The impact of drip irrigation methods and nitrogen application rates on soil salinity and nitrogen distribution, and fruit quality in arid regions of Northwest China

Abstract

The labor-saving intensive planting of Korla fragrant pear has emerged as an innovative cultivation model in recent years. Exploring drip irrigation methods and nitrogen application rates compatible with this model is crucial for mitigating soil salinization and improving the yield and quality of fragrant pears. A field experiment was conducted to evaluate the effects of drip irrigation methods and nitrogen application rates on the soil salt accumulation (SSA), soil nitrogen content, fruit yield and quality of fragrant pears during the growing seasons of 2022 and 2023 in Xinjiang, China. Two drip irrigation methods, i.e., surface drip irrigation (DI) and subsurface drip irrigation (SDI), and four nitrogen application rates, i.e., 100 kg ha⁻¹ (N1), 200 kg ha⁻¹ (N2), 300 kg ha⁻¹ (N3), and 400 (N4) kg ha⁻¹, were included. The results showed that the SDI treatment significantly reduced the SSA in the root zone of pear trees by 1.5–3.8 g kg⁻¹ during the growing stages. The lowest SSA was obtained at nitrogen application rates of 300 kg ha⁻¹and 200 kg ha⁻¹ under the DI and SDI treatments, respectively. In addition, the overall quality score was evaluated via principal component analysis (PCA). The yield and overall quality score under the SDI treatment were 10.7–24.4 % and 150.2–315.3 % higher than those under the DI treatment. The pear yield and overall quality increased and then decreased with increasing nitrogen application rate, with appropriate values of 300 kg ha⁻¹ and 200 kg ha⁻¹ under the DI and SDI treatments, respectively. The structural equation model (SEM) indicated that drip irrigation methods and nitrogen application rates primarily improved pear yield and overall quality by reducing soil salinity. Considering the soil salinity, pear yield and quality, SDI combined with 200 kg ha⁻¹ nitrogen application is recommended for the young Korla fragrant pear trees.