Question

Make a list of any three out breeding devices that flowering plants have developed and explain how they help to encourage cross pollination.

Answer 1

Out breeding devices are used to prevent self pollination, which is the main cause of low variety and quality of the plant product and thereby encourage cross pollination to occur between plants.

Some outbreeding devices used are :-

1. Self incompatibilty : It is a method used to prevent the germination of pollen grains on the stigma of the same flower to prevent self fertilisation .eg, tobacco,mustard and potato plant.

2. Unisexuality : plants bearing either male flower or female flower used to prevent both autogamy (self fertilisation) and gietonogamy (pollens grains come from the same plant). eg, papaya

3. Dichogamy : The maturation time for both anther and stigma is different. This is basically of two type protogny and protandry

(a) Protogny : Gynoceium matures prior ot androceium. eg mirabilis ,bajra.
(b) Protandry : Androceium of the flower become mature before gynoceium. eg, maize, cotton, sunflower