Effect of phosphorus and silicon application on the uptake and utilization of nitrogen, phosphorus and potassium by maize seedlings

This study tested the effect of three levels of phosphorus (P)1.0 mmol (P)·L^-1 (P_1.0), 0.1 mmol (P)·L^-1 (P_0.1) and 0.01 mmol (P)·L^-1 (P_0.01) and three levels of silicon (Si)1.5 mmol (Si)·L^-1 (Si_1.5), 0.75 mmol (Si)·L^-1 (Si_0.75) and 0 mmol (Si)·L^-1 (Si₀) on a range of characteristics of'Zhenghong 2' and'Zhenghong 115' maize cultivars. The study analyzed dry matter, leaf area, root morphology and NPK contents of maize to determine the effects of the combined application of Si and P on maize root growth, dry matter accumulation and NPK accumulation and utilization at seedling stage. The results indicated that P deficiency not only suppressed maize seedling growth, but also decreased root length, root volume, root surface area, leaf area, NPK assimilation and dry matter accumulation, and the effects were strengthened with decreasing P concentration. The enhanced maize root-to-shoot ratio at seedling stage increased the distribution rates of P and N in root system and the accumulation efficiency of NPK in dry matter, which improved the adaptation of rice to P-deficient environments. P deficiency stress enhanced root growth and P absorption and accumulation more in'Zhenghong 115' than in'Zhenghong 2' maize cultivar. However, the distribution rate in the root system of'Zhenghong 115' maize cultivar increased substantially under P deficiency. Si accelerated maize root growth, increased NPK accumulation, improved the distribution rate of NPK in aboveground system, increased leaf area and dry matter accumulation under normal P condition (P_1.0). Under medium P deficiency (P_0.1), the application of Si alleviated P deficiency stress through increasing NPK accumulation in maize seedlings, furthermore, it also accelerated growth of both root and shoot system. Under severe P deficiency (P_0.01), the application of Si had no significant effect on root growth and dry matter accumulation, but it increased the PK accumulation in root system. It was therefore concluded that there existed significant synergetic and coordination effects of P and Si on beneficial traits of maize at seedling stage.