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AGRICULTURE TRIBUNE | Monday, June 19, 2000, Chandigarh, India |
Pollen, pollinators and people By R.K. Goel COME spring and the colourful and fragrant flowers are blooming all around. Apart from tickling our aesthetic sense, flowers play an important biological role of perpetuating the race of the plants bearing them through fruits and seeds. This role can be played only if pollen grains or the male gametes are transferred to pistil or the female sex organ of the plant. This process termed as pollination takes place in nature by a mind-boggling diversity of methods. New method of tapping resin Boon
for farmers in Pinjore block Weather
forecast for hill farming |
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Pollen, pollinators and people COME spring and the colourful and fragrant flowers are blooming all around. Apart from tickling our aesthetic sense, flowers play an important biological role of perpetuating the race of the plants bearing them through fruits and seeds. This role can be played only if pollen grains or the male gametes are transferred to pistil or the female sex organ of the plant. This process termed as pollination takes place in nature by a mind-boggling diversity of methods. The easiest and simplest being the self-pollination as in rice and wheat. Since it precludes the introduction of new genetic traits into the offspring, self-pollination in many plants is prevented by one or more processes in nature e.g. self-incompatibility, presence of male and female sex organs in different flowers or plants or their non-synchronous maturity. If self-pollination cannot occur, then the pollen must reach the other flowers of the same species i.e. it must be cross-pollinated. The most common method of cross-pollination is through wind or water. As this is a chancy proposition, the number of pollen grains produced is enormous. If you have ever parked a car under a pine tree in the spring season, you can have some idea of the amount of pollen produced by a wind-pollinated plant. Food crops, including maize, bajra (pearl millet) and trees like papaya, pine and oak are wind-pollinated. Air-borne pollen can travel long distances at times up to 50 km. Wind-borne pollen is the cause of considerable human discomfort, particularly during spring as any asthma or hay fever victim can testify. Some persons are so sensitive that inhalation of even a few pollen grains can cause severe allergic reactions in them. In some cases allergies to specific pollen may be inherited. The allergic reactions are caused by proteins in the outer walls of pollen grains. These proteins move from the pollen to the sensitive linings of the nose where they release some chemicals already in the victims immune system. It has been suggested that minute, sharp bumps and spines on the pollen wall are also physical irritants to sensitive cells in the nose. Cross-pollination mechanisms involving animals, especially insects, attract attention the most. Pollen is a rich source of proteins, fats, carbohydrates and minerals for insect pollinators like wasps, moths, beetles and flies. The association is obligatory since a large number of wild plants and many of our crops e.g. sunflower, mustard, berseem and cotton are dependent on insects for pollination. During the course of evolution, both flower and its pollinator have adapted structurally and functionally for mutual survival. Bees are attracted to plants for the nectar, the classical drink of the gods secreted by cells at the base of shiny petals. Apple flowers produce nectar daily, just before bees leave their hives. Since bees work hard, requiring sugar for energy, nectar must contain at least 18 per cent sugar to make its collection efficient. The hair on the bees body collect pollen as they feed which is then deposited at the female sex organs of the other flowers. German zoologist Karl von Fritsch, who decoded the communication among worker bees about the source of nectar, was awarded the Noble prize in 1973. Bees have colour vision, seeing the best in the blue and near ultraviolet (UV) ranges. Recently it was discovered that red and white flowers reflected solar UV rays and to a bees eye appear as bright spots against a dull background of leaves and grasses. In some plants, the UV-reflecting areas of petals are arranged in streaks or a series of dots, which like painted stripes on an aeroplane landing field guide the bee directly into the centre of the flower. The mouth parts of other insect pollinators are structurally adapted to the flowers they visit. Flower shape and strong scent are the main attractions for wasps. Beetles, too, are attracted to flowers by their odour. Some pollinating flies have mouth parts similar to those of bees, thus competing for the same flowers. others are fairly crude, flying about and bumping into anthers (pollen sacs). One scientist described them as unindustrious, unskillled and stupid. Some tubular flowers, however, trap them for several days where these flies buzz around madly trying to escape, only to be released when the flower is pollinated. Birds may be more important than bees as pollinators in the tropics e.g. humming birds in the Americas, sun birds in Africa and Asia and honey eaters in Australia. Most birds have an excellent vision but a poor sense of smell. Flowers visited by birds are usually red, orange or yellow. Some bats also feed on
nectar and small insects present in the pools of nectar.
Flowers visited by them are night bloomers, big and with
white petals. The pollinating bats have a slender muzzle
and long and extendable tongue. Bats are guided to
flowers by sight and by the fruity odours. The colour and
fragrance of a flower, thus, is not designed to attract
human beings but is keyed to the organs of sight or smell
of its pollinators. |
New method of tapping resin ALARMED at the large-scale drying of pine trees, the Himachal Forest Corporation has decided to switch over to the new bore-hole technique from the rill method for tapping resin. The experience of the past 15 years has shown that the modern rill method, which was introduced in 1983 to replace the traditional cup-and-lip method, was no better as far as damage to trees was concerned. Intensive tapping has resulted in drying of thousands of pine trees over the past decade. It has also been observed that the application of higher concentration of acid, used as freshener, had adversely affected the growth of trees. The farmers have been for the past quite some time alleging that intensive tapping by the rill method was causing damage to trees but this fact was established only after the government set up a committee to look into the matter. After inspecting selected forests subjected to intensive tapping, the committee found that the volume of total growing stock had been reduced by a whopping 19 per cent due to drying and retarded growth of trees. The main reason for this was that the parameters laid down for blazes were not being followed in the field. The blazes mostly exceeded the prescribed length and the trees were not being given the required rest and were tapped continuously. Some higher diameter trees had been tapped for 16 years. Worse, the rill method was no more efficient than the traditional method. The increase in yield was on account of higher area tapped and not due to efficiency of the method. It was found that the area tapped was much higher than prescribed for each blaze. For instance the area tapped for 418 blazes (1994-95 season) examined by the committee was 4,54,801 sq cm against the required 3,17,680 sq cm. Similar discrepancies were revealed in blazes examined for different tapping seasons. On average the tapped area exceeded the prescribed area by 50 per cent. The average yield of resin per section (1,000 blazes) came to 40.38 quintals, whereas if the additional area tapped was taken into account the yield should have been above 60 quintals. The corporation has now decided to discard the rill method from this season. It is using the new bore-hole method for 20,000 blazes. Under the new technique only a 2-cm deep bore is made on the tree which suffices for seven to eight weeks. Just three bores are required to tap resin during a season and thus the exercise is completed in 20 to 22 weeks as against eight months in the case of the rill method. The yield is almost the same. The biggest advantage of the new method is that resin is tapped after the fire season around June 15, thus the tapped trees are not exposed to the fire hazard, says Mr O.P. Sharma, Managing Director of the corporation. It would also save labour and thus bring down the cost of resin tapping by about 25 per cent. At present the cost was about Rs 2,100 per quintal, which would come down to around Rs 1,600, he adds. Besides, the quality of
resin will be much superior and without dust and other
impurities as it would be collected in a polythene bags
attached to the bore. The quality of rosin, turpentine
oil and other products manufactured from it will also be
much better and fetch higher prices, says Mr Sharma. |
Boon for farmers in Pinjore block A DREAM of the small and marginal farmers of Pinjore block of Panchkula district, which had been deprived of the fruits of the Green Revolution, has come out to be true with the installation of deep tubewells in the area. With this their production of foodgrains has more than doubled. Moreover, they themselves are managing the distribution of the water from tubewells. The benefit of irrigation in Haryana had not reached certain areas. One such region was the Shivalik foothills area specifically located in Pinjore block. The annual rainfall in the area, though favourable, had served a limited purpose, apart from the disadvantage that the flashy streams and rivulets caused excessive soil erosion in the heavily undulated terrain in the Pinjore area. This had resulted in low grain productivity due to dry land farming and also suffered the vagaries of droughts and failure of crops. The cost of installation of deep tubewells in the boulder-prone zone with comparatively deep soil water level was beyond the economical means of the cultivators of the area who are mostly small and marginal farmers. Mr Arun Kumar, Managing Director of the Haryana State Minor Irrigation and Tubewells Corporation (HSMITC), said that all these adverse conditions in the Shivalik area had led to poor socio-economic status of the local people. The only recourse for agricultural development in Pinjore block was thus installation of deep tubewells by the state government as the farmers themselves were not in a position to afford them because of the high cost. One deep tubewell costs Rs 11 lakh. Hence, the Shivalik Development Board decided to install deep tubewells in the Doon area of Pinjore block where the ground water potential had hardly been exploited to the extent of only 7 per cent. While the finances for this was provided by the Shivalik Development Board, these were installed by the HSMITC. Mr Arun Kumar said that 12 deep tubewells had been installed in various villages of the Doon area and the depth of tubewells varied from 467 feet to 550 feet. All these tubewells had been tested and the quality of water was favourable for irrigation purpose. The area of the Shivalik hills being highly undulated, the distribution of tubewell water to the beneficiaries in an equitable manner was being carried out by laying of underground RCC pipelines which also had additional advantage of saving the land of small and marginal farmers, thus bringing more area under cultivation. Each tubewell provided irrigation facilities in 200 acres, he said. Another special feature of this project is that the operation and maintenance of the tubewells are being carried out by the beneficiaries as a water users association in respect of each tubewell in the form of a cooperative society. This is the first time that such an experiment has been attempted and it has been proved that if the people of any village decide to take up any project it can be made a success. Though there were many teething troubles, yet with the interest taken by the district administration things became alright. The efforts required a number of meetings on regular basis by the district administration and the HSMITC and now with the development of irrigation, the scheme is moving towards success. As the working of tubewells requires technical expertise, the district administration took an initiative to provide the MITCs tubewell operators on every tubewell for a period of six months. The operators provide guidelines to the cooperative societies for the operation and maintenance of tubewells and for distribution of water by warbandi so that there are no disputes among cultivators and there is no misuse of irrigation water by any dominant group or person. Encouraged by the success, the district administration has got five more deep tubewells installed in the area by the HSMITC under the Member of Parliament Local Area Development Scheme. The commissioning of these tubewells by the Haryana Vidyut Prasaran Nigam and providing underground RCC pipelines are being taken up on priority. Additionally, at a meeting held to review the work of the MPLAD scheme, it was decided to get installed 12 more such tubewells. Of these 12, one tubewell in Kheranwaki village, have been completed and in Khuda Baksh village, the work is in progress. Mr Arun Kumar said that
the Haryana Government proposed to extend the work of
drilling of deep tubewells to all such
irrigation-deprived areas. |
Weather forecast for hill
farming RECENT years have witnessed immense changes in weather conditions in lower hilly and plain areas of Himachal Pradesh. Such fluctuations have been adversely affecting crop performances. During the current season, the mango crop has faced huge damage at the flowering time and pre-mature fruit fall has occurred owing to heavy stormy winds which prevailed both in May and June. The farmers are presently busy with sowing of maize crop with the occurrence of pre-monsoon showers well ahead of recommended time. In the past, it has been observed that early seeding leads to lodging and prevalence of erwinia stalk root disease in maize. The lodging problem is also prevalent in oilseed and pulses.These can be avoided if the farmers could be informed and guided well in advance through a procedure of weather forecast. Even in the rabi season, the farmers in the hills sow the field crops without any adjustment with predicted weather conditions. The sowing of early and timely sown wheat varieties under the late=sown conditions (with occurrence of winter rains) have also been observed in some cases leading to poor yields and sometimes complete failures. Weather forecast provides guidelines for long range or seasonal planning and selection of crops and varieties most suited to anticipated climatic conditions. Researchers have indicated that occurrence of rainfall must be predicted at least a week in advance so that the farmers may plan for seed variety in respect of date of sowing, land preparation, fertiliser arrangements, spray schedule and harvesting of crops so as to make the best use of favourable weather conditions and adjustment with the adverse weather. Strengthening of various
agro-climatic zones in the state with weather forecasting
facilities could mitigate the problems of both
agriculturists and fruit growers and will provide
remunerative prices for their farm produce. The existence
of automatic weather stations at the district level would
go a long way in assisting technical personals engaged in
the farming profession to guide the farmers in the area. |