Abstract:
This study was carried out to determine total protein and activity of the enzymes malondialdehyde (MDA), phenoloxidase (PO), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) in healthy and necrotic kernels and in healthy parts of necrotic kernels of different hazelnuts (Corylus avellana L. cvs. 'Tombul,' 'Palaz' and 'cakildak'). The highest total protein was measured in the necrotic kernels of all cultivars, whereas healthy kernels of all cultivars except 'cakildak' had the lowest total protein. The highest MDA and GPX were noted in necrotic kernels of 'Tombul' cultivar, whereas the lowest values were determined for the healthy part of the necrotic kernels. Nevertheless, healthy kernels recorded the highest activities of CAT and PO compared to other kernel types. The highest values for MDA and CAT in 'Palaz' cultivar were measured in the healthy part of the necrotic kernels, while healthy kernels had the lowest values. Contrastingly, the highest and the lowest values of GPX were recorded in healthy kernels and healthy parts of the necrotic kernels, respectively. Necrotic kernels of 'cakildak' cultivar had higher values for MDA and PO than the rest of the kernel types. Likewise, the highest and the lowest values for GPX and SOD were recorded for healthy kernels and healthy parts of the necrotic kernels, respectively. It is concluded that damage caused by the green shield bug has significant impact on the activities of antioxidant enzymes in hazelnut kernels in relation to their defense mechanisms.