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.

Automated summary

The study found that low phosphorus availability negatively affects cotton growth, but genotypes with strong tolerance are less affected. Root morphology and physiology play important roles in the low phosphorus tolerance of cotton, and cotton grown under low phosphorus conditions has lower yields.