Abstract:

The objectives of this study were to investigate the effect of different rotational tillage patterns （i.e. rotation of tillage and no-tillage cropping in different years） on crop yield and quality in a dryland summer maize （Zea mays）-winter wheat （Triticum aestivum） double cropping system （hereafter referred to as the maize-wheat double cropping system）. A field experiment was conducted with five treatments： no tillage in both the maize and wheat seasons （MNWN）， subsoiling in the maize season and no tillage in the wheat season （MSWN）， no tillage in the maize season plus 3 consecutive years of no-tillage and 1 year of ploughing in the wheat season （MNW3N1P）， subsoiling in maize season plus 3 consecutive years of no-tillage and 1 year of ploughing in the wheat season （MSW3N1P）， and conventional consecutive ploughing in the maize and wheat seasons （CK）. These treatments were established in 2004 at the Luoyang Arid Farming Experimental Station of the Chinese Academy of Agricultural Sciences. The crop yields in 2015-2021， the grain nitrogen， phosphorus， and potassium contents， the protein yield of maize and wheat， and the contents of grain protein components of wheat in 2020-2021 were determined. The results showed that the differences in the grain yields of summer maize and winter wheat were not significant between MNWN and the rotational tillage treatments （MSWN， MNW3N1P， and MSW3N1P）. However， the grain yields of summer maize and winter wheat were higher in all of these patterns than in CK， and the extent of the improvement varied depending on the annual precipitation. The use of rotational tillage resulted in a considerable yield enhancement compared with CK， with increases of 56.2%-65.2% for wheat （increases of 28.2%-32.6% for annual yield in the dry year） and 47.5%-57.7% for maize （increases of 25.7%-29.8% for annual yield in a normal year）， and 18.9%-31.2% for wheat yield in a rainy year. Among the three rotational tillage patterns， MSW3N1P showed the best effect in terms of enhancing the grain nitrogen， phosphorus， and potassium contents and the protein yield for maize and wheat， and to improve the contents of grain protein components in wheat. Compared with CK， MSW3N1P resulted in significantly increased nitrogen and potassium contents and protein yield in maize grains （by 4.5%， 15.6%， and 25.8%， respectively）， and increased nitrogen and phosphorus contents， protein yield， gluten content， glutenin∶gliadin ratio， and storage protein content in winter wheat grains （by 7.7%， 15.2%， 109.8%， 16.1%， 9.6%， and 11.9%， respectively）， ultimately leading to a 38.5% increase in annual protein yield. While the MNW3N1P treatment also significantly increased wheat grain gluten content， the glutenin∶gliadin ratio， and storage protein content （by 15.9%， 14.4%， and 9.2%， respectively， compared with CK）， the MSW3N1P treatment further significantly increased the gliadin and storage protein contents in wheat grain by 5.4% and 2.5%， respectively， compared with MNW3N1P. Therefore， MSW3N1P is recommended as the optimal rotational tillage pattern for high-yield and high-quality crops in dryland maize-wheat double cropping systems.

Key words: rotational tillage pattern, dryland, maize-wheat double cropping system, grain yield, protein and protein components