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In this project, research centres on the study of `The role of information-acquiring systems in plant-plant interactions'. By information-acquiring systems we understand sensory mechanisms such as those mediated, for example, by phytochrome. In plant-plant interactions we include both negative ones, such as competition, and positive ones like facilitation.
The kinds of phenomena under study are: (1) Interactions between individuals in a pure stand. (2) Interactions between different plants species. (3) Scaling up of individual plant responses to stand behaviour. The kinds of mechanisms to study are: (1) photomorphogenesis, (2) allocation of resources (photosynthates and mineral nutrients) within individuals and capture of resources by individuals, and (3) effects of plants on the canopy microclimate (including light quality).
Work is mainly on plant-plant interactions mediated by light transmitted signals, and under current environmental conditions. Part of the research is applied, and related to forest tree nursery problems such as the management of growth density of seedlings and its consequences for performance after outplanting.
The information being obtained is useful: (1) for mechanistically predicting/modelling canopy properties and behaviour based on the eco-physiology of the individuals; (2) to improve crop and forest management practices so that (a) weed control can be done with a much reduced, or without, use of chemical herbicides, (b) maximum stand uniformity can be achieved even after disturbances early in the season/life-cycle, and (c) to attain high seedling densities in forest tree nurseries without compromising performance after outplanting.
Plant species studied include trees of commercial importance in Finland (birch, pine, spruce). In the future our work may be extended to species particularly easy to work with (e.g. arabidopsis, tobacco) and include the study of mechanisms for which we will make use of manipulations of the of the plant genotype in addition to experimental manipulation of environment. Mutant and transgenic lines could be used to study how disabling the response of the individuals to particular environmental signals affects the behaviour of the plant stand. The main measurement techniques used are: growth analysis, gas-exchange, microscopy, stable isotopes, chemical analyses and micrometeorological methods.
Aphalo P J (1994) Kasvatustiheyden vaikutus paakkutaimien ominaissuuksiin (Effect of density during growth in the nursery on the properties of containerised seedlings). In: Taimitarhapäivät Suonenjoen tutkimusasemalla: 17.-18.8.1993, H. Smolander, J. Rautala (eds). Metsäntutkimuslaitoksen Tiedonantoja 496, 41-47.
Aphalo P J, Ballaré C L (ex aequo) (1995) On the importance of information-acquiring systems in plant-plant interactions (Essay review). Functional Ecology 9, 5-14.
Aphalo P J, Lehto T (1997) Effects of light quality on the growth and N accumulation of birch seedlings. Tree Physiology 17, 125-132.
Aphalo P J, Rikala R, Sánchez R A (1997) Effect of CCC on the morphology and growth potential of containerised silver birch seedlings. New Forests 14, 167-177.
Rikala R, Aphalo P J (1998) Kasvatustiheyden ja paakkukoon vaikutus taimien ominaisuuksiin taimitarhalla ja menestymiseen istutuksen jälkeen (Effects of> density and container size on seedling properties in the nursery and their performance after planting). In: Taimitarhapäivät Jyväskylä: 11.-12.2.1998, M. Poteri, J. Rautala (eds). Metsäntutkimuslaitoksen Tiedonantoja, 696, 21-35.
de la Rosa T M, Aphalo P J, Lehto T. (1998) Does far-red light affect the mineral nutrition of Scots pine seedlings? Plant and Soil, 201, 17-25.
de la Rosa T M, Lehto T, Aphalo P J. (1999) The effect of far-red light on the growth, morphology and mineral nutrition of Scots pine seedlings growing in forest soil. Plant and Soil, 211, 259-268.
Aphalo P J, Ballaré C L, Scopel A L. (1999) Plant-plant signalling, the shade avoidance response and competition. Journal of Experimental Botany, 50, 1629-1634.
Aphalo P J, Lehto T. (2001) Effect of lateral far-red light supplementation on the growth and morphology of birch seedlings and its interaction with mineral nutrition. Trees - Structure and function, 15, 297-303.
Luoranen J, Rikala R, Aphalo P J. (2002) Effect of CCC and daminozide on the growth of silver birch container seedlings during three years after spraying. New Forests, 23, 71-80.
Aphalo P J, Rikala, R (2003) Apparent quality and actual field performance of silver-birch seedlings grown in containers of different volume and at different spacings. New Forests, 25, 93-108.
Aphalo P J, Rikala R (2006) Spacing of silver birch seedlings grown in containers of equal size affects their morphology and its variability. Tree Physiology, 26, 1227–1237.
de la Rosa, T M (2002) Responses of forest tree seedlings to far-red and ultraviolet-B signals. PhD thesis. University of Joensuu, Faculty of Forestry. Joensuu. ISBN 952-458-121-3.
Author: Pedro J. Aphalo.