Occurrence characteristics and integrated control technology of weedy rice in the area along the Yangtze River
In recent years, weedy rice has developed into an important malignant weed in rice production along the Yangtze River, which seriously threatens rice production, especially in dry-field cultivation of paddy field weedy rice. How to find out the occurrence characteristics of weedy rice as soon as possible, actively explore the control methods of weedy rice, and integrate the supporting and effective prevention and control technology of rice field weedy rice and promote its application has become a key technical problem that needs to be solved in rice production. . To this end, we conducted continuous investigations and experimental studies on the morphological characteristics, occurrence characteristics, and prevention and control measures of weedy rice from 2010 to 2017. The relevant experimental research and survey results are summarized as follows:
I. Overview of the occurrence of weedy rice along the Yangtze River
Tongzhou District, Nantong City, Jiangsu Province is located in the Yangtze River downstream of the Yangtze River. In terms of agricultural production, the perennial rice and wheat (oil) are both cooked, and the per capita land is only about 0.6 mu. The grain and oil are basically self-sufficient. Since the mid-1990s, rice cultivation has promoted large-scale cultivation techniques such as throwing, dry and thin planting, dry direct seeding, etc. Since the dry-lived cultivation method is simpler, it has developed into the main cultivation method in the late 1990s. In Xingren Town of Tongzhou District, 18,600 mu of rice is planted all year round, of which 16800 mu is cultivated in dry land, accounting for more than 90% of the total area of ​​rice. Due to the small per capita land area, in order to ensure the demand for rations, rice cultivation has been continuously cropped for many years, and the area of ​​continuous cropping accounts for more than 95% of the planted area. This provides good ecological conditions for the occurrence of malignant weeds such as weedy rice. Weedy rice was rare in the field in the early 1990s. At that time, the damage was not outstanding, but it began to spread rapidly at the beginning of this century, and its area was less than 10% from the initial 10%. The field grass rate is also increased from an average of 1 plant per square meter to 2 to 3 plants, and individual fields are as high as 5 to 6 plants. Weedy rice grows in the field and rice, and its growth potential often exceeds that of rice cultivation, contending with rice, vying for water, competing for fertilizer, and seriously affecting rice quality, becoming a rice killer, and farmers are deeply hated.
2. Morphological characteristics and occurrence characteristics of weedy rice
1. Morphological characteristics of weedy rice
It has been observed that the morphological characteristics of weedy rice are different from conventional rice. Leaf type: Weedy rice leaves are broad and green; plant type: plants are generally high, often divided into two types, high in dwarf species, loose plant type, large tiller angle, soft and tender leaf sheath, dwarf Relatively high species compact; root system: more developed than cultivars, irregular roots in nodes; spike type: indica type, larger and curved panicle, more grains per spike, sparse rice arrangement, awning, lower seed setting rate The husk is golden yellow or brown, entering the stem of the late growth stage, the leaves are rapidly senescent, the stem becomes weak, and the ground is easy to lick; the granular type: the rice is thin and long, the rice is brittle, the rice husk is reddish brown, and the thousand grain weight is low. . (see picture 1)
2. Characteristics of weedy rice
Weedy rice not only has certain characteristics of cultivated rice, but also has the characteristics of wild rice. It is called rice, non-rice, grassy and non-grass. It can reproduce naturally in rice fields and continue its offspring, and compete with cultivated rice for light, water and fertilizer. Such natural resources, because of its harm like weeds, it is called weedy rice. According to the investigation and observation, it has the following characteristics:
First, the leaves are quick to shoot at the seedling stage. Under the conditions of sowing with cultivated japonica rice, the early emergence of seedlings, early hairpins and early leaves were observed. In the dry field, the leaves were usually 1~3 leaves. Second, it is strong. The performance is faster and more divided. According to the comparison with the same field in early July 2013, the weedy rice is generally 2~3 more than the cultivated rice. Third, the heading period is early. Generally, it is 5 to 7 days earlier than cultivated rice, and the filling is fast, and the functional leaves are aging faster. Fourth, it is strong in falling. This is also an important feature. It tends to fall into the grain when it matures. This avoids harvesting. A large number of seeds fall into the field before harvesting, which provides conditions for natural reproduction. Seeds without grain can also be harvested normally with rice. With emergence, the emergence rate can still reach more than 90%. Fifth, the seed has obvious dormancy characteristics, and the dormancy period can reach 10 years. The seed that has been dormant will sprout out as long as the temperature is suitable. Sixth, weedy rice has extraordinary resilience. Weedy rice can still emerge after wintering in the field, but cultivated rice is impossible. The seventh is the poor rice traits of weedy rice, which is characterized by low yield, poor appearance quality and processing quality, and is not suitable for consumption. Eight is that weedy rice is harmful to cultivated rice. With the increase of the density of weedy rice in the field, it affected the normal growth of cultivated rice, and the number of spikes per plant, the number of grains per panicle, the seed setting rate and the 1000-grain weight of cultivated rice decreased significantly, so the reason for the decrease of cultivated rice yield It should be caused by the common number of spikes per plant, number of grains per panicle, seed setting rate and 1000-grain weight. Nine is the fertility of weedy rice. According to the data, when there are 1 plant, 3 plants, 5 plants, 7 plants and 9 plants per square meter of cultivated rice fields, the yield reduction can be caused by 1.37%, 24.7%, 36.9% and 44.6%, respectively.
Third, weed rice control technology research
Weedy rice and cultivated rice belong to the same family of Gramineae, it is not possible to weed with selective herbicides , but it is not helpless to deal with weedy rice. Through our recent research and consulting related literature, we can find that agricultural measures can be used to deal with It can be started from the following aspects:
1. Improve cultivation methods and implement water and drought rotation
According to our investigations in Xingren Town and Wuji Town, the method of water and drought rotation can effectively stop the harm of weedy rice. For example, there are more than 30 farmers in the village group of 52 and 53 in Dayigang Village of Wujie Town. For many years, it has been used for water and drought rotation (that is, the first year of planting dry rice, the second year of planting soybeans), and it has been rotated for nearly 10 years. According to the survey, the germination rate of weedy rice can be reduced to less than 0.01 plants/m2, which is much lower than that of dry-field continuous cropping. The effect is very obvious. (See Table 1)
2. Improve farming methods
First, it is a long-awaited rotation. According to the results of the Jiangsu Academy of Agricultural Sciences and the Taihu Institute of Agricultural Sciences, the ammonium nitrogen can be increased by 70%, the available phosphorus can be increased by 35%, and the available potassium can be increased for the continuous tillage of more than 6 years of paddy field. Increase by 43%, so that the fertility of the soil under the tillage layer can be significantly improved. Therefore, the current no-till field should be implemented in a reasonable rotation in the future; every year or 2 to 3 years, a round of ploughing (10~15cm of ploughing depth), if combined with the application of organic fertilizer, this is undoubtedly a farmland Major improvements. The benefits of this can not only significantly improve the physical and chemical properties of the soil, but also improve the productivity of the soil. It can also make the seeds of malignant weeds such as weedy rice buried deep under the soil and greatly reduce the germination rate.
The second is to improve the cultivation method. In summary, there are mainly five types of rice cultivation methods promoted in the past 20 years, namely dry live broadcast, direct water broadcast, artificial throwing, dry and thin planting, and machine transplanting. These five cultivation methods have their own advantages and disadvantages in improving rice yield and quality, improving soil and inhibiting weeds. Among them, dry-seeded rice is easy to operate, but it is beneficial to the occurrence of weeds including weedy rice. Cultivation methods such as artificial throwing, dry breeding, and transplanting, because of the need to plow the land before planting, there is no such worry. Therefore, the author suggests to minimize the planting area of ​​dry-broad rice, especially continuous direct seeding rice, expand the artificial planting, especially the area of ​​machine transplanting, and create conditions to adopt the water-and-dry rotation method, which is beneficial to the benign ecological balance of the soil, benefiting and eliminating the disadvantages, and achieving the suppression of miscellaneous Grass improves soil, reduces planting risk, prolongs growth period, and ultimately helps to improve rice yield and quality.
The third is to manually remove the impurities. The field where weedy rice occurs can be manually removed. Although it is time-consuming and laborious, in the case where other methods are difficult to work, in the area where the labor is abundant and the density of the weedy rice in the field is not too high, the implementation of this method is still An effective method, such as the author's town in the town of 18,600 acres of rice in 2013, the manual extraction of weedy rice, the first census in early July, the dry grass field weed rice field density, from the average of 2.3 before extraction / M2 is reduced to 0.1 strain/m2 or less. On September 20th, the grass density of weedy rice was still checked at 0.1 plants/m2, and the herbicidal effect was 95.65%. The artificial weeding effect was very significant.
Practice has proved that to do a good job of manual mixing, the key is to master two points: First, we must grasp the seedling stage to remove, the weedy rice in the seedling stage is easy to identify, and its plant height, stem diameter, leaf width and growth are obviously different. The second is to grasp the seedling stage before the fruiting (to avoid the seeds falling into the field) and to remove the whole plant and bring it out of the field.
The fourth is to carry out strict supervision during the whole growth period and to make four good customs. The first is to shut down the seeds. Strengthen the monitoring of seed breeding fields, and carefully select the grain selection (the japonica seeds and weed seeds are easily identifiable) before planting to prevent the weedy rice seeds from being mixed into the field. The second is to make good education. When selecting the nursery base, the planting files of the former crops should be checked, and the field where the rice is dry and directed is used as a breeding base to avoid the soil propagation. The third is to make a good pass. For the scorpion that has been rotated, it is also necessary to prevent the artificial or chemical from being left behind to prevent the seed from being left behind. The fourth is to close the harvest. The machine is harvested and cleaned up to avoid the introduction of weedy rice sources when harvesting from different places.
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