A seed which does not remain after the completion of the embryo is called a sterile seed.

A seed in which a seed exists after the completion of the embryo is called a viable seed.

The fusion of the diploid secondary nucleus with the haploid sperm of the embryo is called triploidy. That is, the union of three nuclei with two polar nuclei and one pungamete occurs in triploidy. Hence it is called Trimilan.

One of the two sperm unites with the egg, a phenomenon called syngamy. Strasburger first observed syngamy in 1884.

 

1. The growth of the female gametophyte stops at the octanuclear stage. Growth resumes after double-fertilization.
2. Beans provide nutrients to the growing embryo. Double fertilization is essential for viable seed formation.
3. The secondary nucleus stops cell division before fertilization. Triple fusion helps the dormant nucleus acquire the ability to divide.
4. Dichotomous stamens help determine plant and host characteristics.

The process of simultaneous fertilization of two spermatozoa, one with the ovum and the other with the secondary nucleus, is called double fertilization. Dicotyledons occur in herbaceous plants. In 1990, scientist Williams Friendman discovered bi-toxicity in the gymnosperm Ephedra. In 1898 scientist Navasin observed double fertilization in Lilium martagon and Fritellaria tenella plants. Double fertilization occurs in paddy, wheat, bhutra, redi etc.

Uterus → fruit

Intein → tegmen

Uterine wall → ovary

Ovary→Sperm

Ovule→seed

Nucellus → destroyed, perisperm

Ovum → Embryo

Secondary nucleus→seed or endosperm

Ovule or micropyle → Spore

Helper cells or synergids are destroyed

Umbilical cord or Hyalum → Umbilical cord

Antipodal→destroy

Ovule or Funiculus → Spore

Ovule or calaja→sperm or perishes

Exine→testa/seed coat

A third layer is formed when the ovule develops into a seed. It’s called Ariel. Such as litchi, kathlichu, nutmeg, betel nut etc.

1. In the process of fertilization, the sperm of the stamen unites with the egg of the female. Because the sperm and egg have different characteristics, there is a possibility of creating a new species. The new variety is different from the parent plant.
2. Iri-8 rice was developed in the Philippines by crossbreeding Indonesia’s Peta rice and Taiwan’s Dee-gee-woo-gen rice. The yield of this rice is 90-100 maunds per acre.
3. Erichile rice was developed by breeding Peta rice from Indonesia, TKM-6 rice from India and Taichu-1 rice from Taiwan. The yield of this rice is 70-75 maunds per acre. The yield of Iri-5 rice is 70-75 maunds per acre. High yielding Eri rice is Eri-20, Eri-28, Eri-29 etc.
4. Bangladesh Rice Research Center developed Birishail rice by crossbreeding BR-20 and BR-3. The four Ufshi rice varieties developed by the Bangladesh Rice Research Center are Chandina (BR-1), Mala (BR-2), Shahi Balam (BR-15) and Shrabni (BR-26).
5. Bangladesh Agricultural Research Institute (BRRI) has developed 17 Ufshi varieties of wheat through hybridization. High yielding wheat varieties are Balaka, Akbar, Kanchan, Barkat and Saugat. Besides, Ez-27 and Ez-28 wheat are more improved.
6. Disease-resistant varieties are developed by breeding cultivated disease-causing crops with wild disease-resistant crops. Mukta (BR-11), Ghazi (BR-14), Mohini (BR-15) etc. disease resistant varieties of rice.
7. Artificial breeding has created varieties of plants that can grow in adverse environments. All these varieties can tolerate drought, flood, salinity etc. due to different characteristics.
8. The characteristics of grain size, color, smell, taste etc. have been improved through artificial breeding.
9. Through artificial hybridization it has been possible to reduce the cultivation period of the crop to 20-30 days. This new variety yields before the onset of unfavorable conditions.

1. Fertilization involves the union of sperm and egg with different characteristics. The new plant thus created is different and diverse in size, shape and structure.
2. Fertilization results in the development of disease-resistant plants from susceptible plants. Disease resistant plants are of different characteristics and varieties.
3. Mating of two different plants through fertilization results in varieties that are antagonistic. All these plants have a collection of various adverse resistance properties. These diverse plants can easily tolerate drought, flood, salinity, heavy rain, no rain etc.
4. Fertilization process produces various traits in crop plants. The grain size, color, smell, taste etc. of these plants are different.