Prediction of grain protein content and gluten quality of bread wheat in the early vegetation period by optical sensors

Estimation of the end-use quality characteristics of bread wheat in the early phenological period and before harvest is critically important for the flour industry. This study investigated the usability of the Normalized Difference Vegetation Index (NDVI) and Chlorophyll Meter (CM) values obtained by GreenSeeker and Chlorophyll Meter for prediction of protein content and gluten quality in the early growth stage of bread wheat. The results demonstrated that protein content was positively correlated with NDVI and CM values of the optical sensors, which can be predicted by using the equation developed with NDVI Zadoks (ZD)(3.1) period values (R-2 = 0.92, p < 0.01). Compared to the NDVI values, higher correlated equations were obtained with the CM for the sedimentation volumes. Both sensor readings showed strong correlation with the GlutoPeak GSI (Gluten Strength Index) and GRI (Gluten Rheological Index) values in the ZD(3.1) period. Also, while Cu, Fe and Mn contents of the grain tended to increase with increasing nitrogen doses according to both optical sensor readings, Zn content was inversely proportional to the NDVI and CM readings. The results of this study reveal that the grain protein content and gluten quality of bread wheat can be estimated successfully in the ZD(3.1) period.