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Light acclimation in leaves of the juvenile and adult life phases of ivy ( Hedera helix )
Author(s) -
Hoflacher Hans,
Bauer Helmut
Publication year - 1982
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1982.tb00321.x
Subject(s) - hedera helix , photosynthesis , acclimatization , biology , juvenile , botany , chloroplast , rubisco , crassulacean acid metabolism , horticulture , ecology , biochemistry , gene
Hoflacher, H. and Bauer, H. 1982. Light acclimation in leaves of the juvenile and adult life phases of ivy ( Hedera helix ). – Physiol. Plant. 56: 177–182. Light acclimation was investigated during the juvenile and adult life phases of the whole‐plant‐development in Hedera helix L. For this purpose, cuttings of the juvenile and adult parts of one single parent plant were grown under low‐light (PAR 30–50 μmol photons m −2 s −1 ) and high‐light (PAR 300–500 μmol m −2 s −1 ) conditions: CO 2 exchange, chloroplast functions, and specific anatomy of fully developed leaves differentiated under these conditions were determined. In juvenile plants the leaves formed under low and high light had light‐saturated rates of net photosynthesis of 6.5 and 11.1 mg CO 2 (dm leaf area) −2 h −1 , respectively. In adult plants the rates were 9.4 and 22.2 mg dm −2 h −1 , indicating a more pronounced capacity for acclimation to strong light in the adult life phase. Higher photosynthetic capacities were accompanied by higher conductances for the CO 2 transfer through the stomata, leading to almost the same CO 2 concentration in the intercellular spaces. Thus, stomatal conductances were not primarily responsible for the different photo‐synthetic capacities. The higher rates in adult and high‐light grown leaves were mainly the result of formation of thicker leaves with more chloroplasts per unit leaf area. Expressed per chloroplast, the photosynthetic capacity, the Hill reaction, and the activity of ribulose bisphosphate carboxylase were almost identical in plants grown in low‐light and high‐light. Measurements of photosynthetic capacity and thickness of leaves of Hedera sampled from field habitats with contrasting light regimes confirm the results of growth chamber studies. It is, therefore, concluded that both life phases of Hedera are capable of acclimating to strong light, but that during the juvenile phase this capacity is not fully developed.