Exploring the response relationship between crop rooting, seedling emergence and soil water, heat and salt environmental factors in dry sowing wet emergent cotton fields
Jianqin Ma, Yu Ding, Jianghui Zhang, Kangqi Fan, Yungang Bai, Bifeng Cui, Xiuping Hao, Guangtao Fu, Bangxin Ding
Abstract
The new water management technology of dry sowing wet emergence (DSWE) saves water, increases efficiency, and improves seedling emergence rate, which has significant application value in arid areas. In order to explore the most suitable soil moisture, temperature, and salinity environment for cotton growth in the dry zone of Northwest China, and to optimize the DSWE irrigation pattern, this study conducted DSWE field irrigation experiments in 2021 and 2022 in Aksu, Xinjiang, with three levels of emergence water (6 mm, 10.5 mm, and 15 mm) and two levels of drip frequency (2 and 4 times)， and the local conventional winter irrigation (225 mm) was selected as the control treatment. The results showed that the soil moisture content showed a significant difference in space, and the covered area showed a higher level in horizontal dimension. The high-frequency irrigation treatment yielded substantially higher water content in the 0–30 cm surface soil layer compared to low-frequency applications, demonstrating a 15.2 % increase in average soil water content. A consistent pattern emerged across both study years, where increasing emergence water volume corresponded to a progressive decline in average soil temperature. The D2 treatment resulted in a 3.86 % reduction in average soil temperature relative to D1 conditions. The soil electrical conductivity measurements revealed markedly lower values under winter irrigation compared to DSWE treatments, with high-frequency irrigation proving particularly effective in reducing soil EC levels. Increased irrigation frequency and enhanced emergence water volume demonstrated significant positive effects on root morphological development, manifested through augmented root length density (RLD) and vertical root distribution patterns. The W2D2 treatment exhibited more concentrated root distribution compared to the control group, while the W3D2 treatment yielded notably expanded root distribution patterns with an 18.74 % increase in RLD. The dual factors of drip irrigation frequency and seedling emergence water volume in the DSWE system exhibited positive correlations with soil moisture content (SMC) and RLD, subsequently facilitating improved cotton seedling emergence rates and yield performance. This study aims to explore the relationship between soil-root environmental factors and crop roots, emergence rate, and yield by analyzing soil moisture, temperature, electrical conductivity, and root distribution under the DSWE scheme, optimize the DSWE water irrigation scheme, and promote the sustainable development of cotton crops in arid areas.