Briefly explain the significance of mendel's technique of removing the stamen from one plant and brushing pollen from another plant on the remaining carpel

Once Mendel had established true-breeding pea plants with different traits for one or more features of interest he began to investigate how the traits were inherited by doing a series of crosses.
To do that he removed the stamen from one plant and brushing pollen from another plant on the remaining carpel, that way he could control the mating of his plants.

It allows water to resist freezing and thawing cycle.