Pollination of cotton by bees
Cotton is an important crop in the world, so it is important to get large yields from every hectare of fields. One way to increase the yield of cotton is pollination by bees. However, pollination of cotton is very different from pollination by bees of other crops. Therefore, the pollination of cotton requires special measures to improve the efficiency of the work of bees. In this article, we will consider the intricacies of pollinating cotton by bees.
Content
- Cotton culture in the world
- What does bee pollination of cotton crops give?
- How to pollinate cotton with bees
- Density of bees for cotton pollination
- What are the best bees for pollinating cotton?
- Where to place bees for cotton pollination
- Features of training bees for cotton
- Features of preparation and pollination of cotton by bees
- Risks for bees when pollinating cotton
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Cotton culture in the world
Cotton - the main supplier of raw materials for the production of woven fiber in the world - is not in vain received the second name "white gold". Cotton seeds are used in various ways as a raw material for the production of oil for food and technical purposes. At present, cotton is cultivated in tropical and subtropical zones in more than 80 countries of the world. Cotton occupies 2.5% of the world's agricultural land, which annually produces approximately 25 million tons of cotton fiber. The main cotton producing countries include China (crop in 2012-2013 - 6.7 million tons), India (5.1), USA (3.8), Pakistan (2.1), Brazil (1. 5), Australia (0.9), Uzbekistan (0.9), Turkey (0.6), countries - former French colonies in Africa (0.4), Turkmenistan (0.3), Greece (0.3) , Mexico (0.2), Burkina Faso (0.2), Mali (0.2). The rest of the countries in 2012-2013 accounted for about 1.7 million tons of cotton harvest.
Cotton is also grown in Russia. Work on the resumption of cotton growing in the southern regions of Russia began in 1992 in the Krasnodar and Stavropol Territories, as well as in the Astrakhan Region. Productivity fluctuated within 12-15 c/ha. At the same time, it was found that the conditions of the Krasnodar Territory are not suitable for cotton due to high humidity and rich soils. The Stavropol Territory and the Astrakhan Region turned out to be more favorable for growing cotton. According to A.N. Abaldov in these regions, more than 300 thousand hectares can be taken for cotton. Breeders have bred ultra-early varieties that make it possible to grow cotton in the Volgograd region, which is the northern border of cotton growing in Russia.
The average yield of raw cotton in the world is 2.3 t/ha, the highest (more than 4-4.5 t/ha) is observed in developed countries where modern technologies for its cultivation are used - Australia, Israel, China. It is interesting that in such countries as the USA and Uzbekistan, where the cultivation of cotton is of great economic importance, the average yield is close to the world average - 2.4-2.5 t/ha. Despite the low yield of cotton fiber in Uzbekistan, this country is a leader in cotton exports.
As you can see, cotton is an important crop that occupies vast areas, both in the world and in Russia, Uzbekistan, Kazakhstan, Turkmenistan, Tajikistan, and Azerbaijan.
Nevertheless, it is always tempting to get more yield from one unit of area. Especially when you consider that the yield in these countries is below or equal to the world average. This is especially important for the countries of Central Asia, where population growth requires an increase in the area under food crops, while at the same time the need to save water for irrigation, which means it is important to get a larger cotton yield from each existing field.
One way to get more cotton yields is to receive pollination from bees.
What does pollination of cotton crops by bees give?
Cotton is usually considered a self-pollinating crop. However, cotton responds well to cross-pollination. Pollinators can be wild bees and honey bees, with wild bees playing a minimal role in pollination due to their small body size. Therefore, the main place in the pollination of cotton belongs to honey bees.
But what does bee pollination of cotton crops give?
Earlier, during the Soviet era, a number of experiments were carried out, which showed the following results.
With good pollination of cotton flowers by bees, the percentage of falling ovaries decreases by 18-19%, the average number of bolls per bush increases, and the average weight of each bolus noticeably increases. It is important to note that a decrease in the weight of the calyx was observed, that is, while the weight of parts of the flower not directly related to reproduction decreased, the weight of seeds and voles (fibers), i.e. those parts that are directly related to it, increased .
The yield of cotton can be increased at the same time by 5-9 centners per 1 ha, which, depending on the conditions of pollination by bees of cotton, was 10.1 - 27.7% increase in the number of full-fledged bolls. And in some cases, the increase was 11.2 centners per hectare - 29.2%.
When pollinated chelami cotton bolls ripen faster by 5-9 days and ripening is more even.
When pollinated by bees, the strength of the fibers increases.
With good pollination of cotton by bees, there is a slight increase in the length and output of the fiber, as well as coarsening of seeds.
The use of bees for cotton pollination will also prove to be most effective in seed-growing work with cotton.
In general, it can be noted that as a result of pollination by bees of cotton, the number of seeds increases, as well as their weight (the mass of 1000 seeds is 2.7–7.83 grams heavier), and in addition, the quality of the seeds is much higher than with self-pollination.
With the help of bees, without any additional labor costs, intra-varietal crossing of plants will be carried out, which will improve heredity and increase the vitality of seed offspring.
Depending on the conditions of existence and varietal characteristics, the degree of cross-pollination of cotton varies from 0 to 100%; at the same time, it was found that with additional cross-pollination of its flowers, the egg is completely fertilized, and as a result, the yield increases and the quality of raw cotton improves.
Cotton seeds obtained as a result of cross-pollination are distinguished by better germination and vigor of germination; at the same time, there is less dropping of buds and ovaries, the boxes open more amicably, and as a result, higher yields are obtained from seeds of cross-pollination than from seeds set after self-pollination.
With prolonged self-pollination of cotton, after 2-3 years, a decrease in the productivity of varieties begins, a weakening of seedlings is noted, and after 4-5 years of self-pollination, sterile and semi-sterile plants appear. The quality of seeds, under the influence of pollination by bees of cotton, increases from year to year.
The number of bolls formed in one plant after a three-year pollination of cotton by bees was on average 23-48% more than in plants of the third generation obtained without pollination by bees. The weight of the boxes, starting from the first generation, increases. In the third generation, this increase averages 20-27%.
How to pollinate cotton with bees
Density of bees for cotton pollination
It is believed that for good pollination by bees, 5 families of bees per 1 hectare of cotton are needed. According to the Bureau of Entomology and Plant Quarantine in Arizona, made in the middle of the twentieth century, up to 12 colonies of bees per 1 hectare of cotton are required.
How many bees are needed to pollinate 1 hectare of cotton?
The experience of Uzbekistan in the mid-twentieth century shows that the density of 4.9 colonies of bees per 1 hectare gave an increase of 4.5 centners of raw cotton per 1 ha, which amounted to an increase in yield by 20.9%. The density of 6.6 colonies of bees per 1 hectare gave an increase of 9.2 centners of raw cotton per 1 hectare, which amounted to an increase in yield by 45.5%.
However, there are also lower standard densities of bees for cotton pollination. So Professor A. M. Kuliev suggested 0.3-0.5 bee colonies for commercial crops and 0.5 - 1 bee colony for seed plots. But still, such densities seem to be too small to ensure efficient pollination of cotton. Apparently, these densities were calculated focusing not so much on the high-quality pollination of cotton, but on obtaining an acceptable honey yield in case of passing pollination of cotton by bees.
In far-abroad countries, many authors agree that pollination by bees has a positive effect on the yield, but experiments on the optimal density of bees in cotton fields have not been carried out. Therefore, let's say in Australia, the density of bees for pollinating cotton is 1 bee colony per 1 hectare.
Which bees are best for pollinating cotton
It was recommended to attract long-proboscis bees for pollination of cotton. As a rule, long-proboscis bees are gray or yellow Caucasian bees, which can not only visit cotton flowers well, but also tolerate high temperatures well.
Where to place bees for cotton pollination
As with other crops, it is true for cotton that as the plants move away from the hive, pollination efficiency decreases. It has been experimentally established that bees visit cotton flowers best of all within a radius of up to 50 m from the hive.
When the plants are 500 meters away from the hive, the bees visit them weakly, and there is no significant increase in yield. Therefore, as a rule, bees are taken out to the middle of the field or hives are placed in small groups along the perimeter of the field, at intervals of 150 m.
The beehives are taken to the field by the beginning of flowering and kept until the end of the flowering of cotton.
When setting up beehives for pollination of cotton, one should not neglect methods to reduce the effect of heat on bees (shading the hives). There must be a source of water nearby or the hives must be equipped with intra-hive drinkers, otherwise the mass of bees will be busy bringing water to the hive, and not pollinating the cotton.
Features of training bees for cotton
As a rule, the training of bees for enhanced visits to cotton according to the generally accepted method, when the flowers of the plant are added to the syrup, does not positive result and is not expressed in additional pollination of cotton. This is explained by the fact that, crawling along the inner wall of the corolla, the bees do not touch the anthers and stigmas.
Therefore, the number of bees on cotton flowers increases, but pollination does not increase from this. It was found that only 18.41% of visits by bees to the inside of the flower lead to cross-pollination.
Therefore, the task of developing a conditioned reflex in honey bees to visit the anthers and stigmas of a cotton flower is not so simple.
For effective training of bees, feeding with syrup is used according to the following recipe.
Instead of whole flowers, anthers are added to the syrup, cut with a razor from 50 flowers, which are added to 100 g of sugar syrup containing 50 g of sugar and 50 g of water. In the future, the distribution of syrup to bees for training bees is carried out according to the general method.
After training the bees, they flew to the cotton flowers. At the same time, the bees came into contact with the anthers and were covered with cotton pollen. Not finding nectar in the anthers, the bees began to intensively search for food, moved their antennae to the sides and gradually descended down the stamen filament. At the same time, the body of the bees was more and more covered with pollen. In the end, not finding nectar, they flew to another cotton flower.
This trick is based on the knowledge that each part of the flower has its own distinct scent, which is what makes bee training successful.
Also a good result is the training of bees with the help of syrup with the addition of stigmas of cotton flowers.
Arriving at the flower, the bees sit directly on the stigma, then move their antennae in one direction and the other and gradually descend down the stamen filament. At the same time, the entire body of the bee was covered with pollen. Having descended to the base of the flower, the bees move their antennae and then stick their proboscis to the nectaries.
When applying such training (feeding with syrup with the smell of anthers and stigmas), bees pollinate cotton flowers well, which allows increasing the amount of cotton fiber by 35 - 40%.
Features of preparation and pollination of cotton by bees
When preparing bee colonies for cotton pollination, it is important to keep them in working order. So at the end of April, the gardens finish blooming and the herbs dry up, and the temperature rises to 35 - 40 C, and this lasts more than a month before the start of cotton flowering. That is, a non-blooming period of 30-45 days causes a weakening of the strength of families. Families need to migrate or sow honey plants near a stationary apiary. This will keep the families in working order by the beginning of cotton pollination.
It is important to note that when bees pollinate other crops, one of the methods to increase the pollination activity of bees is to select frames with bee bread and install pollen traps. In the case of pollination of cotton, not everything is so simple. The bees don't always carry cotton. The increased pollination of cotton by bees is due to the fact that their cephalothorax is simply strewn with pollen and this works great for pollinating cotton, but they do not always form a pollinator that can be removed with a pollen trap. This is due to the peculiarities of the pollen itself, in some varieties of cotton, it is large and spiked, which does not allow the bees to form pollen, in other varieties of cotton, the pollen is small and the bees easily form pollen.
Therefore, this technique - the selection of frames with bee bread and the installation of a pollen trap, can be carried out only on those varieties of cotton on which bees have the opportunity to form a bee pollen. In the case of pollination of cotton varieties, where the bees cannot form a pollinator, protein supplements will be useful to support the development of bee colonies.
Risks for bees when pollinating cotton
An important feature of cotton pollination by bees is the need to take measures to save bees from the action of chemical field treatments. In this case, it is important to establish communication between the beekeeper and the farmer in order to receive timely information about future treatments, so that the beekeeper has time to isolate the bees for several days or transport them to a safe place.
There are also opportunities to complete chemical treatments before cotton blooms.
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