Abstract: In order to promote the further promotion of green manure planting in Tianjin, a field experiment was adopted, and 9 spring Brassica napus L. varieties were overturned with spring fallow fields as a control to study the effects of different spring Brassica napus L. on soil potassium content and maize nitrogen metabolism.The results showed that there were differences in the biomass and nutrient content of different spring Brassica napus L. varieties. Among them, Zhongyoufei 1901(7 716.50 kg/ha), 1804(6 577.02 kg/ha), and 1907(6 457.03 kg/ha) had higher biomass and nutrient content.The change trend of soil total potassium and available potassium in 2019 was the same as 2020. Among them, the content of total potassium and available potassium in the soil under the treatment of spring Brassica napus L. of Zhongyoufei 1901, 1804, and 1907 was higher than that of other tested varieties in different periods, and the total potassium and available potassium content of soil in 2020 were higher than those in 2019.The potassium uptake by the whole plant of maize and the total potassium uptake by the hectare of the three varieties of maize were higher than those of other tested varieties. Compared with 2019, the potassium uptake of the whole plant of maize treated with different spring Brassica napus L. in 2020 increased by 15.70%-24.34%;the NR and GS activities of the ear leaves in different spring Brassica napus L. treatments increased by 2.16-14.22 nmol/(min · g), 0.99-2.30 μmol/(h · g), respectively. The top 3 NR and GS activities of the maize ear leaves were the same as the potassium uptake of the whole maize plant. Compared with spring fallow, spring Brassica napus L. treatments' yield of maize increased by 10.02%-33.47%, which was 1.09-1.41 times of the spring fallow, and the highest yield in two years was 15 700.94 kg/ha (2020 Zhongyoufei 1901). It could be seen from the path analysis that the nitrate reductase activity of the leaf at the ear position had a direct effect on the protein content of corn grains.In the indirect effect, leaf protein content contributed the most to maize grain protein through leaf nitrate reductase activity.Correlation analysis showed that there were significant and extremely significant positive correlations among Brassica napus L. total potassium, soil potassium, maize potassium uptake, key enzymes in maize leaf nitrogen metabolism, maize leaf protein content, and maize grain protein content.

Key words: Spring Brassica napus L., Soil potassium, Maize nitrogen metabolism, Path analysis, Correlation analysis

CLC Number: 

• S513

• S158