A tree of Japanese persimmon
Japanese persimmon is considered as the national fruit of Japan. It was, however, introduced in India by the European settlers somewhere in 1921. At present it is being grown on a limited scale in Jammu and Kashmir, Himachal Pradesh, hilly areas of Uttar Pradesh and parts of eastern India. No organized cultivation of this fruit has yet been undertaken in India but with the diversification in fruit culture, its cultivation is gaining importance and more areas are being opened for its cultivation.
Japanese persimmon fruits on tree
There are several problems which have limited the commercial cultivation of persimmon. While there is limited but loyal public buying persimmon, there are those who have tried the fruit for the first time and found it hard, astringent and puckery. Also, the growers have panted small acreages of numerous cultivars, which are not suited for marketing. The growers also face the problem of poor setting or heavy dropping or young fruits due to inadequate cultural knowledge resulting in poor returns. The growers or consumers also do not have sufficient knowledge regarding the fruit maturity, i.e. when to harvest and consume the fruit. If the above difficulties could be overcome, growing demand for this fruit undoubtedly could be fulfilled.
Climate and soil
Persimmon can be grown in a wide range of subtropical and warm temperate climate. The trees are deciduous and enter a rest period and complete their dormancy in the middle of February in India. Temperature 8-11C for about 850 hors is enough to complete dormancy. The trees, when dormant, can tolerate fairly low minimum temperature with some cultivar surviving temperature as low as -15 C. However, freezing damage may occur in some seasons with alternating warm-cold cycles. Non-astringent cultivars require warmer conditions for fruit maturation than the astringent types. The best fruit quality in the non-astringent cultivars is between 16 and 22 C and the amount of sunshine recorded during the growing season exceeds 1,400hr.
During the maturation period, temperature is the most important factor for obtaining quality fruits. If non-astringent cultivars are grown under cooler condition, the fruits may not loose their astringency completely by the time they reach maturity, fail to mature properly and have low sugar content. The percentage of reducing sugars decreases at high temperature and increase at lower one. Fruit production tin the warmer area has better color and sweetness. In general, non-astringent varieties are more suitable for warmer areas and astringent varieties for cooler areas. The main sugars present in the flesh of mature fruit are fructose and glucose, the total amount being more than 90% of the total sugars. At the harvest, a minimum Brix between 14 and 16 is required.
Foliage of Japanese persimmon
Although persimmon can grow on a wide range of soils, it performs best on well-drained, lighter soils, which have good subsoil containing some clay. Yield is reduced on heavy alluvial soils due to increased fruit drop. The soil pH for optimum growth is 6.0-6.8.
The Japanese persimmon has at least 1,000 varieties which show wide variations in size, shape and color. These are broadly classified into two major groups—non-astringent and astringent. Both the groups have been divided into two sub-groups, based on their response to pollination—(PVNA), Astringent and pollination constant (PCNA). Non-astringent and pollination constant (PCNA), non-astringent and pollination variant (PVNA), astringent and pollination constant (PCA) and Astringent and pollination variant (PVA) varieties. Non-astringent varieties are consumed fresh but astringent varieties are edible only after removal of tannin-based astringency or as dried fruits.
Japanese persimmon fruits
Astringency can also be removing by various chemical treatments. In pollination variant, non-astringent types, the soluble tannins disappear after pollination if enough seeds (usually4-5) are formed. However, if only one or two seeds are formed, some parts of the fruit remain astringent. In pollination constant, non-astringent types, fruit is edible when the flesh is firm but mature, regardless of whether or no pollination has occurred.
Not all the Oriental persimmons are astringent when firm. Cultivars which have dark colored flesh are usually sweet and non-astringent, and may be eaten before they become soft. Most of the persimmon cultivars have originated in Japan. Breeding and selection from within seedling populations have also occurred in Australia, New-Zealand and Brazil. Over 40 non-astringent cultivars or selections are now being evaluated in various countries. Only one non-astringent cultivar, Fuyu, is grown in subtropical climate. This has reddish, flesh flattened, sweet and mellow and does not attain the size of Hachiya. Several strains of Fuyu exist which show differences in fruit shape and size and tree growth characteristics. Other non-astringent cultivars or persimmon grown in different parts of the world are Izu, Maekawa Jiro, Ichikikei Jiro, Matsumoto Wase Fuyu, Hana Fuyu, Suruga, Fuyu Hana and 20th century.
A flower of Japanese persimmon
In Japan, most popular non-astringent cultivars grown are Fuyu and Jiro covering about 50% of the area. In Italy, Fuyu, Suruga, O Gosho, Hana Fuyu, Jiro and Kawabata are most promising non-astringent cultivars. In Florida, most important non-astringent cultivars are Ichikikeri Jiro, Fuyu and Jiro. In California, most promising cultivars are Fuyu, Hana Fuyu, and Twenteeth Century.
Hachya is astringent cultivar grown in India. This is leading commercial cultivars of California. It is usually seedless but may also contain one or two seeds. Deep orange-red; flesh deep yellow, astringent until soft, rich and sweet when ripe. The fruits ripen as well off the tree as on the tree. In Australia, the most popular astringent cultivars grown are Nightingale and Flat Seedless. Triumph is the most important astringent cultivar grown in Isreal. Fruits of this cultivar are treated with carbon dioxide at maturity to remove astringency. The most promising astringent cultivars grown in Florida are Giombo, Tanenashi, Eurella and Sheng. In Italy, most promising astringent cultivars are Hiratanenashi, Aizumishirazu, Amankaki, Kakitipo. The most important astringent cultivar of persimmon in Japan is Hiratanenashi. In Himachal Pradesh, the important varieties grown are Fuyu, Jiro, Hachiya and Hyakuma.
Propagation and rootstock
Propagation is done by grafting the scion on seedling rootstocks, using the whip-graft for smaller diameter stocks and the cleft and veneer grafting on the larger stock. It is better to replant with young stock rather than top-work old trees. In India, Diospyros lotus is used as the rootstock. The fruits of D. lotus ripen during late-October. On ripening, the fruits become soft and should be pulped and fermented for about a week. After all the flesh is fermented from the seed, the seeds are washed thoroughly and the floaters are discarded. Improved germination of D.kaki, D.lotus and D. virginiana seeds has been reported after stratification for 60-90days. In Australia, seed germination of D. kalvi has been reported to be high when extracted from soft but non-decomposed fruit and planted immediately and no stratification is necessary. The best seed germination is obtained at 28`C. The seeds at this temperature take about 2-3 weeks to germinate. Young seedlings usually take a year to be of a suitable size for grafting.
Scion cultivars can either be grafted or budded with as success rate of 80%. Veneer grafting is generally more successful than budding and should be carried out in September with the start of sap movement. Tongue grafting is also done with a success rate of 60-65%. Green grafting in summer has also been successful in New Zealand. Timing of vegetative propagation varies wit location and climate. T-budding is suitable, provided the buds are taken from mature wood. Budding may be carried out in spring or early-autumn.
Three rootstock species have been used for propagation of Japanese persimmon. These are D. kaki, D. lotus and D. virginiana. There appear to be some incompatibility problems between D. lotuses also appear more susceptible to crown gall. The D. virginiana is used as rootstock for Japanese persimmon in Israel and USA. It is particularly well adapted to damp heavy soils and very cold hardy conditions. However, D. virginiana often suckers badly and trees on this rootstock are not always uniform in size and vigour. It is also highly susceptible to cephalosporium wilt. For these reasons, D. kaki is preferred to D. lotus and D. Virginiana as rootstock for persimmon. In Japan, Saijo produces very uniform seedlings and is extensively used as rootstock.
In India, winter planting during January-February is recommended when trees are dormant. Planting after bud break generally result in poor survival. The trees are transplanted at a distance 5.5-6.0m. The pits of 1m x1m x 1m are dug. Well-rotten farmyard manure is mixed while filling the pits in the same manner used for other deciduous trees. At the time of planting, the bud union should be kept straight. The young plants should be protected from frost by providing shelter such as thatching of dry grass.
The planting density for persimmon depends on cultivar, rootstock and soil type. Dwarfing cultivars (Ichikei Jiro) can be closely planted at 5m X 2.5m (800 trees/ha), semi-dwarf cultivars Fuyu at 5m x 3m (660trees/ha) and vigorous cultivars at 6m x 4.5 m (370 trees/ha).
Training and pruning
The trees should be trained to form a low head. To achieve this, the plants are headed back at 60cm from the ground at the time of planting to develop a framework of strong branches. Cultivars differ markedly in vigour and growth habit. Some cultivars are dwarf and highly precocious, whereas others are vigorous, upright and late producers. The dwarf cultivars are best trained to a modified central leader system. The more vigorous, upright, narrow crotch angle types should be trained to a vase or palmette system. The pruning is done during winter when the trees are dormant in January. Since flowers of D. kaki are borne on current season’s wood, heavy pruning reduces crop setting by forcing excessive vegetative growth. Summer pruning of mature trees may thicken laterals and increase fruit size and color. With more vigorous and less precocious cultivars, techniques such as cincturing and limb spreading may be beneficial to achieve higher and earlier fruit production. In case of grown-up trees, practically no pruning is done except for removing weak, interfering, discarded or insect damaged shoots and branches.
Manuring and fertilization
Persimmon does not require high fertilizer doses. However, relatively high amount of K and rather low amount of P are required. A large amount of K is transferred to the fruit during its growth; and if K supply is low, fruit growth is reduced. On the other hand, excessively high K content leads to rough skin and lower fruit quality. Rates of fertilizes need to be adjusted according to cultivar, crop load and leaf nutrient levels. Young tees up to three years of age require an application of complete fertilizer (11:4:15) before bud –break and 3-4 lighter follow-up applications of urea at monthly intervals at the peak growing period. Once trees begin cropping, and application of complete fertilizer is applied 4-6 weeks before harvesting. Leaf nutrient levels and sampling procedures for persimmons have also been established. In Japan, leaf samples of persimmon are collected about two months prior to harvest. The youngest fully expended leaves are selected from non-fruiting laterals. Leaf nutrient concentrations for the non-astringent cultivar, Fuyu, are presented in Table1.
Table1. Nutrient concentration in leaf tissue of Fuyu
Magnesium deficiency causes leaf tissues between veins to become gradually pale and change to yellow, and leaf drop ensure. In order to prevent Mg deficiency (soil having a strong acidic reaction), Ca should be added; foliar strays of 2-3% MgSO4 are also very effective. As a consequence of Mn deficiency, leaves show abnormal patterns, assume yellow color and drop early. Foliar stray of MnSO4 (0.3-0.5%) with addition of Ca is very effective.
Many cultivars are susceptible to fruit drop and calyx cavity if N levels are too high when fruits are sizing. Nitrogen levels should be reduced if these problems are evident.
After planting, young need a continuous care for their survival. The plants need staking to keep them in a straight position which helps in selecting the well-spaced laterals in the coming growing season. Watering at 7-10 days interval is essential. The plant basins are kept free of weeds. During hot summers, when the evapotranspiration rate is high, the plants require mulching with dry grass/dry leaves Mulching needs to be done in the first week of March. During pre-bearing stage, more emphases is required to be given on training, since the pruning requirements of the tree are very low compared to other deciduous fruits. No growth on scion or below the graft union should be encouraged.
Irrigation is considered essential for the successful production of persimmon. Dry periods during fruit growth reduce the size, quality and number of fruits carried to maturity. The early summer period is most important in determining the yield and quality of fruits. High levels of soil moisture are required for better leaf growth and flowering. Moisture deficiency during early summer may increase fruit drop.
The maximum water use by the plant is in mid-summer due to high evaporation. The irrigation is very essential during dry summers to maintain uniform soil moisture.
The water requirements of plants start decreasing during fruit maturity, although good soil water status is still necessary. Moisture stress during this period can cause premature leaf drop, reduction in sugar levels in maturing fruits and increasing susceptibility to sunburn. Line cracking of fruits may also develop due to water stress at this sage. Irrigation on a regular schedule should be applied to maintain uniform levels of moisture in the soil.
Persimmon like other deciduous plants sheds its leaves during winter and enters in dormancy period. Creation of water stress to achieve dormancy is not necessary. Once the harvesting is over, irrigation can be reduced. Before the trees enter into dormancy, irrigation is essential to keep trees healthy during dormancy period. The young plants at the time of planting require watering at 8-10 days intervals.
Harvesting and postharvest management
Persimmon fruits are harvested when they have attained yellow to reddish color but are still firm. The fruits are clipped from the tree which shears leaving the calyx attached to the fruit together with a short stem. More care is needed to avoid bruising. Persimmon fruits mature in mid-September, although the period of maturity varies among the different varieties. If fruits are harvested too early, they develop poor color,sweetness and flavour. Fruits after harvesting should be wrapped individually in paper and packed in a single layer crate. Persimmons soften at room temperature. Ripe persimmons are delicious. Flesh is sweet and jelly like. As persimmons are delicate, it is essential to minimize handling as much as possible. Brix level at maturity in different varieties varies between 14`and 17`C.
The persimmon trees start bearing 4-5 years after planting. However, dwarf and semi-dwarf cultivars start bearing 2-3 years after planting. Mature trees of fuyu are capable of producing 50kg fruit/ plant. Jiro cultivar has recorded over 80 kg plant, whereas in the Hachiya, the yield is over 100kg/plant. The decrease in astringency during growth and maturation of astringent cultivars and disappearance of astringency from non-astringent varieties are most striking. This reflects in the tannin content of fruits. Various methods have been suggested to remove the astringency from the astringent cultivars, however, most of these results in partial softening of fruits. Treatment of the fruit with carbon dioxide has been the most successfully developed technique till date. Dipping of fruits in 500 ppm Ethephon solution for two minutes helps in removing the astringency in cultivar Hachiya and the fruits are ready for consumption within 2-3 days of storage. The persimmons are also allowed to sweeten naturally after harvesting from the plants at room temperature, although they can be held in firm condition for 2-3 months at 30`-32`C and 85-90% relative humidity. Average freezing point of flesh is 28.2`C.
Persimmons are graded by size and quality. During grading and packing, handling should be kept minimum to avoid bruising. The most popular packages for persimmons are single layer trays commonly used for stone fruits.
So far, there is no specific market in India. Fruits are marketed to the local markets from where they are sent to distant markets. Fruits to be shipped should be well shaped, plump, smooth, highly colored with unbroken skin and with stem cap attached. The fruits should be displayed in a single layer at the sales counter, nested in a wrapping paper to avoid bruising.
Fruit drop is one of the most important physiological problems, which may be related to a number of causes including excessive fruit rot, lack of pollination, water stress, excessive nitrogen application and insect damage. The first wave of drop occurs in early-June just after petal fall and continues up to late July. Thereafter, no fruit drop occurs in most of the varieties. But in some varieties, late drop is also note which is not equivalent to preharvest drop of apples and seems to be a unique feature of persimmon. The late drop is affected by the nutrition conditions of trees. Ringing, blossom thinning, and nitrogenous fertilizer applications reduce fruit drop. Moreover, a high negative relation exists between leaf area per fruit and fruit drop. All fruit drop immediately after defoliation under ringed conditions. This shows that fruit drop in persimmon is closely related to the nutrient status of tree.
Calyx cavity can be a serious problem in persimmon. The symptoms of this disorder are a sparse space or cavity that occurs directly beneath the calyx of the fruit. This cavity becomes a habitat for mealy bugs and fungal growth.
Some cultivars are more susceptible than others. The incidence of calyx cavity appears to be less on trees which have heavier crop loads and where fruits have been pollinated. Control measures include the avoidance of excessive N and K fertilizers, especially in later spring/summer and close to harvest; thinning early in the season to enhance calyx growth and optimizing pollination to produce more than three seeds/ fruit. Sites with deep, fertile and poor-draining soils are likely to encourage this disorder as also areas with high autumn rainfall.