小西氏石櫟開花結實習性與無性繁殖之潛力

Abstract

本試驗第一部分，探討小西氏石櫟之繁殖。分別利用空中壓條之高壓法、扦插以及嫁接法，來了解小西氏石櫟無性繁殖之可行性。高壓法之發根率低且需時較久。經由14個月的扦插試驗可以得知，9月至1月皆有扦插發根的可能性，其中又以1月為最高。無論幼年性枝條或成熟枝條亦都具有發根成活之能力。以3種發根劑處理插穗，與對照組相比，未能顯著提高發根的比例。小西氏石櫟適宜於1至3月進行嫁接，其中以2月有較高之嫁接存活率。 本試驗第二部分，觀察小西氏石櫟之枝梢發育、芽體的分化、小花至成熟果實的生長與發育及發育過程中營養元素與碳水化合物的變化。小西氏石櫟於春季抽出第一次梢，其枝條上有花序原體的形成能萌發出春花。夏季萌發第二次梢，其上亦能觀察到花序原體的形成，於秋季萌發秋花。小花至果實之發育，無論直徑、高度、重量或體積等性狀，皆呈現雙S型模式。利用顯微切片觀察可得知，雌花開花時，胚囊尚未分化，花粉管生長至花柱基部後經長時間停滯，春花及秋花並於隔年六至七月以後，即開花13及8個月後，胚囊才開始發育，方能完成受精。所以雙S型發育模式中，第一個S曲線為小花的發育，第二個S曲線為真正果實的發育。營養元素與碳水化合物的含量變化，與植株的生長發育有相關。 第三部分為小西氏石櫟種子與果實性狀相關性調查與初步選拔。結果顯示種子的重量與果實重量及體積有較高之相關性，可以作為選拔目標。調查小西氏石櫟16株植株的果重、種子重與可食率，確實有部分植株具有大果、大種子與高可食率之特性。

The first section of this experiment investigated the propagation of Pasania konishii. Layering, cutting, and grafting were practiced. Rooting percentage of layering was low and demanded for a long period. The experiment of cutting among 14 months indicated that cuttings were collected properly from September to January, and the higher rooting percentage occurred in February. There was no discrepancy of rooting percentage among control or rooting stimulator treatments. Both juvenile and mature shoots were able to develop roots. Survival percentages of grafting were higher in January, February, and March, and highest in February. The second sections were observation of bud development, flowering and fruiting behavior, variation of nutrient and carbonhydrate content. P. konishii sprouted in spring and autumn, vegetative bud might develop on the new shoot in both season, so inflorescence primordia could be observed on the spring and autumn spouts. The curve of growth from flower to fruit were fitted the double S model in diameter, height, weight, and volume. Since there were no embryo sacs developed in the ovary, the pollen tubes might stay in the base of style until embryo sac matured next year, and resumed growth. As the result, the first S curve was development of flower and the second S curve was development of fruit. Variation of nutrient and carbonhydrate content related to growth of P. konishii. The third section were investigated the relationship between seed weight and fruit characteristics. The result indicated that seed weight related to fruit weight and fruit volume. Some fruit characteristics could used as early selection indicators. Among 16 selected trees, fruit weight, seed weight, and edible ratio of the fruits were investigated. We could found some trees had characteristics of big fruit, big seed, and high edible ratio.