NaCl胁迫对野生苜蓿种子萌发特性的影响

Comparative study on seed germination characteristics of two wild Medicago species under NaCl stress

摘要:

以2种野生牧草杂花苜蓿(Medicago varia)和黄花苜蓿(M.falcata)为试验材料,测定了NaCl浓度0、50、100、150、200 mmol/L处理下种子的发芽率、发芽势、发芽指数、活力指数和苗长、胚根长等萌发指标,分析2种野生牧草种子萌发期耐盐性变化规律。结果表明:1)NaCl胁迫对2种野生苜蓿种子发芽都产生了抑制作用,高浓度NaCl胁迫对黄花苜蓿发芽率影响大,且高浓度下黄花苜蓿的发芽率高于杂花苜蓿。2)NaCl浓度为0~50 mmol/L时黄花苜蓿的发芽势低于杂花苜蓿, 100~200 mmol/L时高于杂花苜蓿。3)杂花苜蓿和黄花苜蓿种子发芽指数在100 mmol/L时均较对照下降50%。对照活力指数黄花苜蓿种子是杂花苜蓿种子的2倍。4)2种野生苜蓿种子在NaCl 胁迫下胚芽长和胚根长表现出不同的下降规律,NaCl 胁迫对黄花苜蓿胚芽长度下降较杂花苜蓿大,但杂花苜蓿的胚根长下降较黄花苜蓿大。利用隶属函数对2种野生牧草萌发期各指标综合评价得出:黄花苜蓿的耐盐性较杂花苜蓿强,可用于盐渍化土壤的建植。

Abstract:

This study studied seed germination and seedling growth of two Medicago species,Medicago varia and M.falcate,including seed germination rate,germination potential,germination index and vigor index,seedling length and radicle length under five NaCl concentrations(0,50,100,150,and 200 mmol/L).The results showed that seed germination of both wild alfalfa species was inhibited by NaCl stress.Seed germination rate of M.varia.under low NaCl concentration was lower than that of M.falcate.while greater than M.falcate under high NaCl concentration.Seed germination potential of M.falcat was lower than that of M.varia L at 0 and 50 mmol/L NaCl,while was higher at 100,150 and 200 mmol/L.Seed germination index of both M.varia and M.falcate decreased by 50% at 100 mmol/L compared with the control.Seed vigor index of M.falcate was twice higher than that of Medicago varia in the nil-NaCl control.Germ length and radicle length of two wild alfalfa seedlings showed different response to increasing NaCl stress.The germ length of M.falcate reduced more than that of M.varia.in response to NaCl stress.However,the radicle length of M.varia decreased more than that of M.falcate Medicago falcate had better salt tolerance than M.varia based on the membership function for the comprehensive evaluation of the indicators at the germination stage.Therefore,M.falcate could be planted in saline soil.