However, under drought conditions the lack of water may reduce top growth while photosynthesis remains active. This results in the accumulation of carbohydrates at relatively low canopy heights. Forage stands that have growth retarded by drought can then have a vigorous regrowth once good rain is received. Another result of drought stress is that even though yields are reduced, forage quality at a given stage of development is increased. The effects of cool weather in the spring or fall are similar.
Cool temperatures reduce plant growth rates more than photosynthesis.
This allows for an increase in reserve carbohydrates in the plant and higher forage quality. In the fall this also allows plants to develop root reserves and continue root growth, as long as there is adequate photosynthesizing leaf area, even though there is little increase in top growth. Plant development is the process of a plant changing from one growth stage to another. This could be the development of tillers on a grass plant or flower buds on a legume plant. As plants change from vegetative to reproductive stages, forage quality decreases.