Effects of Sowing Date and Sowing Depth on Winter Wheat Growth before Overwintering

The climate change will lead to tremendous environmental risk. As a common agrometeorological disaster of winter wheat, the frequency and loss of low temperature and freezing injury are also significantly increased. In order to study the effect of different cultivation measurements on morphological indexes of winter wheat before overwintering, including leaf area per plant, main stem leaf age, tillering number, aboveground biomass, tillering node depth, stem length in the ground and plant height, the randomized block field trials with seven sowing dates (Oct 3, Oct 13, Oct 23 in 2015, and Sep 23, Oct 3, Oct 13, Oct 23 in 2016) and three horizontal seeding depths (2 cm, 4 cm and 6 cm) were carried out during 2015-2017, using 'Nongda211' as object at the Shangzhuang Experimental Station of China Agricultural University in Beijing. The gradient deep-sowing experiment with different sowing dates (Sep 23, 2016, Oct 3, 2016, Oct 13, 2016, and Oct 23, 2018, Nov 3, 2018) was further carried out to quantitatively simulate the depth of tillering node. The results of field experiment on sowing date and sowing depth showed that with the delaying sowing date, the leaf area, leaf age of main stem, tiller number of single plant and aboveground biomass of winter wheat were decreased significantly. With the deepening of sowing depth, the depth of tillering node, stem length in the ground and the height of plant were increased gradually. The sowing date, sowing depth and the interactive effects of sowing date and sowing depth all had significant impact on the tillering node depth of winter wheat. There was a linear relationship between the tillering node depth of winter wheat and the accumulated temperature before overwintering. As the sowing date was delayed, the tillering node depth was gradually increased. And the winter wheat tillering node depth and sowing depth showed a logarithmic curve. The tillering node depth was increased with the increase of depth of sowing. The quantitative relationship between the soil depth of tiller node and the effective accumulated temperature before winter was established with the experiment data of gradient seeding depth at different sowing dates. The results could provide a reference model for further study of freezing damage. © 2022, Chinese Society of Agricultural Machinery. All right reserved.