Cotton plant size and fiber developmental responses to FR/R ratio reflected from the soil surface

Cotton ( Gossypium hirsutum L.) plants were grown in irrigated field plots over red, green or white soil covers (mulches). The far-red (FR) to red (R) light ratios were higher in upwardly reflected light over the red and green surfaces than in incoming sunlight. Plants that grew over the white mulches received higher photosynhetic photon flux (PPF), but the reflected FR/R ratio did not differ significantly from that in incoming sunlight. At five weeks after emergence, seedling stern lengths were significantly longer over red and green than over white surfaces. At maturity, plants that had grown over the red and green surfaces had longer stems, larger shoots, more bolls (fruit), more seed cotton, and longer fibers than plants grown over the white surfaces even though those grown over the white surfaces had received more reflected photosynthetic light during growth and development.