Suitable Drilling Depth of Sunflower Seeds in Saline-alkali Soil Drip-irrigated with Saline Water in Hetao Irrigation District

Abstract

【Objective】 Crops grown in saline-alkali soil are vulnerable to salinity during its germination and seedling stages, and the seed drilling depth hence has a significant impact on plant establishment. Taking sunflower as an example, this paper experimentally investigated the combined effects of sowing depth and pre-sowing irrigation on germination and seedling development in a saline-alkali soil in Hetao Irrigation district. 【Method】 We drilled the sunflower seeds into four depths: 2, 4, 6 cm and 8 cm of the soil that was irrigated with 21, 28 cm and 35 mm of water prior to the sowing. In each treatment, we measured emergence rate of the seedling and its subsequent development. 【Result】 ①With the increase in sowing depth, the seedling emergence rate increased first followed by a decrease, and the highest seedling emergence rate was 93%, reached when the sowing depth was 4 cm. Increasing the sowing depth led to an increase in below-ground biomass at the expense of the above-ground biomass. ②When the sowing depth was 4 cm, pre-sowing irrigation with 28 mm and 35 mm of water did not have a noticeable difference in their impact on the seedling emergence rate. Increasing irrigation amount improved soil desalination, especially in the 0~10 cm soil. When irrigation amount was increased from 21 to 35 cm, the desalination rate of the top 10 cm soil increased from 37.5% to 62%. 【Conclusion】 In Hetao Irrigation district and areas where water resource is scarce and saline water is used as a supplementary irrigation source, combining ridge tillage with mulching by irrigating 28cm of water prior to drilling the sunflower seeds to the depth of 4 cm is a suitable cultivation to ensure seed germination and the subsequent seedling establishment.

Keywords

• sunflower
• seeding emergence
• drilling depth
• saline water irrigation
• saline-alkali soil