Application of Spectral Reflectance for Water Stress Detection of Corn (Zea mays L.) at Different Irrigation Treatments
Mary Hazel Joy C. Ugot, Roger A. Luyun, Jr., Ronaldo B. Saludes, Victor B. Ella, Marck Ferdie V. Eusebio, and Yaminah Mochica M. Pinca
Received: September 16, 2021/ Revised: May 24, 2022/ Accepted: June 01, 2022 (https://doi.org/10.62550/IP107021)
Spectral reflectance indices have shown potential in crop water stress detection. Spectral reflectance was measured to determine vegetation indices, and its use as an indicator of water stress in corn under different irrigation treatments was explored. A completely randomized experimental design was conducted to detect water stress in potted IPB Var13 corn (Zea mays L.) under screenhouse conditions. Corn plants were subjected to three water stress treatments with three replications during the late vegetative (42 - 60 days after planting (DAP)) and reproductive (55 - 77 DAP) stages based on the total available water (TAW) in the soil: well-watered (> 50% TAW), moderately water-stressed (35% -50% TAW), and severely water-stressed (20%-35% TAW). Hyperspectral vegetation indices computed from the leaf spectral reflectance measurements which include the Water Index and the Normalized Water Indices (NWI-1, NWI-2, NWI-3, and NWI-4) were calculated and correlated with leaf relative water content, Crop Water Stress Index, and grain yield. Results revealed that the vegetation indices considered for this study showed no significant response to the implemented water stress treatments for both sampling growth stages. However, it was found that NWI-3 (r = -0.88878073) and NWI-2 (r = -0.92222618) produced the most significant correlation with corn grain yield for the vegetative and reproductive stages, respectively. Hence, these spectral indices could be significantly used for early corn grain yield assessment during its late vegetative and reproductive stages.