Objectives Screening crop genotypes with low-Pi tolerant and Pi-high-efficiency is of great significance for improving the phosphate utilization efficiency, decreasing the phosphate fertilizer input, and lowering the potential environmental risks caused by excess phosphate application. This study is to investigate the Pi use efficiencies of tobacco and its Pi efficiency characteristics, and thus providing a reference for the P-efficient cultivar breeding.

Methods A hydroponic experiment with low-Pi (0.01 mmol/L) or normal-Pi (1.0 mmol/L) supply was conducted, a total of 71 seedlings of tobacco genotypes was collected for the tested materials. All the seedlings were grown in normal Pi nutrient solution until the fifth leaf sprout, then treated with low-Pi for 21 days. The main developmental, morphological and physiological indexes of the tobacco seedling were measured, the index for low-Pi tolerance were screened, and the Pi efficiency of genotypes were classified under low-Pi stress.

Results The total plant P accumulation, biomass of aboveground and root parts, plant height, total root length and root diameter were used as indexes to screen the seedling of low-Pi tolerant tobacco genotypes. Using the heatmap clustering analyses, the relative values of total P accumulation and aboveground biomass, 8 of low-Pi tolerant genotypes, 21 of low-Pi sensitive genotypes and 42 of medium genotypes were identified, respectively. Meanwhile, scatter diagram analyses on Pi efficiency comprehensive value showed the presences of total 4 types with low-efficiency under both low-Pi and normal-Pi, total 2 types with high-P-efficiency under both low-Pi and normal-Pi, and 2 types with P-high-efficiency under low-Pi but low-efficiency under normal-Pi in low-Pi tolerant genotypes, and total 14 types with low-efficiency under both low-Pi and normal-Pi, and only 1 types with Pi-high-efficiency under both low-Pi and normal-Pi, and total 6 types with low-efficiency under low-Pi but high-efficiency under normal-Pi in low-Pi sensitive genotypes.

Conclusions We primarily concluded that the K326 and Yunyan 105 are identified to be the low-Pi tolerant and P-efficient genotypes, and the G28, minyan 3, DB101, Oxford 2028, 14P10, CV70, yunyan98, MSB44, danyu 2, jingyehuang, CB1, Zhongyan101, RG11 and MSB31 are identified to be the low-Pi sensitive and P-insensitive genotypes.