Physiological Responses of the Roots of 16 Camellia Oleifera Varieties to Aluminum Stress and Screening of Aluminum-tolerant Genotypes

Targeting 16 varieties of Camellia oleifera planted in different regions, this paper explores the influence of aluminum (Al) stress over several physiological indices, namely, root activity, superoxide dismutase (SOD) activity, malondialdehyde (MDA) content, hydrogen peroxide (H2O2) content, proline content, and soluble sugar content and evaluates the overall Al tolerance of each variety. The purpose is to identify the difference between different C. oleifera varieties in physiological indices under Al stress, and to screen the varieties with relatively strong Al tolerance. The results show that: Al stress lowered the root activity and SOD activity, while enhancing MDA content, H2O2 content, proline content, soluble sugar content, and Al content. But the physiological indices of different C. oleifera varieties changed by vastly different amplitudes under Al stress. The variation amplitudes of root activity, MDA content, SOD activity, H2O2 content, proline content, soluble sugar content, and Al content were -47.06%-42.86%, 12.50%-133.33%,-8.33%%-26.28%, 11.11%-71.88%, 76.47%-420.00%, 4.97%-56.41%, and 23.43%-101.12%, respectively. Furthermore, the Al tolerance coefficients of the 16 C. oleifera varieties were analyzed comprehensively by membership functions. The results show that C. oleifera ‘Huajin’, C. oleifera ‘Huashuo’, and C. oleifera ‘Huaxin’ have relatively strong Al tolerance, while C. oleifera ‘Ganyou No.2’, C. oleifera ‘Ganxing No.48’, and C. oleifera ‘Ganzhou No.70’ have relatively weak Al tolerance.