Characteristics of seeds
The seed is the medium of plant breeding. New plants grow from the seed. Seed means fertilized and mature ovule, for example, the seed of paddy, wheat, jute, etc. In broad sense, seed is any living part of plants which is used as the medium of propagation of paddy, stalk of sweat potato, stem of suger came, leaf of air plant, onion, potato, etc.
Task : Identify seeds by seeing some of them as plants that grow in Bangladesh in your class. Quality of a good seed
So far we have seen many seeds and can identify the names of seeds. Now we will know about the characteristics of a good seed.
- Purity of seed : Any kind of other crop seed, weed seed, stone particles, etc should not be mixed with expected crop seeds and so care should be taken. The purity of seeds will not be kept otherwise. 2. Variety purity : Purity of seed is lost, when any seed sample contains seeds of other varieties of the same crops. Such as if, Nazershail rice seed is mixed with Binashail rice seed, the seed will not be varietally pure. Breed or variety purity is maintained if the seed is produced and processed in a controlled environment. 3. Germination capacity : This matter is called the germination capacity of seed. The quality of seed is measured by determining the percentage of germination of seed in a particular sample. The germination capacity may be upto 100% of a good seed. But all the time all seeds do not germinate at this rate. If at least 80% of the seeds germinate, they may be called good quality seeds. 4. Vigorousness of seed : When the seedlings of the sample are vigourous, living and healthy and can grow under adverse conditions, the seeds are called as high vigourous seeds.
- Humidity of seed : The percentage of moisture contained in the seeds of the sample is called seed moisture. Seed moisture keeps seeds living. 8-10% moisture is best to keep cereal seed grains well.
Rice seed (Normal) Figure : Rice seed (abnormal) (6) Seed colour : Seed of every variety has an independent colour. So a good seed should have normal bright colour. Normal bright colour is the primary symptom for identification of good seeds. Classification of Seeds Classification of seeds will be discussed in this lesson. Seeds may be classified in different ways, such as : 1. According to use, seeds are divided into two division :
(a) Botanical seed : According to plant scientists fertilized and mature ovule is called seed for example- rice, jute, wheat etc. seed. (b) Agronomical seed : According to agronomical scientists, any plant part that under favorable conditions can produce new plants of self variety is called an agronomical seeds for example: rice seed, wheat seed, zinger and turmeric
bulb, vine of sweet potato, teasel gourd root, sugarcane stem, etc. 4. Seeds are divided into two categories based on the presence of seed coat, for
example: (a) Seeds without seed coat : There is no seed coat in this seed, such as pine,
cycus, etc. (b) Seed with seed coat: Seed coat is present in these seeds, such as rice, wheat, jute, mustard, etc.
- Seed is divided into 3 divisions according to cotyledon. For example:
(a) Mono cotyledonous seed : Only one cotyledon is in these seeds, such as
rice, wheat, maize, etc. (b) Dicotyledonous seed : Two cotyledons are in these seeds, such as- gram, mango, jackfruit, etc.
(c) Poly cotyledenous seed : More than two cotyledons are in these seeds, such as pine.
Task : Classify seed samples from some sample mixture of various seeds.
Lesson- 11 : Classification of Fertilizers Plants take food from the soil as similar we eat food. Plant needs 1 7 essential nutrients to complete its life cycle. But it does not need all the nutrients in equal quantity. It requires some of the nutrients more. We use these nutrients such as urea, TSP, MOP as fertilizer. Fartilizers are classified into two categories based on its sources. a) Organic fertiliger b) Chemical fertilizer
a) Organic Fertilizer : The Fertilizer which is produced from bodies of living beings, that is, from debris of plants and animals is called organic fertilizer such as cow-dung, compost fertilizer, green manure, oil-cake etc. All necessary food elements for plants are available in the organic fertilizer.
• All the necessary plant nutrients are available in the organic fertilizer.
• It increases fertility of the soil.
• It increases the activities of the soil micro-organisms.
• It develops soil structure.
• It increases water absorption capacity of soil.
• It increases air movement in the soil. b) Chemical fertilizer :
Fertilizer produced in the factories is called chemical fertilizer e.g. urea, DAP, zipsum, zinc, etc.
The table below shows a list of some fertilizers and the nutrients : : Use of fertilizer in agricultural activities : Bangladesh is a populous country. Population of the country is increasing every year but the quantity of cultivable land is decreasing. So it is essential to apply fertilizer to produce a large quantity of crops from a small area of land. The demand of fertilizers in Bangladesh is increasing day by day. Organic and inorganic fertilizers are mainly used in our country. But some factors are to be considered to apply the right quantity of any specific fertilizer, for example :
- Condition of soil fertility 2. Type and variety of the crop 3. Time and methods of applying fertilizer 4. Degree of fertilizer loss 5. Level of soil moisture Discuss in group and present on “the role of fertilizers in crop production”.
• analyse the importance of weather and climate in agricultural activities.
identify agro-ecological zones on the basis of weather and climate. identity low rainfall, heavy rainfall, flood prone, tidal areas in the map of Bangladesh.
Weather and Climate