Effects of Mn application amounts on physiological characteristics and Mn content of aromatic rice

Objective To investigate the effects of MnSO₄ basal applications on physiological characters and Mn content of aromatic rice, and to provide a theoretical basis for cultivating high-quality aromatic rice.

Method Pot experiment was carried out using Meixiangzhan and Nongxiang 18 as planting materials. Four basal applications of MnSO₄ were employed with the concentrations of 6.67 (Mn1), 10.00 (Mn2), 13.33 (Mn3) and 16.67 (Mn4) mg·kg^-1 respectively. There was a control treatment (CK) with none MnSO₄ application. The experiment was arranged in a randomized block design. The Mn contents of leaves, stems and brown rice grains were measured. The enzyme activities of superoxide dismutase (SOD) and peroxidase (POD), and the content of malondialdehyde (MDA) in rice leaf were investigated.

Result Compared to the control, Mn4 was more beneficial to increase the Mn content of brown rice grains in early and late seasons by 22.02% and 6.75% respectively for Meixiangzhan, and 1.48% and 4.26% respectively for Nongxiang18. Mn4 treatment was better to increase the Mn content in the stems and leaves of early and late aromatic rice varieties after booting stages. Mn4 treatment improved the net photosynthetic rate of leaf and dry mass of above-ground of early and late aromatic rice varieties. Moreover, Mn4 treatment was more effective to improve the SOD and POD activities and decrease the MDA content in the leaves of early and late aromatic rice varieties.

Conclusion Appropriate basal application of MnSO₄ would be more effective to improve the net photosynthetic rate and the Mn contents of stem, leaf and brown rice grains, enhance the resistance, adaptability and growth of aromatic rice variety. The optimal application amount of MnSO₄ is 16.67 mg·kg^-1 in this study.