欧亚国际

摘要

最初用于预测番茄茎直径短期和长期变化的一个综合植物模型，在冬季时，无法用于同化光照下生长的番茄植株。在冬季长时间的日照下，出现了一种非典型的昼夜模式，显示在开灯1-2小时后茎直径增加。为了解释这种特定的植物行为，SAP流量传感器和线性可变位移传感器安装在番茄植株（茄属LycopsiL.Loundation）上。植物每天被光照18小时⁻结合自然阳光和HPS灯（169µmol m⁻²s⁻¹)。 我们提出了两个假说来解释这种不典型的植物行为，并随后进行了研究：（i）糖从叶向根的运输降低了韧皮部水势，韧皮部水势从木质部导入水分，导致茎直径增加；以及（ii）光照强度的突然增加导致木质部水势下降，空化引起水力传导的变化，进而影响木质部和贮藏之间的水交换，从而影响茎直径的变化。

Revised sap flow driven stem diameter model for tomatoes grown under assimilation lighting 

Abstract and Figures 

A comprehensive plant model that was originally developed to predict short- and long-term variations in tomato stem diameter stopped working properly when used for tomato plants grown under assimilation lighting during winter. Under these prolonged day lengths in winter, an atypical diel pattern emerged showing an increase in stem diameter 1-2 h after the lights were turned on. In order to explain this specific plant behavior, sap flow sensors and linear variable displacement transducers were installed on tomato plants (Solanum lycopersicum L. ‘Foundation’). Plants were lighted for 18 h day⁻¹ with a combination of natural sunlight and HPS lamps (169 µmol m⁻² s⁻¹). Two hypotheses to explain this atypical plant behavior were formulated, and subsequently examined: (i) transport of sugars from leaves to roots decreases phloem water potential, which imports water from the xylem and causes an increase in stem diameter; and (ii) the sudden increase in light intensity causes a drop in xylem water potential, resulting in changes in hydraulic conductance due to cavitation, which in turn affects the water exchange between xylem and storage and, hence, the variation in stem diameter.

(a) Measured (red) and simulated (black) stem diameter variation for a 3-day period (30 January to 1 February 2016). Simulated data is the output from the original model (De Swaef et al., 2013a). (b) Measured sap flow. Dark grey areas represent the dark period when there was no sunlight or assimilation light. Light grey areas represent periods when assimilation light was used to prolong the day length. White areas represent the day-time with sunlight and potential assimilation light. Arrows show unexpected Dstem increase.