Current issue: 54(2)

Impact factor 1.683
5-year impact factor 1.950
Silva Fennica 1926-1997
1990-1997
1980-1989
1970-1979
1960-1969
Acta Forestalia Fennica
1953-1968
1933-1952
1913-1932

Articles containing the keyword 'mesophyll'.

Category: Article

article id 5136, category Article
Sirkka Soikkeli. (1981). The types of ultrastructural injuries in conifer needles of northern industrial environments. Silva Fennica vol. 15 no. 4 article id 5136. https://doi.org/10.14214/sf.a15363

Ultrastructure of mesophyll of second-year green needles of Picea abies (L.) H. Karst. and Pinus sylvestris (L.) has been studied in several polluted areas in Finland since 1976 (Soikkeli and Tuovinen 1979, Soikkeli 1981a). Four different types of injuries have been found. The types differ with the origin of the material:

1) In needles collected from areas pollute by S-communds the types with reduced grana and/or the with lightening of plastogobuli with simultaneous accumulation of lipid-like material are observed.

2) In needles expose to fluorides (alone or in addition to other pollutants) the type with swollen and/or that with curled thylakoids are found. Both of the latter have also stretched envelopes. In each type of the injury three stages of cell disruption have been described: slight-medium, severe and very severe. On the slight-medium stage the injuries are usually found only in chloroplasts. On severe stage other organelles show injuries, too. In very severe injury all cell organelles are badly disorganized or they disappear completely. The most abundant injuries are usually in needles collected after their second winter. The severity of cell injury depends on the closeness of emission source or on the measured concentration of SO2.

  • Soikkeli, ORCID ID:E-mail:
article id 7596, category Article
Olavi Luukkanen. (1978). Investigations on factors affecting net photosynthesis in trees : gas exchanges in clones of Picea abies (L.) Karst. Acta Forestalia Fennica no. 162 article id 7596. https://doi.org/10.14214/aff.7596

The net photosynthetic rate per unit of foliage was studied in two-year old cuttings of Norway spruce (Picea abies (L.) H. Karst.), representing four clones, at varying temperature and soil moisture. The CO2 compensation point (Γ), photorespiration, dark respiration, and water balance were also investigated. All these characteristics indicated differences among the clones. A correlation between CO2 exchange and transpiration suggested that stomatal control determined at least a part of this variation during a favourable water balance. An inverse relationship existed between Γ and net photosynthetic rate, and the same curvilinear model explained this variation in unstressed as well as stressed plants at a given temperature. An increase in Γ seems to be a normal result of water stress, particularly at high temperature, indicating an increase in mesophyll resistance to CO2 diffusion. This result was in agreement with calculated values of mesophyll resistance. It also supported our earlier conclusions about the significance of mesophyll resistance during water stress.

  • Luukkanen, ORCID ID:E-mail:

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