Estimation of fall dormancy in alfalfa by near infrared reflectance spectroscopy

Estimating fall dormancy (FD) in alfalfa (Medicago sativa L.) is time-consu ming and expensive. The objective of this study was to estimate the FD clas s of alfalfa using near infrared reflectance (NIR) spectroscopy. Eleven alf alfa cultivars ranging in FD from 1 to 11 were grown as spaced plants at fo ur diverse locations. In early autumn, 55 to 65 plants were randomly select ed at each location and FD determined for each plant. For each sample, NIR spectra were collected and FD values regressed against first and second der ivative transformations of spectra by modified partial least squares regres sion. The optimum equation had a calibration R-2 of 0.90 and a mean and sta ndard error of 7.93 +/- 1.14. Blind validation samples showed that this equ ation could accurately predict the FD class of individual plants (r(2) = 0. 85) as well as entire cultivars; (r(2) = 0.94). We concluded NIR spectrosco py has the potential to estimate FD classes of alfalfa.