细叶鸢尾种子休眠原因及解除休眠的方法研究

A study on the causes of Iris tenuifolin dormancy and the methods for breaking dormancy

细叶鸢尾种子存在休眠。通过种子的吸水性研究、切割处理、萌发抑制物测试等方法对其内在休眠原因进行了研究,并探讨了解除其休眠的方法,进一步分析休眠解除过程中种子内部产生的响应。结果表明,细叶鸢尾的离体胚不休眠,种皮和珠孔端胚乳均能显著抑制种子的萌发;种皮中存在萌发抑制物质,且为醇溶性的极性物质;浓硫酸处理60min和变温层积(4℃/25℃)120和150d均能有效打破其休眠,萌发率分别从0升至51.11%,36.67%,40.00%,发芽指数也提高为0.45,0.42和0.51,而低温层积150d的萌发率仅为7.78%;变温层积过程中种子的珠孔端组织(种皮和胚乳)机械阻力的降低和胚生长势的增大是萌发率提高的根本原因。综合整个试验结果得出,细叶鸢尾种子属生理休眠,是由珠孔端组织的机械阻力和种皮中的萌发抑制物共同作用而成。

The causes of Iris tenuifolin seed dormancy were studied by the hygroscopicity of seeds,different scarification treatments and germination inhibitor tests.The embryo was not responsible for dormancy,while the seed coats and micropylar endosperm played important roles in reducing germination percentage.Additionally in the seed coats,there were polar germination inhibitors which were soluble in methanol.Sulphuric acid treatment for 60 min or cold-warm stratification（4℃/25℃） for 120 or 150 d effectively promoted germination percentage,from 0 to 51.11%,36.67% and 40.00%,respectively,and also increased the germination index to 0.45,0.42 and 0.51.The germination percentage was only 7.78% if the seeds were stratified at 4℃ for 150 d.The main reason why cold-warm stratification was better for germination,was that the mechanical resistance to embryo growth was considerably reduced and the growth potential of embryos was considerably enhanced.In summary,the seed of I.tenuifolin has a physiological dormancy,which is caused by both the mechanical resistance of micropylar tissue and germination inhibitors in seed coats.