Abstract: In order to explore the corresponding relationship between nutritional quality of alfalfa （Medicago sativa L.） and drying time during drying process in saline-alkali land and the correlation between respiratory metabolic enzyme activity and nutritional quality of alfalfa during drying process，seven drying time nodes were set up in non-saline-alkali land （CK） and saline-alkali land （LS） treatment in this study， and the changes of nutritional quality content and respiratory metabolism-related enzyme activity with drying time were analyzed. The results showed that the drying time significantly affected the nutritional indexes of alfalfa except the Crude ash （Ash） of CK. Saline-alkali stress （LS） increased Crude protein （CP） （22.35 % vs CK 20.58 %） and Relative feed value （RFV） （137.13 vs CK 104.60）.After drying for 8 h， the activities of Pyruvate kinase （PK）， Glucose-6-Phosphate Isomerase （GPI）， Pyruvate dehydrogenase （PDH）， Succinate dehydrogenase （SDH） and Cytochrome c oxidase （COX） in CK significantly decreased， while Alternative oxidase （AOX） increased. For LS， only COX decreased and AOX increased. LS generally inhibited the activity of respiratory metabolic enzymes. The correlation showed that COX in CK was significantly correlated with CP， AOX in LS was significantly correlated with CF and NDF， and LS significantly affected AOX and COX. In summary， saline-alkali stress reduced the nutrient loss of alfalfa during drying by regulating EMP， TCA， PPP pathway and electron transport chain （key enzymes COX and AOX）.

Key words: Hay modulation, Respiratory metabolic enzymes, Alfalfa, Salt alkali stress

摘要： 为探究盐碱地紫花苜蓿（Medicago sativa L.）在干燥过程中营养品质与干燥时间的对应关系，以及呼吸代谢酶活性与紫花苜蓿干燥过程中营养品质的相关关系。本研究通过设置非盐碱地（CK）与盐碱地（LS）处理和紫花苜蓿干燥过程中7个干燥时间节点，探究其营养品质含量及呼吸代谢相关酶活性随干燥时间的变化规律。结果表明：除CK的粗灰分（Crude ash，Ash）外，干燥时间显著影响紫花苜蓿营养指标。盐碱胁迫（LS）提升了粗蛋白质（Crude protein，CP）（22.35% vs CK 20.58%）和相对饲喂价值（Relative feed value，RFV）（137.13 vs CK 104.60）。干燥8 h后，CK中丙酮酸激酶（Pyruvate kinase，PK）、磷酸己糖异构酶（Glucose-6-Phosphate Isomerase，GPI）、丙酮酸脱氢酶（Pyruvate dehydrogenase，PDH）、琥珀酸脱氢酶（Succinate dehydrogenase，SDH）、细胞色素氧化酶（Cytochrome c Oxidase，COX）活性显著下降而交替氧化酶（Alternative oxidase，AOX）上升；LS仅COX下降且AOX上升。LS总体上抑制呼吸代谢酶活性。相关性显示CK中COX与CP、LS中AOX与CF、NDF显著相关，且LS显著影响AOX，COX。综上，盐碱胁迫通过调控EMP，TCA，PPP途径及电子传递链（关键酶COX、AOX），降低了紫花苜蓿干燥过程的营养损耗。

关键词: 干草调制, 呼吸代谢酶, 紫花苜蓿, 盐碱胁迫