西番莲花芽分化过程观察及花生长模型的拟合

Observation of Flower Bud Differentiation Process and Fitting of Flower Growth Model of Passion Fruit

【目的】明确我国南方生态区主栽西番莲品种的花芽分化过程,建立西番莲花芽形态分化的花生长模型,为西番莲促花保花提供参考。【方法】以紫果类主栽品种‘台农1号’(TN)和黄果类广西主推新品种‘壮蜜05’(同‘壮乡蜜宝’,MB)为试验材料,通过扫描电镜和石蜡切片解剖观察两品种花芽分化过程,观察茎顶端分生组织以下各节位分化进程,并测量各节位花芽的第一苞片长、叶片长、卷须长;通过将茎顶端分生组织以下第7节记为初始标记节位,此时花芽为第一苞片分化期,跟踪调查标记后0—16 d花芽分化进程及标记后至开花的第一苞片长、花蕾长等5个花形态指标的动态变化,构建花生长模型。【结果】供试的两个西番莲品种花芽分化的主要过程包括第一苞片形成期、额外苞片形成期、萼片形成期、花瓣形成期、雄蕊形成期、雌蕊形成期和副花冠形成期等,其中第一苞片形成到雌蕊形成历时10—12 d,TN较MB进程快1—2 d,雌蕊形成是西番莲花芽发育成功的重要标志,此时花芽第一苞片长度为3—4 mm,第一苞片形成到开花历时36—44 d,TN较MB进程快3—4 d。茎顶端分生组织以下第4—5节位可见卷须分化,第6节位花原基分化,着生于卷须旁侧,第7节位可见第一苞片分化,第9节位出现腋生营养分生组织,单独位于卷须和花芽内侧,第10—11节位可见腋芽形成,第14—15节位雌蕊原基分化。利用Origin软件对MB和TN的第一苞片长度、第一苞片宽度、花梗长、花蕾长、花梗和花蕾总长共5个花形态指标和标记后天数进行Logistic模型的非线性回归拟合,决定系数R2为0.9524—0.9988,标准化均方根误差(n RMSE)为8.54%—19.62%,模型方程的拟合效果较好。根据模型参数和实际观察,苞片的长度在标记后即第一苞片形成期后11—12 d进入快速增长期,标记后24—26 d进入缓慢增长期后趋于稳定;之后花梗和萼片迅速生长,萼片长度超过苞片,花蕾和花梗总长在标记后24—25 d进入快速增长期,标记后41—42 d进入缓慢增长期到最大值后开花。【结论】西番莲的花芽与卷须紧靠,而与营养芽分开独立;西番莲花芽分化和形态分化可分为3个阶段,第一苞片形成期到雌蕊形成期,历时10—12 d;苞片生长期,历时12—14 d;花梗和花蕾生长期,历时15—17 d。在西番莲实际生产中,可通过花生长模型预测开花时间,通过苞片长度等形态指标判断花芽分化进程,为促花保花方案提供参考依据。

【Objective】This study aimed to elucidate the flower bud differentiation process in the primary passion fruit(Passiflora edulis)varieties within Southern China’s ecological region.Additionally,it sought to establish a flower growth model depicting the morphological differentiation of passion fruit flower buds,so as to serve as a reference for promoting and retenting passion fruit flowers.【Method】Tainong No.1(TN)as the predominant cultivar of the purple fruit variety,and Zhuangmi 05(also known as Zhuangxiangmibao,MB)as the main cultivar of the yellow fruit variety in Guangxi,China,were utilized as experimental materials.The scanning electron microscopy and paraffin section dissection were employed to observe flower bud differentiation process in these varieties.The differentiation process of nodes below the shoot apical meristem,and measured the first bract length of flower buds,leaf length,and tendril length at each node were observed too.The 7th node below the shoot apical meristem was marked as the initial marker node,and this marked the onset of the first bract differentiation phase of the flower bud.The flower bud differentiation from 0 to 16 days after marking were investigated,as well as the dynamic changes in five flower morphological indicators,such as the length of the first bract and bud from marking to flowering were tracked,for facilitating the construction of a flower growth model.【Result】The primary process of flower bud differentiation in the tested passion fruit varieties encompassed first bract formation stage,additional bract formation stage,sepal formation stage,petal formation stage,stamen formation stage,pistil formation stage,corona formation stage,etc.The duration from first bract formation to pistil formation spanned 10-12 days,with TN exhibiting 1-2 day advancement over MB.Pistil formation emerged as a vital marker for successful passion fruit flower bud development,characterized by a 3-4 mm first bract length.The duration from first bract formation to flowering ranged between 36-44 days,with TN progressing 3-4 days earlier than MB.Tendril differentiation was visible at the 4th-5th nodes below the shoot apical meristem,flower primordium differentiation at the 6th node,appearing alongside the tendril,first bract differentiation at the 7th node,vegetative meristem appearing at the 9th node,which were positioned separately on the inner side of the tendril and flower bud,axillary vegetative shoot formation at the 10th-11th nodes,and pistil primordium differentiation at the 14th-15th nodes.The non-linear regression fitting of a Logistic model in Origin software was performed for the first bract length,width,pedicle length,flower bud length,length of flower bud and pedicle along with days after making for both MB and TN,and the results showed the determination coefficient R2 ranged from 0.9524 to 0.9988,and the normalized root mean square error(nRMSE)was between 8.54%to 19.62%,indicating a good fit of the model equation.Based on the model parameters and actual observations,the length of bract entered a rapid growth period 11-12 days after marking(i.e.after the first bract formation stage)and stabilized 24-26 days after marking.Subsequently,the pedicels and sepals grew rapidly,with the sepals surpassing the bracts length,and the total length of the flower bud and pedicel entered a rapid growth phase 24-25 days after marking,blooming after reaching maximum growth at 41-42 days after marking.【Conclusion】The flower buds of passion fruit were closely associated with tendrils,and independent of nutritional buds.The flower bud differentiation and morphological differentiation of passion fruit could be divided into three stages:the first bract formation period to the pistil formation period,lasting 10-12 days;the bract growth period,lasting 12-14 days;and the flower buds and pedicels growth period,lasting 15-17 days.In actual production of passion fruit,the flowering time could be predicted using the flower growth model,and the flower bud differentiation process could be assessed using morphological indicators,such as bract length,which provided a reference basis for promoting flowering and promoting flowers.