Development of Inflorescence Buds for the Top-grafting Flower-budwoods of Julip Pear
Date Issued
2010
Date
2010
Author(s)
Tsao, Ching-Wen
Abstract
Pear (Pyrus spp.) is a temperate fruit tree with high economic value. Mr. Chang invented the technique of top-grafted pear in Taiwan in 1976. Now most top-grafting flower-budwoods are imported from Japan and some from high altitude area in Taiwan. In this study, horizontal and upright flower-budwoods of Julip pear were examined to verify the development of inflorescence buds and the sugar contents.
Flower-budwoods of Julip pear were sampled at Lalashan and Taiwan Agricultural Research Institute (TARI) from Jul. to Oct. Stereomicroscope, scanning electron microscope (SEM), and paraffin section were used to examine the external and internal structures of pear inflorescence buds. For the sugar contents, soluble sugar and starch were examined by anthrone method. An inflorescence bud of Julip is composed of twelve scales, ten bracts, and one inflorescence containing eight flower primodia and two vegetative primodia. Development of inflorescence buds on flower-budwoods of Julip pear was divided into seven stages.“Inflorescence primodium” stage was vegetative bud turning into inflorescence bud.“Flower primodium”stage was flower primodium without any flower organ initiated.“Sepal” stage was flower primodium with five sepals initiated.“Petal”stage was flower primodium with five petals initiated.“Stamen” stage was flower primodium with stamens of first and/or second rows initiated.“Pistil 1”stage was flower primodium with carpels initiated.“Pistil 2”stage was flower primodium with inside face-concaved carpels initiated. Inflorescence bud development was earlier at TARI than at Lalashan. At Lalashan, inflorescence buds were at early stages in Jul., and nearly at final stages in Oct. 18–37.78% flower primodia were with carpels in Aug. and 71.72–93.62% in Sep. At TARI, flower primodia with carpels already existed in Jul. Dead flower primodia were some in Aug. and 21.75–57.75% in Sep. Development of inflorescence buds was earlier on horizontal flower-budwoods than upright flower-budwoods at both areas.
Soluble sugar in buds had significantly difference among months with the highest contents in Jul. (Lalashan, 35.73–42.16 mg/g DW; TARI, about 21 mg/g DW). Starch in bud bases gradually accumulated among months (In Oct., Lalashan, 93.64–131.69 mg/g DW; In Sep., TARI, about 75 mg/g DW), and all were significantly higher on horizontal flower-budwoods than upright flower-budwoods at Lalashan. Soluble sugar and starch contents had significantly differences among different sites of shoots with their highest contents at upper site. During the development of inflorescence buds, soluble sugar and starch in buds decreased, and starch in bud bases increased. Therefore, the above results suggested that sugar is closely related to the inflorescence bud development of Julip pear.
The temperature is lower at Lalashan than at TARI. Development of inflorescence buds at Lalashan was from Jul. to Oct., and a large amount of starch was accumulated in bud bases in Oct. Moreover, sprouting and flowering of inflorescence buds were even, and their rate were high after top-grafting. Hence, we suggested that Lalashan is a suitable place to produce top-grafting flower-budwoods. Also, horizontal budwoods are better than upright budwoods for the more starch contents in the bud bases. However, upright budwoods were more in nature, and our results showed that starch in bud bases of upright budwoods indeed reached high contents. With appropriate selection, upright budwoods might be acceptable for top-grafting.
Subjects
Julip pear
top-grafting flower-budwoods
development of inflorescence buds
soluble sugar contents
starch contents starch contents
Type
thesis
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