Effects of the potassium application rate on lipid synthesis and eating quality of two rice cultivars

Lipid content has an important effect on rice eating quality,but the effects of fertilizer application rate on the lipid synthesis and eating quality of rice are not well understood.Potassium(K)has a strong influence on rice quality and the requirement for K fertilizer in rice is greater than for nitrogen(N)and phosphorus(P)fertilizers.To investigate the effects of K fertilizer on the lipid synthesis and eating quality of rice,we used Nanjing 9108(NJ9108,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 content,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 first increased and then decreased with increasing K in both cultivars.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 among the K treatments.The protein and oxaloacetic acid(OAA)contents and phosphoenolpyruvate carboxylase(PEPCase)activity of NJ9108 first decreased and then increased 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 the 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 was 135 kg ha^(-1)for both cultivars.

施氮量对水稻籽粒脂类合成的影响

【目的】为明确氮肥对水稻脂类合成的影响,为水稻优质栽培提供参考。【方法】以南粳9108(粳稻)和IR72(籼稻)为材料,设置N0(0 kg/hm^2)、N1(90 kg/hm^2)、N2(135 kg/hm^2)、N3(180 kg/hm^2)4个施氮处理,研究不同施氮水平对脂类合成及其积累的影响,并分析脂类合成相关酶对粗脂肪、游离脂肪酸、脂肪酸组分影响。【结果】随施氮量的增加,两品种粗脂肪、游离脂肪酸含量显著增加;对不同品种的不饱和脂肪酸而言,南粳9108和IR72分别在N1和N2处理下亚油酸含量最高,棕榈酸、硬脂酸和花生酸含量最低,且不饱和脂肪酸含量高于其他处理。在不同氮肥处理下,南粳9108不饱和脂肪酸含量高于IR72。进一步分析表明,2个水稻品种的乙酰辅酶A羧化酶(ACCase)、脂肪酸合酶(FAS)、3-磷酸甘油脱氢酶(3-GPD)和磷脂酸磷酸酯酶(PPase)酶活性均随施氮量的增加显著提高。【结论】氮肥通过提高脂类合成相关酶的活性,进而促进粗脂肪,游离脂肪酸的积累,并影响脂肪酸组分;且在N2处理下,2品种脂类合成相关酶活性大,粗脂肪和游离脂肪酸含量高,不饱和脂肪酸比例达到最优水平。