引发处理对甜高粱种子萌发阶段生理生态影响

Eco-physiological responses of seed germination of sweet sorghum to seed priming

为了探讨种子引发处理对甜高粱种子萌发和早期幼苗阶段的影响机制,分别以KCl、CaCl2溶液(50、100和200 mmol·L-1)和具有相同水势的PEG溶液为引发试剂,对种子进行吸水-回干处理,分析了"M-81E"甜高粱品种在引发处理过程中的吸湿、回干情况,引发处理后分析了种子在不同浓度NaCl溶液中发芽率、形态响应、生物量分配以及幼苗体内Na+、K+、Ca2+积累情况。结果表明:在引发处理过程中,甜高粱种子存在快速吸水期和快速失水期,分别发生在吸湿、回干的前3 h;在随后的发芽试验过程中M-81E甜高粱表现出较高的耐盐性,NaCl浓度低于200 mmol·L-1时,种子发芽率、发芽速度差异不显著,除CaCl2引发处理对50和200 mmol·L-1NaCl胁迫下种子发芽速度有显著的促进作用外(P<0.05),不同引发试剂对种子发芽率、发芽速度影响差异不显著;引发处理对幼苗胚根长、胚轴长及全长影响差异显著(P<0.05);在无盐胁迫条件下,引发处理对幼苗生长产生负效应,随着盐胁迫浓度增加,引发处理能够明显促进甜高粱幼苗生长,且不同引发处理效果具有一定的差异性;随着盐浓度升高,幼苗体内Na+、Ca2+含量显著增加,但对K+含量无显著影响;引发处理显著降低了K+含量(KCl引发除外);总体而言,不同引发方式均不同程度地增加了甜高粱幼苗生长、生物量积累以及盐胁迫条件下的离子调节能力,其中CaCl2引发效果略优于其他两种引发方式。

A germination test was conducted to understand the effects of seed priming on seed germination and early seedling growth of sweet sorghum （M-81E）. The hydrationdehydration processes of M81E were analyzed with KCl or CaCl2 solution （50, 100, or 200 mmol·L-1） or isosmotic PEG solution being used for pretreatment, and the germination percentage, germination rate, seedling growth, biomass allocation, and Na＋, K＋ and Ca2＋ contents in different NaCl solutions were determined after seed priming. The results showed that the first 3 hours of hydration and dehydration processes of M81E were the quick water absorption period and quick dehydration period. The germination percentage and germination rate were not significantly different when the NaCl stress was lower than 200 mmol·L-1. The different priming conditions had no significant effects on the germination percentage and germination rate except the positive effect of CaCl2 pretreatment to the germination rate in 50 and 200 mmol·L-1 NaCl solutions. However, the seed priming significantly affected the radical length, hypocotyl length and the whole seedling length. Seed priming had negative effects on seedling growth in nonsalt treatments but significantly improved the seedling growth with the increase of salt concentration, and the different pretreatment reagents had different effects on seedling growth. The contents of Na＋ and Ca2＋ in seedlings were significantly increased with the increase of salt concentration, but not for the content of K＋. Seed priming significantly decreased the content of K＋, with the exception of KCl pretreatment. In conclusion, the different pretreatment reagents increased the seedling growth, biomass accumulation and the capacity of ion adjustment to different extents. The seed priming effect of CaCl2 solution was better than that of the other two solutions.