聖誕紅品種耐熱性評估與提升耐熱性之方法

Abstract

聖誕紅(Euphorbia pulcherrima Willd.)是臺灣產量第二大的盆花作物，在臺灣夏季栽培時易發生植株生長停滯、盲芽、停心及狹葉化等生理障礙。本研究目的為評估聖誕紅品種的耐熱性，並透過施用水楊酸(salicylic acid, SA)和氯化鈣(calcium chloride, CaCl2)藥劑及生長阻礙劑(plant growth retardant)等方式改善耐熱性。 品種耐熱性評估方面，利用葉綠素螢光、葉片溫度及細胞膜熱穩定性評估聖誕紅品種耐熱性，並根據隸屬度(membership function value, MFV)綜合上述各項評估指標，結果顯示‘美貝拉’(‘Marbella’)、‘彼得之星’( ‘Jacobson Peterstar’ )、‘聖誕玫瑰’( ‘Winter Rose’ )、‘四季桃喜’(‘Luv U Pink’ )、聖誕節’( ‘Noel’ )及 ‘紅寶石’(‘ Primero Glitter’ )等品種之平均隸屬度>64%，為較耐熱品種；‘倍利’(‘Pepride’)、‘桃莉’(‘Dulce Rosa’)、‘光輝’(‘Red Splender’)、‘黃金粉’(‘Monet Early Red’)、‘聖誕卡羅’(‘Christmas Carol’)及‘紅絲絨’(‘Red Velveteen’)之平均隸屬度介於64% 至 44% 之間，為中度耐熱品種；‘冰火’(‘Ice Punch’)、‘威望’(‘Prestige Early’)、‘旺德福’(‘Wonderful’)、‘檸檬雪’(‘Lemon Snow’)及‘聖誕情閃耀’(‘Red Glitter’)之平均隸屬度<44%，為較不耐熱的品種。 水楊酸和氯化鈣改善耐熱性方面，試驗以‘Winter Rose’、 ‘Noel ’ 、 ‘Ice Punch’扦插 6 週苗為材料，試驗共分為去離子水(對照組)、10 mM CaCl2、200 μM SA、400 μM SA、10 mM CaCl2 + 200 μΜ SA、10 mM CaCl2 + 400 μΜ SA等6種處理，SA和CaCl2藥劑可恢復‘Winter Rose’ 和‘Ice Punch’之Fv/Fm值至0.7以上，並降低三個品種聖誕紅之葉片相對傷害值(relative injury, RI)，‘Winter Rose’以400 μM SA + 10 mM CaCl2處理之RI值最低； ‘Noel’以200 μM SA + 10 mM CaCl2、400 μM SA + 10 mM CaCl2及10 mM CaCl2三種處理之RI值最低；‘Ice Punch’則是處理間無顯著差異。在植株生長表現方面，經藥劑處理可提高‘Winter Rose’ 和‘Ice Punch’之側芽萌發率和新葉數，對‘Noel’則無顯著影響。藥劑處理可提升三個品種聖誕紅之外觀等級，‘Winter Rose’以10 mM CaCl2、400 μM SA + 10 mM CaCl2最佳；‘Noel’各藥劑處理間無顯著差異；‘Ice Punch’則以200 μM SA + 10 mM CaCl2最佳。澆灌或噴施200 μM SA + 10 mM CaCl2均可降低‘Winter Rose’之RI值並提升Fv/Fm和Y(Ⅱ)值，兩種處理方式間無顯著差異。施用200 μM SA + 10 mM CaCl2可顯著降低‘Noel’ 高溫逆境後之丙二醛(malondialdehyde, MDA)含量，並提升過氧化氫酶(catalase, CAT)之活性，對超氧歧化酶(superoxide dismutase, SOD)則沒有顯著影響。總結來說，以外觀品質和葉片相對傷害值作為標準，各品種最佳之藥劑配方為：‘Winter Rose’為400 μM SA + 10 mM CaCl2；‘Noel ’為400 μM SA + 10 mM CaCl2 和200 μM SA + 10 mM CaCl2；‘Ice Punch’為200 μM SA + 10 mM CaCl2。 生長阻礙劑提升耐熱性方面，巴克素(paclobutrazol, PP-333) 23.5 mg·L-1或克美素(chlormequat, CCC) 1500 mg·L-1可增加‘Winter Rose’、‘Noel’、‘Ice Punch’之Y(Ⅱ)值和Fv/Fm值，並降低‘Ice Punch’之RI值。另分別於摘心後側芽長2、3、5 cm時澆灌23.5 mg·L-1 PP-333，結果顯示摘心後側芽長2 cm時施用PP-333之株高最低，葉長和葉寬最小，葉綠素計讀値亦較其他兩個處理低；於摘心後側芽長5 cm時施用PP-333除了降低株高，並兼具提升葉綠素計讀値以及葉長葉寬之效果。耐熱指標方面，摘心後各時期施用PP-333皆可減緩高溫處理後Fv/Fm和Y(Ⅱ)下降的幅度，並且降低RI值，各時期處理間則沒有顯著差異。負日夜溫差(difference in day and night temperature, DIF)(25/30℃)處理30天可降低‘Winter Rose’之株高，但對各項耐熱指標均無顯著影響，推測影響聖誕紅耐熱性之因子可能為生長阻礙劑之化學特性，其他矮化植物的方式對耐熱性不一定有顯著影響。 總結來說，本試驗耐熱性評估結果與桃園區農業改良場專家實際栽培經驗、吳(2015)之結果相似，表示以隸屬度綜合各項耐熱指標評估聖誕紅耐熱性應具有相當的參考價值。施用SA和CaCl2可提升聖誕紅各項耐熱生理指標，唯複合施用更能提升外觀等級，最適濃度依品種而異。施用PP-333可提升聖誕紅耐熱性，待摘心後側芽長5 cm施用可兼具降低株高和提升耐熱性之效果。

Poinsettia (Euphorbia pulcherrima Willd.) is the second most pot flower in Taiwan. Heat stress in summer could inhibit plant growth and result in abnormal leaf, which is the most severe problem that producer is facing. This research aims at evaluating heat tolerance in poinsettia cultivars and improving heat tolerance by applying salicylic acid (SA), calcium chloride (CaCl2), and plant growth retardant. Three heat tolerance index (leaf temperature, chlorophyll fluorescence and cell membrane thermostability) were integrated by membership function value (MFV). Results shows that ‘Marbella’, ‘Jacobson Peterstar’,‘Winter Rose’, ‘Luv U Pink’, ‘Noel’ and ‘Primero Glitter’ were heat tolerant cultivars, the MFV of which were more than 64% ; ‘Pepride’, ‘Dulce Rosa’, ‘Red Splender’, ‘Monet Early Red’, ‘Christmas Carol’ and ‘Red Velveteen’ were medium heat tolerant cultivars, the MFV of which were between 44% and 64%; ‘Ice Punch’, ‘Prestige Early’, ‘Wonderful’, ‘Lemon Snow’ and ‘Red Glitter’ were heat sensitive cultivars, the MFV of which were under 44%. ‘Winter Rose’, ‘Noel’ and ‘Ice Punch’ were sprayed on various concentrations of SA (0, 200, 400 μΜ) and CaCl2 (0, 10 mM). Fv/Fm values were higher (more than 0.7) and relative injury (RI) values were lower in ‘Winter Rose’ and ‘Ice Punch’ which were sprayed on SA, CaCl2. RI values were lowest by applying 400 μM SA + 10 mM CaCl2 for ‘Winter Rose’ , 200 μM SA + 10 mM CaCl2, 400 μM SA + 10 mM CaCl2 or 10 mM CaCl2 for ‘Noel’. For ‘Ice Punch’, all treatment could increase Fv/Fm values and reduce relative injury, and there was no significant difference among treatments. There were more lateral buds and young leaves of ‘Winter Rose’ and ‘Ice Punch’ sprayed on SA and CaCl2, but no effect on ‘Noel’ was found. Appearance quality was better of all cultivars sprayed on SA and CaCl2. Appearance quality was highest by applying 10 mM CaCl2、400 μM SA + 10 mM CaCl2 for ‘Winter Rose’, 200 μM SA + 10 mM CaCl2 for ‘Ice Punch’. No matter sprayed or drenched 200 μM SA + 10 mM CaCl2, RI value was lower and Fv/Fm value was higher of ‘Winter Rose’. The effects of spraying or drenching were similar, and there was no significant difference between two methods. MDA could be reduced by spraying 200 μM SA + 10 mM CaCl2, but there was no effect on increasing activity of superoxide dismutase (SOD) and catalase (CAT). Considering RI value and appearance quality as a standard, the optimal concentration of SA and CaCl2 was 400 μM SA +10 mM CaCl2 for‘Winter Rose’; 400 μM SA + 10 mM CaCl2 or 200 μM SA + 10 mM CaCl2 for‘Noel ’; 200 μM SA + 10 mM CaCl2 for ‘Ice Punch’. Drenched in 23.5 mg．L-1 or chlormequat (CCC) 1500 mg·L-1, there were higher Fv/Fm and Y(Ⅱ) values in 3 cultivars of poinsettia, and RI values was lower in ‘Ice Punch’. Fv/Fm and Y(Ⅱ) values were higher of ‘Noel’ and ‘Ice Punch’ drenched in PP-333. Treated PP-333 when lateral bud was 5 cm could reduced plant height and increased quality of appearance and heat tolerance. Plant height was lower of ‘Winter Rose’ with negative difference in day and night temperature treatment (-DIF, 25/30℃), but there was no significant effect on heat tolerant indexes with -DIF treatment. It was supposed that heat tolerance was affected by chemical compounds of plant growth retardants instead of other retardant method. In conclusion, results of evaluiation of heat tolerance was similar with previous studies including the field experience of specialists in Taoyuan district agricultural improvement station, COA, EY, and the results of 吳(2015). Therefore, leaf temperature, chlorophyll fluorescence and cell membrane thermostability may be a reliable way of evaluation of heat tolerance. Applying SA and CaCl2 could improve heat tolerance, and the optimal concentration varied from different cultivars. Treated PP-333 when lateral bud was 5 cm could not only reduce plant height but improve heat tolerance.