Question

You have two parents (1)fast-growing vines with weak stalks, and (2) slow-growing vines with strong stalks.
You cross the two pure-breeding vines but obtain only slow-growing plants with weak stalks. You then self-cross the F1 vines a number of times, but obtain only the F0 or F1 phenotypes, never the fast-growing, strong plants that are desired.
Are the genes that control stalk strength and growth rate on the same or separate chromosomes?

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I thought they were on the same chromosome but are really close to each other, so no crossing over can occur thus the fast and strong plant phenotype is not exhibited. and then that means that the dominant alleles are weak stalks and slow growing vines.

Do I have this right or am I on the wrong path?
Thanks