Humble honeybee major yield booster
R.C. Sihag
T

Seed, vital yet neglected input 
C.L. Bhardwaj
Seed propagating material possessing specific characters such as high yield, drought resistance, pest resistance, and quality attributes constitutes prime agricultural input.

TREE TALK
Silver lining to avenues
K.L. Noatay
A native of Queensland and New Southwales in Australia, thus exotic to Asia, silver oak was introduced on Indian subcontinent by officials of the East India Company during the 17th and 18th centuries for road-side avenues and residential colonies.

LETTER
Regular wood market wanted
Poplar, introduced in the Yamunanagar area on contract basis by a private company in the eighties, attracted farmers of the area, who went in for it on a large scale, followed by farmers of the adjacent western UP and some parts of Punjab. This resulted in the production of large quantities of poplar wood and Yamunanagar is now its largest market.

Humble honeybee major yield booster
R.C. Sihag

The average yield of crops in India is much below optimum. One of the major reasons for this is inadequate pollination. Most crop plants are angiosperms, i.e., they bear flowers. For the setting of seed/fruit, the flower must be pollinated, i.e., the pollen must be transferred from the anthers (male part) to the stigma (female part).

If the flower utilises its own pollen for seed set, this is called self-pollination (autogamy) and if the pollen comes from other flowers, it is cross-pollination (xenogamy). Most crops need cross-pollination due to the presence of strong reproductive barriers. These include self-incompatibility, differential maturity of the reproductive organs and unisexuality. As such, a flower is not able to utilise its own pollen. Self-incompatibility is the case when pollen of a flower is genetically incapable of setting seed in the same flower or even in a flower of genetically same ramet/genet. This happens in many oilseed, vegetable as well as fruit crops.

Under differential maturity of reproductive organs, there can be two situations. When anthers (male part) mature before the receptivity of stigma (female part), it is called protandry. In this, if pollination occurs due to self-pollen, it will go waste as it cannot germinate. This pollen can be useful only for other flower(s) that have a receptive stigma. Some cultivars of sunflower, jujube, onion, carrot, celery and parsnip, fennel, coriander, cumin, lavender, etc., are examples of protandry.

On the contrary, if stigma becomes receptive much before the liberation of self pollen (protogyny), the former will be in need of pollen that can come only from other flower(s). This stigma dries up/becomes non-receptive much before self-pollen is liberated. Examples of protogyny are black pepper, and fruit papan and cherimoya.

In certain crops, contrary to the above, either the plant bears flowers of one sex only (papaya, date palm and Chinese gooseberry) or separate male and female flowers are borne on the same plant (cucurbits, asparagus, coconut, oil palm). This is called unisexuality.

Under all these situations, pollen self-pollen cannot be utilised for pollination and pollen from other flower(s) must be brought. Bees, due to their morphological (they bear branched hair to collect pollen) and nutritional (feed on pollen and nectar) adaptations can accomplish this task most efficiently Among bees, honeybees are the best suited crop pollinators (except in some cases where specialist pollinators are needed) due to their high floral constancy, i.e., an individual bee makes repeated visits to the same floral source till it is exhausted; this behaviour makes the bee a faithful visitor.

Two species of honeybees, Asian hive bee and European honeybee, are utilised for pollination of crops due to two main reasons: 1) these can be kept and managed in artificial wooden boxes (the hives) that can easily be transported from one place to the other and 2) their population can easily be manipulated depending upon the pollination requirements of the given crop area. Inadequate pollination leads to low seed set and misshapen fruits in cross-pollinated crops.

Significant increase in yield has been reported in cross-pollinated crops when honeybees have been employed. However, beekeeping as an input in agriculture has not yet been recognised by farmers and seed growers, especially in developing countries, due primarily to their ignorance.

The major problem lies with agri-scientists and agri-biotechnologists, who are not willing to share the credit of their high-yielding varieties with other inputs. It is now well established that despite the use of high-yielding varieties, good crop management practices, including agronomical recommendations, use of irrigation, fertilisers and pesticides, the yield of cross-pollinated crops remains very low if there are no pollinators. This is because the seed production in these crops is pollinator limited, i.e., due to the inadequate number of honeybee pollinators, the pollination level remains inadequate. In self-incompatible and unisexual crops the effect is much severe.

At present there is a standard requirement of over 150 million honeybee colonies in the country for pollination of crops and, in addition, they can produce over 2.25 million metric tons of honey. In 1982, there were 0.6 million honeybee colonies in the country. After that, Indian hive bee (Apis cerana indica) was badly affected by the Thai Sac Brood Virus (TSBV) disease. This caused a great loss as majority of the colonies of the Indian honeybee were lost by the start of 1990s.

India has badly failed to recognise the importance of this humble creature, as has been done by China, a major honey exporting country. At present, the estimated number of honeybee colonies in India remains even less than 0.5 million against a fixed target of 6 million, and a potential of 150 million colonies.

Honeybee research should be given top priority and specialised honeybee research centres should be established.

Seed, vital yet neglected input 
C.L. Bhardwaj

Seed propagating material possessing specific characters such as high yield, drought resistance, pest resistance, and quality attributes constitutes prime agricultural input. This leads to better productivity under optimum fertility conditions and high-tech crop management practices. The higher cost-benefit ratio of inputs like fertilisers, irrigation, and integrated pest management also depends on the quality of seeds and propagating materials, since it helps better plant stand and low pest incidence.

Quality seed and propagating material would possess genetic purity (natural or incorporated, screened artificially), vigour and plumpness, quick germination and will be free of pests. This helps in maintaining appropriate plant stand, economy in use of costly seeds, and in turn higher yield.

The production and supply of quality seed and propagating materials depends on three business-oriented sectors of agriculture development: 1) traditional—through farmers, 2) public sector—through government organisations such as the seed certification and supply agencies or the National Seed Corporation, and 3) private sector companies.

It has been estimated that 10 to 15 per cent increase in production can be achieved by replacing farmer-produced seed/propagating material with improved varieties through the public and private sectors. The production and supply of quality propagation materials has not picked up the desired momentum. This has also hindered refinement of production technology.

The annual replacement rates are very low for propagating materials of long-duration crops. Recently there has been a move towards hybrid seeds, but purchasing such seeds every season may be beyond the financial capacity of small and marginal farmers.

A serious constraint faced by farmers is the non-availability of quality seeds of improved varieties at the appropriate sowing time. To overcome the problem, the concept of community approach —establishing cooperatives of farmers for quality seed production and supply — needs more attention and motivation. Farmers can be taught to re-orient their enterprise in this direction. Propagating materials so produced can be cheap and conveniently available to the farmers.

TREE TALK
Silver lining to avenues
K.L. Noatay

A native of Queensland and New Southwales in Australia, thus exotic to Asia, silver oak was introduced on Indian subcontinent by officials of the East India Company during the 17th and 18th centuries for road-side avenues and residential colonies. With the scientific name Grevalia robusta, the species belongs to the family Proteacea. The plant grows reasonably well in plains but does much better in undulating hills with laterite soil and moderate climate—minimum and maximum temperatures between 10º and 35º C and precipitation, i.e. rainfall and snow fall, between 1000 and 1500 mm.

Distribution

In the Asian scenario various landowners like foresters, tea-gardeners, town planners, highway engineers, etc., were attracted by this plant for its showing growth better than several similar indigenous species. The tree was thus planted on a large scale on the Deccan platueu, especially rolling tracts comprising parts of present-day Maharastra state, as also vast areas of Madhya Pradesh, which were become denuded because of large-scale mining for a variety of minerals.

Phenology

Silver oak is a fairly fast-growing large tree. It attains a height of about 30-35 m and diameter 60-70 cm in about 30 years. Its young shoots are silvery grey with tomentose lenticell hair, hence the name. The leaves are alternate, compound, pinnae, 10”-30” long, and deeply pinnatified. Individual leaflets are entire and lanceolate in shape. Their colour is light green and glabrous above with greyish tinge beneath. The tree being evergreen it keeps shedding old leaves throughout the year. The sprouting of new buds also goes on throughout the year. The phenomenon, however, is more brisk during spring. The tree flowers during March-April. The recemes are 7-15 cm long. Individual florets are yellow and make the tree canopy look like a gorgeous golden pyramid. The fruit appears during April-May. It ripens to mature seeds by September-October. The trunk is generally cylindrical without much branches and the bark is ash-grey with vertical fissures.

Silvicultural requirements

Silver oak is sun loving, but does better in shade in earlier years. While it can tolerate low temperature, also frost to an extent, water logging is inimical. As such it adjusts well to a variety of climatic conditions prevailing in temperate to tropical tracts. Land wise it adjusts to a variety of soils like laterite, boxite, etc., though well-drained loam is the best. Its stem being soft and wood brittle, it is highly susceptible to damage by wind and storm. Insects too attack it during early age.

Regeneration

Silver oak can regenerate itself naturally under mother trees in protected pockets where biotic factors like grazing, trampling, grass cutting, etc., are excluded. However, being an ornamental tree it is raised by sowing seed direct on ground cleared and hoed well for the purpose.

For large-scale planting it is advisable to raise an adequate stock of seedlings in raised beds in a well-prepared and carefully watered nursery. For this purpose mature seed is collected from healthy mother trees during November-December. Sowing in nursery beds is done during December-January or June-July, depending on the moisture content in the soil vis-à-vis availability of irrigation facility. The beds sown are covered with thatch grass and watered twice a day with a rose-head watering can.

One-year-old seedlings are transplanted in the field preferably during monsoons/winter rains. In direct sowing as well as transplanting of nursery stock 60 x 60 x 60 cm pits are dug well before the sowing and or transplanting time and refilled with good loam soil mixed with farmyard manure. In areas receiving heavy rainfall naked root plants are suitable for transplanting. But in dry areas seedlings raised in ploythene bags give better survival if transplanted as such.

The wood

Silver oak being a fast growing species, its wood – weighing nearly 20 kg per cubic foot – is light, and has good grain. When sawn by experienced men and worked by knowledgeable carpenters its wood exhibits excellent sliver grain. That makes the timber good for panelling, parquet flooring and also furniture. While this ornamental tree is seldom felled with commercial intent, its wood fetches about Rs 800 per cubic foot, if and when available from removable mature, dying or dry trees.

State forest departments, intuitions imparting education about forestry and horticulture not only provide the requisite know-how, but also nursery plants on highly subsidised rates like Rs 2 for a one-year-old sapling. 

LETTER
Regular wood market wanted

Poplar, introduced in the Yamunanagar area on contract basis by a private company in the eighties, attracted farmers of the area, who went in for it on a large scale, followed by farmers of the adjacent western UP and some parts of Punjab. This resulted in the production of large quantities of poplar wood and Yamunanagar is now its largest market.

— Ravi Datt Sharma, Jagadhri