氮和鉀源對矮牽牛於無土介質之生長與開花之影響

Effect of Nitrogen and Potassium Source on Growth and Flowering of Petunia in Soilless Mix

矮牽牛White Cascade或Old Glory White於冬春將成苗定植於砂／杉木屑無土介質，行不同氮鉀源肥料試驗。氮和鉀濃度各為200ppm，由KCl、KNO2與K2SO4三鉀源，與（NH4）2SO4，尿素，NH4NO3及Ca（NO3）3四種氮源行複因子完全逢機設計，結果以KNO3與NH4NO3組合者，對矮牽牛生育最佳，KCl與（NH4）2SO4或尿素組合者，生育最差，地上部鮮重、花朵數極顯著減少，葉黃化致眨低觀賞販賣價值。分析葉無機礦物成分，以KCl為鉀源者，葉含K機顯著減少，顯示於無土介質施用KCl肥效低，不如KNO3與K2SO4為鉀源者，老葉易於黃化，致生理性缺K。對不同氮源而言，NH4NO3與Ca（NO3）2優於（NH4）2SO4與尿素，若K源採用KNO3或K2SO4，則肥效差異不大。植株較大再施與不同氮鉀源，則施用KCl之缺K症狀較晚出現。文中顯示不同鉀源所含Cl（上標 -），NO3（上標 -）與SO4（上標 -3）三陰離子極顯著地影響矮牽牛之生育。

Petunia hybrida (Vilm) ”White Cascade” and ”Old Glory White” were grown in sand-sawdust mix during winter-spring season and watered with 8 or 12 nutrient solutions containing varying combination of nitrogen [(NH4)2 SO4, urea, NH4NO2, Ca(NO3)2] and potassium (KCl, KNO3, K2SO4)sources, each resulting in a total 200 ppm N plus 200 ppm K. KCl combination with (NH4)2SO4 or urea limited the growth and flower production and showed physiological K deficiency and ammonium toxicity symptoms which were revealing by chlorosis or necrosis on the lower leaves, and low K content through tissue analysis. There were significant increased in fresh weight, flowers and K content in combination KNO3 with four N sources, and the best result was shown in KNO3 plus NH4NO3. Plant growth was increased as the K2SO4 source substituded with KCl, while reduction of growth was found when compared with KNO3 as K source. The results indicated that growth of petunia was more significant influenced by K source than N source.