珍稀濒危植物金丝李种子脱水耐性和贮藏特性

Dehydration tolerance and storage characteristics of seeds of rare and endangered plant Garcinia paucinervis

关键词:  种子含水量, 萌发率, 脱水敏感性, 顽拗性种子, 种子贮藏

Key words:  moisture content of seeds, germination percentage, dehydration sensitivity, recalcitrant seeds, seed storage

摘要:

为测定不同脱水程度金丝李(Garcinia paucinervis)种子的萌发情况及其复水后的吸水率、脱水过程中抗性生理指标的变化以及不同贮藏方式下种子的萌发情况,该文研究了金丝李种子的脱水敏感性和储藏特性。结果表明:(1)金丝李种子初始含水量为45.29%,室内通风处放置35 d失水率即达45%。(2)种子失水率低于18%时,萌发率和复水后的吸水率变化不显著; 失水率超过18%时,萌发率和复水后吸水率均显著下降,失水率为42%时萌发率为0。其种子的临界含水量为27.29%,半致死含水量为12.72%。(3)随着种子脱水程度的加深,相对电导率、可溶性糖及脯氨酸含量逐步上升; 丙二醛含量在失水率低于24%时变化不大,高于24%时显著提高; SOD和POD的活性均呈波动性变化,失水率为18%时活性均最高。(4)室温干藏1个月和-1、-20 ℃下湿藏1个月的种子均不能萌发; 水浸贮藏1个月的种子萌发率显著降低; 4 ℃湿藏1、3和6个月均显著延缓种子萌发,但对萌发率无显著影响。表明金丝李种子在失水率低于18%时,种子可通过抗性调节维持细胞的正常代谢,能忍受一定程度的脱水和低温; 当失水率超过18%时,种子代谢失衡发生劣变直至死亡,属于低度的顽拗性种子。4 ℃湿沙藏(含水量7.5%)是短期贮藏其种子的较好方法。

Abstract:

We studied the dehydration sensitivity and storage characteristics of G. paucinervis seeds by measuring the germination of seeds with different dehydration extents and the water absorption after rehydration, the change of physiological indices of resistance in the process of dehydration as well as the seed germination under different storage methods. The results were as follows:(1)The initial moisture content of G. paucinervis seeds was 45.29%. The dehydration rate was up to 45% when placed after 35 d in the indoor ventilated place.(2)When the dehydration rate was less than 18%, germination percentage(GP)and the water absorption rate after rewatering were not significantly different from those of fresh seeds. However, when the dehydration rate exceeded 18%, GP and the water absorption rate after rewatering were significantly decreased, and GP was 0 at dehydration rate 42%. The critical moisture content of seeds was 27.29%, and the lethal moisture content of 50% was 12.72%.(3)The relative conductivity, the contents of soluble sugar and proline were increased gradually with the deepening of seed dehydration. The content of malondialdehyde(MDA)changed little when the dehydration rate was less than 24%, and increased significantly when exceeding 24%. Both activities of superoxide dismutase(SOD)and peroxidase(POD)showed a trend of fluctuation and peaked at dehydration rate 18%.(4)Seeds with desiccation storage for one month at room temperature, and all the seeds with storage in damp sand at -1 ℃ and -20 ℃ for one month could not germinate. GP of seeds with water immersion for one month dropped significantly. Germination processes of seeds with storage in damp sand for one month, three months or six months at 4 ℃ were delayed, but there was no significant effect on GP. It indicates that when the dehydration rate of G. paucinervis is less than 18%, seeds can regulate resistance to maintain normal metabolism of cells. The seeds can endure a certain degree of dehydration and low temperature. When the dehydration rate exceeds 18%, the metabolism of seeds is unba-lanced, and then deteriorated until death, which belong to minimally recalcitrant seeds. It also indicates that storage in damp sand at 4 ℃(moisture content 7.5%)is a good method for short-term storage of G. paucinervis seeds.