Evaluation of Individual Plant Growth Estimation in an Intercropping Field with UAV Imagery

Gert Kootstra,Norazlida Jamil,Lammert Kooistra

doi:10.3390/agriculture12010102

Gert Kootstra, Norazlida Jamil + Show 1 more

Open Access

https://doi.org/10.3390/agriculture12010102

Copy DOI

Abstract

Agriculture practices in monocropping need to become more sustainable and one of the ways to achieve this is to reintroduce intercropping. However, quantitative data to evaluate plant growth in intercropping systems are still lacking. Unmanned aerial vehicles (UAV) have the potential to become a state-of-the-art technique for the automatic estimation of plant growth. Individual plant height is an important trait attribute for field investigation as it can be used to derive information on crop growth throughout the growing season. This study aimed to investigate the applicability of UAV-based RGB imagery combined with the structure from motion (SfM) method for estimating the individual plants height of cabbage, pumpkin, barley, and wheat in an intercropping field during a complete growing season under varying conditions. Additionally, the effect of different percentiles and buffer sizes on the relationship between UAV-estimated plant height and ground truth plant height was examined. A crop height model (CHM) was calculated as the difference between the digital surface model (DSM) and the digital terrain model (DTM). The results showed that the overall correlation coefficient (R2) values of UAV-estimated and ground truth individual plant heights for cabbage, pumpkin, barley, and wheat were 0.86, 0.94, 0.36, and 0.49, respectively, with overall root mean square error (RMSE) values of 6.75 cm, 6.99 cm, 14.16 cm, and 22.04 cm, respectively. More detailed analysis was performed up to the individual plant level. This study suggests that UAV imagery can provide a reliable and automatic assessment of individual plant heights for cabbage and pumpkin plants in intercropping but cannot be considered yet as an alternative approach for barley and wheat.

Highlights

Monocropping is a common practice in many agricultural production systems
To fill the knowledge gap, the present study investigates an approach to estimate and monitor plant height of individual plants in an intercropping system using a Unmanned aerial vehicles (UAV) platform equipped with a RGB camera
Individual plant locations are indicated with the circles, which depict the buffer size used in the experiments

Summary

Introduction

Monocropping is a common practice in many agricultural production systems. It is the practice of growing one crop species at a given time in a large field. Intercropping involves two or more crop mixtures grown in the same space during a crop cycle [5] It offers ecological mechanisms for suppressing weeds [6], controlling pests and diseases [7], conserving soil resources [8], increasing yields [9], and using light, space, and water more efficiently than monocropping [10]. There is a need for a better understanding of the plant interactions for different combination of species, cultivars, and field layouts [5] This requires vast amounts of spatial–temporal data to study plant growth and development in the field at the level of individual plants, which can only be obtained by automated digital monitoring systems

Objectives

Methods

Results

Discussion

Conclusion