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摘要
本研究目的在由生理與生化之觀點探討狼尾草分蘗與植物荷爾蒙之關係。利用71-12-B品
系及7301矮性品系，於1986年9月至1988年12月，盆栽於台大人工氣候室30/25℃及20/15? J（日／夜）（以下同）二種不同溫度下進行不同氮肥處理。生長6週後青割，青割後，分
析全株各節位休眠芽之內生植物荷爾蒙含量與分蘗數，並針對留椿莖基上之分蘗芽，在
7天內每天取樣分析內生植物荷爾蒙之含量，探討其與分蘗之關係。又在青割後取割
後取莖基與根，探討青割後7天內貯藏性碳水化合物（澱粉與蔗糖）之含量及相關代
謝酵素活性與分蘗之關係，及植物荷爾蒙之調節。並以人工合成之植物生長調節劑外
加處理狼尾草切離莖節、噴施田間栽培之狼尾草及以肥料施用，探討田間應用技術，
及對狼尾草分蘗、產量與品質之影響，試驗結果如下：
1.狼尾草全株不同節位上芽內之植物荷爾蒙含量不等，IAA、zeatin、GA3與ABA愈近
莖頂含量愈多，隨節位依序增加；但dzeatin-riboside含量則相反，隨節位而依序減
少。
2.狼尾草青割後，分蘗芽之生長與芽內生植物荷爾蒙含量關係密切，尤其依
cytokinin/IAA比值而定，當比值大於1時，分蘗芽開始生長。芽中IAA、zeatin、GA3
及ABA含量隨芽之生長而增加。zeatin-riboside則相反。各植物荷爾蒙含量均因多施
氮肥而增多。各植物荷爾蒙含量，在高溫下增加較快，與在高溫下芽之生長較快相吻
合。
3.莖基與根中所含澱粉、蔗糖及還原糖，因分蘗芽之生長而急速減少。且不論何時期
，何品種，在高溫下比低溫下含量高，高氮肥下比低氮肥下含量為多。碳水化合物水
解酵素；α-amylase、invertase及sucrose synthase之活性，因芽之生長而急速升
高：且其活性亦因溫度及氮肥施肥量而異。其活性以高溫或高氮肥下均較低溫或低氮
肥酵素活性為高。
4.α－amylase、invertase、及sucrose synthase活性與莖基及根中之可溶性蛋白質
含量呈顯著正相關，而與根與莖基中澱粉、蔗糖及還原糖含量呈顯著負相關，與分蘗
數、芽長及芽鮮重亦均呈顯著正相關，與芽中IAA含量、zeatin、GA5、ABA及
zeatin/IAA，比值呈顯著正相關。此表示α－amylase、invertase及sucrose
synthase三種酵素之活性受內生植物荷爾蒙之調節。
5.增施氮肥使nitrate reductase (NRase)及nitrite reductase (NiRase)之活性即
增加，且在高溫環境下活性均較高。NRase與NiRase之活性與分蘗芽中可溶性蛋白質
含量，分蘗數、芽長及芽鮮重均呈顯著相關，活性並隨分蘗之生長而增加。
6.以植物生長調節劑處理切離莖節之試驗中，IBA、TIBA、GA3、CCC、BA、ABA及
AgNO310-3 M∼10-8M及PP333、ethrel (100∼1000ppm)處理，以BA(10-3∼10-5M)處
理對分蘗芽之生長最具促進效果，其他調節劑在高濃度下均有抑制作用。
7.以IBA、GA3、CCC、BA、ABA及AgNO310-3∼10-5M，PPP333及ethrel各1000、800、
600ppm處理青割第二天之狼尾草，結果：以TIBA處理對狼尾草之分蘗、產量及品質之
效果最大：BA處理之效果，其他調節劑在高濃度下均有抑制作用。
8.以N肥500、1000、1500公斤／公頃施用於青割後之狼尾草，之分蘗、產量及品質因
N肥施用量增加而增加。
狼尾草之分蘗受內生植物荷爾蒙cytokinin與IAA共同調節，而分蘗所需之能量來自莖
基與根中之非結構性碳水化合物，而與非結構性碳水化合物代謝有關之酵素活性、受
內生植物荷爾蒙如IAAd、cytokinin、GAs及ABA所調節。內生荷爾蒙之變化受環境因
子影響甚大，可由N肥之施用達到改變內生植物荷爾蒙含量變化、而調節狼尾草分蘗
、產量與品質之目的。
\\\\\\ The Regulation of Plant Growth Substances on the Tilering in Napier Grass
(Pennisetum Pnrpnreum Schumach)
Summary
The objects of the experiments were to determine the relationship between
plant hormones and tillering, and the physiological and biochemical
mechanisms of tillering in napieer grasses. The strain 71-12-B and dwarf
strain 7301 used as plant materials were planted in pots in phytotron at
30/25 and 20/15℃(day/night) by different levels of N application from
September 1986 to December 1988. Six week old plants were cut and used for
the measurement. After cutting, the endogenous plant hormones in the
tiller buds at stem basses and the nonstructural carbohydrates in roots
and stem bases were determined each day, activities of the enzymes related
to the carbohydrate metabolism were also assayed.
The combined effect of plant growth regulators and different levels of N
fertiligers on the tillering, yield and forage quality of napier grasses
growing in the field was also discussed.
The results were summaried as follows:
1.The levels of plant hormones were were different from nodes. IAA,
zeatin.GA and ABA contents were higer in the stem base and dereased
generally to the top. But zeatin-riboside were increased from top to base.
2.Zeatin/IAA ratio in the tiller buds was related to the growth of tiller
buds. The growth of the tiller buds was enhanced by the ratio of zeatin
/IAA, when the ratio was more than 1, the tiller buds to started grow.
3.The levels of IAA, zeatin, GA2 and ABA were increasing when the tiller
buds were growing, but the contents of zeatin-riboside were decreasing.
The more N fertilizer applied, more the increase of levels of endogenous
plant hormones. The hormone levels in the tiller buds were found to
increase under the high temperature condition.
4.The contents of nonstructural carbohydrates (starch, sucrose and
reducing sugar) in the stem bases were fount to decrease within 7 days
after cutting, while the activities of α-amylase, invertase and surose
synthase were increasing. When grasses were growing under the high
temperature condition with a high level of N fertilzer, the nonstructural
carbohydrates and the activities of their metabolic enzymes were higher.
5.The activities of α-amylase, invertase, sucrose synthase were
significantly correlated with the soluble protein content, but negative
correlated with the starch, sucrose and reducing sugar contents in stem
bases and roots. The activities of the enzymes length of tiller buds and
the fresh weight of tiller buds. Furthermore, a close relationship betweem
the enzymes activities and all the levels of IAA, zeatin, GA3, ABA and
zeatin /IAA ratio was found. These results surgested that the plant
hormones may regulate the carbohydrate metabolism and the relative enzymes
during the tillering stage in napier grasss.
6.The activities of nitrate reductase and nitrite reductase, as
carbohydrate metabolic enzymes were enhanced by N fertilizer application.
and as tiller buds growth and as increase temperature. The activities of
nitrate reductase and nitrite reductase singnificantly correlated with
soluble protein contents, tiller no., the length of tiller buds and the
fresh weight of tiller buds.
7.The most optimum pH for the growth of tiller buds in the stem segments
is 5.0. BA. at the concentration of 10-5∼10-3 M, could promote the growth
of tiller buds on stem segments. Other, PP333, ABA, AgNO3, and ethrel,
would inhibite the growth of tiller buds on stem segments at high
concentration.
8. TIBA application was the most effective treatment for increasing
tillering, yield and forage quality when it was applied after cutting in
the field; BA was the next, No differences were observed in the exogenous
application of other plant growth regulators.
9, Nitrogen fertilizer was applied at the levels of 500. 1000 and 1500
kg/ha, and the tiller no., yield and forage quality increased with N
fertilizer increasd.
So, the tillering of napier grass was mostly regulated by endogenous
cytokinins and IAA. The energy of tillering was from the nonstructural
carbohydrate storaged in the stem bases and roots. The emzyme activity of
carbohydrate metabolism was also regulated by endogenous plant hormones.
Environmental factors could change the levels of endogenous plant
hormones, and then regulate the tillering of napier grass. We could
improve the yield, tillering and forage quality of napier grass by means
of N ferfilizer application and foliar sprays of plant gowth regulator.
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