Submitted to: Advances in Agronomy
Publication Type: Book / Chapter
Publication Acceptance Date: 11/9/2006
Publication Date: 5/21/2007
Citation: Pettigrew, W.T., Gerik, T.J. 2007. Cotton Leaf Photosynthesis and Carbon Metabolism.. Advances in Agronomy. 94:209-236. Interpretive Summary: Photosynthesis is the process where plant use energy from sunlight to convert carbon dioxide, acquired from the air, and water, acquired from the soil, into food for growth. It's one of the most essential processes in nature because it not only supports plant growth but it also releases oxygen into the atmosphere as a result of the process. This review chapter complies information from numerous journal references and other sources to present the current state of the art and understanding of cotton leaf photosynthesis and carbon utilization. Cotton geneticists can make use of this information to implement breeding strategies with goal of improving cotton photosynthesis as a component toward yield improvement. Crop physiologists and agronomists can use this information in designing cotton production practices that enhance photosynthetic and yield performance by minimizing exposure to detrimental environmental influences. This chapter can also fortify the knowledge base and background that consultants and extension specialists draw upon to advise their producer customers and clients.
Technical Abstract: Photosynthesis is the basis of plant dry matter production and a major determination of yield in cotton (Gossypium hirsutum L.). Much of the cotton yield increases in recent years can be attributed to the improved partitioning of dry matter into reproductive growth rather than vegetative growth. However, this strategy can only be taken so far before the amount of photosynthesizing leaf area becomes the limiting factor. Therefore, improved plant photosynthesis coupled with good dry matter partitioning could lead to additional yield improvements. Research has identified both genetic and environmental variation in the rate of cotton photosynthesis. Superior leaf photosynthetic performance has been exhibited by okra and super-okra leaftypes compared to the normal leaftypes. Photosynthetic variation has also been identified within the normal leaftype pool of germplasm. However, geneticists have generally not targeted this trait for genetic improvement in cotton. In addition, leaf tissue concentration of the three major plant nutrients (nitrogen, potassium, and phosphorus) need to be maintained at sufficient levels for optimum photosynthesis. Under deficient soil fertility conditions, supplemental fertilization can increase overall growth due to both increased leaf area production and increased photosynthetic rate per unit leaf area. Both excessive and deficient soil moisture conditions can depress the photosynthetic performance of the plant and its corresponding growth. Similarly, an optimum temperature range exists, above and below which the photosynthesis is negatively impacted. This knowledge of variation in both genetic and environmental influences on photosynthesis offers hope of improved photosynthetic performance through either a concerted genetic selection or modified production systems that minimize exposure to some of the rate-limiting environmental conditions.