Biodegradable mulches have become the focus of attention, as pollution caused by leftover plastic mulch material becomes increasingly severe. However, the impact of biodegradable mulches to the soil needs to be further investigated. An experiment was conducted to evaluate the impact of no-mulch, biodegradable film mulch (BM) and polyethylene film mulch (PM) on the soil’s physical, chemical and biological properties after six years (2013–2019) of mulching in garlic growing season in a garlic-maize rotation. Results showed that the soil bulk density of the 10–20 cm soil layer under BM decreased by 12.09–17.17% compared with that under PM. The soil total nitrogen content increased significantly by 14.75–28.37%, and the soil available phosphorus and potassium content increased by 64.20% and 108.82%, respectively. In addition, BM increased the soil’s microbial, soil urease, and soil catalase activities compared with those for PM. To sum up, BM can reduce soil bulk density, and long-term use of BM does not cause a decrease in soil nutrient content and microbial activity. On the contrary, it can improve soil quality. This study helps accumulate data for the environmental safety evaluation of BM and provides theoretical and technical support for the large-scale promotion of biodegradable mulches.

Winter wheat and cotton are the main crops grown on the North China Plain (NCP). Cotton is often transplanted after the winter wheat harvest to solve the competition for cultivated land between winter wheat and cotton, and to ensure that both crops can be harvested on the NCP. However, the root system of transplanted cotton is distorted due to the restrictions of the seedling aperture disk before transplanting. Therefore, the investigation of the deformed root distribution and water uptake in transplanted cotton is essential for simulating soil water movement under different irrigation methods. Thus, a field experiment and a simulation study were conducted during 2013–2015 to explore the deformed roots of transplanted cotton and soil water movement using border irrigation (BI) and surface drip irrigation (SDI). The results showed that SDI was conducive to root growth in the shallow root zone (0–30 cm), and that BI was conducive to root growth in the deeper root zone (below 30 cm). SDI is well suited for producing the optimal soil water distribution pattern for the deformed root system of transplanted cotton, and the root system was more developed under SDI than under BI. Comparisons between experimental data and model simulations showed that the HYDRUS-2D model described the soil water content (SWC) under different irrigation methods well, with root mean square errors (RMSEs) of 0.023 and 0.029 cm³ cm⁻³ and model efficiencies (EFs) of 0.68 and 0.59 for BI and SDI, respectively. Our findings will be very useful for designing an optimal irrigation plan for BI and SDI in transplanted cotton fields, and for promoting the wider use of this planting pattern for cotton transplantation.

Aerobic irrigation can effectively improve the oxygen environment in the root zone, and enhance crop quality and yield. However, how aerobic irrigation regulates root growth has not been elucidated. In this study, tomato plants were irrigated with three levels of oxygen (high, medium, and low) under underground drip irrigation. The morphology, activity, transcriptome, and hormone content of tomato roots under oxygen irrigation were analyzed. We found that the aeration irrigation significantly promoted root development. Notably, in the high-aeration irrigation treatment (HAI), the total root length, total surface area, total volume, and root activity were 12.41%, 43.2%, 79.1%, and 24.15% higher than in the non-aeration irrigation treatment (CK), respectively. The transcriptome of tomato roots under aeration irrigation was determined with a total of 272 differentially expressed genes (DEGs), including 131 up-regulated and 141 down-regulated genes. The Kyoto encyclopedia of genes and genomes (KEGG) analysis revealed that the DEGs were enriched mainly in the metabolic pathways and plant hormone signal transduction. Among the plant hormone signal transduction, 50% of DEGs belonged to IAA signal-related genes and were upregulated. LC-MS analysis showed that the content of auxin hormones in the tomato roots subjected to aeration irrigation was significantly higher than that in CK. The content of Indole-3-acetic acid (IAA), Indole-3-carboxylic acid (ICA) and Indole-3-carboxaldehyde (ICAld) were 2.3, 2.14 and 1.45 times higher than those of the CK, but insignificant effects were exerted on the contents of cytokinins, salicylic acid, jasmonic acid, abscisic acid, and ethylene. Meanwhile, the key enzyme of auxin synthesis flavin monooxygenase (YUCCA) was significantly up-regulated. The aforementioned results show that aeration irrigation may promote the growth and development of roots by auxin regulation.

Flat (F), mini-ditch (MD), and ridge-furrow (RF) are three conventional cotton planting patterns that are usually adopted around the world, yet soil and crop responses to these three patterns are poorly studied, as is their suitability for increasing yield for coastal areas in Eastern China. The effects of three planting methods on water and salt dynamics as well as on growth and lint yield of cotton (Gossypium hirsutum L.) were investigated in a saline field in Bohai Rim, China, to select the best planting pattern for cultivating coastal saline fields of Eastern China. Soil moisture in the root zone with RF was 11.9% and 12.1% higher than with F and MD, whereas the electrical conductivity of a saturated soil extract (EC_e) in the root zone with RF was 18.0% and 13.8% lower than with MD and F, respectively, during the growth period, which indicated that RF could efficiently collect rainfall and leach salt in the root zone. After drip irrigation, the infiltration and salt-leaching depth with RF were both deeper than that with F and MD. The stand establishment of MD was the highest (80.3%) due to the greenhouse effect from film mulching, and was 12.8% and 4.6% higher than that with F and RF, respectively. Growth indicators and lint yield demonstrated that RF was superior to F and MD because of the higher soil moisture and lower EC_e. The lint yield was significantly higher in RF, suggesting that RF can be an optimal planting pattern for agricultural reclamation in similar saline-alkaline areas around the world.

Light quality is an important variable affecting plant growth, so we aimed to explore the impact of light quality on plants under salt stress. The salt tolerance of pea (Pisum sativum L.) seedlings illuminated by LED red light and 4:1 of red/blue light in a hydroponic system was evaluated at three salinity levels (0, 50, and 100 mmol/L of NaCl) for their morphological and physiological parameters and their root growth characteristics in response to salt stress. Results demonstrated that, as salt stress intensified, the plant height, aboveground fresh/dry mass, root growth indices, and chlorophyll content of pea seedlings exhibited a decreasing trend, while the malondialdehyde (MDA) content and the activity of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in leaves increased. Also, more sodium (Na⁺) but less potassium (K⁺) ions were detected due to the change in electrolyte balance. Compared with pea seedlings under no salt stress, the growth rate, plant height, and K⁺ ion content significantly increased with the red light treatments, but both lights did not affect the aboveground fresh/dry mass, chlorophyll content, or root growth index. Under medium salt stress (50 mmol/L), red light helped generate more chlorophylls by 17.06%, accelerate leaf electrolyte exudation by 23.84%, accumulate more K⁺ ions by 46.32%, and increase the K⁺/Na⁺ ratio by 45.45%. When pea seedlings were stressed by 100 mmol/L salinity stress, red light was able to maintain the leaf chlorophyll level by 114.66%, POD enzyme activity by 157.78%, MDA amount by 14.16%, leaf and stem electrolyte leakage rate by 38.76% and 21.80%, respectively, K⁺ ion content by 45.47%, and K⁺/Na⁺ ratio by 69.70%. In conclusion, the use of red light has proven to enhance the salt tolerance of pea seedlings in a hydroponic system, which can and should be a promising approach to prime pea seedlings for more salt tolerance.

Yellow River sediment is the potential resource for saline–sodic soil reclamation. Experiments of one-dimensional soil columns were conducted to investigate the upward and downward soil water transportation characteristics for saline–sodic soil mixed with different sediment addition (0, 10, 20 kg/m² in the top 20 cm layer). The saturated hydraulic conductivity, ratio of macroporosity, cumulative capillary adsorption and infiltration rate all increased with the increase in sediment addition. No significant differences were detected for both the initial capillary rise rate and the initial infiltration rate for the upward and downward water transportation treatments, respectively. The average adsorption and infiltration rates showed an increasing trend with the increased sediment addition. The initial and average infiltration rates were higher than the initial capillary rise rate and average adsorption rates. The Philip model seems the optimal choice for the dynamic simulation of both upward and downward soil water transportation. The results may provide useful information for soil salinization amelioration.