不同品种文冠果种子萌发对低温储藏的响应

Responses of seed germination to low temperature storage in different cultivars of Xanthoceras sorbifolium

关键词:  文冠果品种, 冷藏处理, 种子萌发, 储藏物质, 激素, 解休眠机制

Key words:  Xanthoceras sorbifolium cultivars, cold storage, seed germination, reserve substance, hormone, breaking dormancy mechanism

摘要:

为研究不同文冠果品种种子的休眠与萌发机理,该文选择4个文冠果品种[‘普通'(PT)、‘奇红'(QH)、‘沃丰'(WF)、‘沃石'(WS)]种子作为研究材料,分别在-20 ℃下进行不同时间段(30、60、90、120、150 d)的储藏处理,测定各阶段文冠果种子的发芽指标,并对储藏前、储藏后、萌发7 d间的种子内含物、激素水平进行研究。结果表明:(1)-20 ℃储藏能显著提高小粒种子(PT、QH)的发芽质量,处理60 d的效果最好,其发芽率分别达 48.3%、58.3%,但大粒种子WF、WS品种的效果低于前两者。(2)-20 ℃储藏60 d及种子湿沙萌发7 d内,4个品种油脂含量、种壳厚度均出现显著下降,在3～7 d下降幅度大(WS除外); 而种仁含水量在萌发1～3 d内快速增加,之后缓慢增加到第7 天的峰值,种仁可溶性糖等指标都在发芽3～4 d时显著积累。(3)低温冷藏可提高文冠果小粒品种种子的GA/ABA和tHor/ABA的比值,进而促进油脂降解、种壳变薄,从而解除种子的休眠。总之,文冠果种子大、种壳厚、硬度大、生理后熟是导致其休眠的主要原因,属综合休眠类型; 低温冷藏可破除种子休眠,提高其种子的发芽率,小粒品种效果好于大粒品种; 大粒品种如‘沃石'可通过延长低温冷藏时间(150 d)提高种子发芽率(38.7%); 低温冷藏+湿沙萌发是一种快速和简便的促进文冠果种子萌发的方法。该研究结果为文冠果优良品种的推广和种子解休眠机制的研究提供了技术支持和理论基础。

Abstract:

To study the seed dormancy and germination mechanism of Xanthoceras sorbifolium, the seeds of four cultivars [‘Putong'(PT),‘Qihong'(QH), ‘Wofeng'(WF)and‘Woshi'(WS)] were stored at -20 ℃ for different periods(30, 60, 90, 120, 150 d). The seed germination indexes were determined in each treatment, and the changes of reserve substance and hormone content were also analyzed in three stages including before storage, after storage, and 7 days of germination. The results were as follows:(1)Cold storage could significantly promote the germination rate and germination potential of small seeds(PT, QH). The best treatment was cold storage for 60 d, and the germination rate was up to 48.3% and 58.3%, respectively. The effects of cold storage on large seeds(WF and WS )was lower than that of small seeds.(2)The kernel oil content, seed shell thickness(SST)in four cultivar seeds all decreased significantly during periods of cold storage and germination, especially in 3-7 days of germination, the oil content and SST(except WS cultivar)decreased notably. However, water content in kernels increased rapidly within 1-3 days of germination and then slowly increased to the peak value on the 7th day. The contents of soluble sugar in kernels increased significantly at the 3-4 days of germination.(3)Cold storage increased GA/ABA and tHor/ABA ratios in small seeds(PT, QH), promoted oil degradation, made seed shell thinning and break seed dormancy. In conclusion, the main factors leading to dormancy in X. sorbifolium seeds are larger in size, higher shell thickness and more hardness, physiological post-ripening, and belongs to comprehensive dormancy type. Cold storage at -20 ℃ for 60 d can improve the germination rate of PT, QH and WF seeds, reduces dormancy degree, while the cold storage time of WS seeds needs prolonging to 150 d. The method using -20 ℃ storage with wet sand germination is a rapid and simple method to promote X. sorbifolium seeds germination. This study provides a reference for the promotion of superior varieties and the research on the seed breaking dormancy mechanism in X. sorbifolium.