Everything you need to know about pear cultivation, growth and harvest. Learn about:- 1. Introduction to Pear 2. Climate and Soil Required for Pear Cultivation 3. Propagation and Rootstock 4. Planting 5. Training and Pruning 6. Manuring and Fertilization 7. Weed Control 8. Harvesting and Postharvest Management 9. Varieties.
Contents:
- Introduction to Pear
- Climate and Soil Required for Pear Cultivation
- Propagation and Rootstock of Pear
- Planting of Pear
- Training and Pruning of Pear
- Manuring and Fertilization of Pear
- Weed Control of Pear
- Harvesting and Postharvest Management of Pear
- Varieties of Pear
1. Introduction to Pear:
Pear (Pyrus communis) is one of the world’s oldest cultivated and beloved fruits. Pears are placed in the Rose family (Rosaceae), subfamily Pomoideae along with apple and quince. The genus Pyrus is composed of about 22 species, found in Asia, Europe, and northern Africa.
Two major species are commercially cultivated:
1. European pear – Pyrus communis L. This species does not occur in nature, and possibly derives from P. caucasia and P. nivalis (snow pear). This is the major pear of commerce.
2. Asian pear – P. pyrifolia (Burm. f.) Nak. [syn. P. serotina L.]. Also called Japanese or Oriental pear, or Nashi. Grown mostly in the Orient, this fruit has been increasing in popularity in the USA over the last 20 years.
Asian pears were domesticated in China about the same time European pears were in Europe, 3000 years ago. P. pyrifolia is native to central and southern China, and probably the first to be domesticated since fruit of wild trees is edible. Fruit of wild P. ussuriensis is astringent, small, and course- textured, so that it was hybridized with P. pyrifolia prior to domestication.
Asian pears appear more like apple than or like the relative the apple, the European pear is not found in the wild. Its probable progenitors are native to Eastern Europe and Asia Minor near the Mediterranean, but it is not known when they may have hybridized to yield P. communis.
Asian pears moved from China to Japan, Korea, and Taiwan, where they are cultivated commercially today. European pears have hard, crisp flesh like apples when ripe, unlike the melting flesh European pears. Also, Asian pears will ripen on trees like apples, but European pears are subject to core breakdown if allowed to ripen fully on- tree.
According to FAO (2004) the total world production of pears is 17,909,496 MT. Pears are produced commercially in 81 countries on 4.3 million acres.
Pears are the temperate fruits in India. It is grown under temperate and subtropical conditions. The plants have wider climatic and soil adaptability. It is primarily grown in hills at 1,700-2,400 m above mean sea-level in Himachal Pradesh, Jammu and Kashmir and Uttar Pradesh. Low-chilling pears have adapted very well in the subtropical regions.
Pear is one of the most important fruits of northern India and is being extensively cultivated in various parts of Punjab. It makes sound farming and economic sense to go in for planting and nurturing orchards, especially since the state government has gone in an overdrive to promote diversification.
It is a medium sized, upright growing tree, to 30 ft tall, generally 8-18 ft tree. Tree size is heavily dependent on rootstock and training system. Leaves are elliptic/ovate with acute tips, with finely serrate or entire margins, 2-4″ in length. The flowers are about 1″ in diameter with white petals, and similar to apple except for having longer pedicels. The inflorescence is corymbose, containing 5-7 flowers (also different from apple). The pollination of most cultivars require cross pollination for commercial fruit set.
Some cultivars are partially self-fruitful. Honey bees/ are the main pollinator. The fruit is a pyriform (European) or round (Asian) pome. As in apple, the fleshy edible portion is derived from hypanthium tissue. There are 5 central seed cavities, usually bearing 2 seeds each as in apple. The flesh contains grit cells (termed brachysclereids), which are thick-walled, lignified cells that give the characteristic European pear flesh texture. Pears are thinned to 1-2 fruit per spur, spaced 6″ apart.
2. Climate and Soil Required for Pear Cultivation:
Pears have very similar climatic requirements to apples and can be grown in a wide range of climatic conditions. It can tolerant as low as 26 °C temperature when dormant and as high as 45 °C during growing period. It cannot tolerate humid, wet springs. A large number of pear cultivars require about 1,200 hr below 7°C during winter to complete their chilling requirement to flower and fruit satisfactorily.
Pears require 900-1000 chill hours to break dormancy, although some low chill cultivars exist, and many Asian pears have lower chill requirements and can be grown as far south as northern Florida. Pears have similar or slightly lower cold hardiness than apples, tolerating -10° to -20 °F. Pears bloom 1-3 weeks before apple, and are therefore prone to frost damage in most regions. Pears mature as little as 90 days, or as long as 200 days.
The chilling requirements of pear depend on type of variety. For example Bartlett needs about 1,500 hr compared with other temperate pears while Patharnakh needs only 150 hr of chilling and can also withstand high temperature and hot winds during summer.
LeConte, Keiffer, Pineapple, Hood and Gola are medium chilling varieties and can perform well in mild winter areas. Spring frosts have detrimental effects on production. Pear cannot even survive at – 3.3 °C or below (harmful for open blossom). Therefore, the planting should not be done in lowlands.
Pears tolerate heavy, poorly drained soils better than most tree fruits. However, productivity is best on deep, well-drained loams with pH 6-7.5. In India, Pear grows best in deep, well-drained, fertile, medium-textured and relatively more clay soil. It is more tolerant to wet sols but less tolerant to drought than apple.
Pears even do well on poorly aerated heavy soil with high watertable which is heavy in texture for most of deciduous fruits. They grow well in a soil with depth of about 180 cm. Plants growing on deeper soils give about twice the yield than those in shallow soils. The highly fertile soils rich in N are not very suitable for pear growing as the incidence of pear psylla and fire blight is more in these soils.
3. Propagation and Rootstock of Pear:
Propagation is done by rootstock. The Kainth and Shiara seedlings are used and clonally propagated. In Punjab, root suckers of wild pear are also employed as rootstock. In some areas in plains of north India, own-rooted cuttings of Patharnakh are also used for propagation.
For raising rootstock, seeds of pear, Kainth and Shiara are extracted from fully mature fruits. For stratification (chilling treatment) sow the seeds in open nursery in November or placing them in alternate layers with the moist sand and/or vermiculite at optimum low temperature (5°-7°C) for the required duration during October-November.
Keep the seed in stratifying medium till the uppermost layer of seeds pushes the sand upward and protrudes the radical. The germinating seeds are sown in the beds or directly in the nursery rows immediately at a distance of 10-15 cm in rows 15 cm apart.
Healthy, good yielding and dormant trees cuttings are selected in December. The cuttings dipped in IBA 100 ppm for 2 hr and are placed in moist sand for callusing. The callused cuttings are then planted in the nursery rows. Kainth cuttings are also prepared and treated in the same manner to raise clonal rootstock. These are later budded /grafted.
Raising Rootstock from Root Suckers:
Root suckers are also used for plant propagation. The healthy pear trees with good root system are separated in October-December. These suckers are tongue grafted and planted in the nursery at 15-20 cm distance 30 cm apart, leaving 60 cm space after 2 rows. The new sprouts come during February-March which becomes budable during August-September.
The clonal rootstock of Quince A variety is most used. It produces about 50 to – 60% trees of the standard size. The rootstock of this cultivar has poor compatibility with most of the commercial cultivars. The compatibility can be improved by double grafting with Old Home or Hardy varieties. Mound layering is generally done to propagate this rootstock clonally.
Pear plants are commonly propagated by T-budding during April-September or tongue grafting done during December-January. Standard sized pears are chip or t-budded onto compatible rootstocks like most tree fruits. However, where quince (Cydonia oblonga) is used as a dwarfing stock, most pear scions require an inter-stem for compatibility (of major cultivars, only ‘Anjou’, ‘Comice’ and ‘Hardy’ are compatible with quince, and all Asian cultivars are incompatible).
4. Planting of Pear:
Pear orchards are designed very similar to apple orchards. Standard trees are spaced at 25 x 25 ft (70 trees/acre), but hedgerow forms are more common in high density plantings, with hundreds of trees per acre. Pollinizers are planted in alternate rows, or every 10th or 15th tree within hedgerows.
The land is prepared by carrying out preliminary operations before planting and depends upon the condition of land. If the land is already under cultivation then it should be cleared of all the old stems and roots of previously-growing crops and leveled properly giving slopes for water drainage. A planting plan and layout system depend on plant density to be adopted and topography of land. Generally, square or rectangular system is followed.
In hilly areas and rolling land the contour system is suitable. In this system, first row is drawn at the highest elevation and all the trees in a row come at the same elevation. The distance between rows depends on the slope, being closer on the steeper slope. The planting distance depends on the slope, being closer on the steeper slope, soil fertility, cultivar, rootstock, training system and climate of the region.
In hilly areas, the trees on seedling rootstock are planted at a distance of 5 m but for clonal rootstocks distance can be reduced to 3 m. In plains, the planting distance of 6 m and 8 m is recommended for pear Baggugosha and Patharnakh respectively. The planting of trees can be done anytime from December to mid-February in plains. In regions where winter is mild and soil has enough moisture, late fall planting is desirable but in the contradictory conditions early spring planting is the best.
A pit of 1 m x 1 m x 1 m size is dug at such places and filled with a mixture of soil and well-rotten farmyard manure or compost and 30 g Aldrin or BHC dust. Irrigation is given after filling pits to settle down the mixture. Planting may be done in a small hole to accommodate all the roots.
5. Training and Pruning of Pear:
Training and pruning is essential for the development of strong framework. These help to maintain vigour and growth, spread the fruiting area uniformly, secure fruits of good size and quality, encourage regular bearing and to provide convenience of pruning, spraying and harvesting. The modified central leader (MCL) is the common system for free-standing trees and some form of palmette for trellised orchards.
Initial tree training is particularly important with pear since scaffolds tend to grow nearly vertically, causing poor crotch angles and delayed fruiting. Other than this tendency to grow upright and therefore greater need for limb spreaders, pears are trained and pruned in the same way as apples. In this method, 4 or 5 well-spaced limbs are developed during initial 3-4 years and then the leader is headed off.
In first year, plants are headed back at 90 cm low-headed trees and at 125 cm for high-headed trees at the time of planting. The lowest branch is allowed to develop at a height of 60 cm from the ground level. Four or five primary scaffold branches arising at wider angle, well-spaced, 10-15 cm apart and spirally arranged around the tree trunk are selected.
Two to three secondary branches are selected on the primary scaffold during second dormant pruning. During subsequent years, training consists of thinning out unwanted branches and cutting others to desirable side limbs. The leader should be removed to keep a well-placed, outward growing lateral in the fourth year of training.
The summer pruning of established wall or espalier-rail trees consists chiefly in the timely displacing, shortening back, or rubbing off of the superfluous shoots, so that the winter pruning, in horizontal training, is little more than adjusting the leading shoots and thinning out the spurs, which should be kept close to the wall and allowed to retain but two or at most three buds. In fan-training the subordinate branches must be regulated, the spurs thinned out, and the young laterals finally established in their places.
When horizontal trees have fallen into disorder, the branches may be cut back to within 9 in. of the vertical stem and branch, and trained in afresh, or they may be grafted with other sorts, if a variety of kinds is wanted. Pruning intensity varies with the bearing habit of a cultivar and vigour of a tree. In hills, dormant season, when the danger of heavy snowfall is over, is the best time of pruning. Early pruning may result in severe cold injury.
6. Manuring and Fertilization of Pear:
Manuring and fertilization doses for 10-year-old plants is 60-100 kg farmyard manure, 700 g N, 350 g P2O5 and 700 g K2O is suitable. These are to be applied before snowfall (December). Three weeks before flowering, half of N is added while remaining after fruit set. If the trees suffer from the deficiency of Zn and Fe, the young foliage should be sprayed with 0.4-0.5% zinc sulphate and ferrous sulphate respectively in April.
After planting there are several operations should be done to maintain the plants.
These include:
1. The basins should be prepared around the plants.
2. The soil near the trunk should remain slightly higher than the level of the basin.
3. Irrigate the plants immediately after planting and second irrigation after 2- 3 days.
4. Plants should be regularly irrigated, they should not be under water stress.
5. The young plants are staked.
6. To avoid sun burn whitewashed the trunk.
7. The extra branches should be removed.
8. The sprouts on the rootstock and root suckers should also be removed.
In heavier soils, the moisture in upper 1 m is essential and needs light irrigation while the lighter soils or soil with a gravel substratum need more frequent and heavier irrigation. The loam soils should remain moist upto 1.5- 1.8 m deep. In hills, pear cultivation is mostly done under rainfed conditions soil may not needs irrigation.
Besides rainfall, 75-100 cm irrigation may be applied annually in some regions. Excessive or scanty moisture conditions affect colour, composition and keeping quality of fruits.
Pear trees may be intercropped with green gram, mash, toria and sunflower during kharif, while in rabi wheat, peas, gram and senji can be grown in young orchards. Intercropping needs extra dose of fertilizers. Peach can also be planted as fillers in pear plantations.
7. Weed Control of Pear:
Mechanical weeding and hoeing or uses of herbicides are the best methods of weed eradication. Use Hexuron 80wp (Diuron) @ 4 kg/ha as pre-emergence in the first fortnight of March and Glycel 41SL (Glyphosate) or Grammaxone 24WSC (Paraquat) @ e litres/ha as post-emergence weedicide when weeds are 15-20 cm in height. The weedicides are dissolved in 200 litres of water.
8. Harvesting and Postharvest Management of Pear:
Fully mature fruits are harvested for fresh consumption. The flesh firmness is used as a maturity index. The maximum flesh firmness should be 15-9 ponds – force. The other indices include corking of lenticels, pattern of starch content, and internal ethylene concentration.
The quality indices depends on the appearance (color, size, shape, freedom from internal breakdown, blackened, russeting, bruising, scars, sunburn, insect damage, and other defects), texture (firmness of the flesh, presence of sclereid cells), flavor and taste related to contents of sugars and organic acids; aroma which is dependent upon volatiles (production may be enhanced by ethylene treatment during ripening of pears).
Therefore, harvesting depends on firmness and green for canning and distant markets. For local consumption, fruits are picked at slightly later stage, because fruits hanging on trees make a considerable gain in size, weight and overall quality. The storage life is reduced if the fruits are picked up after little maturity. It will develop unattractive chalky colour of fruits.
The fruits are picked individually by giving a gentle twist rather than direct pull. Harvesting should be-done in 2-3 pickings at 3-4 days interval rather than single picking. A well-managed orchard of pear Bartlett yields 30-35 tonnes/ha. The pear cultivars ripen and develop best dessert quality at 15.6°-21°C and 80-85% relative humidity. High ripening temperatures (above 26°C) may impair flavour and texture of the fruits as they become mealy and fail to ripen.
The fruits require the optimum temperature of -1 to 0°C; freezing temperatures -1.5° to -2°C with an optimum relative humidity of 90-95%. Pears after harvesting are cooled. Fruits do not require pre-cooling if consumed within a few weeks of harvesting. Hydro-cooling reduces the incidence of shriveling and brown core without affecting weight loss or incidence of rot.
Pear fruits respond to ethylene. Treating pears with 100 ppm ethylene for 1 to 2 days can substitute for cold storage (4 to 8 weeks at -1° to 0°C) in enhancing ripening. Optimum conditions for ripening are 15 – 22 °C, the higher the temperature the faster the ripening) and 90-95% relative humidity; CO2 should be kept below 1%.
Responses to Controlled Atmospheres (CA):
The optimum range is 1-2% O2 + 0-1% CO2 Winter pear varieties can be stored in CA at -1 °C for up to 4 months or 6 months while maintaining their capacity to ripen and attain good flavor and texture.
Oxygen levels below 1% and/or carbon dioxide above 1% for longer than two weeks can induce physiological disorders; severity increases with lower O2%, higher CO2%, higher temperatures, and longer storage time.
The fruits are graded after harvesting. For example Bartlett pears are graded as extra-large (8 cm), large 8 cm), medium (6.5) and small (5 cm) sizes. The misshapen, damaged, blemished and scared fruit excluded from the harvested batch.
The fruits are packed in wooden, plastic or cardboard boxes with layers.
The bottom and top of the containers are properly cushioned with newspaper or dry grass for avoiding compaction and bruises to fruits. The fruits can also be wrapped individually in 10 micron HDPE bags before packing which maintains freshness and improves fruit quality compared with unwrapped fruits.
9. Varieties of Pear:
There are relatively few cultivars of European or Asian pear grown worldwide.
Only about 20-25 European and 10-20 Asian cultivars represent virtually all the pears of commerce. Almost all European cultivars were chance seedlings or selections originating in western Europe, mostly France. All of the Asian cultivars originated in Japan and China. ‘Bartlett’ is the most common pear cultivar in the world, and represents about 75% of US pear production.
Pear varieties belong to 3 groups: European, Asian and hybrids.
The varieties recommended for different states of India are as follows:
Bartlett and its sports are referred to as summer pears since they ripen in July – August in California (115-140 days). Winter pears are those harvested in autumn and marketed throughout the winter months, such as Anjou, Bosc, Cornice/Hardy, Winter Nelis, and Packham’s Triumph.