溫度對岩桐屬生長之影響及雜交後裔性狀表現

Abstract

岩桐屬(Sinningia)植物具多樣化的花形與花色，適宜栽培於居家環境，故廣受歡迎；然目前有關岩桐原生種植物之育種或栽培研究不多，因此本研究探討原生種岩桐花粉對溫度之反應及授粉適期，並調查雜交後代之性狀表現，以供雜交育種之應用；另探討原生種對溫度的生長反應，以瞭解植株適合栽培溫度與耐熱性。 取斷崖女王[Sinningia leucotricha (Hoehne) H.E. Moore]、艷桐草[Sinningia cardinalis (Lehm.) H.E. Moore]、美花岩桐(Sinningia eumorpha H.E. Moore)、香岩桐[Sinningia conspicua (Seem.) Nicholson]、Sinningia aggregata (Ker Gawl.) Wiehler及超迷岩普希拉[Sinningia pusilla (Mart.) Baill]之花粉，於25 oC水浴槽中以不同蔗糖濃度之BK培養基培養2小時，結果以含5%至15%蔗糖濃度的BK培養基處理之花粉發芽率較高。將原生種花粉以5至45 oC的水浴溫度培養，結果以S. aggregata花粉發芽適溫為原生種中最高，達30 oC，而美花岩桐最低，約25 oC。 香岩桐、白花香岩桐、美花岩桐及斷崖女王四種原生種最適栽培的日夜溫度為25/20及30/25oC，其地上部乾重較重、塊莖較大，且淨光合作用亦較高。而15/13及20/15 oC的涼溫促進香岩桐及白花香岩桐的光合產物累積於塊莖，而非地上部。參試原生種岩桐的葉圓片經25至65 oC水浴溫度處理30分鐘後，結果顯示相對熱傷害值(relative injury, RI)與水浴溫度呈S形曲線關係。且栽培溫度提高則致此S曲線向右偏移，顯示岩桐植株可被熱馴化，且高溫栽培可提高植株對熱的耐受性。 各日/夜溫下生長之原生種葉圓片以47及50 oC水浴30分鐘，可知香岩桐及美花岩桐經47 oC水浴後，栽培溫度較高者之RI值分別為15.5%及28.3%，而50 oC水浴則已造成細胞膜損壞，離子滲漏率及RI值皆較高。然白花香岩桐及斷崖女王以47 oC水浴處理，葉片RI值均低，為9.5%至14.4%及3.8%至10.7%，而在50 oC水浴處理下，提高生長溫度仍可明顯降低該RI值。 岩桐花粉培養適溫與RI值具相關性，花粉培養適溫較低的美花岩桐及香岩桐之葉片經50 oC水浴處理已顯著提升滲漏率，而花粉培養適溫較高的斷崖女王葉片不論經47或50 oC水浴處理，RI值均低。 岩桐為雄蕊先熟之植物，然不同原生種成熟時期相異，香岩桐與艷桐草分別於開花後一天及開花前一天花藥始開裂。隨開花天數增加，艷桐草花粉發芽率顯著下降。於開花後不同天數的艷桐草行自交授粉，以開花後一、二日為最適授粉時期，處理之果莢數較多且較大、種子數較多、結種率高。由苯胺藍染色觀察花粉管生長情形亦可知，於授粉適期行自交授粉，花柱內被苯胺藍染色之花粉管較多。 艷桐草、美花岩桐、香岩桐及S. aggregata等四種原生種岩桐行自交授粉，後代族群間之株形、花形及花色等性狀無明顯差別，且與親本相似。種間雜交授粉所得F1後代的性狀表現，介於兩親本之間。調查艷桐草為種子親，斷崖女王為花粉親的後代，及美花岩桐與香岩桐正反交之後代，顯示後代族群間的株形、花形、花色等重要性狀皆無明顯差異；然以香岩桐為種子親，斷崖女王為花粉親的後代表現，則有花色表現多變之情形，此現象可能與參與花朵呈色之物質有關。

Sinningia native species have a wide range of flower colors, shapes, and sizes. They are important ornamental plants due to their tolerance of low light and warm temperature encountered under sub-tropical interior conditions. The objectives of this study were 1) to determine the effects of temperature on pollen germination, 2) the duration of flower receptivity, 3) the characteristics of selfed or cross progenies, and 4) the effects of different day/night temperatures on plant growth, photosynthesis rate, and cell membrane thermostability of Sinningia native species. Pollens of six Sinningia native species were used, including S. leucotricha (Hoehne) H.E. Moore, S. cardinalis (Lehm.) H.E. Moore, S. eumorpha H.E. Moore, S. conspicua (Seem.) Nicholson, S. aggregata (Ker Gawl.) Wiehler, and S. pusilla (Mart.) Baill. The pollens were cultured at 25 oC in the deionized water or BK medium containing various sucrose concentrations ranging from 0% to 20%, and the pollen germination was measured after 2 h incubation. The medium consisted 5% to 15 % sucrose, especially 10% sucrose, which was suitable for each native species. The effect of temperature on pollen germination was conducted from 5 to 45 oC at 5 oC intervals. The optimum temperature (Topt) of pollen germination differed significantly among species. S. aggregata exhibited the highest Topt of 30 oC, while S. eumorpha had the lowest Topt of 25 oC. More growth and higher net photosynthesis were measured at growing temperature of 25/20 or 30/25 oC for S. conspicua, S. tubiflora, S. eumorpha, and S. leucotricha. Low temperatures (15/13 oC and 20/15 oC) increased assimilate partitioning to tubers in S. conspicua and S. tubiflora. The relationship between the relative injury (RI) value occurring in leaf tissue discs of four Sinningia native species and water bath temperature was sigmoidal. Higher cultural temperatures decreased leaf RI values, exhibiting heat-acclimation of four species. S. conspicua and S. eumorpha had higher, but S. tubiflora and S. leucotricha had lower, RI values at 50 oC. Water bath temperature of 50 oC for 30 min had already damaged the membrane of leaf discs in S. conspicua and S. eumorpha. The optiumal temperature for pollen germination was higher in S. leucotricha than S. eumorpha and S. conspicua. Both leaf electrolyte leakage and relative injury at 50oC water bath treatment were lower in S. leucotricha than S. eumorpha and S. conspicua. In Sinningia, the anthers matured several days before stigma receptive. Anther dehiscence occurred on day 2 after anthesis in S. conspicua, while on day 1 befoe anthesis in S. cardinalis. Flower age at pollination had significant effects on both capsule width and seed number per capsule. Self pollination 1 and 2 days after anthesis (DAA) resulted in bigger capsules and more seeds. Pollen tubes were observed in styles by aniline blue staining on 1 and 2 DAA. Native species and S1 progenies of S. cardinalis, S. eumorpha, S. conspicua, and S. aggregata exhibited similar appearance and morphology. Characteristics of F1 hybrids from S. cardinalis ×S. leucotricha, S. eumorpha ×S. leucotricha, and S. cardinalis ×S. eumorpha were uniform; F1 progencies from the reciprocal crossing between S. eumopha and S. conspicua exhibited similar plant type, flower type, and color. Flower color and shape of the F1 was intermediate between the parents. However, the corolla colors varied in F1 hybrid population of S. conspicua ×S. leucotricha, but all flower color density of progenies was between two parents.