Air is fulled of plant species pollen grains, these pollen grains landing on stigmas, some germinate producing pollen tubes and then ceased to extent within stigma tissues, some other never germinate, other germinate and and of the same variety accomplished fertilization. However, even of the same variety failed to fertilize the egg.
Dear Dr. Caser,
The pollen grain germination is the result of a series of factors that depends on the crop, weather, and location. I believe that my review below can introduce you in this subject. Like seed germination, the pollen grain depends on population statistics which is a fact that requires more information than only the biological effects. Best regards. Walter
Dear Dr. Caser
I believe that the problem lays on development of pollen grain on its mother plant. It may be cause of lack of starch or unbalanced auxin content. such pollen grains seems to germinate on a nutritive medium. it may be the reason for presence of hundred of pollen grains in each plants even in cleistogame plants that do not need to spread pollen grains.
A.shomali
Self-incompatibility (SI) is a general name for several genetic mechanisms in angiosperms, which prevent self-fertilization and thus encourage outcrossing and allogamy. It should not be confused with genetically controlled physical or temporal mechanisms that prevent self-pollination, such as heterostyly and sequential hermaphroditism (dichogamy). In plants with SI, when a pollen grain produced in a plant reaches a stigma of the same plant or another plant with a similar genotype, the process of pollen germination, pollen-tube growth, ovule fertilization and embryo development is halted at one of its stages and consequently no seeds are produced. SI is one of the most important means of preventing selfing and promoting the generation of new genotypes in plants, and it is considered as one of the causes for the spread and success of angiosperms on the earth.
For details refer following links:
https://en.wikipedia.org/wiki/Self-incompatibility_in_plants
http://www.biology-pages.info/S/SelfIncompatibilty.html
Dear colleagues Esq.
It is all about genomes that been deposited in exine of pollen grain and that on stigma these two sets should recognize each others through reactions after pollen grain landing on stigma if recognition is matched the pollen grain will germinate and fertilization will occur if not callose will formed and then blocks the tube germination
@ Caser,
1. It is also important to know which 'elements/components' make them to 'recognize' each other and cause them to interact each other.
2. When we see anthers open and filled with pollens in a flower from a plant, are 100% of these pollens equally mature, healthy and ready to go? Or, small portion of them doom to fail for fertilization if they land on the stigma due to not-known-yet reasons?
3. Was the statement in your last post above also apply to the SAME VARIETY (as you mentioned in your question)? Usually, under normal conditions, pollination (or 'recognition') between plants (i.e. outcross species) of a same variety should be no problem.
Dear Yuan-Yeu Yau
Such small portion of defected pollen grains been produced with assimilate scarcity owing to the competition over nutritional source......
Dear Caser,
Thanks for response. But, first, is there such a thing that a small portion of defected pollen grains always present in a healthy anther? Is any report to support this? I am curious and want to know.
Dear Yuan-Yeu Yau
This obvious whenever more than one sink over a given resource are occurred not only in biology, therefore, the closet seed to flower end of pods in legume for instance possesses the best nutritional values and rarely find aborted ovule in this position unless there is a defects, the pod seeds gain better as they arranged in the order of the stem end of pod, moreover the second bearing pod is of less quality until you approach the apical you find pods with small seeds as hard as stones..... and leathery pods..... Similar to snake cucumber the flower end tasty and nourish in contrast to to hard seedless stem end...... when ovule fertilized first take adequate assimilate and then spear the rest to the following ones.
Too many apples in the twig gives small apples.... too many stolons in potato produce smaller tubers ..... abortion comes from low available assimilates... life is source and sinks ..... now fruits in pepper reduces photosynthesis and too many examples
Dear dr.
It seems that there are pre-fertilization barriers in some varieties and species. There are techniques for overcoming pre-fertilization barriers such as: use of mixed and mentor pollen, style and ovary maniplations (stump pollination, cut style or amputated- style pollination) and chemical treatments.
Dear Caser
The most probably causes of that problem was the healthy of the mother plant which produce those pollen grains and its relation to the receptive status of the pistil. It is because the incompatibility (self or cross) and sterile concepts are occurred in consistency with the plant habituation in common. This means that the self-incompatibility or sterile plant types will not produce seeds at all, and is not only for the individual plant failure to enter in the fertilization phase.
The reason may be due to the un germinate pollens are not viable because of its formation from the mother cell or because of un favourable environmental conditions when it transfered from the anther, or may be related with a problem in the pistil .
Pollen germination also depends on the longevity, time of anther dehiscence and pollen dispersal.
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