao i između različitih šumskih kompleksa. Mlade bukve na plohama iz Kočevskog pokazale su veću toleranciju na sjenu, a odziv na porast koncentracije CO2je pri istim intenzitetima osvijetljenosti bio veći nego kod mladih bukava iz Pohorskog kompleksa. Odziv mladih bukava bio je signifikant no različit između prašume (Rajhenav) i gospodarske šume unutar istog šumskog kompleksa: odziv u prašumi pokazuje veću toleranciju na sjenu.
Althought most of the literature data indicate that the maize plants are resistant to triazine herbicides, there are some inbred lines in which an increased susceptibility has been noticed.
The aim ...of this work was to study the effect of atrazine (2-chloro- -4-ethylamino-6-izopropylamino-s-triazine) on the photochemical activities and content of chlorophylls in four inbred lines (OH-43, C-103, R-59, TD-191) and two hybrids (ZP SC-666t, ZP SC-48A).
The rate of oxygen evolution in the suspension of isolated chloro- plasts with potassium ferricyanide as an electron acceptor has been measured by application of an oxygen electrode. The rate of ATP synthesis by non-cyclic photophosphorylation as well as the contents of chlorophyll per gram of fresh leaf have also been recorded.
The results indicate that atrazine applied in concentration 1,02 X 10 min4 mols/2,7 kg. of sand for 10 plants has an inhibitory effect on the tested photochemical activities.
The photosyntetic activity of tissues with transforming plastids has been measured by means of a Warburg apparatus. At the same time the chlorophyll content of the tissue has been determined by ...spetropho- tometric measurements of ethanolic extracts. The data obtained are compared with electron microscopic findings of ultrastructural changes in plastids of the corresponding developmental stages. The investigations have given the following results:
1) During the transformation of chloroplasts into chromoplasts the photosynthetic activity ceases simultaneously with the disappearance of chlorophyll.
2) Fully developed chromoplasts never contain chlorophyll and never show any photosynthetic activity.
3) The regreening chromoplasts regain their photosynthetic activity simultaneously with the reappearance of chlorophyll.
4) The presence of chlorophyll and the existence of photosynthetic activity appear to be closely correlated with the appearance of grana.
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