Dynamics, plant physiological and environmental controls of energy exchange in a grapevine greenhouse in Northeast China

Abstract

The dynamics of latent heat flux (LE) in greenhouse agricultural production, an integral component of water and energy balance, are yet to be comprehensively understood. A four-year experiment (2017–2019, 2021) was conducted in a solar greenhouse with grapevines to examine the patterns of energy and water vapor and their underlying mechanisms. The results indicated that LE was responsible for most of the net radiation (Rn), comprising 55.13–73.62 %. Sensible heat flux (H) accounted for 16.42–22.80 % of Rn, whereas the ratio of soil and wall heat flux to Rn was relatively minor, ranging from −7.3 % to 16.5 % during the four growing seasons. The order of LE/Rn in the different growth stages (I, II, and III) of grapevines was: II > III > I. The average value of Bowen ratio (β = H /LE) in the entire growth period was 0.34–0.44. The close relationship between β and leaf area index (LAI) demonstrated that LAI significantly influenced the energy distribution of the greenhouse, with a larger impact in stage I than in stages II and III (R2 at 0.19–0.50). The high values of the decoupling coefficient (0.69–0.82) and the Priestley–Taylor coefficient (α, 0.90–1.02) suggested that Rn was the main factor determining LE during the growing seasons. However, throughout stages I and III, LE was primarily influenced by vapor pressure deficit (VPD) and crop surface conductance (Gc), and the controlling effect of Rn on LE weakened. Gc was closely related to α (R2 = 0.59–0.90), suggesting that Gc significantly affected daily LE. In addition, changes in normalization of VPD by photosynthetically active radiation and LAI affected Gc, which in turn affected LE and energy distribution in the greenhouse. These findings are important for studying water vapor transport in greenhouses and for developing energy-driven models, that may improve water management for irrigation in greenhouses.