Low Phosphorus Tolerance in Cotton Genotypes is Regulated by Root Morphology and Physiology.

Low phosphorus (P) availability is a major problem for cotton production. However, little is known about cotton agronomic and physiological traits associated with low P tolerance. Therefore, the agronomic and physiological performance of three cotton genotypes with strong tolerance to low P (STGs) and three cotton genotypes with weak tolerance (WTGs) was characterized under low and normal P conditions in hydroponic and pot culture. The results showed that low P significantly reduced dry matter production, photosynthesis, and carbon metabolism in both STGs and WTGs; however, the reduction was more in WTGs. In contrast, low P improved root morphology, carbohydrate accumulation, and P metabolism, especially in STGs genotype Jimian169, whereas the opposite responses were observed for WTGs mainly DES926. The multivariate analysis suggested that root morphological traits, carbohydrate contents, and enzymes related to P metabolism were strong positively correlated and contributed more to the genotypic variation, suggesting the importance of root over shoot in low P tolerance. Moreover, plants grown under low P produced low yields than normal P, whereas WTGs yields were lower than the STGs yield. Overall, it was suggested that the low P tolerance of cotton genotypes is closely related to root morphology and physiology. In the future, the identified contrasting low P tolerant cotton genotypes Jimian169 and DES926 will be used to understand the molecular mechanisms of low P tolerance in cotton. [ABSTRACT FROM AUTHOR]