毛柿成為經濟果樹之評估

Evaluation of Diospyros philippensis (Desr.) Gurke as a Fruit Crop

洪聖峰(Sheng-Feng Hung)

指導教授 ： 陳右人

國立臺灣大學/生物資源暨農學院/園藝暨景觀學系/博士(2016年)

https://doi.org/10.6342/NTU201602568

摘要

毛柿Diospyros philippensis (Desr.) Gurke雌雄異株，心材烏黑堅硬，俗稱臺灣黑檀，也是良好的綠化樹種。臺灣南部墾丁地區的花期在4-5月，果熟期在8-9月，臺灣北部臺北市的植株則各晚約1-1.5個月；營養生長高峰在3及8月；後者生長量低於前者。依最小變異法，雌雄枝條及雌雄花的最適生長基溫及累積溫量分別為11℃, 830.1 degree-day、11℃, 660.0 degree-day、12℃, 942.6 degree-day及12℃, 883.3 degree-day；生存的最低溫限度可能在0-5℃之間。在1月份剪去結果母枝的頂芽，仍可能由側芽取代並立即開花，所以1月可能是其花芽形成的最晚期限。
毛柿嫁接後約3-4個月才穩定成活，嫁接最適期是3月，成活率可達84.2 ± 12.8％，6月份次之。接穗及砧木均影響成活率。以一年生枝條做為接穗，春梢枝條成活率優於秋梢枝條。3年生砧木優於6年生砧木，尤其是雄砧木顯著優於雌砧木，且雄砧木嫁接隔年就可開花結果。由於接穗皆為側枝，因此新生枝條均具有惰性生長現象。SNA處理接穗對毛柿嫁接成活呈反效果，接穗僅沾蒸餾水 (即SNA 0 μg∙mL-1) 也明顯使成活率下降，濃度到達5000 μg∙mL-1時成活率下降到0％，需更深入研究。嫁接初期土壤水分不宜過高，嫁接當日澆灌之成活率僅5.0％，嫁接前2-3日澆灌後斷水，嫁接1週後恢復灌溉，成活率可達75-80％，因此建議嫁接前2日至嫁接後5日不宜澆水。芽接法無論嫁接時期或有無使用SNA，皆無法成活，芽接法於毛柿之應用還需更多研究探討。
毛柿種子為熱帶異儲型，10℃低溫及失水均可造成活力下降。墾丁地區果實在8月中旬至9月上旬成熟掉落腐爛後，種子隨即發芽，不具休眠性。毛柿初生葉卵形至橢圓形呈對生狀，第1本葉以後之幼年葉披針形呈互生狀。大部分天然苗在初生葉或第1本葉展開後停止生長，並以此狀態渡冬，停滯時間可達5個月以上。小苗在墾丁 (南臺灣) 天然林中生長極為緩慢，一年生植株平均株高16.7 ± 3.1公分，葉片 (不含子葉) 5.0 ± 1.8片，存活率46.6％；二年生植株平均株高19.8 ± 4.8公分，葉片 (不含子葉) 9.2 ± 5.1片，存活率38.6％。人工環境下種子發芽率高達92.5％，生長停滯期可大幅縮減，一年平均株高22.8 ± 4.9公分，葉片 (不含子葉) 9.5 ± 2.3片，存活率98.2％；二年平均株高46.2 ± 10.4公分，葉片 (不含子葉) 28.5 ± 5.6片，存活率88.8％。水分及光照是加速苗期生長最重要因子，介質及肥料施用影響則較小。適宜的人工條件下栽培可大幅縮短毛柿育苗期，播種後1.5年即可供應嫁接砧木苗。
採集或觀察毛柿訪花生物，考慮訪花頻率、訪花狀態、生物特性及花粉攜帶狀況，總結6個重點：1. 除了薊馬與螞蟻，沒有其他訪花者的訪花頻率足以成為毛柿主要傳粉者。2. 傳粉距離及水系隔絕說明螞蟻不可能是毛柿的主要傳粉昆蟲。3. 除了黃胸薊馬之外，花內沒有觀察到別種薊馬。4. 毛柿雄花提供隱密場所及大量花粉做為食物，每朵雄花都有眾多黃胸薊馬生活其內，包括生活史中的卵期、幼蟲期及成年期。5. 毛柿雌花未開放即可有黃胸薊馬鑽入，開放後也普遍觀察到黃胸薊馬訪花。6. 無論在雌雄花採集的黃胸薊馬，均在其身上觀察到毛柿花粉的記錄，其它訪花者則不全然。這6點說明了黃胸薊馬可能是毛柿主要傳粉昆蟲。
毛柿花粉在蔗糖溶液中培養，0.5小時內即可發芽 (10％及15％)，發芽率可達84.0 % (10％, 2小時)；花粉管伸長速率最快達760 μm∙hr-1 (5％, 2小時)，以此估算授粉至花粉管到達花柱底部最快可能需13.2小時。螢光顯微觀察則顯示花粉管1日內即可到達胚珠內，並以開花當日及開花後1日為最佳授粉時機。
毛柿果具濃郁香氣，是目前市售柿子所缺乏，共分析出39種香氣成分。營養價值高，尤其膳食纖維達3.2％，蘋果酸達227.1 mg∙100 g-1，鈣及鋅含量各達42.8及3.6 mg∙100 g-1，亦含維生素B2、B3、葉酸、泛酸及氯化膽鹼等營養成分。
大果選株的果實可達300 g以上，平均為218.0 ± 66.2 g，扣除種子後果肉平均為193.0 ± 58.5 g，與族群全果平均103.9 ± 34.0 g及扣除種子後果肉平均78.6 ± 29.1 g比較，差異顯著。毛柿果與柿子一樣具單偽結果能力，也可以人為操作得到無子果實，大果選株單偽結果的無子果實平均達122.6 ± 24.7 g，亦可用植物生長調節劑誘導果實增大。

關鍵字

毛柿果 (菲律賓名) ； 毛柿 (學名) ； 生長溫量 ； 民族植物 ； 花粉管 ； 黃胸薊馬 ； 傳粉者 ； 植物繁殖 ； 新興果樹

並列摘要

Diospyros philippensis (Desr.) Gurke is dioecious plants, provides high-quality wood and is also a good greening tree species. In Kenting, southernTaiwan, the phonological observation shows that the florescence is in April and May, the fruit ripening stage is in August and September. In Taipei, northernTaiwan, each of two phenophase would delay about 1-1.5 months. There are two peaks of vegetative growth in annual cycle, in March, and in August. Following least variability method, the optimum base temperature and thermal-time of growth of female shoots, male shoots, female flowers and male flowers are 11℃, 830.1 degree-day; 11℃, 660.0 degree-day; 12℃, 942.6 degree-day and 12℃, 883.3 degree-day, respectively; and the minimum survival temperature around 0-5℃. We have to confirm the flower bud differentiation stage through sliced organization. But, shoot-tip cutting of the terminal bud of bearing base branch at the latest in January, the lateral bud can substitute the terminal bud and blossom immediately, it means that the latest time of flower bud formation is probably in January.
About grafting, it takes 3 to 4 months to attain stable survival rate; the highest survival rate of cleft grafting is in March (84.2 ± 12.8%), and the second highest survival rate is in June. Survival rate are different among scion (and stock) collected from different sources. For grafting, annual spring-shoots scions are better than annual autumn-shoots; 3-year-old rootstocks are better than 6-year-old rootstocks, and the male stocks are better than female stocks. Furthermore, scions on male stocks have got flowering and fruiting next year since grafting, on the contrary, scions on female stocks haven’t. All the survival grafting plants are topophysis, because of using lateral-shoot-scion. Scions treating by SNA lowered survival rates, high concentration (5000 μg∙mL-1) resulted in a total failure of the graft, even dipping scions in distilled water (0 μg∙mL-1) prior to grafting also reduced the survival rate, it needs further study. Rootstock without irrigation from 2-3 days before grafting and re-watering the grafted trees a week after grafting increased survival rate up to 75-80％; watering on the grafting day was only 5.0％ survival rate . Therefore, we recommend a moderate irrigation 2 days before grafting and 5 days after grafting. Chip budding for D. philippensis need futher study.
Diospyros philippensis seed is tropical recalcitrant type, both 10℃ and dehydration can decrease vitality. Diospyros philippensis fruits, mabolo, in Kenting, southern Taiwan, mature and fall from the trees during mid August and early September, and the non-dormancy seeds germinate as soon as fruits decayed. The shape of two primary leaves are opposite and ovoid to elliptic, and the true juvenile leaves are alternate and lanceolate. Most of natural seedlings stop growing while they have 2-3 leaves, and persist through the following winter. This stage of rest condition of seedling may take more than 5 months. Diospyros philippensis seedlings in natural forest showed a very low growth rate. The average height of 1-year-old seedlings is 16.7 ± 3.1 cm, and the average leaves number is 5.0 ± 1.8. Seedlings of 1 year after sowing were 46.6% survived. Average height of 2-year-old seedlings is 19.8 ± 4.8 cm, and the average leaves number is 9.2 ± 5.1. Seedlings of 2 years after sowing were 38.6% survived. Under artificial facility, the seed germination rate was up to 92.5%, and the resting stage was also shorter. The average height of 1-year-old seedlings under artificial facility is 22.8 ± 4.9 cm, and the average leaves number is 9.5 ± 2.3. Seedlings of 1 year after sowing were 98.2% survived. Average height of 2-year-old seedlings is 46.2 ± 10.4 cm, and the average leaves number is 28.5 ± 5.6. Seedlings of 2 years after sowing were 88.8% survived. Soil water and light intensity were the most important factors for seedling growth, while medium and fertilization were less important. The suitable conditions are necessary for speeding growth rate up. Under good control, we can provide mabolo seedlings for rootstock-use in 1.5 years.
We sum up 6 emphases by observing flower visitor’s characteristics of D. philippensis including visiting frequency, foraging status, biological nature and pollen carried status as follows. First, except for thrips and ants, no other flower visitors with enough visiting frequency are considered as major D. philippensis pollinators. Next, pollination distance and water barrier indicate that ants are most unlikely major D. philippensis pollinators. Third, except for Thrips hawaiiensis, other species of thrips are not observed. Fourth, the male flower provides intimate spaces and a large number of pollen as food, and every male flower was occupied by the numerous thrips either as egg, larva or adulthood. Fifth, the thrip visits the female flower which is either in blooming or not in blooming. Finally, the pollen is found with the thrip not other visitors after visiting male and female flower. We can conclude that the T. hawaiiensis is the probably main pollinator for D. philippensis.
The pollens of D. philippensis can germinate in 0.5 hours when cultured in vitro in sucrose solution (10％ and 15％), and the highest germination rate is 84 % (10％, 2hrs); the pollen tubes growth speed is up to 760 μm∙hr-1 (5％, 2hrs), it requires about 13.2 hours from pollination to the pollen tube reaching stigma bass. The observation result of fluorescence microscopes shows that the pollen tube can reach the ovule in 1 day, and the best pollination time includes the flowering day and the next day.
Mabolo riches in aroma, a total of 39 fragrance ingredients were found. It is also rich in nutrition, particularly in dietary fiber 3.2%, malic acid up to 227.1 mg∙100 g-1, calcium and zinc up to 42.8 and 3.6 mg∙100 g-1, and also contains Vitamin B group including VitB2, VitB3, folic acid, pantothenic acid and choline chloride.
The biggest intact fruit of selections weighs up to more than 300 g with an average of 218.0 ± 66.2 g; after deducting the weight of its seeds, an average flesh weight is 193.0 ± 58.5 g. The intact fruit of the population weighs an average of 103.9 ± 34.0 g; after deducting the weight of seeds, an average flesh weight is 78.6 ± 29.1 g. Mabolo is the same as persimmon with parthenocarpy; and seedless fruits can be obtained by artificial manipulation. Parthenocarpic seedless fruits weighs an average of 122.6 ± 24.7 g, and the plant growth regulator can help enlarge the fruit.

並列關鍵字

mabolo ； Diospyros philippensis (Desr.) Gurke ； thermal-time ； ethnobotany ； pollen tube ； Thrips hawaiiensis (Morgan) ； pollinator ； plant propagation ； novel fruit

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