Garden pea was selected for Mendel’s experiments of hybridization. The selection of garden pea for Mendel’s experiments was due to the following advantages: –
i) Flower of the garden pea plant are bisexual. The androcium and gynoecium of the flower are more or less completely covered by the petals and so the pollen grains of other flowers cannot enter inside the flower easily. Naturally self fertilization occurs in the flower but and the Times of necessity, artificial cross- pollination may be done.
ii) The garden pea plants posses’ well-defined varieties of characters.
iii) A garden pea plant can be crossed other pea plant being alternative character, then hybrid, or heterogeneous plants are developed. These hybrid plants are fertile, having the power of developing of these subsequent generations and it was very important for Mendel’s experiments.
iv) Garden pea plants can tolerate the extreme climate and so, they can be reared easily in the garden.
v) As the garden pea plant are the annual plant so they have short span of like for which Mendel’s experiments of hybridization can be carried out within a short period.
Hybridization procedure in Mendel's experiments: –
It is essential to know the procedure of artificial hybridization in plants and is essential for Mendel’s experiments. This procedure is followed by some steps and those are described below in brief:
i) Collection of parents: It is essential to collect the parent plant from the local areas for hybridization experiments. The parent varieties of garden pea plans were distributed in the surrounding wild areas of the monastery where Mendel did is experiments. After selection of certain varieties, Mendel collected the pea plants from the surrounding wild environment for the experimental material.
ii) Selection of your parental generation: self fertilizations wire made to verify the purity of the characters of the selected plant material. Due to this purpose, self fertilizations were carried out in the subsequent generations and if the character or characters on which the experiments were made, expressed unchanged in the subsequent generations, those plans were accepted as pure parental generation.
iii) Artificial cross-pollination: in case of bisexual flower of the selected pure parents, the anthers were removed before maturity and these worse done carefully by opening of the flower before losing with the help of a fine forceps and this process in Mendel’s experiments is known as emasculation. Just after you removal of the anthers from the bisexual flower, the stigma was covered by polythene bag so that there was no pollination by foreign pollens.
iv) In case of unisexual parent plant, the male and female flowers were covered separately by polythene bag before maturity. Thus, the foreign pollens neither mix-up with the male flower nor cross-pollination occurred in female flower.
Experiments of Mendel: –
Mendel collected the parent varieties of garden pea plans from the surrounding wild environment. He then carried out self pollinations of those collected pea plants through subsequent generations only to prove their purity in relation to the specific selected characters. Observing that the specific characters of those plans are transmitted from generation to generation which satisfy Mendel about the purity and designated them as pure pea plant. After that he made hybridization experiments between the alternative characters of the two pure pea plants and those pure plants while regarded as parental generation. Mendel made experiments on seven characters and their contrasting alternatives of garden pea plants are:
1) Tall and dwarf plant.
2) Round and wrinkled seeds.
3) yolo and Green cotyledons.
4) Colored and white seed coats.
5) Axial and terminal flowers.
6) Inflated and constricted pods.
7) Green and yolo Pods.
During Mendel’s experiments of hybridization, he carefully removed the stamens from any one flower before maturation, so that no self pollination could occur. After maturation it transferred the pollen grains from another pure plant and artificially cross pollinated by dusting the emasculated flower. Then he covered the flowers with a bag. Then the seeds produced by cross-pollination were collected for plantation again.