I like to use the PLSR model for predicting plant traits from their spectral characteristics. Are there any other models used to predict leaf traits from spectral characteristics of the plant?
I strongly recommend using python to analyze your data with PLS. The following link will help you to do it step-by-step. Also, python will allow you to do not only PLS but also any other chemometric analysis on your data.
If you are familiarized with the R program, you can perform partial least squares regression by using the pls function in the pls package. You can find a detailed explanation on its procedure with an illustration in James et al., (2013, Chapter 6.5.3). You can download the book on the following website (https://www.statlearning.com/)
Reference
James, G., Witten, D., Hastie, T., & Tibshirani, R. (2013). An introduction to statistical learning (2nd ed.). Springer.