養液氮、磷與鉀濃度及氮型態對洋桔梗穴盤苗生長 及後續開花表現之影響

Abstract

洋桔梗[Eustoma grandiflorum (Raf.) Shinn.]為臺灣重要的外銷切花，栽培面積和產量逐年增加，對種苗需求大增，然而目前尚未建立洋桔梗穴盤育苗期間之養分管理標準。本研究於夏季及冬季在25/20℃下探討苗期養液氮濃度、氮型態、磷濃度及鉀濃度對洋桔梗‘克萊利粉’、‘凜白’及‘禮儀彩藍’穴盤苗生長及移植後開花表現之影響。 洋桔梗3品種播種後於25/20℃栽培至子葉完全展開時，每週施用含4-24 (夏季)或4-36 (冬季) mM 氮(N)之強生氏養液1次。小苗自子葉完全展開至第1、2及3對葉展開所需時間以施用16-20 mM N者較少，再提高至24-36 mM者不能再加速生長，施用4-12 mM N者小苗生長緩慢。施用4-8 mM N者全株淨光合作用速率顯著較低，隨養液N濃度提高至20-24 mM而逐漸增加，再提高至28-36 mM不再增加全株淨光合作用速率。隨養液N濃度自4提高至16-20 mM，葉片Fv/Fm值自0.67-0.76增加至0.80-0.82，再提高至24-36 mM處理者Fv/Fm維持在0.80-0.82。葉面積、全株、地上部及地下部乾重隨養液N濃度自4提高至20-24 mM而增加，再提高至28-36 mM不再顯著增加。養液N濃度提高植體N濃度亦提高。養液N濃度自4提高至12 mM使植體磷(P)、鉀(K)、鈣(Ca)、鎂(Mg)濃度隨之下降。以4-8 mM N處理者定植後莖伸長速率較慢，且較晚開花；苗期以20-28 mM N處理者可較早開花與採收。 自子葉完全展開開始施用含20 mM N、銨硝比(NH4+:NO3-)為0:100、25:75、50:50、75:25及100:0之強生氏養液。隨養液NH4+比例提高，介質淋洗液EC值提高，而pH值則下降。隨養液NH4+比例自0%提高至75%-100%，全株淨光合作用速率、根活性、葉面積、全株、地上部及地下部乾重亦提高。苗期之銨態氮比例至少要大於50%，才會使移植後植株較早抽莖與株高較高。 自子葉完全展開開始每週施用1次含0-2.5 (夏季)或0-2.0 (冬季) mM磷(P)之強生氏養液。養液P濃度自0提高至1.0 mM使全株淨光合作用速率增加，但再提高至2.0 mM則光合作用速率會下降。以0 mM P處理者葉片Fv/Fm值最低，其他濃度處理間無顯著差異。根活性亦以2 mM P處理者最低。總葉片數、葉面積和總乾重隨養液P濃度自0提高至0.5-1.0 mM而提高，再提高至2.0-2.5 mM會下降或無顯著增加。植體P濃度隨養液P濃度增加而增加，而植體N、K、Ca、Mg濃度則隨養液P濃度自0提高至0.125-0.25 mM略微增加。苗期施0-0.25 mM P者，移植後會較晚開花，且有部分植株苗期以0 mM P處理者於夏季移植後簇生化，而苗期以0.5-2.5 mM P處理者對移植後開花表現無顯著差異。 自子葉完全展開開始每週施用1次含0-10 mM 鉀(K)之強生氏養液，對植株的全株淨光合作用速率與Fv/Fm值皆無顯著影響。隨養液K濃度提高植體K濃度亦提高。夏季試驗中，隨苗期K濃度由0 mM增至4 mM，‘克萊利粉’葉面積與乾重隨之增加，再提高至10 mM K則不再增加生長，而苗期K濃度對‘凜白’和‘禮儀彩藍’的生長並無顯著影響；冬季試驗中，‘克萊利粉’與‘禮儀彩藍’葉面積與乾重以0-4 mM K處理者較高，隨養液K濃度由6提高至10 mM而減少，養液K濃度對‘凜白’的生長無顯著影響。而苗期K濃度對移植後的開花表現影響並不顯著。 綜合以上試驗結果，參試3品種洋桔梗穴盤苗，自子葉展開至第3對葉展開期間，建議每週施1次含24-28 mM N，且NH4-N的比例應大於50%，及0.5-1.0 mM P和4-6 mM K之強生氏養液。

Lisianthus [Eustoma grandiflorum (Raf.) Shinn.] is an important cut flower for export trade in Taiwan. Market demand has been increasing with increasing planting area and production. However, nutrition management during plug production for Eustoma has not been well established. This study aimed to determine the effects of nitrogen (N), phosphorus (P), and potassium (K) concentration, and nitrogen form of nutrient solution during plug production on seedling growth at 25/20oC and subsequent plant growth and flowering performance of Eustoma ‘Claris Pink’, ‘Rin’, and ‘Ceremony Blue Flash’ grown in summer and winter. Johnson’s solution containing 4-24 and 4-36 mM N were weekly applied from cotyledon fully expanded to the third leaf pair stage during summer and winter, respectively. Seedlings fertilized with 16-20 mM N took shorter time from treatment to the first, second, and third leaf pairs expanded. Seedlings received 24-36 mM N did not exhibit faster growth, while those fertilized with 4-12 mM N grow slower. Whole plant net photosynthesis rate (Pn), increased with increasing N concentretion from 4 to 20-24 mM, and further increased N at 28-36 mM did not increase Pn. Seedlings fertilized with 4-8 mM N had significant lower Pn. Leaf Fv/Fm value increased from 0.67-0.76 to 0.80-0.82 when N concentration increased from 4 to 16-20 mM. Leaf area, whole plant, shoot, and root dry weight increased with increasing N concentration from 4 to 20-24 mM. Tissue N concentration increased with increasing solution N concentration. Tissue P, K, calcium (Ca), and magnesium (Mg) concentration decreased with increasing solution N concentration from 4 to 12 mM, but tissue P, K, Ca, and Mg did not decrease with higher solution N concentration (16-36 mM). After transplanting, plnats took longer time to bolt and flower when seedlings received 4-8 mM N, as compared with other treatments. Time to flowering and harvest was earlier when seedlings fertilized with 20-28 mM N. Seedlings were fertilized weekly with Johnson’s solution containing 20 mM N in 0:100, 25:75, 50:50, 75:25, and 100:0 of NH4+ to NO3－ ratio. Medium EC increased and pH decreased with increasing NH4+ ratio. Pn, root activity, leaf area, and whole plant, shoot, and root dw increased with increasing NH4+ ratio. After transplanting, plants bolted earlier and had longer stem when seedlings fertilized with 50% or higher NH4+ as N source. Seedlings were fertilized weekly with Johnson’s solution containing 0-2.5 and 0-2.0 mM P during summer and winter, respectively. Pn increased when P concentration increased from 0 to 1.0 mM, but decreased when P concentration increased to 2 mM. Leaf Fv/Fm value (0.8) did not differ between treatments, while those fertilized with 0 mM P, had the lowest Fv/Fm value. Seedlings fertilized with 2 mM P had the lowest root activity. Total leaf number, leaf area, and dry weight increased when P concentration increased from 0 to 1.0 mM, but decreased when P concentration increased to 2.0-2.5 mM. Tissue P concentration increased with increasing solution P concentration. Tissue N, K, Ca, and Mg concentration slightly increased when solution P concentration increased from 0 to 0.125-0.25 mM, but did not change significantly with further increases in P concentration. Plants took longer to flower when seedlings were fertilized with 0-0.25 mM P and some plants rosetted in summer when plug seedlings were fertilized without P. Flowering performance was not affected in plants when fertilized with 0.5-2.5 mM P during plug stage. Seedlings were fertilized weekly with Johnson’s solution containing 0-10 mM K during summer and winter, respectively. Solution K concentration did not affect Pn and leaf Fv/Fm value. Tissue K concentration increased with increasing solution K concentration. Plants leaf area and total dry weight in ‘Claris Pink’ increased with increasing K concentretion from 0 to 4 mM, and further increased K to 10 mM did not increase growth in summer. Solution K concentration did not affect growth of ‘Rin’ and ‘Ceremony Blue Flash’ grown in summer. ‘Claris Pink’ and ‘Ceremony Blue Flash’ had higher leaf area and total dry weight when received 0-4 mM K during plug stage in winter High K (8-10 mM) treatments during plug stage reduced leaf area and total dry weight in plants grown in winter. Solution K concentration during plug stage did not affect growth of ‘Rin’ in winter. Flowering performance was not affected in plants when fertilized with 0-10 mM K during plug stage. From the results as shown above, Eustoma seedlings of tested cultivars should be fertilized with Johnson’s solution containing 24-28 mM N with more than 50% NH4-N, 0.5-1.0 mM P, and 4-6 mM K weekly from cotyledon fully expanded to the third leaf pair expanded.