Germination and growth of corn submitted to sowing and cultivation management by subsurface drip irrigation in the North China Plain

The difficulty of crop germination in drought-prone areas during the sowing period is a worldwide problem for subsurface drip irrigation (SDI). Alternate row/bed planting (AP), in which the corn seeds were planted beneath a furrow, was applied to improve the corn germination and yield in Beijing, the North China Plain. Field experiments were conducted to assess the impacts of three furrow depths (FDs), 0 cm (H0), 10 cm (H10) and 15 cm (H15), and two cultivation management practices, backfilling the furrow after germination (BF) and not (NBF), on soil water content and temperature, corn germination and yield by SDI in 2018 and 2019. The results showed that the soil water content around the seeds (theta(seed)) increased with increasing FD, while the soil temperature decreased with increasing FD. BF slightly increased the soil temperature, with an average growing degree days of 26-34 degree celsius at a depth of 0-25 cm. The seed germination time was shortened by 3-5 days, and the emergence rate was improved following the increase in FD. The H15 treatment achieved the maximum emergence rate of 91.8% on average for two years, which was 7-17% higher than those of the H0 and H10 treatments. A Binary quadratic regression equation was adopted to fit the response of the emergence rate to theta(seed) after preemergence irrigation and the average soil temperature during the period from sowing to the emergence stage (STseedVE). The fitting equation indicated that the theta(seed) of 28-30% and the STseedVE of 25-27.5 degree celsius together could give an emergence rate over 90% by SDI. The H15-BF treatment obtained the highest grain yield of 13.1 Mg ha(-1) on average for 2 years, which was 5-24% higher than those of the other treatments. The yield between H15-NBF and H15-BF showed an insignificant difference. There were statistically significant (p < 0.05) effects of FD on the emergence rate and grain yield. In conclusion, the model of AP with an FD of 15 cm is suitable for SDI corn in the North China Plain.