The comparison of Canopeo and samplepoint for measurement of green canopy cover for forage crops in India

Prabhu Govindasamy; Sonu Kumar Mahawer; Debalin Sarangi; Hanamant M Halli; T K Das; Rishi Raj; Vijay Pooniya; L Muralikrishnan; Sunil Kumar; Amaresh Chandra

doi:10.1016/j.mex.2022.101916

The comparison of Canopeo and samplepoint for measurement of green canopy cover for forage crops in India

MethodsX. 2022 Nov 9:9:101916. doi: 10.1016/j.mex.2022.101916. eCollection 2022.

Authors

Prabhu Govindasamy^{1

2}, Sonu Kumar Mahawer¹, Debalin Sarangi³, Hanamant M Halli^{4

5}, T K Das², Rishi Raj², Vijay Pooniya², L Muralikrishnan⁶, Sunil Kumar¹, Amaresh Chandra⁷

Affiliations

¹ Divison of Crop Production, ICAR-Indian Grassland and Fodder Research Institute, Jhansi, India.
² Division of Agronomy, ICAR-Indian Agricultural Research Institute, New Delhi, India.
³ Department of Plant Sciences, University of Wyoming, Laramie, WY, USA.
⁴ Divison of Seed Technology, ICAR-Indian Grassland and Fodder Research Institute, Jhansi, India.
⁵ School of Soil Stress Management, National Institute of Abiotic Stress Management, Pune, India.
⁶ Division of Agricultural Extension, ICAR-Indian Agricultural Research Institute, New Delhi, India.
⁷ Director, ICAR-Indian Grassland and Fodder Research Institute, Jhansi, India.

Abstract

Canopy covers can be measured using destructive (visual) and non-destructive methods (spectral indices, photogrammetry, visual assessment, and quantum sensor). The precision of crop cover estimation, however, is dependent on the selection of appropriate methods. Studies were conducted at the Indian Grassland and Fodder Research Institute, Jhansi to compare the forage crops canopy cover estimated using photogrammetry software (Canopeo and SamplePoint) and visual assessments. Assessments were performed in three summer crops (corn, cowpea, and sorghum), two winter crops (Egyptian clover, and oats), and bare ground condition. For each plot, three nadir images (directly above the canopy) were captured using digital cameras from a height of 1.5 m above the soil surface between 10 AM to 2 PM on bright sunny days. The results indicated that the relationships between visual assessment and Canopeo (regression coefficient, (R² = 0.96), visual assessment and SamplePoint (0.96), and Canopeo and SamplePoint (0.98) were linear when data were pooled across all the crops. SamplePoint and Canopeo is further, appropriate for cowpea (Pearson coefficient (R = 0.99 and 0.94), oats (0.92 and 0.97), and sorghum (0.46 and 0.51), respectively. SamplePoint and Canopeo are not suitable for berseem (-0.15) and corn (-0.61), respectively, due to dead residues after the first harvest in berseem and taller corn might have influenced the image quality. Therefore, the stage of the crop, the height of the crop, and dead residues around the plants can greatly influence the estimation of crop cover. In conclusion, the results indicated that this photogrammetry software can be used for non-destructive crop canopy measurement with the above-mentioned precautions in the forage crops tested. •Forage canopy cover is estimated generally by visual scoring, and the outcome varies widely from person to person.•Photogrammetry methods (Canopeo and SamplePoint) were positiviely correlated with visual scoring for cowpea, oats, and sorghum.•However, Canopeo and SamplePoint may not suitable for taller crops like corn and ratoon crops like berseem.

Keywords: Crop cover; Nadir image; Non-destructive method; Photogrammetry.