Grapevine physiological response to row orientation-induced spatial radiation and microclimate changes

Abstract

Terroir factors and vineyard practices largely determine canopy and root system functioning. In this study, changes in soil conditions, multi-level (vertical, horizontal) light interception (quantitative, photographic, schematic, 3D modelled), leaf water potential and photosynthetic activity were measured during the grape ripening period on NS, EW, NE-SW, and NW-SE orientated (Southern Hemisphere) vertically trellised Shiraz grapevine canopies. It was hypothesised that the spatial radiation interception angle and radiation distribution of differently orientated and vertically trained grapevine rows would affect soil conditions and vine physiological activity. Soil water content showed an increase and soil temperature a decreasing gradient with soil depth. In the afternoon, soil layers of EW orientated rows reached their highest temperature. This, along with measured photosynthetic active radiation received by canopies, complimented the diurnally-captured photographic, constructed and 3D modelled images (also schematically) of canopy and soil exposure patterns. The top, bottom and outside of NS canopies mainly received radiation from directly above, from the E and the W; during midday, high radiation was only received from above. The EW rows received the highest radiation component from above and from the N. The NE-SW rows received high levels of radiation from above, from the SE until 10:00, and from the NW from 13:00. A similar profile can be described for NW-SE rows, but with high radiation received from the NE up to 13:00 and from the SW from 16:00. Overall, lowest leaf water potential occurred for NE-SW canopies, followed by those orientated NW-SE, NS and EW. Photosynthetic activity reflected the positive radiation impact of the sun azimuth during the grape ripening period; best overall performance seemed to occur for E and N exposed canopy sides. This was largely driven by the responsiveness of the secondary leaves to radiation. Photosynthetic output decreased from apical to basal canopy zones with low, erratic values in the light-limited canopy centre. The NS and EW orientated canopies generally showed the highest average photosynthesis, while it was lower for the sides facing S, SE and SW. The results provide a better understanding of the physiological functioning of horizontal and vertical leaf layers in differently orientated grapevine canopies, as affected by climatic conditions. The study contributes to the longstanding challenges of capturing the complexity of parallel microclimatic and physiological output of grapevine canopies under open field conditions. The results can be directly applied to the selection of vineyard practices and seasonal management to ensure the attainment of yield, grape composition and wine quality objectives.

Prediction of Grape Berry Temperature Using Wireless Dataloggers Contained Within a Grape Mimic

“…Measuring point-in-time berry temperature between 1200 and 2000 HR may help industry members determine if critical temperature thresholds are being met and thus guide best leaf removal practices at their site. However, training system, row orientation, and growing region will change the time of day when the greatest solar radiation within the fruit zone is experienced (Campos et al 2017;Hunter et al 2020).…”

Optimising grapevine summer stress responses and hormonal balance by applying kaolin in two Portuguese Demarcated Regions

“…Moreover, the improved leaf gas exchange of grapevines located in the Alentejo region over the two summer seasons, indicates that the grapevines were subjected to better environmental conditions for sustainable plant growth and development. This result may partly be explained by the different row orientation in each vineyard (Hunter et al, 2020), since the E-W orientation of the Douro vineyard suggests higher midday sunlight canopy exposition compared to N-S orientation of the Alentejo vineyard. In addition, heat accumulation during the experiment also increased in 'Douro'.…”

Implication of Row Orientation Changes on Fruit Parameters of Vitis vinifera L. cv. Riesling in Steep Slope Vineyards

“…Slightly excessive light and temperature leads to metabolic protective mechanisms, e.g., accumulation of phenolics or heat shock proteins, known to alter later wine quality [38][39][40]. Previous research conducted on flat vineyards focused on differences in microclimate [41,42], physiological behaviour of the grapevine [43,44] and its effects on fruit parameters [45,46] and wine [47][48][49] in respect to row orientation changes, further considering differences in canopy sides. However, to our knowledge, literature about the impact of row orientation on steep slopes on grapevine fruit composition as well as a differentiation between canopy sides is not available.…”