Research on exploiting wheat-maize grain yield theory and technology in the eastern low plain of Hebei Province

Medium and low-yield fields in the low plains of East Hebei Province are critical for “Bohai Granary” project for increasing grain yields at national level. Winter wheat-summer maize double cropping system is the main planting pattern for agricultural production in the area. The growth of winter wheat and summer maize is seriously restricted by water deficit, soil fertility and climate fluctuations, which results in the decreasing of grain yield. Summer maize growth season is accompanied by sufficient rain and heat, while winter wheat season is deficit in both rain and heat. There is a high potential to increase grain yield by selecting suitable cultivars, reasonable date of sowing matching with harvesting, optimization of planting, cultivation and management modes and technologies. The main aim of this research was to exploit increasing measures of winter wheat and summer maize grain yields with enhanced potential and use efficiency of resources such as water and fertilizer (by underground roots) and light and heat (by over-ground canopy). A total of eight field experiments were designed in the research, which included winter wheat seeding date, winter wheat cultivar, summer maize seeding date, summer maize harvesting date, summer maize planting pattern adjustment, deep scarification of summer maize planting, potassium fertilizer dose for summer maize, and phosphorus and organic fertilizer doses for winter wheat. The results showed that postponement of sowing date and increased seeding rate of winter wheat did not change grain yield. Early maturity winter wheat cultivar reduced the effect of dry hot wind which in turn stabilized grain yield and quality. Early seeding of summer maize by 10 days increased grain yield by 17.2%, while late harvesting by 8 days increased grain weight by 19.5%. Adjustment of summer maize planting patters improved canopy structure and enhanced the use efficiency of photosynthetically active radiation. Row spacing of 40 cm wiht 80 cm and the same of row and plant spacing of 38 cm were superior to other planting patterns, which increased grain yield by more than 15%. Planting summer maize with deep scarification increased grain yield by 31.3% and improved the next winter wheat grain yield by 5.6%. However, these effects were not observed in successive deep scarification in the following years. Summer maize with increased potassium fertilizer improved grain yield by 2.6%, winter wheat with phosphorus fertilizer improved grain yield by 7.4%, and winter wheat with organic fertilizer improved grain yield by 6.8% compared with that of control. However, when phosphorus and organic fertilizers were used simultaneously, winter wheat grain yield increased by 8.8%, without obvious superposition effect of fertilizers. The steady increase in grain yield was due the selection of suitable cultivars which matched with the sowing periods and other management practices, planting patterns, planting technologies, fertilization schemes, tillage patterns, etc. The planting mode which stabilized winter wheat grain yield and increased the potentials of summer maize grain yield was most suitable in the study area. This mode made the fullest use of local climate factors such as precipitation, sunlight and soil heat.