Photosynthesis and partitioning of photoassimilates among developing plant parts are both important in cotton plant growth and in the development of seed and fiber. Nearby growing plants and dead plant residue in minimum tillage systems affect the amount of reflected far-red light (FR) and the FR/R ratio. The FR/R ratio acts through the phytochrome system within a growing plant where it influences partitioning of photoassimilates. We conducted this study to compare cotton plant growth and fiber responses to altered FR/R ratio. Plants were grown in trickle-irrigated field plots over red, green or white soil covers to obtain different amounts of photosynthetic light and FR/R ratios in reflected light without interfering with incoming sunlight. Plants that grew over the white surfaces received more reflected photosynthetically active light, but the reflected FR/R ratio did not differ significantly from that in incoming sunlight. Those that grew over the red and green surfaces received less reflected photosynthetic light than plants grown over white, but the reflected FR/R ratios over the red and green surfaces were much higher than the ratio in incoming light. At five weeks after emergence, seedling stem lengths were significantly longer over red and green than over white surfaces. The young plants that received the higher FR/R ratios had thinner leaves and higher chlorophyll concentrations. At maturity, plants that had grown over the red and green surfaces had longer stems, larger shoots, more bolls, more seed cotton, and longer fibers than plants grown over the white surfaces even though those grown over the white surfaces had received more photosynthetic light during growth and development. More detailed studies on effects of reflected light spectra during cotton fiber development are in progress.