Dormancy and germination in seeds of the medicinal Asian tree species Phellodendron amurense var. wilsonii (Rutaceae) --Effect of seed storage and GA3 on germination

The effects of alternating temperatures, cold stratification and gibberellic acid (GA3) on seed germination of Phellodendron amurense var. wilsonii were investigated. Incubation at 35/10°C or stratification at 4°C prior to incubation of freshly harvested seeds significantly increased germination percentages from less than 5% to greater than 87%. Germination percentage was increased only slightly in intact seeds treated with up to 2000 ppm GA3. However, partial removal of the seed coat by mechanical scarification plus GA3 resulted in a drastic increase in both germination percentage and rate. Storage in liquid nitrogen for one and seven months enhanced germination percentage, and the beneficial action was due to cracking of the seed coat. Embryos excised from their enclosing tissues and embryos surrounded by endosperm germinated to a much higher percentage than intact seeds, indicating that the water-permeable seed coat plays a mechanical role in preventing radicle protrusion in nontreated intact seeds. Improved germination responses were obtained when the physiological dormant seeds of P. amurense var. wilsonii were pre-treated for 3 months of cold stratification, whilst GA3 treatments also promoted their germination.本研究探究了变温、冷层积与赤霉素（gibberellic acid, GA3）对威尔逊黄檗（Phellodendron amurense var. wilsonii）种子萌发的影响。对刚收获的种子采用35/10℃变温培养，或先置于4℃进行冷层积后再行培养，可将种子萌发率从不足5%显著提升至87%以上。仅用最高浓度2000ppm的GA3处理完整种子，萌发率仅小幅提升。然而，通过机械破皮法部分去除种皮并结合GA3处理，可使种子萌发率与萌发速率均大幅提升。液氮储存1个月及7个月均可提升种子萌发率，其有益作用源于种皮开裂。从包裹组织中剥离出的胚，以及被胚乳包裹的胚，其萌发率均远高于完整种子，这表明未处理的完整种子中，透水种皮通过机械阻碍作用抑制了胚根伸出。对该黄檗变种的生理休眠种子进行3个月冷层积预处理后，可获得更优异的萌发响应，同时GA3处理也可促进其萌发。