Biology Question about genotypes?

A Swiss scientist wanted to investigate the idea that altitude affects the growth rate of plants. He transplanted plants that were growing in a valley to an alpine setting and in time he noted that the transplants grew more slowly than they did in the valley....The scientist then took the offspring of these plants and placed them in the valley environment. He found that the change in growth rate that had occurred in the alpine environment was not ped to the next generation. What can he conclude about the genotypes and phenotypes of the two generations of plants as a result of this data?