Abstract: To reveal the effects of phosphorus placement depth on root characteristics of spring maize under the subsoiling measures, achieve adequate spatial coupling between root system and phosphorus, to provide scientific basis for the rational operation of high yield phosphate fertilizer in maize cultivation, the root biomass, specific root length and root activity of maize with different phosphorus placement depth were studied, and the correlation between the indicators and yield was analyzed by means of the split plot design. In the main area of tillage practices, rotary tillage and subsoiling plus rotary tillage were set up, and the secondary area was phosphorus placement depth with 6 (P6, normal phosphorus placement depth), 12 (P12), 18 (P18), and 24 cm (P24) treatments. The results showed that the P12 and P18 treatments at silking stage and P12 treatment at milking stage in root dry weight of spring maize in 0-20 cm soil layers under rotary tillage measure. But the P24 treatment showed lower and higher root dry weight compared with P6 at silking stage and milking period, respectively. In 20-60 cm soil layers, the root dry weight of three phosphorus treatments were heavier than P6 at silking stage and milking stage, and the P12 treatment reached the highest value. Under subsoiling plus rotary tillage measures, three phosphorus treatments in the root dry weight at silking stage were heavier than P6. In 0-20 cm soil layers, the P12 and P18 treatments showed higher root dry weight at milking stage. Similarly, better performances also were found in P12 and P18 treatments in 20-60 cm soil layers at silking stage and milking stage. Under rotary tillage condition, the P12 treatment, significantly differing from P6, had the biggest specific root length in 0-20 cm and 40-60 cm soil layers at two stages. However, the P24 treatment had the highest value in 20-40 cm soil layers. To specific root activity in three soil layers and root length in 0-20 cm and 40-60 cm soil layers, the P12 treatment showed the highest value under rotary tillage. Under subsoiling plus rotary tillage condition, except for the root activity of 20-40 cm soil layer at silking stage, P18 were significantly differ from P12,they were higer than P6. The P12 treatments showed highest specific root length in 0-20 cm, and the P24 treatment was lowset at silking stage and milking, P18 were no significantly differ from P12 in 40-60 cm soil layers, the P12 was higer than P6 and P24. The changing trends of the root biomass, specific root length and root activity of two spring maize varieties were basically the same. Except for the root biomass of 20-60 cm soil layer at silking stage, the root dry weight, specific root length and root activity of various soil layer were significantly correlated with yield at two growth stages. The correlation analysis suggested that the root biomass and specific root length at milking stage were mainly affected by the subsoiling treatment and phosphorus placement depth, and the higher root activity of each soil layer was closely related to the subsoiling treatment. In conclusion, the root dry weight, specific root length and root activity of various soil layer were significantly correlated with yield at two growth stages;the subsoiling plus rotary tillage treatment was better than rotary tillage;the phosphorus placement depth was suitable for 12 cm under rotary tillage treatment and 12-18 cm for subsoiling plus rotary tillage treatment.

Key words: Spring maize, Subsoiling, Phosphorus placement depth, Root characteristics

CLC Number: 

• S513.01

• S143.2