Effect of leaf-to-fruit ratios on phenolic and sensory profiles of Malbec wines from single high-wire-trellised vineyards.

BACKGROUND: The single high-wire system is a free canopy trellis system suitable for warm to hot climates. In a global warming scenario, it arouses as a technological solution since it prevents berry overheating and sunburn. Canopy management practices manipulate leaf-to-fruit ratios, affecting berry and wine composition. We aimed to evaluate the phenolic and sensory profiles of Malbec wines from single high-wire trellised vineyards in a hot region in Mendoza (Argentina) and to assess the effect of varying leaf-to-fruit ratios on these attributes. We manipulated leaf-to-fruit ratios by varying shoot trimming (experiment 1: 0.45 m, 0.80 m, and untrimmed) and winter pruning severity (experiment 2: 16, 24, 32, and >32 countable buds per meter). We characterized wine attributes by a descriptive analysis, color by the CIELAB space, and global phenolics compounds and anthocyanins by high-performance liquid chromatography with diode array detection. RESULTS: We found that wines where shoots were trimmed to 0.80 m or left untrimmed had similar and greater intensity of color, violet hue, astringency, and alcohol and a richer aroma profile than wines where shoots were trimmed to 0.45 m. Meanwhile, wines from 16 and >32 buds/m treatments (the latter simulating a box pruning) were similar to each other and had higher color intensity, violet hue, acidity, alcohol, and astringency and a more complex aroma profile than the other pruning treatments. CONCLUSIONS: The best quality wines were achieved by leaving 16 or >32 buds/m and by trimming shoots to 0.80 m or leaving them untrimmed. The modulation of cultural practices in sprawling canopies offers the potential to produce wines with different styles in hot regions. © 2020 Society of Chemical Industry.

Phototropins but not cryptochromes mediate the blue light-specific promotion of stomatal conductance, while both enhance photosynthesis and transpiration under full sunlight.

Leaf epidermal peels of Arabidopsis (Arabidopsis thaliana) mutants lacking either phototropins 1 and 2 (phot1 and phot2) or cryptochromes 1 and 2 (cry1 and cry2) exposed to a background of red light show severely impaired stomatal opening responses to blue light. Since phot and cry are UV-A/blue light photoreceptors, they may be involved in the perception of the blue light-specific signal that induces the aperture of the stomatal pores. In leaf epidermal peels, the blue light-specific effect saturates at low irradiances; therefore, it is considered to operate mainly under the low irradiance of dawn, dusk, or deep canopies. Conversely, we show that both phot1 phot2 and cry1 cry2 have reduced stomatal conductance, transpiration, and photosynthesis, particularly under the high irradiance of full sunlight at midday. These mutants show compromised responses of stomatal conductance to irradiance. However, the effects of phot and cry on photosynthesis were largely nonstomatic. While the stomatal conductance phenotype of phot1 phot2 was blue light specific, cry1 cry2 showed reduced stomatal conductance not only in response to blue light, but also in response to red light. The levels of abscisic acid were elevated in cry1 cry2. We conclude that considering their effects at high irradiances cry and phot are critical for the control of transpiration and photosynthesis rates in the field. The effects of cry on stomatal conductance are largely indirect and involve the control of abscisic acid levels.

Gregarious bamboo flowering opens a window of opportunity for regeneration in a temperate forest of Patagonia.

Rare gregarious flowering of understorey bamboo species occurs in temperate and subtropical forests around the world, but the ecological consequences of this phenomenon for forest regeneration are not well understood.Field experiments were conducted in an old-growth temperate forest in Patagonia,Argentina after a massive bamboo flowering event, to examine whether light quality and other changes in microhabitats could affect seed germination and growth of overstorey species. Germination of southern beech (Nothofagus obliqua) was positively correlated with red:far red (R:FR) ratios in a range of microhabitats generated by the death of the understorey bamboo (Chusquea culeou). Experimental modification of understorey R:FR ratios to mimic alternative light environments reversed this germination response in plots with senescent understorey, but not in plots with live bamboo. Laboratory incubations demonstrated a significant interaction between R:FR ratios and thermal amplitude in promoting seed germination. Microhabitats also significantly affected the growth of emerged seedlings. Microenvironmental changes generated by this flowering event appear to have opened a window of opportunity for germination and growth of overstorey species.We demonstrate that natural gradients in light quality associated with this ecological phenomenon are a major component affecting forest regeneration in this ecosystem.