Comparison Study On Physiological And Biochemical Characteristics Of Different Maize Inbred Lines Under Phosphorus Deficiency Stress

Phosphorus (P) plays an important role in plant physiology and is a limiting factor in agricultural production in the world. In traditional agriculture, excess application of phosphorus fertilizers leads to environmental pollution. The plant-available phosphorus can form insoluble compounds with iron and aluminium, which greatly reduces the utilization efficiency of P fertilizers. The most efficient and environment-protective strategy is to screen and adopt plant genotypes with high phosphorus utilization efficiency (HPUE). In this research, under solid-substrate (perlite) cultivation, four maize inbred lines were subjected to no-phosphorus (NP) treatment using full P level (0.25 mol/L KH₂PO₄) as control (CK). Their morphological and physiological responses to P deficiency were investigated, providing physiological foundation for the selection of HPUE inbred lines of maize. The main results are as follows:Growth responses of maize inbred lines under NP condition. The shoot was depressed greater than the root. The relative dry biomass of the root was abviously higher than that of the shoot. The relative height and relative leaf area of line 040651 were more stable than those of all other lines, indicating that its growth was less influenced by NP treatment.Root characteristics of maize inbred lines under NP condition. Phosphorus deficiency promoted root elongation. Root surface area and the root/shoot ratio increased distinctly. The increasing of root/shoot ratio demonstrated that more dry matter produced by photosynthesis was transported to the root to promote phosphorus absorption. However, the absolute values of protein contents in the root and the shoot of NP plants were still lower than those of the CK.Membrane lipid peroxidation of maize inbred lines under NP condition. The results indicated that it was unreliable to adopt only one protective enzyme to judge whether a maize inbred line was tolerant or sensitive to low phosphorus condition. Accurate evaluation can only be made based on a series of indices, such as the activities of superoxide dismutase (SOD), peroxide dismutase (POD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR), and the content of malondialdehyde (MDA). In this research, as the stress went on, activities of all the protective...