Effects of potassium application rate on lipid synthesis and eating quality of two rice cultivars
2022
CHEN, Guang-yi | PENG, Li-gong | LI, Cong-mei | TU, Yun-biao | Lan, Yan | WU, Chao-yue | Duan, Qiang | ZHANG, Qiu-qiu | Yang, Hong | Li, Tian
Lipid content has an important effect on rice eating quality, but the effects of fertilizer application rate on lipid synthesis and eating quality of rice are not well understood. Potassium (K) has a great influence on rice quality and the requirements for K fertilizer is greater than that of nitrogen (N) and phosphate (P) fertilizer in rice. To investigate the effects of K fertilizer on lipid synthesis and eating quality of rice, we used Nanjing (NJ) 9108 (japonica) and IR72 (indica) rice as experimental materials and four K levels, K0 (0 kg ha⁻¹), K1 (90 kg ha⁻¹), K2 (135 kg ha⁻¹) and K3 (180 kg ha⁻¹). The results showed that the lipid, free fatty acid (FFA) content, unsaturated fatty acid (UFA) content, malonyl-CoA (MCA) content, phosphatidic acid (PA) content, lipid synthesis-related enzyme activities and eating quality of both cultivars first increased and then decreased with increasing K. The maximum values were obtained under K2. However, the saturated fatty acid (SFA) content showed the opposite trend. No significant differences were found in pyruvate (PYR) content between K treatments. Protein and oxaloacetic acid (OAA) contents and phosphoenolpyruvate carboxylase (PEPCase) activity of NJ 9108 first increased and then decreased with increasing K and the minimum values were obtained under K2 while IR72 showed the opposite trend and the maximum values were obtained under K1. Overall, increasing K optimized fatty acid components and increased the lipid content and eating quality of rice by enhancing lipid synthesis-related enzyme activities and regulating substrate competition for lipid and protein synthesis. The optimal K application rate for lipid synthesis, eating quality and grain yield of both cultivars was 135 kg ha⁻¹.
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