In this article we will discuss about the cultivation of temperate nuts.
After cashew-nut and peanut, walnut Juglans regia, (family Juglandaceae) is the next most important nut produced in India. The wood of the tree is used for carvings and for making butts of guns and cabinets of highest quality. The bark is used by women for cleaning their teeth and gums.
The walnut is called English or Persian walnut, but is native to the Western Himalayas. It requires a very cool climate and is grown mostly in Kashmir at 1,300 to 2,300 metres like the apple. Most of the walnut trees are scattered and there are very few regular plantations. Most of the trees are seedlings with hard nuts. A tree yields about 40 to 80 kg of nuts.
The other temperate nuts grown in India include the European chestnut (Castania sativa), which grows at 1600 to 2300 metres above sea level and the ornamental horse chestnut (Aesculus indica) both grown from seedlings and the Filbert or European hazel-nut (Corylus avellana) locally called ‘Bindak’ or ‘Bhotia badam’.
Wild forms of the latter are found growing in the Western Himalayas from 1,800 to 3,300 metres in partially-shaded gullies. The Turkish hazelnut (Corylus colurna) also grows wild in the Himalayas. Pecan nuts (Carya illinoensis) and macadamia nuts (Macadamia ternifolia) have been recently introduced.
Some other minor temperate fruits are also grown in India. One of these is strawberry. The cultivated strawberry (Fragaria ananasa) is believed to be a hybrid between two American species, Fragaria chiloensis and Fragaria virginiana. The fruit is most delicious, refreshing, soft and highly perishable berry, which is botanically an aggregate fruit.
The fruit is rich source of pectin (0.55%), an important ingredient of jelly making. The fruits are mostly eaten fresh. However, it is processed into various added products like canned strawberry, jam, ice-cream and other drinks etc.
It prefers light porous soil which is rich in humus, slight acidic (pH 5.5 to 6.5) and well drained. Water logging even for a limited period kills the plants, encourages lead and fruit rot diseases.
Strawberry is grown mostly in Shimla, Katrain of Himachal Pradesh, Kumaon and Garhwal regions of Uttaranchal, Saharanpur of U.P., Mahabaleshwar of Maharashtra and to some extent in nearby area of Delhi.
The plant is small herb with shallow roots. The propagation is done by one-year-old runners. The runners should not be allowed to grow till after the fruit has been harvested. Multiplication on large scale is done through tissue culture, which are disease free and high yielding of quality fruits.
The best time of planting in subtropical climate (plains) is 3rd week of October to 1st week of November, while in hilly tracts it is August-September. The soil is covered with straw mulch during fruiting or during freezing weather. Hence the name is strawberry. The plants are generally planted 22 cm apart on raised beds. The midpoint of the crown is set at the level of soil surface to escape rot.
With the introduction of varieties like Tioga, Torrey, Elista, Shasta, Robinson and Fairfax etc., its cultivation has got a boost. Pusa Early Dwarf from IARI, New Delhi is suitable for cultivation in sub-tropical areas. The plants are dwarf, bearing medium size fruits with red colour of varying intensity. It is good table cultivar with medium T.S.S. (7.8%) and acidity (0.8%).
The plants deficient of nitrogen show stunted growth with pale yellow leaves. At least 40 kg nitrogen per hectare should be given after initiation of growth but before flowering. The leaves of phosphorus deficient plant curl downward. Reduction in plant growth, fruit size and yield is due to potassium deficiency. Deficiency of micronutrients may be corrected by spraying 0.5% each of zinc sulphate, copper sulphate and iron sulphate.
The fruits are harvested along with their stalks when about 75 per cent of the skin has attained red colour.
The other fruit is the Japanese persimmon (Diospyros kaki) belonging to the family Ebenaceae, which yields ebony wood. It is a monoecious tree and grows up to a height of 1700 metres. It is often considered a sub-tropical fruit. It is cultivated mostly in the Kulu Valley. The propagation is by crown-grafting on seedlings of Diospyros lotus. The scions are kept covered with soil till they sprout.
The adult tree requires little winter chilling and practically no pruning. The fruit is harvested when it has attained proper colour but is still hard. The berry becomes soft on ripening. Most varieties are astringent till they are fully ripe. Fuyu is a non-astringent variety with tomato-shaped fruit. Twentieth Century is a non-astringent and the earliest variety. Hachiya is an astringent variety with oblong pointed fruit.
Dai Dai Maru is a successful variety from the Nilgiris. The fruit can be ripened by keeping them with pears in airtight chambers for three days.
The ripening and removal of astringency can also be done by storing the fruits with tomato, mangosteen, passion fruit, cape gooseberry and more slowly with banana. The ethylene gas released by these fruits during their own ripening helps ripen and remove the astringency of persimmon.
The commercial trees of persimmon generally bear only female flowers and bear seedless fruit through parthenocarpy. Trees with male flowers and both male and female flowers on the same trees are also found. Fruit-thinning when the crop is very heavy helps the tree to bear a crop regularly every year.
Some of the other species related to persimmon and found in India are D. tomentosa (tendu), D. lotus (Amlok) and in South India, D. discolor, D. embryopteris and D. melanoxylon, which yields Coromandal ebonywood. Many other wild species of Diospyros are found in India.
The raspberry (Rubus idaeus), the blackberry and the purple raspberry, which are important bramble fruits in the west and bear aggregate fruits on two-year-old canes of bushy plants, are not grown commercially in India.
However, some species like Rubus ellipticus (Heer or Hinsar) with yellow fruits and the dark-fruited raspberry locally called Kailkha are found growing wild in the Himalayas and the cultivation of the improved types in these areas should be possible. In fact, the cultivation of blackberries has been found quite successful at Coonoor and even at Bangalore.