Accelerated circadian cycles of photoperiod favor photosynthetic efficiency and growth in grapevine

Abstract

Climate change presents a challenge for agriculture worldwide. Yet, crop productivity is negatively impacted by abiotic hazards such as high temperatures and water deficit. In this context, agricultural production is shifting towards areas either of higher altitude or latitude, to lower crop exposure to such constraints (Muluneh, 2021). Meanwhile, the expansion of urban areas reduces the availability of arable land and represents a threat to food sustainability. To increase the efficiency of agricultural systems, artificial devices in urban area including growth chambers and greenhouses deserve more attention. Light intensity, spectrum and duration are essential factors for plant productivity under indoor growing conditions, to which the circadian rhythm must also be added (Paradiso & Proietti, 2021).

In plants, the photoperiod duration and the circadian rhythms regulate various processes such as stomatal opening and growth (Caluwé et al., 2016). Previous studies indicate that prolonged photoperiods can cause photoinhibition, a negative feedback mechanism that limits photosynthesis and growth to avoid damage to the photosynthetic apparatus when the plant receives more light than it can use (Takahashi & Badger, M., 2011). On the other side, short and frequent photoperiods have been shown to optimize photosynthetic productivity in annual species and microalgae (Zhang et al., 2019). However, little is known about the possible impacts of accelerated circadian cycles on carbon metabolism and growth of perennial crops, such as grapevine. Addressing the impact of circadian rhythm on grapevine functioning is thus necessary to determine the most efficient light conditions under indoor growing systems.

Microvine (Vitis vinifera) is a natural mutant that allows short experiments in fully controlled environment in growth chambers due to its small size, fast juvenile cycle and continuous fruiting (Torregrosa et al., 2019). Moreover, microvine varieties resistant to mildews, recently released from our breeding programs, considerably lower the use of chemicals, which is a pre requisite when working under confined spaces. Lastly, microvine vegetative development and individual berry growth and metabolism were shown to be very similar to grapevine (Luchaire et al., 2017; Torregrosa et al., 2019). Altogether, these properties make the microvine a suitable model for determining how changes in the circadian rhythm could impact the efficiency of grapevine functioning and resource requirements.