Kaolin-based, foliar reflective film protects photosystem II structure and function in grapevine leaves exposed to heat and high solar radiation

Abstract

Extreme conditions, such as drought, high temperature, and solar irradiance intensity, are major factors limiting growth and productivity of grapevines. In a field experiment, kaolin particle film application on grapevine leaves was examined during two different summer conditions (in 2012 and 2013) with the aim to evaluate benefits of this practice against stressful conditions hindering photochemical processes. We used chlorophyll a fluorescence to investigate attached leaves. Two months after the application, during the hottest midday, the kaolin-treated plants showed by the JIP test significantly higher quantum yield of PSII photochemistry, flux ratios, maximum trapped excitation flux of PSI, absorption flux, electron transport flux, maximum trapped energy flux per cross section, and performance index than plants under control conditions in the warmer year. On the contrary, the treated plants showed a lower initial slope of relative variable fluorescence and a decrease in the absorption and electron transport per cross section. The JIP test showed higher efficiency of PSII in the plants treated with kaolin mainly in 2013 (higher temperature and drought). Our results supported the hypothesis that the accumulation of active PSII reaction centres was associated with decreased susceptibility to photoinhibition in the kaolin-treated plants and with more efficient photochemical quenching. Grapevines in the Douro Region seems to profit from the kaolin application.

Liming and application of nitrogen, phosphorus, potassium,and boron on a young plantation of chestnut

“…Probably this lack of significant differences was due to the fact that these protocols are not sensitive to nutrient stress until very low levels are reached (Baker and Oxborough, 2004), although they can be very useful for detecting and measuring other plant stresses, such as drought (Gomes et al, 2012), high irradiance, and extreme temperatures (Dinis et al, 2016).…”

Grapevine abiotic stress assessment and search for sustainable adaptation strategies in Mediterranean-like climates. A review

“…The JIP test is a tool to analyze the polyphasic rise of Chl a fluorescence transient from basal to maximal fluorescence (F 0 and F m , respectively), corresponding to the redox states of PSII and photosystem I (PSI), and to electron transfer effectiveness (Papageorgiou 2004). The polyphasic fluorescence rise (O, J, I, and P steps) is observed after the illumination of dark-adapted leaves, providing information on the relationship between function and structure of PSII reaction center and core complexes (Dinis et al 2015).…”

“…The physiological processes of grapevine initiate when the average temperature is around 10°C; however, above 35°C, plants start triggering adaptation mechanisms (Ferrandino and Lovisolo 2014). The most pronounced effects of summer stress on plant physiology comprise the decrease of photosynthetic rates by photoinhibition of photosystem II (PSII) and reduction in stomatal conductance (Moutinho-Pereira et al 2007;Pinheiro and Chaves 2011;Dinis et al 2015). Nonphotochemical quenching (NPQ) is the primary protective mechanism against photoinhibition, involving xanthophylls for the dissipation of excessive non-radiative energy (Hendrickson et al 2004).…”

“…Alternatively, other types of treatments can be applied to increase grapevine leaf and berry pigments, such as the application of humic acid or polyamines (Abdel-Salam 2016a; Mirdehghan and Rahimi 2016). Many authors have focused their research on the development of environmentally friendly practices, like kaolin application, to sustain yield and quality in a challenging climate, through the reduction of leaf and fruit berry surface temperature, thus improving the antioxidant machinery (Glenn 2012;Boari et al 2015;Dinis et al 2015). In fact, foliar application of solar protectants, has already shown promising results regarding grapevine increased yield, physiological performance, and general fruit quality potential, in the context of climate change at a local scale (Coniberti et al 2013;Dinis et al 2016;Bernardo et al 2017;Dinis et al 2017;Conde et al 2018;Dinis et al 2018).…”

Viticulture in Portugal: A review of recent trends and climate change projections

“…olive trees) or artificial, can help overcome this shortcoming (Greer et al, 2011;Shahak et al, 2008). Furthermore, the use of chemical sunscreens for leaf protection against sunburns may also represent an important alternative (Dinis et al, 2016). Another option to consider is the -65 -OENO One, 2017, 51, 2, 61-69 ©Université de Bordeaux (Bordeaux, France)…”