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The low efficiency of light and nitrogen resources, poor yield and profit, and environmental pollution of maize production are main problems in many areas of China. We hypothesized that optimizing nitrogen fertilizer density management strategies could alleviate the above issues. To address this, a 3-year on-site experiment with three planting densities and four nitrogen rates was conducted in the Sichuan Hilly Region. The results indicated that increasing the planting density could increase the extinction coefficient and solar radiation interception of maize populations as well as enhance the utilization efficiency of light and nitrogen resources and yield. For every 100 kg ha−1 increase in nitrogen fertilizer, RUE increased by 0.16%, NUE decreased by 25.0%, and soil apparent nitrogen loss quantity increased by 67.8 kg ha−1. There was a certain interaction between planting density and nitrogen rate. The appropriate planting density and nitrogen rate combination was 67,500 plants ha−1 with 180 kg N ha−1 under the experimental condition. Excessive close planting in weak-light areas and excessive nitrogen reduction after densification are not advisable. This study indicated that nitrogen–density strategies should be matched with the local natural resources such as sunlight. The results provide a theoretical for high-yield and high-quality maize production in these areas. [ABSTRACT FROM AUTHOR]

The construction of an appropriate cropping pattern is crucial for the improvement of regional agricultural economic efficiency and sustainable development. Despite previous efforts, there remains a gap in optimizing cropping patterns that fully leverage climate resources to enhance production efficiency. This study addresses this gap by systematically comparing the differences in climate resource allocation, production efficiency and crop response among models by constructing four new triple-maturing cropping models at typical ecological sites in the hilly areas of southwest China. To solve the above problems, we constructed eight cropping patterns and classified them to three as follows: the Traditional Double Cropping System, the Traditional Triple Cropping System, the Novel Triple Cropping System. The results showed that the new multi-maturing planting pattern was significantly better than the traditional two-maturing netting pattern and the traditional three-maturing planting pattern in terms of light, temperature and water productivity. Compared with the traditional two-maturity net cropping model and the traditional three-maturity cropping model, the new cropping model increased light energy productivity by 97.88% and 50.00%, respectively; light energy use by an average of 0.48% and 0.31%; cumulative temperature productivity by an average of 84.70% and 49.14%; and rainfall productivity by an average of 101.04% and 49.61%. An assessment of the light, temperature and water meteorological resource use efficiency of the different treatments showed that the resource use efficiency of the new multi-maturing planting pattern was on average 111.58% and 74.78% higher than that of the traditional two-maturing net planting pattern and the traditional three-maturing planting pattern, with the T6 pattern having the highest resource use efficiency. The new multi-ripening cropping pattern has demonstrated production stability in response to changes in light, temperature and water resources, better adapting to weekly climate changes, stabilizing yields and improving efficiency. In summary, the results of this study can provide a theoretical basis for optimizing cropping patterns and promoting the use of climate resources in agriculture and sustainable development. Future research should focus on further refining these models, exploring their adaptability to various climatic conditions, and evaluating their long-term economic and environmental impacts. [ABSTRACT FROM AUTHOR]

Optimizing Cropping patterns is important for the improvement of regional agricultural economic efficiency and sustainable development. However, there are few studies on the sustainability of cropping patterns in hilly areas. Here, we studied four new three-maturing cropping patterns in a typical ecological site in the hilly areas of southwest China. An analytical method combining economic efficiency evaluation and energy value analysis was used to evaluate and compare the economic efficiency and sustainability of the new cropping model and the traditional cropping model. We explored the construction of a new three-crop cropping model suitable for the southwest hilly area to improve the economic benefits of agricultural production and improve the sustainability of agricultural production. To solve the above problems, we constructed eight cropping patterns and classified them as follows: The Traditional Double Cropping System: T1, oilseed rape-summer soybean; T2, oilseed rape-summer maize; T3, wheat-summer maize. Traditional Triple Cropping System: T4, wheat/spring maize/summer soybean. Novel Triple Cropping System: T5, forage oilseed rape-spring maize/summer soybean; T6, forage oilseed rape-spring maize/peanut; T7, potato-spring maize/peanut; T8, potato-spring maize/summer soybean. The results of the study showed that compared with the Traditional Double Cropping System and the Traditional Triple Cropping System, the Novel Triple Cropping System increased the economic yield by an average of 100.39% and 49.18%, the economic production capacity by 71.32% and 36.48%, the biological yield by 12.53% and 4.90%, and the biological production capacity by 13.59% and 5.80%. The economic benefits of the Novel Triple Cropping System were significantly improved, with economic profits increased by CNY 9068 ·hm−2 and CNY 7533 ·hm−2 compared with the Traditional Double Cropping System and the Traditional Triple Cropping System. The energy value analysis further revealed the characteristics of the Novel Triple Cropping System as a high input and high output model. The Novel Triple Cropping System increased energy value inputs by 6.56% and 4.25%, and energy value outputs by 13.69% and 4.27% compared with the Traditional Double Cropping System and the Traditional Triple Cropping System, respectively. This high level of inputs stems mainly from a significant increase in labor inputs. Meanwhile, the energy-value indicator analysis of the Novel Triple Cropping System shows its lower dependence on natural resources, greater production intensification, and increased system stability. As a result, the Novel Triple Cropping System showed higher sustainable production capacity. In summary, the results of this study can provide a theoretical basis for optimizing cropping patterns and promoting high-yield and the sustainable development of agriculture. [ABSTRACT FROM AUTHOR]

Dense planting effectively increases maize yield while increasing stalk lodging risk. Appropriate row spacing can improve the maize population structure and stalk lodging resistance, but its physiological ecological mechanisms and interaction with planting density are unclear. Here, a two-year field experiment to determine the joint effects of row spacing and planting density on maize stem characteristics and the quantitative relationship of the light condition within a maize population with stalk lodging resistance indicated that the stalk mechanical strength showed a quadratic function relationship with photosynthetically active radiation (PAR), whereas the lodging rate showed an exponential function relationship with basal light transmittance (LT). Further, the basal LT was significantly positively correlated with basal internode thickness, dry weight per unit stem length (DWUL), mechanical and cortical tissue thickness, and lignin and cellulose contents. Increasing the planting density decreased the basal LT and PAR; correspondingly decreased the basal internode thickness, DWUL, mechanical and cortical tissue thickness, lignin and cellulose contents, and stalk mechanical strength; and increased the lodging rate, while increasing row spacing did the opposite. Thus, optimizing the row spacing enhanced the lodging resistance through LT and PAR improvement of the lower part of the population and further increased the grain yield by optimizing the yield components. The appropriate row spacing varied with the planting density. The proper strategy for high stalk lodging resistance and grain yielding under this experimental condition was 67,500 plants ha−1 density with 60 + 60 cm equal row spacing. [ABSTRACT FROM AUTHOR]

Although there are many new types of environmentally friendly fertilizers that can improve maize yield, chemical fertilizers are the most widespread type of fertilizer used in the agricultural sector of China due to their low cost and ease of application. However, the misuse of chemical fertilizers could lead to environmental problems, such as the massive emission of greenhouse gases (GHG). Therefore, it is important to determine how fertilizer-use efficiency (FUE) could be improved to stabilize or increase maize yield while reducing GHG emissions. In this study, we collected 6618 date records which include three datasets (for N, P, and K) from five maize-growing regions in China from 2005 to 2018, and performed a meta-analysis on the effects of N, K, and P fertilization levels on maize yield, partial factor productivity (PFP), agronomic efficiency (AE), and the carbon footprint of maize production. Additionally, scenario analyses were performed to estimate optimal fertilizer application rates for stabilizing or increasing maize yield while reducing GHG emissions. It was shown that FUE and maize yield responses to fertilization level varied in different regions. Compared to the past, the maize production of China has improved significantly in terms of FUE and its carbon footprint in recent years. Because of improvements in maize cultivars and cultivation technologies, it is possible to decrease N, P, and K application rates and reduce per unit area carbon footprint of maize, without compromising yield. In the future, N fertilization should be reduced by 10% from current levels, and the application of P and K fertilizers should be increased or decreased depending on the conditions of each maize-growing region. Thus, it should be possible to stabilize or even increase yields and reduce GHG emissions of maize production, thereby achieving green and efficient development. [ABSTRACT FROM AUTHOR]

As urbanization is growing quickly in China, many migrant elderly following children (MEFC) migrate to big cities to care for their grandchildren (grandchildren of MEFC=GMEFC). This study aimed to explore the effects of the living environment, health statuses of family members, and MEFC's attitude regarding the care of their children (children of MEFC=CMEFC) for their GMEFC on GMEFC's health statuses in Weifang, China. Multistage cluster random sampling was used to select the participants, and 613 MEFC were included in total. Descriptive analysis, univariate analysis and binary logistic regression were used to investigate the association between the related variables and GMEFC's health statuses. It was found that 74.9% of the GMEFC had excellent health statuses. The GMEFC who had siblings, the CMEFC with excellent health statuses, and the MEFC with excellent health statuses were more likely to have excellent health statuses. Moreover, the GMEFC who were female, elevators occasionally malfunctioned, the MEFC who were dissatisfied with the CMEFC's time spent on caring, and the MEFC who did not understand or forgive the CMEFC's limited time on caring were less likely to have GMEFC with excellent health statuses. The results indicated that a better living environment, better health statuses of family members, and a positive attitude of the MEFC regarding the care of CMEFC for GMEFC would result in a better health status of GMEFC. [ABSTRACT FROM AUTHOR]

China is currently facing a severe challenge of population ageing. However, no study has specifically explored the association between social support and cognitive impairment in Chinese urban elderly aged 60 and older. We explored the prevalence of cognitive impairment and its relationship with social support among the urban elderly aged above 60 years in Jinan, China. A total of 522 urban elderly individuals were recruited using multi-stage cluster random sampling, of which 35.55% were males and 64.45% were females. The average age of all participants was 69.66 ± 8.91 years old. Social support was assessed using the Social Support Rating Scale. Cognitive status was assessed using the Mini-Mental State Examination. Data were collected through face-to-face interviews using structured questionnaires. Descriptive analysis, chi-square tests, and logistic regression analyses were conducted. After analysing the data from 512 participants, 154 (30.1%), 352 (68.8%), and 6 (1.2%) participants had high, moderate, and low levels of social support, respectively. In addition, 125 participants (24.4%) had a cognitive impairment, while the other 387 participants (75.6%) had a normal cognitive status. Binary logistic regression analyses showed that age, educational level, occupation or pre-retirement occupation, and social support were statistically associated with cognitive impairment. A significant association between social support and cognitive impairment was found among the urban elderly in Jinan, China, which provided useful information for the intervention of cognitive impairment. More attention should be paid to the social support of the urban elderly to effectively reduce the occurrence of cognitive impairment. [ABSTRACT FROM AUTHOR]

Social support has been demonstrated to be associated with the health status of old adults, but no study has clarified the relationship between social support, morbidities and self-rated health among the migrant elderly following children (MEFC) to new cities. This study aimed to explore the effect of social support and morbidities on self-rated health among MEFC to Jinan, China. A total of 656 MEFC were included in this study by using multi-stage cluster random sampling. Social support was measured by the Social Support Rating Scale. Correlation analysis and multivariable logistic regression analysis were employed to clarify the association between social support, morbidities and self-rated health among the MEFC. Approximately 75.9% of the MEFC rated their health as good. Logistic regression analysis showed that MEFC who lived with family were more likely to have a higher level of self-rated health. In addition to social support, body mass index (BMI), monthly income, one-year living style, the presence of an elevator, heart disease, stroke, duration of chronic disease, and outpatient service attendance were also associated with the self-rated health of MEFC. Social support and morbidities were significantly associated with self-rated health among MEFC. Targeted policies should be made to improve social support status and lower the morbidities in MEFC. [ABSTRACT FROM AUTHOR]

To investigate the knowledge, preventive practices, and depression of Chinese university students living in South Korea and Mainland China during the COVID-19 outbreak and explore the determinants of depression among these students, an online cross-sectional questionnaire survey was conducted from 23 March to 12 April 2020. The online questionnaire included questions on knowledge and preventive practices related to COVID-19, and the Patient Health Questionnaire-9 was used to diagnose depressive symptoms. A total of 420 Chinese university students were finally included in the study (171 students from South Korea and 249 students from Mainland China). The majority of these students had a good level of knowledge of COVID-19. Students living in South Korea displayed better preventive practices than those living in Mainland China; however, the proportion of students (28.7%) with moderate-to-severe depression in this group was relatively higher than that (18.9%) of the Mainland Group (χ2 = 5.50, p < 0.05). More severe depression was related to high levels of concern about family members and contracting COVID-19 as well as suspecting themselves of having come into contact with patients. Displaying more preventive behaviors decreased the depressive symptoms in both groups. These data could be used as a reference for further studies in different regions to take measures (e.g., psychological counseling and encouragement for physical activities) to reduce depressive symptoms in university students. [ABSTRACT FROM AUTHOR]

With accelerated urbanization in China, an increasing number of the migrant elderly following children (MEFC) have appeared. This study aims to explore the effects of living conditions, subjective integration, and social networks on the health-related quality of life (HRQOL) of MEFC in Jinan, China. HRQOL was assessed by the 12-item Short-Form Health Survey, which included the mental component summary (MCS) and the physical component summary (PCS). Univariate analyses and binary logistic regression were used to investigate the association between the above indicators and HRQOL. A total of 656 MEFC were selected by multi-stage cluster random sampling, 25.2% and 25.0% of whom were defined as poor MCS and poor PCS, respectively. Those who understood the local dialect, could trust others, and connected with friends were more likely to have good MCS; those with a nanny, faulty elevator, and no support from their spouse were the reverse. MEFC who were trans-city, had no elevator or a faulty elevator, and went to the hospital alone were more likely to have poor PCS; those who approved of living conditions in their hometowns were the reverse. Results indicated that better living conditions, stronger subjective integration, and wider social networks led to higher HRQOL of MEFC. Implications of the government, communities, and families of MEFC were given to improve their HRQOL. [ABSTRACT FROM AUTHOR]