What are good quality healthy seeds and why do they sink in water?


A seed is basically a plant embryo that has not been developed yet. In flowering plants, the seeds develop and grow into a fully matured plant through the process of germination. For agricultural purposes, the seed to be sown should be of good quality and must be healthy, that is they should not be infected by disease or infested by pests. Hence, for a better output that is the crop yield, the input that is the seeds should be selected properly.

In order to understand why healthy seeds, sink in water, let us first know what are good quality healthy seeds.

Selection of Seeds

The selection of seeds is important so that the farmers can understand which seeds to choose for a higher productivity rate. This step should be performed very carefully as it is the basis of meeting all the basic needs of human life. If a farmer loses a crop for a year because of poor-quality seeds the whole nation suffers due to a shortage of food.

Hence, we can say that seeds are the foundation of life. Moreover, healthy seeds ensure a healthy yield. Our government is playing an important role in helping the farmers by providing them with good quality and healthy seeds in places known as seed banks. A farmer can either buy their seeds from these banks or can use the seeds of the crop that they had harvested the previous year.

Just as we get infected by different diseases, so do plants. When seeds from infected plants are selected, then the whole field may get infected resulting in yield loss. Thus, the seeds obtained should always be from healthy plants.

Characteristics of A Good Quality Seed

The salient features of a good quality healthy seeds are given below −

Physical Quality

The physical quality of a seed is an attempt to understand the quality of the seed by just looking at it. Characters such as uniform size and shape should be considered. That is the seeds should not be hollow or shriveled. The weight and color of the seed are also taken into account.

That is, they should not be discoloured or moulded or look like diseased. Moreover, the seeds should be clean that is free from any unwanted particles like stones, twigs, or flower petals.

Genetic Purity

The genetic quality of seeds attributes to their genetic makeup, its bulk density, and size of the seed. The seedling from seed should resemble its parent plant in all aspects be it size or viability. It is better if the seeds selected are of better breed quality.

Physiological Quality

Physiological characters of the seed comprise seed germination and seed vigor. The liveliness of seed is known as viability.

Seed Health

A healthy seed is nothing but the absence of insect infestation and fungal infection, in or on the seed. Seed should not be infected with fungi or infested with insect pests.

Activity to Check Healthy Seeds

Here we are going to perform an experiment to check the viability of the seeds

Aim: To select healthy seeds for sowing.

Requirements: Bucket, water, hand full of seeds


  • Pour the seed grains into a bucket or a pan containing water.

  • Stir the contents well.

  • Most of the seeds will settle down at the bottom of the bucket but a few seeds will float on water.

Observation and Inference

An object floats in water because of a property known as density. Lighter objects float on water while heavier objects sink. The seeds that sink at the bottom of the bucket are healthy seeds. This is because healthy seeds contain all the basic required nutrients and other materials which make them heavier. Due to this reason, their density is higher than the density of water, hence, the healthy seeds sink at the bottom of the bucket.

On the other hand, seeds which are floating are not healthy. These unhealthy seeds float because they are light in weight as they can be partially eaten by pests or damaged by disease. These unhealthy seeds may look alike but can actually be empty and lack the basic required nutrients and other important materials required for a plant to grow.

As we can see from this experiment the density of seeds plays an important role in understanding which seeds are healthy and which are not.

Importance of Healthy Quality Seeds

Good quality and healthy seeds ensure that the crop has physical, genetical, and physiological purity. Such seeds will produce crops that can withstand adverse climatic changes. The seedlings will grow fast, have strong roots, and can resist pests and diseases. The roots developed in such crops are more efficient and can absorb nutrients and water more efficiently, which in turn results in higher yields. A high-quality seed can increase the production rate of least 10 – 12 %.


A good quality healthy seed should have a high physical quality that is good shape, size, and colour. Also, it should have appropriate weight. It should also have higher physiological vigor and viability as well as a higher germination rate, approximately 90 to 95% depending on the crop.

For a better and higher yield seeds should not be mixed with any other type of seeds. Other crop seeds are those plant seeds that are cultivated alongside. For example, seeds of wheat and barley are mixed together. If these seeds are mixed together, their yield might get affected.

A good quality healthy seed should be free from diseases. These diseases can spread far and wide, when they are present in the field. For example, loose smut of wheat. Sometimes if not taken proper care, they can pass on through generations.

Moreover, a good quality seed should be free from weed seeds. Weeds are harmful for the crop as their seeds are similar to size and shape of the crop seed that is difficult to remove mechanically. Also, they start competing with the crops for space, soil, water and sunlight. They can also serve as a host for pests and diseases.


Q1. Why are good quality seeds preferred?

Ans. Good quality seeds are preferred because they give a higher yield.

Q2. Good quality seeds will float or sink?

Ans. Good quality seeds sink as they contain all the important nutrients required by the plant to grow. Unhealthy seeds float on the water because they are actually empty and lack the required nutrients.

Q3. What are the physical characteristics that should be observed while selecting good quality seeds?

Ans. A good quality seed should have uniform size, weight, and colour. They should be clean that is free from stones, debris, dust, leaves, twigs, stems, flowers, and fruit well without any other crop seeds. They should look good and not be shriveled, diseased, moulded, or discoloured, or damaged.

Q4. What is seed selection?

Ans. Seed selection is the process of selecting healthy, viable, and disease-free seeds for cultivation to produce higher yields.

Updated on: 27-Mar-2023


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