Interactions in stomatal function: the modulation of the light sensitivity of stomata by other environmental factors. Physiological bases and ecological role.
How stomatal responsiveness is modulated by past growing conditions is a subject related to research that P. J. Aphalo did at the start of his career. Some of the hypotheses could not be then tested with the depth now possible. The photoreceptors involved in light sensing had not been characterized at the molecular level. Both knowledge about molecular events in guard cells and measurement techniques have advance enormously. Equipment available and know-how at our department makes research along this line possible at the front of current advances in the subject.
The research in course has important implications for understanding acclimation of plants to different growing conditions, and also for crop and tree breeding and management. The knowledge acquired can be also use in the design of LED luminaires for use in horticulture and forest tree seedling production.
Light mediated plant-plant interactions: mechanisms, ecological implications and practical applications
P. J. Aphalo started doing research on this subject before arriving in Finland. This was the first research subject of the group and it has continued to be one of its focuses. There have been periods of more intense activity and periods when because of availability of funding the focus had to shift. Some of our papers on this subject had high impact on the ecophysiological and ecological research community. Currently part of our research relates to applications of management of light quality in forest tree nursery conditions and in greenhouse cultivation of ornamentals and vegetables.
Direct effects of natural ultraviolet radiation on plants and indirect effects on other trophic levels
We have been studying for about 18 years the effects of UVB and UVA radiation on the growth and secondary metabolism of woody and herbaceous plants. Initially we focused on direct effects and herbivory. Later we studied effects on leaf litter decomposition and soil fauna. We also did an assessment of the suitability of different action spectra for describing different responses measured outdoors in mature trees and tree seedlings. Initially we focused on simulating ozone depletion and enhancing UV with lamps. Lately we have been studying natural UV using filters to attenuate or remove it from daylight. Our most significant recent work on the subject is related to the study of the molecular events behind responses of plants to solar ultraviolet radiation. There currently very limited information at the molecular level on responses of plants to the ultraviolet component of sunlight, as most previous studies have been done indoors. The results of our experiments indicate that responses observed indoors are not always consistent with those observed outdoors.
Development and validation of instruments and methods
We put considerable effort in the development of methods. Four aspects have been important: 1) development and testing of hardware for measurement of plant properties and behaviour, 2) development of hardware and software for measurement of environmental variables, and validation of quantification methods, 3) development of hardware and software for environmental control and visible and ultraviolet radiation treatments application, and 4) statistics, in relation to design of experiments and data analysis.
Our philosophy and method
Our research philosophy is to look at interactions in addition to effects of single variables. We mainly work with whole plants, either indoors or in the field. We do manipulative experiments, both in the field and in controlled environments. We also study the characteristics of the natural habitat of plants, to relate it to plant ‘behaviour’ in acclimation and adaptation. Our research is problem centred and most frequently spans different levels of organization and scientific disciplines. We are very careful about experimental design and statistics as a way of obtaining reliable data even in the outdoor environment that is subject to more random variation than a controlled environment. Sometimes we develop simulation models to study the coherence and implications of the results we obtain from our experiments, and to generate new testable hypotheses. In many cases, our experiments have been made possible by the novel instrumentation and software that we have developed for studying the different research questions.