基于4-PHF(the four-parameter Hill function)法比较6种四照花种子的休眠特性

4-PHF-based Analysis on Seed Dormancy of 6 Cornus Species

【目的】四照花属(Cornus)树种具有很高的园林观赏价值,有较高开发利用前景。本研究利用4-PHF(the four-parameter Hill function)法比较6种四照花种子的休眠特性,为四照花种质资源保存、种子贮藏及开发利用等提供理论依据。【方法】以6种四照花,包括大花四照花(CF)、中国四照花(CKC)、香港四照花(CH)、东京四照花(CHT)、秀丽四照花(CHE)和尖叶四照花(CE)种子为材料,用500 mg·L^(-1)赤霉素(GA3)溶液浸泡3 d后进行低温层积处理,并设7个层积时间梯度(0、10、20、30、40、50、60 d);采用4-PHF法拟合6种四照花种子发芽曲线,计算发芽参数包括起始发芽时间(lag)和发芽高峰时间(TMGR)及休眠指数(DI)。【结果】层积有效地促进了四照花种子休眠的解除,但每个种达到最大发芽率所需层积时间存在差异:CKC仅需层积30 d发芽率可达78%,CH和CF层积60 d后发芽率分别达71%和89%,CHE、CHT和CE层积50 d后发芽率分别达63%、69%和54%。用4-PHF方程拟合的发芽曲线表明:随着休眠的解除,发芽参数lag和TMGR值持续下降,DI则呈现增加的趋势。【结论】结合各个发芽参数得出落叶类四照花CF、CKC种子休眠程度较浅,而常绿种CH、CHT、CHE和CE种子休眠较深,由DI值得出本试验处理未能充分解除常绿类四照花种子休眠,4-PHF方程进行种子萌发曲线拟合及萌发参数lag和TMGR可从生物学角度诠释层积处理对6种四照花种子的萌发差异,但DI值不宜用于比较种间休眠程度的差异。

【Objectives】Seed dormancy of 6 species of ornamental Cornus was studied using the 4-parameter hill function(4-PHF)method to aid the resource conservation,seed storage,plant development,and landscape planning.【Method】Seeds of C.florida(CF),C.kousa subsp.chinensis(CKC),C.hongkongensis(CH),C.hongdongensis subsp.tonkinensis(CHT),C.hongdongensis subsp.elegans(CHE),and C.elliptica(CE)were soaked in a 500 mg·L^(-1) GA3 solution for 3 d.Then,at durations of 0,10,20,30,40,50,and 60 d,the seeds were stratified at low temperature.The 4-PHF method was used for curvefitting to describe germinating patterns,as well as calculating estimates on the time at germination onset(lag),time at maximum germination rate(TMGR),and dormancy index(DI)for the 6 species.【Result】The stratification effectively facilitated the break of seed dormancy.However,the holding time required for maximal germination varied among the 6species.For CKC,78%germination was achieved in 30 d;for CH and CF,it was 71%and 89%,respectively,in 60 d;and for CHE,CHT,and CE,it was 63%,69%,and 54%,respectively,in 50 d.The germination curves showed steady declines after break of dormancy on lag and TMGR but increase on DI.【Conclusion】As indicated by the germination parameters,it appeared that the evergreen variety of dogwoods went into a deeper dormancy than the deciduous ones.The DI showed the current treatment could not fully break the seed dormancy on the evergreen dogwoods.The germination curve-fitting and the 4-PHF-estimated lag and TMGR could explain the biological differences on the seed germination among the 6 dogwood species by the stratification treatments.On the other hand,DI could not be used to compare the degree of dormancy.