Are Vitis vinifera plants blind to see their neighbours?

GONZALEZ, CARINA VERONICA; VILA, HERNÁN; JOFRE, MARÍA FLORENCIA; BOTTINI, RUBÉN; GIORDANO, CARLA VALERIA

Córdoba

Congreso; 16th International Congress on Photobiology; 2014

GRAFOB

Low red:far-red (R:FR) ratios perceived by phytochromes, are an indication of canopy shading and of the proxim¬ity of plant neighbors. Many plant species favor stem elongation as part of the shade avoidance syndrome (SAS) to escape from neighbours and succeed in competition for light. Phytochromes also regulate anatomical and physiological parameters involved in plant water relations and carbon economy, and participates in responses to different stresses (i.e. drought, cold, herbivory and pathogens). Thus phytochromes act as integrators of different environment signals [1]. Many crop management decisions and cultural practices can alter the light environment experienced by crops and hence affect important agronomical traits such as yield and fruit quality [2]. This study aimed to asses the photomorphogenic performance of the primary cultivated grape species, Vitis vinifera L. in response to different light environments. We evaluated anatomical, morphological and physiological traits involved in plant architecture, water and carbon balance and drought tolerance. Pot-grown plants of Syrah and Torrontés Riojano cultivated in a greenhouse were exposed to lateral illumination with FR radiation that reduced the lateral R:FR ratio, mimicking the proximity of other plants. None of the cultivars showed differences in stem growth, internodes length, petiole length and angle, leaf area, leaf thickness, photosynthetic pigments, stomata density and stomata index in response to the light treatment; as well, there were no differences in stomatal conductance (gs), plant conductance (K), stem hydraulic conductivity (Kmax) and in the components of leaf water potential (Ψw) estimated through pressure-volumen analysis. However, both varieties showed increases of GA1, GA3 and IAA leaf-levels but not in ABA, suggesting that phytochrome light signaling is uncoupled in this species. Grapevines performance under shade conditions and the implications of our results will be discussed in an agronomical context. Acknowledgments authors acknowledge the Agencia de Promoción Científica y Tecnológica (PICT 2010 N° 1755) and Secretaria de Ciencia, Tecnica y Posgrado UNCuyo (M008) for financial support. [1] J.J. Casal, Annu Rev Plant Biol, 2013, 64, 403. [2] M. Keller, Chapter 5, in The Science of grapevines-anathomy and physiology, ed. Academic Press, Burlington, MA, 2010, pp. 125?167.