Acousto-optic tunable filter（ AOTF） hyper-spectral imaging system with acousto-optic tunable filter are used to collect the hyper-spectral images of tomato seedlings’ various parts

such as main stem

new leaves and old leaves. In this experiment

tomato seedlings were cultivated at 10 different nitrogen-treatment levels. The spectral information from 615 nm to 1000 nm are extracted from the hyper-spectral imaging by template matching preprocessing. Competitive adaptive reweighted sampling（ CARS） method is adoptded to select feature. The experimental results show that the performance of nitrogen quantitative model

built by the leaves and stems set is the worst

that of the model built by the leaves set is better

and that of the model built only by the old leaves is the best. The best model is established by 5 fold partial least square（ PLS） regression method on the base of 10 wavelength points selected by CARS including 703 nm

906 nm and so on. The best principal component number is 9

the determine coefficient R

2

is 0.95 and the root mean square error of cross validation（ RMSECV） is 0.08.Therefore

it is possible to monitor the nitrogen content of tomato seedlings with the AOTF hyper-spectral imaging technology. The old leaves with relative stability of old leaf nitrogen content should be recommended to build quantitative analysis model

and the preferred feature wavelength for nitrogen analysis is 703 nm and 906 nm.