POLLINATION LESSON 6 PRESENTED BY - SHREYAA SHARMA
OUTBREEDING DEVICES OR CONTRIVANCES TO ENSURE CROSS POLLINATION DICLINY - in this case, the flowers are unisexual eg. Mulberry, Papaya) e DICHOGAMY - in this case the anthers and stigmas mature at different times. Can be a case of Protandry (e.g. Sunflower, Salia) or Protogyny (e.g. Gloriosa, Mirabilis) e PREPOTENCY - in this case, the pollen grains of another flower germinate more rapidly on the stigma, as compared to own pollen grains (e.g. Apples, grapes) SELF STERILITY - also known as self incompatibility (e.g. Tobacco, potato , etc.) HETEROSTYLY -different height of styles and stamens (e.g. Primrose, jasmine , etc.) e HERKOGAMY mechanical devices to prevent self pollination (e.g. Pansy, orchids, etc.)
ADVANTAGES OF CROSS POLLINATION Helpful in case the plants are self sterile . Helpful in case the plants are self sterile VIt introduces genetic recombination and hence, variations in the progeny VHelps to increase the adaptability of the offsprings towards the changes in the v Plants produced through cross pollination are more resistant to diseases VHelpful in order to introduce better characters and remove the defective ones environment The phenomenon of hybrid vigour comes into play Most importantly , the yield never falls below an average minimum
DISADVANTAGES OF CROS!S POLLINATION e A highly wasteful process for the plants have to produce a larger number of pollen grains and other accessory structures in order to suit the various pollinating agencies Less economical . A factor of chance is involved Incase the pollinator fails to bring about pollination , the crops are subjected to failure. Some undesirable characters may be introduced and some desirable ones may be eliminated in the due course
SEXUAL REPRODUCTION IN FLOWERING PLANTS Flower Formation Pollination Fertilization Seed Dispersal and Germination Fruit and seed formation
POLLINATION PollinationPoln -Anther Filament The process of transference of pollen grains from the anther to the stigma Style Ovule Petal Sepal
Bot & Zoo grad. Qualified IIT JAM. Masters in Envtl. Sc. - Sustainable Devpt. and Disaster Management . A curious learner :-) .