射干种子萌发特性及对干旱胁迫的响应

Study on Characteristics of Iris Belancanda chinensis Seed Germination and Its Response to Drought Stress

对射干(Iris Belancanda chinensis (L.) DC.)种子进行纸上发芽试验,以发芽势、发芽率、发芽指数等作为发芽指标,旨在摸清射干种子萌发特性,筛选出该种子萌发的最适组合条件,探讨聚乙二醇(PEG)模拟水分胁迫对射干种子萌发的影响。结果表明: 1)种子最适的温度条件为恒温20 ℃,且对光照较为敏感,可归为需光种子;2)随着PEG浓度的升高,发芽率、发芽势、发芽指数、相对发对率、萌发胁迫指数、胚芽长均呈现先升高后降低的趋势,且在5% PEG处理下达到最大值,即低干旱水平可促进种子萌发及抗旱能力,高干旱水平会起抑制作用;随着PEG浓度的升高,萌发抗旱指数、胚根长明显降低,即该2种指标与PEG浓度呈负相关关系;胚根/胚芽亦会随着PEG浓度升高而增大,说明干旱胁迫对胚根的抑制作用显著高于对胚芽的抑制作用。用一元线性回归拟合种子发芽率和PEG浓度,预测出射干种子所能抵御的水分渗透势临界值为-0.2 MPa,极限值为-0.4 MPa;3)综合考虑发芽率、发芽整齐度及速度等因素,推荐射干种子在发芽检测时初次计数时间为置床后第8天,末次计数时间为置床后的第15天。

In order to explore seed germination characteristics and screen the optimum combination conditions for seed germination,we executed the seed germinate of Iris Belancanda chinensis L. seeds and determined the indicators including germination potential,germination rate,germination index,etc.Meanwhile,the effects of simulate drought stress by polyethylene glycol (PEG) on Iris B.chinensis were also discussed.The results showed that (1) the optimum seed temperature was constant temperature 20 ℃ and the seed was sensitive to light,which could be classified as seeds requiring light.(2) With the increase of PEG concentration,germination rate,germination potential,germination index,relative germination rate,germination stress index and germ length all showed a trend of first increasing and then decreasing,and reached the maximum value under 5% PEG.In other words,the drought with low level could promote seed germination and drought resistance,while the high level drought could play an inhibitory role.With the increase of PEG concentration,the drought resistance index and radicle length of germination decreased significantly,namely the two indexes being negatively correlated with PEG concentration.The radicle/bud also increased with the increase of PEG concentration and the inhibition effect of drought stress on radicle was significantly higher than that on embryo.The critical value and limit of water osmotic potential were -0.2 MPa and -0.4 MPa respectively.(3) Considering factors such as germination rate,germination uniformity and speed,it was recommended that the initial counting time of shoot dry seeds for germination detection should be the 8 th day after bed placement,and the last counting time should be the 15 th day after bed placement.