中文摘要：

本试验研究了不同光周期对3种秋眠型苜蓿光敏色素和植物体内源激素含量的影响,为揭示苜蓿秋眠性的调控机理提供科学依据.试验采用FQ-PCR SYBR-Green Ⅰ方法,在人工气候室,以美国苜蓿秋眠级标准对照品种Norseman（FD1,秋眠型苜蓿,秋眠1级）、Dupuils（FD5,半秋眠型苜蓿,秋眠5级）和CUF101（FD9,非秋眠型苜蓿,秋眠9级）为材料,设计4个不同的日照长度梯度（7,10,13和16 h/d）,对其植株处理35 d,测定叶片中光敏色素（PHYA、PHYB）mRNA表达量,采用（ELISA）试剂盒法测定内源激素生长素（IAA）、脱落酸（ABA）、玉米素核苷（ZR）、赤霉酸（GA3）的含量.结果表明,3种不同秋眠型紫花苜蓿PHYA和PHYB在短日照条件下合成量大,其中以Norseman表现最为明显.不同秋眠类型苜蓿叶片中的GA3/ABA、ZR/ABA和IAA/ABA均随着光照时间延长而增大;短日照条件下3种秋眠型苜蓿ABA的合成量均为最大,GA3的含量最低,生长严重受到抑制.可能P HYA和PHYB直接或间接影响了内源激素GA3、ZR、IAA、ABA合成量,进而调控了苜蓿的秋眠.

英文摘要：

To explore the effects of photoperiod on phytochromes and endogenous hormones of different fall-dormancy alfalfas （Medicago sativa）,and to reveal the regulatory mechanisms,the expressions of PHYA （phytochrome A） and PHYB （phytochrome B） were observed by the FQ-PCR SYBR-Green Ⅰ method after 35 days in three standard varieties：the fall-dormant variety Norseman（FD1）,the semi-dormant variety Dupuils （FD5） and the non-dormant variety CUF101 （FD9）,under different photoperiods （7,10,13 and 16 h/d）.Their endogenous hormone contents （GA3,ZR,IAA and ABA） were measured by Enzyme-linked immunosorbent assay （ELISA）.The mRNA expressions of PHYA and PHYB in the three alfalfa varieties increased gradually with a shortening photoperiod,especially in the fall-dormant variety Norseman.The ratios of GA3/ABA,ZR/ABA and IAA/ABA decreased with increased photoperiod and those of the Norseman variety were the lowest：it had the slowest growth,the highest ABA level and the lowest GA3 level.It is possible that PHYA and PHYB directly or indirectly influenced the synthesis of GA3,ZR,IAA,ABA and further regulated fall dormancy.