Malbec responses to light quantity and quality

PRIETO, JORGE; GUEVARA, ARANZAZÚ; GIORDANO, CARLA VALERIA; GONZALEZ, CARINA VERONICA

Mendoza

Congreso; XXth Groupe International d'Experts en Systemes vitivinicoles pour la CoOpération (GiESCO) International Meeting; 2017

Plant acclimation to the light environment involves changes in plant morphology, carbon- and water-physiology, yield and quality of harvestable organs. Many cultural practices and crop management decisions alter light quantity and quality. Canopy shade signals include low PPFD, R:FR ratios and UV-B and blue light levels which are perceived trough photoreceptors. Grapevine responses to light intensity have been assessed in diverse varieties; whereas responses to light quality perceived by phytochromes have only been evaluated in Syrah and Torrontés Riojano. This study aimed to investigate the effect of light quantity and light quality perceived by phytochromes on shoot architecture, biomass, leaf morphology and dry matter partitioning in Malbec. We cultivated potted plants under high (750-800 µmolm-2s-1) and low (250 - 300 µmolm-2 s-1) PPFD in a greenhouse. Additionally, we supplemented plants with lateral far red radiation (730 nm) to obtain a low R:FR (0.2) vs. ambient (1). Low PPFD did not induce changes in shoot and internode length, and neither affected aboveground plant biomass. However, reduced PPFD increased petiole length and diameter and individual leaf area (LA) which resulted in a higher LA ratio. Furthermore, low PPFD decreased leaf thickness, and leaves and lateral shoot biomass. By contrast, low R:FR did not affect any morphological trait, neither dry matter partitioning. Malbec plants morphology was affected in response to variation in light intensity but not in light quality perceived by phytochromes, confirming our previous findings in Syrah and Torrontés. We suggest that light signals, other than R:FR, triggers grapevine acclimation to low light.