How is bee pollination carried out for tomato cultivation in greenhouses?
GreenhouseHow is bee pollination used for tomato cultivation?
Fund project: Qinghai Provincial Department of Science and Technology "Agricultural Science and Technology Achievement Transformation and Extension Program - Experimental Demonstration and Extension of New Space Vegetable Varieties" project (project number: 2012-N-507).
Tomato is a self-pollinating crop. In greenhouses, especially during the winter-spring crop season, due to the high air humidity, low temperature, lack of wind and lack of pollinating insects inside the greenhouse, the crop is prone to obstacles such as poor pollen shedding and difficult pollination, and shows severe flower drop, low fruit set rate, and the formation of more deformed fruits. When carrying out artificial pollination of greenhouse vegetables, traditional hormone treatment is relatively ideal for increasing yield, but after pollination the fruit quality and taste are poor, the rate of deformed fruits is also high, and it can also cause hormone residues that contaminate the fruit, and it requires manual flower dipping, which is time-consuming and labor-intensive. Using bumblebees to pollinate greenhouse vegetables can effectively solve the above problems. Bumblebees have the following characteristics: they pollinate a wide range of crops, and are suitable for both plants with nectaries and plants without nectaries, whereas honeybees only visit plants with pollen and nectar; bumblebees tolerate a wide range of temperature and humidity, and are active normally within the range of 10°C to 32°C; they have a long proboscis, and are more effective at pollinating plants with deep corollas, such as tomato, pepper and eggplant; they have strong foraging ability, and can visit 18 to 22 flowers per minute, and each bumblebee can carry millions of pollen grains, so their utilization rate of nectar and pollen sources is more timely and effective than other bee species, and their pollination efficiency is far higher than that of honeybees; they tolerate low temperature and low light, and on cold, overcast days when honeybees do not leave the hive, bumblebees can still leave the hive to forage and pollinate as usual; they have strong humidity tolerance and poor phototaxis, and unlike honeybees they do not fly against glass and greenhouse structures, and can collect from plant flowers even under low temperature and high humidity; their information exchange and transmission system is not well developed, and bumblebees lack a sensitive information exchange system, which is shown in their ability to focus on pollinating a single crop, making them particularly suitable for greenhouse crops; when bumblebees fly, their two wings buzz loudly, and the flowers of some plants release pollen only when shaken by the buzzing sound of insects, which makes bumblebees the ideal pollinators for these buzz-pollinated crops such as tomato, strawberry and eggplant. Bumblebees have extremely strong pollination ability; as long as 60 to 80 worker bees leave the hive, they can meet the pollination needs of 1 to 2 mu of solar greenhouse or plastic greenhouse, and can not only increase vegetable yield, but also effectively prevent pollution and improve fruit quality.
1 Materials and Methods
1.1 Materials
Test material (variety): early-maturing tomato (variety Hezuo 903), from the Xining Seed Station; bumblebees: provided by Hebei Hengshui Wofeng Technology Co., Ltd.
Test chemical: plant growth regulator hormone 2,4-D, purchased from Dalian Songliao Chemical Company (a plant growth regulator commonly used in production).
1.2 Experimental Design
The experiment was a test of the effects of different pollination methods on tomato pollination, designed with 3 treatments and 3 replications. The 3 treatments were: Treatment 1: blank control chamber; Treatment 2: hormone treatment chamber; Treatment 3: bumblebee pollination chamber. The area of each treatment plot was 333 sq m. For each replication of the experiment, three greenhouses with basically consistent basic conditions such as soil composition and fertility were selected, and data collection used a completely random testing method.
1.3 Experimental Methods
The experiment was carried out from April to September 2016 in the greenhouses of Xining Huitian Planting and Breeding Company. In the experiment, tomato cultivation used a wide row spacing of 70 cm, a narrow row spacing of 40 cm, and a plant spacing of 30 cm. Planting was on February 28, pollination was carried out from April 20 to June 20, and the pollination method followed the experimental design; fruit harvesting and data collection were carried out from May 20 to August 10.
1.4 Observation Indicators and Data Processing
During the fruit harvesting period, tomatoes from different treatments were selected for observation of single fruit weight, total number of fruits per plant, number of deformed fruits, fruit longitudinal diameter and transverse diameter, and data statistical analysis used software such as DPS and Excel.
2 Results and Analysis
2.1 Effects of Different Pollination Methods on Tomato Yield
The effects of different pollination methods on tomato production indicators are shown in Table 1, and the results show that: (1) The total fruit number and yield indicators of the hormone treatment and bumblebee treatment performed better than the blank control, with total fruit number increasing by 24.94% and 16.37% respectively, and yield increasing by 26.61% and 13.32% respectively, indicating that both treatments can promote tomato yield. In the indicators of single fruit weight, longitudinal diameter and transverse diameter, the hormone treatment group was inferior to the blank control, while the bumblebee treatment was superior to the blank control, increasing by 29.08%, 3.98% and 3.14% respectively. (2) Although both the hormone treatment and the bumblebee treatment clearly increased tomato yield, their contribution rates to each tomato yield indicator were different. The yield-increasing effect of the hormone treatment was shown only in total fruit number, indicating that hormone treatment is beneficial to increasing the fruit set rate of tomato, thereby leading to increased yield; the bumblebee treatment not only increased the fruit set rate, but also affected other economic indicators to varying degrees. (3) Each production indicator of tomato under the bumblebee treatment
was better than under the hormone treatment, and this was especially obvious in the deformity rate indicator; with the bumblebee pollination method, the fruits were plump and full.
Through analysis of variance on tomato production indicators (see Table 2), the results show that there were differences at different levels among the different treatments for each tomato production indicator. (1) For total fruit number, F=83.09≥F0.01=18 among treatments, and there were differences among treatments; by comparison with the new multiple range method, there were significant differences among treatments at the 5% level, and at the 1% level there was no significant difference between the bumblebee treatment and the hormone treatment, but there was a significant difference between them and the blank treatment. (2) For the deformity rate indicator, F=31.74≥F0.01=18 among treatments, and the differences among treatments were consistent at the 5% and 1% levels; by comparison with the new multiple range method, there was a significant difference between the bumblebee treatment and the hormone treatment, while the difference from the blank treatment was not significant; among blocks, F=2.26≤F0.05=6.94, and the difference among blocks was not large, so the experimental results are reliable. (3) For the single fruit weight indicator, F=56.64≥F0.01=18 among treatments, and the differences among treatments were significant at the F0.01 level; by comparison with the new multiple range method, the bumblebee treatment was significantly different from the hormone treatment and the blank treatment at the 1% level, while the difference between the hormone treatment and the blank treatment was not significant; among blocks, F=5.7≤F0.01=18, and the difference among blocks was not large, so the experimental results are reliable. (4) For the longitudinal diameter and transverse diameter indicators, the F values among treatments were 62.46 and 121.85 respectively, both greater than the F0.05 and F0.01 values, and there were differences among treatments; by comparison with the new multiple range method, for the longitudinal diameter indicator there was no significant difference between the bumblebee treatment and the blank treatment, but both had significant differences from the hormone treatment at the 5% and 1% levels; for the transverse diameter indicator, there were significant differences among treatments at the 5% level, and at the 1% level the hormone treatment performed poorly and had significant differences from the bumblebee treatment and the blank treatment; however, for the longitudinal diameter and transverse diameter indicators, the F values among blocks were 40.97 and 142.5 respectively, both greater than the F0.05 value, and the results show that there were differences among experimental blocks, which would affect the reliability of the above results. (5) For the yield indicator, the F values were 62.46 and 121.85 respectively, both greater than the F0.05 and F0.01 values, and there were differences among treatments; by comparison with the new multiple range method, there were extremely significant differences among treatments at the 1% level.
Table 1 Effects of Different Pollination Methods on Tomato Production Indicators
Table 2 Results of Analysis of Variance
2.2 Effects of Different Pollination Methods on Tomato Quality
Through experimental observation and analysis, it was found (see Table 3) that the different treatments had relatively large differences in their effects on the early-maturing tomato Hezuo 903. (1) The peak ripening period of tomato fruits under the bumblebee pollination treatment was obviously earlier than under the hormone treatment and the blank control. (2) Fruits under the bumblebee pollination treatment showed good ripeness, bright color, and plump, full fruit shape; the blank control treatment showed poor ripeness, dull fruit color, and small fruit that was not plump enough; the hormone 2,4-D treatment showed ripe fruit, relatively fresh color, and plump fruit shape. (3) Fruits under the bumblebee pollination treatment had a rich fruity aroma, were fresh and juicy, and had good seed maturity with many seeds; the blank treatment had little juice, poor taste, and almost no seeds in the fruit; the hormone 2,4-D treatment showed little juice, a relatively hard taste, and low seed content in the fruit that was not mature. Through experimental observation, it was found that bumblebee pollination can significantly increase the marketable rate and yield of tomato, reduce fruit deformity, and improve fruit quality.
Table 3 Effects of Different Pollination Methods on Quality
2.3 Economic Benefit Analysis
The economic benefit analysis (see Table 4) shows that the cost of one box of bumblebees for a 333 sq m greenhouse is about 350 yuan (bumblebee price: 350 yuan/80 bees, with 80 bees per box).
The cost of using 2,4-D is about 1 yuan, but using 2,4-D requires manual flower spotting, and a 333 sq m greenhouse requires 240 yuan in labor costs for flower spotting (6 flower spot treatments in total, each requiring 2 workers for one day to finish, with labor cost of 20 yuan per person per day), so after deducting costs, using bumblebee pollination and using 2,4-D can increase net income per greenhouse by about 896.6 yuan and 117.4 yuan respectively; the input-output ratios per greenhouse for using bumblebee pollination and using 2,4-D were 1:2.28 and 1:1.24 respectively, and farmers can earn more income by using bumblebee pollination in greenhouse tomato production (the total yield of a 333 sq m blank control greenhouse was about 2,500 kg, calculated according to the tomato market price, with 1.2 yuan/kg for good marketability and 0.9 yuan/kg for poor marketability).
Table 4 Economic Benefit Analysis of Different Pollination Methods
3 Summary and Discussion
3.1 Summary
(1) Bumblebee pollination has advantages in production. Using bumblebees to pollinate greenhouse tomatoes is a low-cost, high-efficiency, pollution-free modern high-tech agricultural technical measure, with effects of low input, time saving, labor saving and sustainable development.
(2) All production indicators of tomato under the bumblebee treatment were better than under the hormone treatment, and it can effectively reduce the deformity rate and improve fruit appearance quality and taste.
(3) Using bumblebee pollination in greenhouse production can not only achieve the best pollination effect, but also, because "bumblebees" pollinate when pollen is most abundant and their activity is strongest, they can form more ovules and seeds, making the fruit vegetables firmer in texture, thus improving the quality of vegetables and fruits; moreover, pollination is completed by "bumblebees," the hive is made of natural materials, suitable for "bumblebee" survival, and is equipped with food, so once placed in a plastic greenhouse or greenhouse, no management is needed, saving time and effort; after releasing the bees, the use of toxic drugs is reduced, especially eliminating the use of plant growth hormones and their residues on fruits and vegetables, reducing contamination of fruits and vegetables, and benefiting consumers' food health.
3.2 Discussion
Although bumblebee pollination has advantages in production application, the following matters need attention.
(1) Prevent stinging. Avoid strong vibration of the hive or knocking on the hive, and workers should not wear blue clothes or use perfumes and other cosmetics.
(2) Apply pesticides reasonably. After the bumblebees return to the hive, move the hive out of the greenhouse before applying pesticides, and put it back in the original place two days later. It is strictly forbidden to apply slow-acting insecticides, wettable powders, fumigants and pesticides containing sulfur, etc.
In summary, in order to safely and effectively accelerate the production of pollution-free vegetables in greenhouses in this city, we should increase the promotion and application of bumblebee pollination technology.