方解石与柠檬酸/酒石酸模拟实验中的反应规律

柠檬酸/酒石酸可使方解石产生矿物溶蚀及生物矿化等现象,研究它们之间的反应规律对富含有机酸环境中方解石矿物的稳定性评估及相应的地球化学效应研究具有重要意义。通过批量平衡法,研究开放系统条件下方解石与柠檬酸/酒石酸之间的反应规律及对应的溶液化学变化。结果表明:①初始浓度为20 mg·L-1条件下,初始pH值由7.7升至9.7,柠檬酸与酒石酸的反应去除量均显著下降,这是由于方解石表面的静电效应及溶液中HCO_(3)^(-)与CO_(3)^(2-)的竞争效应不断增强,对两种酸的表面吸附反应起抑制作用。②初始pH值为7.7及8.3条件下,初始浓度为20 mg·L-1的两种酸与方解石反应7 h后便达到平衡,pH值和Ca浓度较空白值变化不大,辅证了反应的主导机制为表面吸附。③在0~900 mg·L-1浓度范围内,柠檬酸和酒石酸在初始pH值为8.3条件下,其反应去除量均能用Langmuir吸附模型很好地拟合,辅证了以上的反应去除机制均为表面吸附;初始pH值为7.7条件下,柠檬酸的反应去除量可用Langmuir吸附模型拟合,反应的主导机制仍为表面吸附,而酒石酸的反应去除量呈现持续陡增现象,Langmuir与Freundlich吸附模型均难以拟合,这是由于酒石酸的反应主导机制是沉淀反应。④初始pH值为8.3,在0~900 mg·L-1浓度范围内,在5℃、20℃、35℃温度条件下,两种酸的反应去除结果均可用Langmuir吸附模型拟合,反应的主导机制仍为表面吸附。与酒石酸相比,随着温度的升高,柠檬酸吸附量的增幅更大;同时,3种温度条件下柠檬酸带来的pH值和Ca浓度增幅均比酒石酸带来的更大。

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。