Maize is a cold-sensitive crop, and it exhibits severe retardation of growth and development when exposed to cold snaps during and right after seedling emergence. Although different agronomic, physiological, and molecular approaches have been tried to overcome the problems related to cold stress in recent years, the mechanisms causing cold resistance in maize are still unclear. Screening and breeding of varieties for cold resistance may be a sustainable option to boost maize production under low-temperature environments. Herein, seedlings of 39 different maize genotypes were treated under both 10 °C low temperature and 22 °C normal temperature conditions for 7 days, to assess the changes in seven growth parameters, two membrane characteristics, two reactive oxygen species (ROS) levels, and four antioxidant enzymes activities. The changes in ten photosynthetic performances, one osmotic substance accumulation, and three polyamines (PAs) metabolisms were also measured. Results indicated that significant differences among genotypes, temperature treatments, and their interactions were found in 29 studied traits, and cold–stressed seedlings were capable to enhance their cold resistance by maintaining high levels of membrane stability index (66.07%); antioxidant enzymes activities including the activity of superoxide dismutase (2.44 Unit g⁻¹ protein), peroxidase (1.65 Unit g⁻¹ protein), catalase (0.65 μM min⁻¹ g⁻¹ protein), and ascorbate peroxidase (5.45 μM min⁻¹ g⁻¹ protein); chlorophyll (Chl) content, i.e., Chl a (0.36 mg g⁻¹ FW) and Chl b (0.40 mg g⁻¹ FW); photosynthetic capacity such as net photosynthetic rate (5.52 μM m⁻² s⁻¹) and ribulose 1,5–biphosphate carboxylase activity (6.57 M m⁻² s⁻¹); PAs concentration, mainly putrescine (274.89 nM g⁻¹ FW), spermidine (52.69 nM g⁻¹ FW), and spermine (45.81 nM g⁻¹ FW), particularly under extended cold stress. Importantly, 16 traits can be good indicators for screening of cold–resistant genotypes of maize. Gene expression analysis showed that GRMZM2G059991, GRMZM2G089982, GRMZM2G088212, GRMZM2G396553, GRMZM2G120578, and GRMZM2G396856 involved in antioxidant enzymes activity and PAs metabolism, and these genes may be used for genetic modification to improve maize cold resistance. Moreover, seven strong cold–resistant genotypes were identified, and they can be used as parents in maize breeding programs to develop new varieties.

Agricultural soil microorganisms play a crucial role in farmland ecosystems and are integral to the material cycle in these environments. The composition and abundance of soil microorganisms are influenced by agronomic measures that alter the soil microenvironment. These changes are pivotal to enhancing crop resistance, maximizing yield, and facilitating nutrient cycling in farmlands. Drawing on prior research advancements, this study systematically examined the functions of soil microorganisms, the effects of various agronomic measures on their populations, and the ways in which agronomic measures regulate soil microorganisms, and this article offers a comprehensive study of agricultural influences on microorganisms. Additionally, it outlines key areas for future research on soil microorganisms in farmlands, aiming to provide valuable insights for the sustainable development of farmland ecosystems.

Diversified cropping, as a crucial measure in modern ecological agriculture, promotes the intensification, industrialization, and diversification of agricultural production. By addressing region-specific and environmental challenges, the development of diversified cropping systems (DCS) tailored to local conditions can achieve the dual goals of improving crop quality and ensuring food security. However, existing crop quality improvement research primarily focuses on molecular techniques, with limited exploration of cropping practices. This review aims to systematically and comprehensively examine the concept, classification, and significance of diversified cropping. It highlights the critical roles and mechanisms of various cropping systems, such as intercropping, crop rotation, relay cropping, and multiple cropping, in enhancing crop quality. Furthermore, the review discusses the limitations and challenges of diversified cropping and offers suggestions for its improvement and application to advance research in this field. By proposing a scientific framework linking DCS with crop quality improvement, this review contributes to the formulation of evidence-based agricultural strategies to meet the growing demand for high-quality food, maintain environmental health, and promote long-term agricultural sustainability.

Nitrogen (N) fixation is essential in the development of sustainable agriculture, but nodulation of legumes is usually inhibited by N fertilization. In this study, we evaluated the increased density of intercropped maize (Zea mays L.) as a means to alleviate the inhibitory effect of soil mineral N on intercropped pea (Pisum sativum L.) and improve system performance. A field experiment was conducted in the Hexi Corridor region of northwestern China from 2012 to 2014. The experiment consisted of monoculture pea, monoculture maize, and a pea/maize strip-intercropping system. Two levels of N fertilization were evaluated in both cropping systems during the co-growth period of intercropping, i.e., 0 kg N ha⁻¹ (N0) and 135 kg N ha⁻¹ (N1), and three maize densities were evaluated with both levels of N fertilization in the intercropping system, i.e., 45,000 plants ha⁻¹ (D1), 52,500 plants ha⁻¹ (D2), and 60,000 plants ha⁻¹ (D3). The application of N reduced the number of nodules of intercropped pea by 135% at D1 and by 9% at D2 compared to no application of N, in all the years examined. The alleviation of the inhibitory effect of soil mineral N on the nodulation of intercropped pea (C_is) was calculated as the percentage increase in nodulation with intercropping relative to monoculture for a given level of N fertilization. With the application of N, C_is was improved by increased intercropped maize density (D3 > D2 > D1) at all stages. The internal efficiency of nitrogen (IEN) of pea was improved with intercropping and, on average, was 19% and 12% greater at D3 than at D1 and D2, respectively. These results demonstrate that increased maize density can alleviate the inhibitory effect of soil N on the nodulation of pea and sustain the productivity of maize/pea intercropping while reducing N fertilizer requirements in arid regions.