Near-infrared reflectance spectroscopy (NIRS) was used as a rapid andnondestructive method to determine the protein content and gossypol content incotton kernel powder samples, using 49 upland cotton (Gossypium hirsutum L.)germplasms and 188 recombinant inbred lines (RILs). The cottonseed samplesharvested from the upland cotton germplasms and RILs grown in different cottongrowing regions in different years were analyzed chemically for protein andgossypol contents, as well as scanned in the reflectance mode of a scanningmonochromator. Using ISI software for scanning and data analysis, protein andgossypol calibration equations were obtained with a standard normal variate +detrending scatter correction and a 2, 4, 4, 1 math treatment and modifiedpartial least square (MPLS) as the regression method. The protein contentcalibration results revealed that the multiple correlation coefficients (RSQ) andstatistic 1-variance ratio (1-VR) for the determination of protein content incottonseed kernels were 0.933 and 0.929, respectively, and its standard error ofcalibration (SEC) and standard error of cross validation (SECV) were 0.623 and0.638, respectively. As the calibration equations were judged by the calibrationRSQ (or 1-VR) and SEC (or SECV), the results indicated that NIRS is comparable tochemical methods in both accuracy and prediction and is reliable in thedetermination of protein content in cottonseed kernels. However, the RSQ, SEC, 1-VR and SECV for gossypol content determination of NIRS were 0.836, 0.811, 0.074and 0.079, respectively. Although it was weaker than that of protein content, theNIRS method is still good enough for the determination and prediction of thegossypol content in cottonseed kernels. Therefore, NIRS models were successfullydeveloped for protein content and gossypol content analysis of cotton kernelpowder sample in the present study and they could be introduced into the cottongermplasm evaluation and breeding program for the cottonseed quality improvement.Gossypol content; Protein content)科研专项经费项目(nyhyzx07-052)资助