Evaluation of Diospyros philippensis (Desr.) Gurke as a Fruit Crop
Date Issued
2016
Date
2016
Author(s)
Hung, Sheng-Feng
Abstract
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.
Subjects
mabolo
Diospyros philippensis (Desr.) Gurke
thermal-time
ethnobotany
pollen tube
Thrips hawaiiensis (Morgan)
pollinator
plant propagation
novel fruit
Type
thesis
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