PEG模拟干旱对毛竹种子萌发及生长生理特性的影响

目的]通过比较不同程度干旱胁迫对毛竹种子萌发及生长生理的影响,探究毛竹种子萌发期对水分胁迫的耐受机理,为毛竹的水分管理提供科学依据。方法]以毛竹种子为试验材料,采用培养皿滤纸萌发的方法研究不同浓度(0%、5%、10%、15%、20%、25%) PEG-6000溶液对其种子萌发、生长、渗透调节物质、抗氧化酶活性的影响。并对种子萌发率、胚根和胚芽的生长量与PEG胁迫浓度间进行回归分析。结果](1)对照组(CK)和5%处理组在第4天开始发芽,其余各处理组的发芽起始时间随处理浓度的升高逐渐延迟,25%处理组不发芽。(2)最终发芽率、发芽势、发芽指数、活力指数、胚根长度、胚芽长度随PEG浓度的升高呈现先增大后减小的趋势,且均在5%浓度达到最大值。干旱胁迫下毛竹种子发芽率日变化曲线中对照组和5%处理组间存在唯一交叉点。毛竹种子在PEG胁迫下发芽率的临界值和极限值分别为14. 49%和19. 27%。(3)胚根和胚芽最终长度均在5%浓度时达到最大值,其后随着浓度的升高而减小,处理间差异显著(P 0. 05)。对照组和5%处理组的胚根平均长度日变化曲线存在交叉点。PEG胁迫下胚根生长的临界值和极限值分别为20. 43和23. 01%。(4)胚根中SOD、POD、CAT的活性均随PEG浓度的升高呈先上升后下降的趋势,且分别在5%、10%、10%浓度时达到最大值。(5) MDA和可溶性蛋白含量随PEG浓度的升高而持续升高,但低浓度(0%10%)时MDA含量差异不显著。结论]低浓度干旱胁迫抑制发芽前期毛竹种子萌发以及胚根的形成,但显著提高毛竹种子的最终发芽率并且促进胚根后期的生长;而高浓度PEG干旱胁迫延迟毛竹发芽,抑制整个发芽时期的发芽率以及胚根、胚芽的生长; PEG浓度高于15%的干旱胁迫使毛竹的抗氧化酶系统发生紊乱,并对组织膜系统造成显著伤害。

Effects of Drought Stress Simulated by PEG on Seed Germination and Growth Physiological Characteristics of Phyllostachys edulis

Objective] To study the tolerance mechanism of Phyllostachys edulis to drought stress during seed germination by comparing the effects of different drought stress on seed germination, growth physiological characteristics of Ph. edulis so as to provide reference for Ph. edulis water management.Method] The effects of different concentrations (0%, 5%, 10%, 15%, 20%, 25%)of PEG stress on seed germination, growth, organic osmoregulation substances were measured with choosing Ph. edulis seeds and using Petri dish and filter paper germination method. The regression analysis were done between growth of radicle and embryo, seed germination and PEG stress.Result] (1) The control group (CK) and 5% test group began to germinate on the 4^th day. The initiation time of the other test groups was gradually delayed with the increase of treatment concentration, and 25% of the test group did not germinate. (2) The final germination percentage, germination energy, germination index, vigor index, radicle length and embryonic bud length increased at first and then decreased with the increase of PEG-6000 concentration,and reached the maximum value at the concentration of 5%. There was a unique cross between the control group and the 5% test group in the diurnal variation curve of Ph. edulis germination rate under drought stress. The critical and the maximum value of the seed germination of Ph. edulis were 14.49% and 19.27% under the PEG stress. (3) The final length of radicle and embryo reached the maximum at 5% concentration, and then decreased with the increase of concentration, and the difference was significant (P<0.05). There was a unique cross between the diurnal variation curve of the radicle length of the control group and the 5% test group. The critical and the maximum value of growth of radicle of Ph. edulis were 14.49% and 19.27% under the PEG stress. (4) The activities of SOD,POD and CAT in the radicle increased with the increase of PEG concentration. And reached a maximum at concentrations of 5%, 10%, and 10%, respectively. (5) MDA and soluble protein content increased with the increase of PEG concentration, but the difference of MDA was not significant at low concentration (0%-10%).Conclusion] Low concentration drought stress can inhibit the seed germination and radicle formation of Ph. edulis at the early stage of germination, but can significantly improve the final germination rate of Ph. edulis seed and promote the growth of radicle in the late period of germination. The high concentration of PEG drought stress will delay the germination of Ph. edulis and inhibit the germination rate and growth of the whole germination period. Drought stress above 15% could cause the antioxidant enzyme system of Ph. edulis to be disturbed and cause significant damage to cell membrane system.