Abstract
Hyperspectral based prediction of nutrient content in maize leaves
Hyperspectral imaging is a promising method to predict crop traits in a
high-throughput manner and unlock quantitative genetic studies. A single
hyperspectral image can be used to predict several unrelated traits at
once using spectral data from 350nm - 2500nm. Researchers have
successfully modeled different physiological traits in maize such as
vegetative Nitrogen content but the effect of different development
stages, genotypes, and treatments on modelling power remains unclear.
Here, I explore the ability to model leaf macro- and micro- nutrient
content and leaf water content from hyperspectral transmittance data
collected with a LeafSpec imaging device. I will compare three different
machine learning algorithms; Partial Least Squares Regression, Random
Forest and a Convolutional Neural Net to model nutrient content
collected from twenty hybrids throughout the 2020 field season in
fertilized and not fertilized blocks. Genotypes and development stages
excluded from model training are used to externally validate models.
Sulfur, Nitrogen, Calcium, Copper, and Iron leaf concentrations were the
most amenable nutrients to prediction with coefficient of determination
scores from 0.78 - 0.73, respectively. Models trained on samples from a
collection of time points were able to accurately predict new time
points and genotypes. The findings demonstrate the ability to predict
nutrient content in field grown maize over a variety of developmental
stages, genotypes, and treatments from a handheld hyperspectral imaging
device.