Grapevine Sap Flow in Response to Physio-Environmental Factors under Solar Greenhouse Conditions

Xinguang Wei,Tieliang Wang,Shining Fu,Siyu Zheng,Dianyu Chen,Yikui Bai

doi:10.3390/w12113081

Abstract

Understanding transpiration responses to physiological and environmental factors is essential for efficient water management practices in greenhouse grapevine farms. To determine the driving factors of grapevine sap flow under solar greenhouse conditions in a typical cold climate, the sap flow, greenhouse micro-environmental conditions, and canopy details were measured and analyzed for the 2017–2018 growing season in Northeast China. The results showed that leaf area index controlled the upper boundary of sap flow rate (SFR). Correlations between SFR and meteorological factors obviously varied with time scales. Besides, the correlations at the hourly scale varied across the seasons. Photo-synthetically active radiation (PAR) was the primary control factor of sap flow, irrespective of time scale or season. The start and stop times of sap flow did not change with weather conditions, but SFR had broader peaks with higher peak values during sunny days. The diurnal variation of SFR lagged behind that of PAR, but remained ahead of those of VPD and temperature. Weather condition changed the sizes of the hysteresis loops, but not the rotation direction. The hydrological and physiological processes involved in sap flow are useful for refining transpiration models and improving water use efficiency in the greenhouse environment.

Highlights

Transpiration is a vital part of water transport in the soil–plant–atmosphere continuum and transpiration-related studies are crucial for understanding the physiological, hydrological, and ecological processes of plants [1]
Leaf Area Index (LAI) growth dynamics was roughly divided into two stages (Figure 2(a1,a2))—rapid increasing stage and relative stabilizing stage
LAI growth dynamics was roughly divided into two stages (Figure 2a1,a2)—rapid increasing during the growing period from May to November (Figure 2(e1,e2))

Summary

Introduction

Transpiration is a vital part of water transport in the soil–plant–atmosphere continuum and transpiration-related studies are crucial for understanding the physiological, hydrological, and ecological processes of plants [1]. Environmental coupling mechanisms of transpiration are important for improving the efficiency and sustainability of water resource management, both under irrigated and rain-fed conditions [2]. Among the various technologies for measuring transpiration in trees, heat-based sap flow methods have been widely used [3,4]. Both physiological (e.g., leaf area, crown size, stem water potential, and stem shrinkage) and environmental factors (e.g., air temperature, precipitation, radiation, vapor pressure deficit, soil type, soil moisture and temperature, and groundwater level) influence sap flow to various extents. Sap flow is often estimated using a variety of models with different forms and complexities considering both environmental and physiological factors [5,6].

Methods

Results

Discussion

Conclusion