外源褪黑素对复合盐碱胁迫下黑果枸杞种子萌发和幼苗生长的缓解效应

Alleviating Effects of Exogenous Melatonine on Seed Germination and Seedling Growth of Lycium ruthenicum under Complex Salt-Alkali Stress

以黑果枸杞种子为实验试材,将中性盐NaCl、Na_(2)SO4和碱性盐NaHCO_(3)、Na_(2)CO_(3)按碱性盐占比由小到大模拟组成中性复合盐L(1∶1∶0∶0)、中度碱性复合盐M(1∶9∶9∶1)和重度碱性复合盐H(9∶1∶1∶9),采用纸上萌发法,研究外源褪黑素浓度(0.1、0.3、0.5、1.0 mmol/L)对不同盐碱组成(L、M、H)及其盐碱浓度(50、100、200 mmol/L)组合胁迫下黑果枸杞种子萌发和幼苗生长的影响。结果显示:(1)黑果枸杞幼苗的生长表型(长势)随盐碱浓度及碱性盐占比升高明显减弱;适当低中浓度外源褪黑素(0.1、0.3、0.5 mmol/L)能在一定程度上缓解盐碱胁迫对幼苗生长的伤害,过高浓度外源褪黑素(1.0 mmol/L)则使伤害加剧;施加外源褪黑素使黑果枸杞幼苗侧根数量明显增多。(2)黑果枸杞种子的萌发进程与盐碱组成、盐碱浓度及褪黑素浓度密切相关,随盐碱浓度和碱性盐占比升高,黑果枸杞种子萌发的起始时间延迟,萌发总时长缩短;施加适当浓度外源褪黑素能使盐碱胁迫下黑果枸杞种子萌发起始时间提前,并延长萌发总时长。(3)在L复合盐处理中,随盐碱胁迫浓度升高,黑果枸杞种子的发芽率(GR)、发芽势(GP)、发芽指数(GI)、活力指数(VI)、芽长(SL)、根长(RL)均先升后降,但在M和H复合盐碱处理中,各项萌发指标均随盐碱胁迫浓度升高呈逐渐下降趋势。(4)外源褪黑素对黑果枸杞种子各项萌发指标具有明显“低促高抑”现象,L复合盐中,在3种盐碱浓度胁迫下,褪黑素浓度为0.1和0.3 mmol/L时对GP、GR、GI、VI、SL、RL有促进作用,并以0.1 mmol/L综合促进效果最佳,褪黑素浓度为0.5和1.0 mmol/L时对GP、GR、GI、VI产生抑制作用,褪黑素浓度为1.0 mmol/L对SL、RL有抑制作用;M和H复合盐中,在3种盐碱浓度胁迫下,褪黑素浓度为0.1、0.3、0.5 mmol/L时对各指标均有促进作用,并以0.3 mmol/L综合促进效果最佳,褪黑素浓度为1.0 mmol/L时则产生抑制。研究表明,低浓度中性复合盐处理对黑果枸杞种子萌发和幼苗生长有一定促进作用,高浓度中性复合盐及中度和重度碱性复合盐则产生抑制作用;外源褪黑素对盐碱胁迫下黑果枸杞种子萌发和幼苗生长的缓解具有明显剂量效应,0.1 mmol/L褪黑素对中性复合盐胁迫的综合促进效果更佳,0.3 mmol/L褪黑素则对中度和重度碱性复合盐胁迫有最佳促进效果。

With the seeds of Lycium ruthenicum as the experimental material,the neutral salt NaCl,Na_(2)SO_(4) and the alkaline salt NaHCO_(3),Na_(2)CO_(3) were simulated to form neutral compound salt L(1∶1∶0∶0),moderately basic compound salt M(1∶9∶9∶1)and severely basic compound salt H(9∶1∶1∶9)according to the proportion of alkaline salts from small to large,we used the Paper Germination experiment to study the effects of exogenous melatonine(0.1,0.3,0.5,1.0 mmol/L)on seed germination and seedling growth of L.ruthenicum seeds under different salt-alkali composition(L,M,H)and salt-alkali concentration(50,100,200 mmol/L)combined stress.The results showed:(1)the growth phenotype of L.ruthenicum seedlings is obviously weakened with the increase of saline-alkali concentration and alkaline salt proportion;Appropriate concentration of exogenous melatonine(0.1,0.3,0.5 mmol/L)could alleviate the damage of saline-alkali stress on seedling growth to a certain extent,while excessive concentration of exogenous melatonine(1.0 mmol/L)will aggravate the damage.At the same time,the application of exogenous melatonine(MT)significantly increased the number of lateral roots of L.ruthenicum seedlings.(2)The germination process of L.ruthenicum seeds is closely related to saline-alkali composition,saline-alkali concentration and MT concentration.With the increase of the salt-alkali concentration and the proportion of alkaline salt,the initial time of germination of L.ruthenicum seeds is delayed,and the total germination time is shortened;Applying an appropriate concentration of exogenous MT can advance the germination start time of L.ruthenicum seeds under saline-alkali stress and prolong the total germination time.(3)In the L compound salt treatment,with the increase of the salt-alkali stress concentration,the germination rate(GR),germination potential(GP),germination index(GI),vitality index(VI),shoot length(SL),root length(RL)all increase first and then decrease;In the M and H compound salt-alkali treatments,all germination indexes showed a gradual decrease with the increase of the salt-alkali stress concentration.(4)Exogenous MT has obvious“low-promoting high-suppressing”phenomenon on the germination indexes of L.ruthenicum seeds,In the L compound salt,under the stress of 3 kinds of salt concentration,when the MT concentration is 0.1 and 0.3 mmol/L,it can promote GR,GP,GI,VI,SL and RL,and the comprehensive promotion effect of 0.1 mmol/L is the best,and when the MT concentration is 0.5 and 1.0 mmol/L,it has a inhibitory effect on GP,GR,GI and VI,when the MT concentration is 1.0 mmol/L,it has a inhibitory effect on SL and RL;Among the M and H compound salt-alkali,under the stress of 3 kinds of salt-alkali concentration,when the MT concentration is 0.1,0.3,0.5 mmol/L,it has a promoting effect on all indicators,and the comprehensive promotion effect of 0.3 mmol/L is the best,and when the MT concentration is 1.0 mmol/L,it has a inhibitory effect.Studies have shown that low-concentration neutral compound salt treatment can promote seed germination and seedling growth of L.ruthenicum to a certain extent,while high-concentration neutral compound salt and moderate and severely alkaline compound salt have an inhibitory effect.Exogenous melatonin has a significant dose effect on the alleviation of seed germination and seedling growth of L.ruthenicum under salt-alkali stress.When the melatonin concentration is 0.1 mmol/L,the comprehensive promotion effect on neutral complex salt stress is better,and melatonin at 0.3 mmol/L,it has the best promoting effect on moderate and severe alkaline complex salt stress.