Reflectance spectroscopy to characterize the response of <i>Corymbia calophylla</i> to <i>Phytophthora</i> root rot and waterlogging stress

Abstract The health of Corymbia calophylla (marri), a keystone tree species in the native forests southwest Western Australia, has been decline for past few decades. Phytophthora root disease and waterlogging have often cited as contributing to this decline. Traditional methods (i.e., field surveys sampling) mapping infection are time-consuming expensive; thus, potential reflectance spectroscopy characterize marri response stress was investigated. Twelve-month old plants were infected with either P. cinnamomi or multivora two glasshouse trials waterlogged 24 h each fortnight. Spectral measurements portable high-resolution spectroradiometer taken weekly. Plant biophysical at harvest time. Normalized difference spectral index (NDSI) calculated every combination values between 400 2500 nm all time points, correlated treatment effects displayed heat maps. Narrowband vegetation indices (VIs), utilizing different wavelengths electromagnetic spectrum, also from data. treatments did not cause significant differences both trials. In second trial, significantly lowered plant top dry weight (P = 0.016) diameter 0.044). Reflectance plotted against wavelength well seasonal trend. NDSI maps indicated that strongest bandwidths visible near-infrared portions spectrum (538–558 701–709 nm). Six VIs (normalized nitrogen 2, anthocyanin 1, photochemical index, Carter Vogelman 3 water band index) able track biochemical changes leaves over 10 weeks, confirming interaction effect cinnamomi, elapsed first trial 0.010). This study demonstrates holds promise characterizing but more work needs be done identify optimum identifying marri.