牛心朴子种子萌发特性及对干旱胁迫的响应

试验设置了不同温度、光照和PEG等梯度处理,以发芽率、发芽势和发芽指数等作为测定指标,筛选牛心朴子种子的最优发芽条件并确定种子对干旱胁迫的忍耐能力。结果表明:1)牛心朴子种子不存在休眠现象,最适的萌发恒温范围为20~30℃,且萌发的起始温度较低,为10℃。光照条件不是限制种子萌发的关键条件,但黑暗条件会影响种子的活力;2)低浓度(5%)的PEG对牛心朴子种子胚根的伸长有一定的促进作用,但对胚芽则表现为抑制作用;随着PEG浓度的增加,胚根/胚芽比值亦增大,而发芽率、相对发芽率、发芽势、发芽指数、种子萌发胁迫指数以及种子萌发抗旱指数则呈明显的下降趋势;3)牛心朴子种子对干旱胁迫具有一定的忍耐能力,在15%浓度的PEG溶液胁迫下,种子可正常萌发;4)牛心朴子种子发芽较快,在置床后的第3天便有超过70%的种子萌发,故推荐该种子萌发的初次计数时间为置种后的第3天,末次计数时间为第8天。

Characteristics of Seed Germination and Response to Drought Stress of Cynanchum komarovii

Different temperature,illumination and PEG gradient treatments were set in the experiment,and germination rate and germination potential and germination index were used as measurement indexes.The optimal germination conditions of Cynanchum komarovii (Cynanchum hancockianum (Maxim.) Al.Iljinski.) seeds were selected and their tolerance to drought stress was determined.The results showed that:1) There was no dormancy phenomenon in the Cynanchum komarovii seeds,the optimal temperature range of germination was 20-30 ℃,and the starting temperature of germination was 10 ℃.Light condition was not the key condition to restrict seed germination,but dark condition would affect seed vitality.2) Low PEG concentration (5%) promoted the radicle elongation of Cynanchum komarovii seeds,but inhibited the embryo growth of it.Meanwhile,with the increase of PEG concentration,the radicle/embryo ratio also increased,while the germination rate,relative germination rate,germination potential,germination index,seed germination stress index and seed germination drought resistance index showed an obvious decreasing trend.3) The seeds of Cynanchum komarovii had a certain tolerance to drought stress,and could germinate normally under the stress oF15% PEG solution.4) The seeds of Cynanchum komarovii germinated quickly,and more than 70% of the seeds germinated on the third day after placing the seeds in the bed.Therefore,it was recommended that the initial counting time of this seed germination should be the third day after placing the seeds,and the last counting time should be the eighth day.