haploid plants and triploid plants - differences between haploid plants and triploid plants (Apr/03/2007 )
hello everybody... 
may i ask help from u guys? I have problem in understanding the difference between haploid and triploid plants. Can haploid plants really grow with only n chromosome? I can understand the dihaploid plants where the chromosome number doubled with colchicine. But dihaploid plants have 2n chromosome, so, can plant with n chromosome grow normally like 2n plants? besides, why should we induce 3n plants if we already have n plants? they are both odd numbered right? Sorry if my question sounds stupid. I'm new in this field... 
may i ask help from u guys? I have problem in understanding the difference between haploid and triploid plants. Can haploid plants really grow with only n chromosome? I can understand the dihaploid plants where the chromosome number doubled with colchicine. But dihaploid plants have 2n chromosome, so, can plant with n chromosome grow normally like 2n plants? besides, why should we induce 3n plants if we already have n plants? they are both odd numbered right? Sorry if my question sounds stupid. I'm new in this field... Haploid and triploid plants are viable (opposite to most animals, except several insect species), but haploid plants are often less vital and smaller, and, as tripoid ones, reproduction is not possible or only very limited possible. Meiosis does not work correctly in both plant types, as you can imagine. Tthe use of it: I guess mostly for research e.g. investigation of genomic mutations, plant breeding (polyploid plants are interesting, due to bigger plants, but only in plants were you harvest vegetative parts (e.g. potato, sugar beets) and ornamentals with bigger (but sterile) flowers.
P.s. Triploids are used in sugar beets, they reach their highest capacity in this stage, don't ask me why, I guess with higher-ploid stages the negative aspects of polyploidy increase to much. For this, breeders cross diploid with tetraploid plants (complete stocks, not single plants), the seeds are then mixtures of different ploid stages (di-tri-tetra).
Nothing to add to hobglobin's explanation.
Here is just another example.
Bananas are triploid too.
Banana fruits are formed by partenocarpy: trees are sterile, since they can't produce seeds.
The embryos produced by the cultivated crosses can't convert to seeds, so they are not viable.
A great amount of pulp sorrounds them.
As a result, when you eat a banana you can find small black dots into the white pulp. 
thanks a lot hobglobin.. i really appreciate ur help 
may god bless you.. you gave me a very good introduction for this topic.. i appreciate it.