Towards a standardization of light conditions in climatic chambers and adapted sampling for a better understanding of the environmental determinants involved in budburst in a woody species

Abstract

The rapidity of the climate change (CC) in progress, the uncertainty of climatic models and the species response diversity to the climate change motivate the scientists to increase the volume of observations and to get quality data. Among them, the phenology of bud burst in line species ask for a particular attention. That is to say, this major factor of the adaptation has not yet given all responses and notably for the photosensitive species like beech that is potentially, in a very near future, subject to a lack of cold temperature to rise the dormancy. This is the reason why the community, through SOERE TEMPO, is mobilized to standardize materials and methods used to study the elements involved in this development period. Among the used devices, programming and characterization of the environment of climatic growth chambers (light, temperature, relative humidity) allowing to testing different hypotheses required to be mastered. Moreover, with energy savings and scientific research in light, we propose to explore how the element "light" has to be used to explain the processes studied. So we were able to highlight (i) that it is compulsory to operate with a minimal intensity and photoperiod to obtain a sufficient percentage of bud burst and a time needed of bud burst necessary to observe the dormancy breaking, and (ii)
that LED technology is a very good alternative to study these processes and to bring coherence to the studies and actions to minimize the impact of CC in progress, because of the significant energy savings it allows. And all the more so, as this innovative technology could allow us to go further and faster towards a scientific front, overlooked here, the involvement of wavelengths other than those around light red in the response of plants to light for budburst in woody plants. In this sense, the sampling carried out allowed us to show (iii) that the difference in threshold or temperature sensitivity over time could explain the early or late character of the genotypes observed at the population scale and (iv) that the difference in light conditions at the time of bud formation above and below the canopy does not induce a different response to environmental conditions in the post-dormant phase.