种子活力与发芽环境对玉米种子蛋白酶α-淀粉酶活性的影响

为探讨不同活力玉米种子田间发芽成苗率存在明显差异的生理原因,测定了不同环境条件下玉米种子发芽期间蛋白酶和α-淀粉酶的活性.结果表明,种子活力对玉米籽粒蛋白酶和α-淀粉酶活性的影响因发芽环境条件而异.高活力种子胚乳的蛋白酶活性在较低的温度下发芽比低活力种子的高,且在不同温度条件下的变化较小.胚乳蛋白酶活性在10℃和25℃下的比值与种子活力密切相关.玉米种子胚中蛋白酶的活性比胚乳的高,且高活力种子胚的蛋白酶活性较高.α-淀粉酶的活动开始于吸水约5 h时的种子中,发芽5～6 d时活性达最高.在10℃发芽时,高活力种子α-淀粉酶活性显著地高于低活力种子,但在25℃发芽时两者差异不显著.在不良环境条件下发芽,玉米种子的蛋白酶活性增高,α-淀粉酶的活性降低.高活力种子的蛋白酶和α-淀粉酶的稳定性和协调性较好.

The Effects of Seed Vigour and Imbibition Environment on The Activities of Protease and α-Amylase in Maize(Zea mays L.) Kernels

The effect of seed vigour on the activities of protease and α-amylase in maize (Zea mays L. )kernels varies with temperature and water environment. The endosperm protease activity at the timeabout radicle protrusion at 10 ℃ and their stability at different temperatures are well correlated to seedvigour. There is higher protease activity in the higher vigour embryos at the time about radicleprotrusion, as well as in the dry embryos. α-Amylase (EC 2.1.1.1 ) activity is found initially in maizekernels at about 5 h and reached its maximum at 5～6 d after imbibition. The α-amylase activity ofthe high vigour seeds is significantly higher than that of the low vigour seeds imbibed at 10 ℃, butthere is no obvious difference between high and low vigour seeds at 25 ℃. The ratios of the proteaseactivities of endosperm at the time about radicle protrusion at 10 ℃ and 25 ℃ are closely correlated toseed vigour. Under unsuitable conditions, the protease activity of maize seeds is significantly higherand their α-amylase activity is significantly lower. The stability and coordination of protease and α-amylase activities are essential for high seed vigour and successful germination of maize seeds.