Causes and prevention of withered pods of Soybean [nongguangtiandi]
Cause and prevention of soybean blight [nongguangtiandi] video from CCTV nongguangtiandi
[nongguangtiandi] causes and prevention of soybean seed blight
A string of round pods, swaying with the wind, seems to be another harvest year. However, if you take a closer look, you will find that many pods are not full, and some are even empty Pods without seeds. This is the phenomenon of withered pods. In Soybean plant In the process, the phenomenon of withered pods was common. Once a large number of blighted pods appear, it will often lead to yield reduction, generally, it can lead to a reduction of about 5% - 15%, or even more serious, about 25%. So, what are the main reasons for the formation of soybean withered pods? How to prevent it? In fact, the main reason for the improper selection of soybean varieties is that they are not suitable for continuous cropping, plant Excessive density, unscientific fertilization, diseases and insect pests, etc. Therefore, in the farmer friend plant In the process of soybean, the corresponding preventive measures must be taken, so as to effectively reduce the occurrence of withered pods, so as to produce large pods and plump seeds.
Withered pods of soybean refers to the phenomenon that the seeds of soybean plants can not form normally after forming pods, resulting in empty pods. According to the investigation, the seed setting and pod forming rate of summer soybean is only 30% ～ 70%. Among them, 5% ～ 25% of the pods can't bulge due to various reasons, which results in the formation of withered pods, which affects the yield. How to reduce the withered pods and improve the normal plumping mature rate of pollinated flowers and pods is an effective measure to improve soybean yield.
1、 The reasons for the withered pods of Soybean (1) there are great differences among varieties in the phenomenon of withered pods. The occurrence of withered pods in middle late maturing varieties is more serious than that in early and middle maturing varieties. The varieties with infinite pod setting habit are more important than those with limited pod setting habit. The middle early maturing varieties and the varieties with limited pod setting habit turn to reproductive growth after a certain stage, while the middle late maturing varieties and infinite pod bearing habits varieties have vegetative growth and reproductive growth at the same time. In the case of suitable conditions and excessive nitrogen fertilizer, the vegetative growth is often too vigorous, which affects the transfer of photosynthetic products to flowers and pods, resulting in withered pods. （2） Because of different varieties and soil fertility levels, the suitable density of over density soybean varies greatly. Some varieties can grow 8000 plants per mu under high fertility conditions, and some varieties can plant 30000 plants per mu on poor land. Soybean planting When the density exceeded the suitable density of the variety, the population was too closed, and the middle and lower leaves turned yellow and fell off quickly due to poor ventilation and light transmission. Although the adjacent leaves can compensate part of the nutrients, the amount of compensation is limited. Therefore, the leaves turn yellow and fall off prematurely, while the flowers and pods can not be fully ripened normally, or fall off or form withered pods. （3） The proportion of nitrogen, phosphorus and potassium is improper, and trace elements are lack of nitrogen nutrients for soybean growth, including inorganic nitrogen absorbed from soil and biological nitrogen fixed by Rhizobium. These two kinds of nitrogen play different roles in the growth of soybean. Biological nitrogen plays a role in promoting balanced nutritional and reproductive growth of soybean, while inorganic nitrogen mainly promotes nutritional growth of soybean Biological nitrogen can not be replaced by inorganic nitrogen. In recent years, the fertilization level of wheat in Huang Huai Hai region has been greatly improved, especially the excessive use of nitrogen fertilizer and the lack of total phosphorus and potassium fertilizer, resulting in the imbalance of the proportion of nitrogen and phosphorus in the soil. More nitrogen fertilizer in the soil inhibited the reproductive activity of Soybean Rhizobium, reduced the nitrogen fixation capacity, resulting in excessive seedling growth, even if flowering and podding, due to less accumulation, transportation and storage of dry matter, finally leading to difficulty in grain filling and withered pods [source: www.nczfj. COM /]. In addition, soybean is lack of some trace elements. Although it can blossom and bear fruit, it often can't drum up seeds and form withered pods. For example, boron and molybdenum are essential trace elements for soybean development, which are closely related to pod formation. However, the content of boron and molybdenum in soil tillage layer of Xiangcheng County is low, so it is bound to increase the empty grain rate of soybean without topdressing. In particular, the empty grain rate of single plant increased year by year in the continuous cropping soybean plots. At present, there are still some problems, such as too shallow fertilization depth, seed and fertilizer in the same bed, same position, low fertilizer utilization rate, which affect the improvement of soybean yield. （4） Climate factors 1. Temperature Summer soybean flowering period is generally from the end of July to the first ten days of August, which is prone to drought and high temperature weather. The daily average temperature is about 30 ℃, sometimes the highest temperature is above 35 ℃. The suitable temperature for soybean flowering is generally about 22 ℃ - 25 ℃. If the temperature exceeds 30 ℃ for a long time, it will cause excessive respiration of plants, resulting in less dry matter accumulation, which will affect soybean flowering After pollination, the embryo plants were aborted to form withered pods. In the late growth stage of soybean, if the low temperature affects the filling speed of soybean, it will also cause higher empty grain rate. 2. Rainfall soybean is a crop that needs more water. The lifetime water requirement of winter wheat, corn, sorghum, millet and soybean is 260-400 tons, 200-300 tons, 200-300 tons, 160-200 tons and 300-400 tons, respectively. Most crops consume 300-650 grams of water per gram of dry matter, while soybean consumes 600-800 grams of water per gram of dry matter. The water requirement of soybean increased from branching to seed filling, which accounted for 60% - 80% of the total water requirement of soybean. The period from flowering to seed filling is the critical period of soybean water. The soil moisture should not be lower than 65% - 70% of the field capacity at this stage, and 80% of the maximum water holding capacity is the best. If the rainfall during this period is small, it will cause a large number of pods falling or soybean seed filling difficulty, reproductive growth is slow, nutrient growth is exuberant, late green, late maturing, withered pod is not solid. If the soil moisture in soybean field is too high, it will also cause the flowers and pods to fall off, and the diseases and insect pests will aggravate, which will lead to the withered pods. In the flowering and pod stage of soybean, waterlogging damage is more serious than drought, especially waterlogging disaster, empty grain rate and lodging rate are high. In addition, if the sowing date was delayed due to drought, the emergence date would be delayed and the energy accumulation during the growth period of soybean would be reduced, which would also result in the empty grain of soybean. 3. Light soybean is a short day crop. In the alternation of day and night, soybean requires long night and short day. Soybean flowering and fruiting requires a certain length of continuous dark time and a certain length of light time alternating. If the illumination time is prolonged, the flowering of soybean plants will be delayed, which will lead to excessive vegetative growth of soybeans, malnutrition of flowers and pods and abscission. （5） Diseases and insect pests in soybean seedling stage aggravate the withered pods of soybean
。 For example, aphids spread virus diseases, and those infected with soybean virus diseases at seedling stage are easy to cause the whole plant of soybean to be green and withered pods; at the filling stage, the diseases and insect pests such as downy mildew, rust, gray spot disease, soybean aphid, red spider, soybean pod borer and soybean pod borer often cause blighted seeds and reduce the 100 seed weight of soybean. （6） Continuous cropping of soybean has led to serious diseases and insect pests of soybean; moreover, due to continuous cropping for many years, soil environment has deteriorated, which affects the reproduction of Rhizobium and reduces the ability of nitrogen fixation, resulting in imbalance of nutritional growth and reproductive growth of soybean, resulting in pods but not solid, forming withered pods. （1） It is an important link to obtain stable and high yield of soybean to select good varieties with strong stress resistance, high quality and low empty grain rate. According to the variety characteristics, combined with soil fertility and local existing conditions, Yudou 25, Xudou 12, Zhonghuang 13, Yudou 29, Xudou 3 and Xiangcheng local variety 94-3 can be selected in Xiangcheng County. At the same time, it is necessary to reasonably close planting, establish high light efficiency population, prevent over density and thinning, so as to make full use of land and improve efficiency. （2） In order to prevent the imbalance of soil nutrients, it is necessary to establish a reasonable system of soil tillage to avoid continuous cropping. Reasonable rotation can not only regulate soil nutrients, improve soil fertility, reduce the harm of diseases and pests and weeds, and improve soybean yield, but also reduce the rate of empty grain by more than 28.4% in soybean rotation plots. （3） The application of organic fertilizer and phosphorus and potassium fertilizer is too short to fertilize because the time is too short to fertilize when wheat and beans are harvested. Organic fertilizer should be applied in the wheat field of the previous crop, which can promote the robust soybean plant, developed root system, more rhizobia and more accumulated substances, which is conducive to the vegetative and reproductive growth. In order to make soybean grow well, high quality and high yield, it is necessary to increase the application of P and K fertilizer, especially for the field with serious withered pods. （4） Reasonable irrigation, timely prevention of drought and drainage of waterlogging before sowing soybean, when the drought moisture is poor, watering the bottom soil moisture can ensure that the soybean is sown at the right time, and the seedlings can be preserved by one sowing, laying a foundation for a bumper harvest; in the seedling stage of soybean, the soil moisture content is less than 15 days after emergence, which can promote the root system to root down, prevent the later lodging, and play the role of crouching seedlings, unless it is too dry or weak seedlings, generally not It is necessary to water; in the branching stage of soybean, i.e. 15-35 days of emergence, watering in case of drought can increase the height of plant and promote the differentiation of flower bud; the flowering and pod stage of soybean, which is about 25 days from flowering to seed filling, needs more water. Therefore, in order to meet the water demand and reduce the withered pods, irrigation should be carried out in time in case of drought and insufficient soil moisture during the filling period of soybean. （5） Foliar fertilizer should be sprayed every 7-10 days after the initial flowering stage of soybean, which can be continuously sprayed 3-4 times. It can not only prevent the plant from being fertilized, but also increase the grain weight and reduce the empty rate. In order to solve the problem of lack of element, spraying 0.2% zinc sulfate solution and 0.1% ～ 0.2% borax solution should be used to solve the problem of lack of boron. In addition, the use of growth inhibitors can reduce plant height, thicken stem, resist lodging, and increase pod number, seed number and 100 seed weight per plant. Generally, 40 grams of Paclobutrazol powder per mu at the initial flowering stage was sprayed with water, and the empty grain rate could be reduced by 7.2% and the yield increased by 17.2%. （6） Attention should be paid to the prevention and control of diseases and insect pests, and the spread of virus should be reduced. The occurrence of aphids should be paid attention to from the seedling stage of soybean. When the rate of aphid is 20% - 30% and some plants have rolled leaves, it should be controlled immediately. Special attention should be paid to the prediction and control of downy mildew, gray leaf spot, soybean borer, legume borer and leaf eating pests in flowering and pod stage.