Exploring Seasonal and Circadian Rhythms in Structural Traits of Field Maize from LiDAR Time Series.

Shichao Jin,Yan Ge,Qinghua Guo,Frédéric Baret,Lingli Liu,Shilin Song,Yongguang Zhang,Yanfeng Ding,Zhonghua Liu,Qin Ma,Qing Li,Yanjun Su

doi:10.34133/2021/9895241

Abstract

Plant growth rhythm in structural traits is important for better understanding plant response to the ever-changing environment. Terrestrial laser scanning (TLS) is a well-suited tool to study structural rhythm under field conditions. Recent studies have used TLS to describe the structural rhythm of trees, but no consistent patterns have been drawn. Meanwhile, whether TLS can capture structural rhythm in crops is unclear. Here, we aim to explore the seasonal and circadian rhythms in maize structural traits at both the plant and leaf levels from time-series TLS. The seasonal rhythm was studied using TLS data collected at four key growth periods, including jointing, bell-mouthed, heading, and maturity periods. Circadian rhythms were explored by using TLS data acquired around every 2 hours in a whole day under standard and cold stress conditions. Results showed that TLS can quantify the seasonal and circadian rhythm in structural traits at both plant and leaf levels. (1) Leaf inclination angle decreased significantly between the jointing stage and bell-mouthed stage. Leaf azimuth was stable after the jointing stage. (2) Some individual-level structural rhythms (e.g., azimuth and projected leaf area/PLA) were consistent with leaf-level structural rhythms. (3) The circadian rhythms of some traits (e.g., PLA) were not consistent under standard and cold stress conditions. (4) Environmental factors showed better correlations with leaf traits under cold stress than standard conditions. Temperature was the most important factor that significantly correlated with all leaf traits except leaf azimuth. This study highlights the potential of time-series TLS in studying outdoor agricultural chronobiology.

Highlights

Plant growth rhythm depicts biological and physiological behaviors of plants, such as “tree sleeping” at night [1,2,3], which is controlled by an endogenous timing mechanism and/or exogenous environment [4, 5]
At the individual plant level, results show that Terrestrial laser scanning (TLS) can describe the seasonal rhythms of several structural traits of maize (Figure 3)
This study demonstrated that TLS can be used to analyze the seasonal and circadian rhythms of structural traits of maize at the plant and leaf levels under natural and cold stress conditions

Summary

Introduction

Plant growth rhythm depicts biological and physiological behaviors of plants, such as “tree sleeping” at night [1,2,3], which is controlled by an endogenous timing mechanism (i.e., biological clock) and/or exogenous environment [4, 5]. Plant growth rhythm exists in most organisms [6]. Exploring the mechanism of plant growth rhythm is important for. Plant growth rhythm has been extensively and accurately studied in plant physiology [7,8,9], but has rarely been explored in structure. It is becoming a promising direction to understand plant rhythm which is more accessible with the development of sensing technologies, computer vision, and deep learning algorithms [11, 12]

Objectives

Results

Discussion

Conclusion