Given below are the events that are observed in an artificial hybridisation programme. Arrange them in the correct sequential order in which they are followed in the hybridisation programme (a) Re-bagging (b) Selection of parents (c) Bagging (d) Dusting the pollen on stigma (e) Emasculation (f) Collection of pollen from male parent.
The correct sequential order of artificial hybridisatian is as following
(a) Selection of parents.
(b) Emasculation (removal of anthers from the flower bud before the anther dehisces).
(c) Bagging (process to cover the emasculated flower with a bag made up of butter paper).
(d) Collection of pollen from other male plant.
(e) Dusting of pollen on stigma.
(f) Re-bagging
$$ \text { Vivipary automatically limits the number of offsprings in a litter. How? } $$
Vivipary is defined as the seed germination, while the fruit is still attached to the mother plant. Plants which grow in marshy places are called Mangroves. In these plants when seeds fall on marshy places, they cannot germinate, because of high salinity and more water conditions.
So, in those plants, seeds germinate when they are still attached to the mother plant. Litter is the off spring at one birth of animal usually 3-8 in number.
Vivipary automatically limits the number of offspring in litter due to the reason that limited number of egg or ovum are produced and fertilised during reproductive cycle of female.
Does self-incompatibility impose any restrictions on autogamy? Give reasons and suggest the method of pollination in such plants.
Self-incompatibility imposes restrictions on autogamy. The season far this may be as Majority of flowering plants produce hermaphrodite flowers and when pollens grains comes in contact with the stigma of the same flower to continue self-pollination.
Such type of continued self-pollination result in inbreeding depression. That's why flowering plants have developed many devices to discourage self-pollination and to encourage cross-pollination. One of the major way to prevent self-pollination is self-sterility.
Self-sterility in some bisexual flowers, if the pollen grains fall on the stigma of the same flower, germination does not occur. But the same pollen grains germinate when they fall on the stigma of other flowers of the same species. It is a genetic mechanism to prevent self pollination.
$$ \text { In the given diagram, write the names of parts shown with lines. } $$
Embryos of monocotyledons possess only one cotyledon. In the grass family the cotyledon is called scutellum that is situated towards one side (lateral) of the embryonal axis.
At its lower end, the embryonal axis has the radical and root cap enclosed in an undifferentiated sheat called coleorrhiza. The portion of the embryonal axis above the level of attachment of scutellum is the epicotyl.
Epicotyl has a shoot apex and a few leaf primordia enclosed in a hollow foliar structure, the coleoptile.
What is polyembryony and how can it be commercially exploited?
Polyembryony is the occurrence of more than one embryo in a seed. In many citrus and mango varieties, some of the nucellar cells surrounding the embryo sac start dividing, protrude into the embryo sac and develop into embryos. In such species, each ovule contains many embryos.
Polyembryony plays a main role in plant breeding and horticulture. The plantlets obtained from these embryos are virus free and has more vigour. Hybrid varieties of several food and vegetable crops are being extensively cultivated and these hybrid cultivars possess high productiviy.