Effects of Low Phosphorus Stress on Root Morphology and Physiological Characteristics of Different Cotton Genotypes at the Seedling Stage

[Objective] Phosphorus is one of three major required nutrients for cotton growth and development. A phosphorus deficiency will lead to retarded cotton growth, undeveloped roots, and the abscission of buds and bolls, which results in serious reductions in cotton yield and quality. While applied phosphorus is easily fixed in soils, it is mostly transferred to occluded P, which is not available to plants. Therefore, this study aimed to provide theoretical support for the study of response mechanisms to low phosphorus stress and the efficient phosphorus uptake and utilization of different cotton genotypes. [Method] The effects of phosphorus accumulation and utilization, leaf photosynthetic characteristics and root morphology of two genotypes of cotton (CCRI 79 and SCRC 28) were studied in hydroponic cultures having different phosphorus concentrations. [Result] CCRI 79 had higher phosphorus utilization rates of 90.92 mg·mg^－1 at the low phosphorus level (KH2PO4 1.0×10^－5 mol·L^－1) and 23.09 mg·mg^－1 at the high phosphorus level (KH2PO4 0.5 mol·L－1) compared with SCRC 28. When phosphorus was deficient, the total root length, total root surface area and total root volume of SCRC 28 increased by 13.05%, 18.78% and 10.50%, respectively, while the total root length, total root surface area and total root volume of CCRI 79 decreased significantly. [Conclusion] Here, we found that SCRC 28 had a root morphology and physiological characteristics that allowed it to adapt to low phosphorusstress, while CCRI 79 utilized phosphorus more efficiently.