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Floral bud distortion (FBD) in soybean

Floral bud distortion in soybean refers to an abnormality or deformity in the development of floral buds in soybean plants (Glycine max). It is characterized by the distortion, malformation, or abortion of flower buds, which can lead to reduced flower production and subsequently affect seed setting and yield. (Easily visible in picture and infographic).

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Floral bud distortion (FBD) in soybean

Author: Prashant B. Kale (Ph.D.)

In recent years the occurrence of floral bud distortion is being consistently observed in the central Indian regions. The symptoms recorded do not resemble the documented diseases or disorders of soybean. Therefore, farmers rarely recognize the symptoms and know the plant by different local names.

Floral bud distortion in soybean can have various causes, including environmental factors, phytoplasmas, viral infections, or hormonal imbalances, and insect involvement. Here are some common factors associated with floral bud distortion in soybean.

A. Phytoplasma in soybean:

Phytoplasmas are specialized bacteria that are associated with a group of plant diseases known as phytoplasma diseases or yellows diseases. These are obligate intracellular parasites, meaning they cannot survive or reproduce outside of plant cells. They are transmitted from plant to plant primarily by insect vectors, such as leafhoppers, planthoppers, or psyllids.

In soybean, phytoplasmas cause "phytoplasma yellows" or "soybean witches' broom." Phytoplasma yellows are characterized by a range of symptoms, including yellowing and wilting of leaves, stunting of plants, abnormal development of shoots, and the formation of excessive branching or "witches' brooms." Most of the time pods get converted to leaf-like structures.

When phytoplasmas infect soybean plants, they multiply within the plant's phloem tissues, which are responsible for transporting sugars and nutrients throughout the plant. This disrupts the normal flow of nutrients, resulting in the characteristic symptoms observed in infected plants. The transmission of phytoplasmas in soybeans primarily occurs through insect vectors. The insects feed on infected plants and carry the phytoplasmas to healthy plants. Phytoplasmas can also be transmitted through vegetative propagation, such as grafting or taking cuttings from infected plants.

B. Other factors responsible for abnormal flowers in soybean-

1. Environmental stress:

Extreme weather conditions, such as high temperatures, drought, or excessive rainfall, can disrupt the normal development of floral buds in soybean plants. Stressful conditions during flowering can result in bud malformation or abortion.

2. Viral infections:

Certain viruses can infect soybean plants and cause floral bud distortion. For example, the Soybean mosaic virus (SMV) and the Bean pod mottle virus (BPMV) have been associated with floral bud malformation and reduced flower production in soybean.

3. Hormonal imbalances:

Disturbances in the balance of plant hormones, such as auxins or gibberellins, can lead to floral bud distortion. Hormonal imbalances can occur due to genetic factors, environmental stress, or chemical imbalances within the plant.

4. Genetic factors:

Some soybean cultivars may be more susceptible to floral bud distortion than others due to inherent genetic traits. Certain genetic backgrounds or specific combinations of genes can make plants more prone to developing distorted floral buds.

C. Integrated control measures:

Floral bud distortion FBD can have a negative impact on soybean yield as it affects flower production and subsequent seed setting. Farmers can minimize the occurrence of floral bud distortion in soybean through the following integrated control measures:

1. Crop management:

Implementing proper crop management practices, such as timely irrigation (critical growth stages), optimal nutrient management, and providing suitable growing conditions, can help reduce environmental stress on soybean plants during vegetative and reproductive phases.

2. Disease management:

Employing disease management strategies, including planting disease-resistant soybean varieties and practicing crop rotation, can help reduce the incidence of viral infections that may contribute to floral bud distortion.

3. Genetic selection and use of disease-resistant varieties:

Planting soybean varieties that are resistant to or tolerant of phytoplasma infections can reduce the impact of the disease. Similarly, soybean varieties that are known to have lower susceptibility to viral diseases and floral bud distortion can be beneficial. Consulting local agricultural experts or plant breeders can provide information on available soybean cultivars with improved tolerance to this issue.

4. Weed control:

weeds are secondary hosts for the disease and peats of main crops. Following effective weed control measures (manual, mechanical and chemical) can help minimize stress on soybean plants and reduce the likelihood of floral bud distortion.

5. Control of insect vectors:

Implementing measures to control or reduce populations of the insect vectors can help prevent the spread of phytoplasmas. This may include using insecticides, employing traditional practices like trap crops or companion planting, or timing planting to avoid insect activity.

6. Rogueing and removal of infected plants:

Promptly identifying and removing infected soybean plants from the field can help prevent the spread of phytoplasmas to healthy plants.

7. Crop rotation: :

Implementing crop rotation practices can help break the cycle of phytoplasma infection. Avoid planting soybeans or other susceptible crops in the same area for consecutive seasons.

Note:

Regular scouting and monitoring of soybean plants before and during the flowering period can help identify early signs of floral bud distortion. If the issue becomes prevalent, consulting with agricultural experts or extension services in the nearest region can provide guidance on appropriate management strategies specific to farming conditions.

Keywords:

"soybean floral bud distortion," "flower malformation in soybean," "abnormal flower development in soybean," "no podding syndrome in soybean"

Reference:

https://www.ajol.info/index.php/ejb/article/view/95782

Tuesday 6 June 2023