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Abstract Background The quality of maize kernels is significantly enhanced by amino acids, which are the fundamental building blocks of proteins. Meanwhile, calcium (Ca) and magnesium (Mg), as important nutrients for maize growth, are vital in regulating the metabolic pathways and enzyme activities of amino acid synthesis. Therefore, our study analyzed the response process and changes of amino acid content, endogenous hormone content, and antioxidant enzyme activity in kernels to the coupling addition of sugar alcohol-chelated Ca and Mg fertilizers with spraying on maize. Result (1) The coupled addition of Ca and Mg fertilizers increased the Ca and Mg content, endogenous hormone components (indole-3-acetic acid, IAA; gibberellin, GA; zeatin riboside, ZR) content, antioxidant enzyme activity, and amino acid content of maize kernels. The content of Ca and Mg in kernels increased with the increasing levels of Ca and Mg fertilizers within a certain range from the filling to the wax ripening stage, and significantly positively correlated with antioxidant enzyme activities. (2) The contents of IAA, GA, and ZR continued to rise, and the activities of superoxide dismutase (SOD) and catalase (CAT) were elevated, which effectively enhanced the ability of cells to resist oxidative damage, promoted cell elongation and division, and facilitated the growth and development of maize. However, the malondialdehyde (MDA) content increased consistently, which would attack the defense system of the cell membrane plasma to some extent. (3) Leucine (LEU) exhibited the highest percentage of essential amino acid components and a gradual decline from the filling to the wax ripening stage, with the most substantial beneficial effect on essential amino acids. (4) CAT and SOD favorably governed essential amino acids, while IAA and MDA negatively regulated them. The dominant physiological driving pathway for the synthesis of essential amino acids was “IAA-CAT-LEU”, in which IAA first negatively drove CAT activity, and CAT then advantageously controlled LEU synthesis. Conclusion These findings provide a potential approach to the physiological and biochemical metabolism of amino acid synthesis, and the nutritional quality enhancement of maize kernel.

The content of kernel starch (STC), which is a fundamental indicator of the nutritional value of maize, is directly correlated with the grain’s taste and aroma. Both calcium (Ca) and magnesium (Mg) are critical nutrients that play a significant role in the growth and development of maize, as well as in the synthesis of STC. To determine the physiological driving mechanisms of Ca and Mg effects on the accumulation of STC synthesis in maize kernels and the characteristics of their effects on endogenous hormones and enzymes of STC synthesis in maize leaves, our study applied foliar Ca and Mg fertilizers at various levels to maize prior to pollination. (1) The levels of Ca, Mg, indole-3-acetic acid (IAA), gibberellin (GA), and zeatin riboside (ZR) in maize leaves increased and then decreased after the supplementation of Ca and Mg. They peaked on the 32nd day after pollination. In contrast, the levels of abscisic acid (ABA) initially decreased and then increased. Ca and Mg had a negative correlation with ABA and a positive correlation with IAA, GA, and ZR. (2) As the levels of Ca and Mg increased, correspondingly rose the activities of enzymes responsible for STC synthesis and the content of STC and its components. Principally influencing the synthesis of STC were ABA, IAA, uridine diphosphate-glucose pyrophosphorylase (UDPG), granule-bound starch synthase (GBSS), and soluble starch synthase (SSS). (3) “IAA–UDPG or GBSS–STC” was the predominant physiological regulation pathway of Ca on kernel STC, whereas “IAA–GBSS–STC” was the dominant physiological regulation pathway of Mg on kernel STC. The regulatory impact of STC by UDPG and GBSS was positive, as were the effects of IAA on UDPG and GBSS. In conclusion, the accumulation of kernel starch was significantly enhanced by Ca and Mg supplementation via the modulation of endogenous hormone levels and key enzyme activities. This research identifies a viable approach to improve the nutritional composition of maize.

Exploring the relationship between human activity, vegetation leaf area index (LAI), and land surface evapotranspiration (ET) on the Loess Plateau in northern Shaanxi is crucial for maintaining regional ecosystem functions and optimally allocating water resources. This study investigated the driving mechanism of LAI on ET under the intervention of the human activity intensity (HAIS) by analyzing seasonal and interannual variability characteristics and processes using remote sensing data of land use, LAI, and ET in typical natural landscapes (forest, grassland, and desert) in northern Shaanxi from 2000 to 2020. The primary findings were: (1) In the previous two decades, grassland HAIS was the largest, mainly distributed in central districts and counties, and gradually decreasing. The LAI and ET were ranked as follows: forest > grassland > desert, with an interannually increasing tendency, and the yearly mean LAI and ET of forest reached 2.18 and 16.47 mm, respectively. (2) The LAI and ET of the three typical natural landscapes changed substantially during the growing season (April-October) of vegetation, which increased and then decreased, reaching a maximum in June-August. The LAI and ET displayed noticeable numerical clustering among the months, with higher and concentrated values in June-August and lower values in April, May, and October. (3) Forest and grassland HAIS negatively affected LAI, and detrimentally regulated ET by primarily influencing LAI4-LAI7 (LAI from April to July). Desert HAIS had a significant positive link with the LAI and primarily regulated ET by positively influencing LAI6-LAI10. Compared to forest and grassland, the coregulatory effect of LAI on ET in the desert lagged relatively in the month. Our study recommends accelerating the conversion of the desert to forest and grassland on the Loess Plateau in northern Shaanxi for stabilizing landscape ecosystem function and the reciprocal feedback between vegetation and water resources faster.

Wang Lingguan is a significant deity in Chinese Daoist beliefs and folk worship. His belief’s formation and proliferation are rooted in specific spatial contexts. This paper introduces a spatial perspective to provide a fresh interpretation of Wang Lingguan’s belief, examining it through the lenses of ritual, temple, and geography. In Daoist rituals that bridged sacred and secular spaces, Wang Lingguan emerged as Sa Shoujian’s protector, manifesting his divine power to devotees. For the purposes of ritual simplification and spatial solidification, believers constructed Daoist Temples as emblems of sacredness and reimagined Wang Lingguan as the protector of these temples in their design. The active involvement of the Ming royal family in building Daoist Temples significantly contributed to establishing regional belief centers for Wang Lingguan. During the Qing Dynasty, although Wang Lingguan’s royal patronage waned, his belief spread across most of China, becoming more localized and secularized. The dynamic interplay of ritual, temple, and geographical factors illuminates the establishment, dissemination, and evolution of Wang Lingguan’s belief throughout China.

Geographic and temporal patterns of ecosystem service value (ESV) and their dynamic coupling response to human activity and climate change are critical for allocating land resources and maintaining healthy ecosystems in the loess hills. Based on five phases of land use data and climate data in Yan'an from 2000 to 2020, our study utilized the value-equivalent method and statistical analysis to systematically reveal the spatio-temporal dynamics of human activity and climate change, as well as their coupled driving mechanisms on ESV, and to establish and optimize synergy/trade-off strategies between them. The findings revealed that land use degree diminished between 2000 and 2020, population distribution increasingly widened. The precipitation fluctuated and increased, but the dryness trend persisted. Significant contributions were made by regulating services, supporting services, grassland, and forest to the interannual total ESV, which grew steadily at a rate of 6.89 % and reached 722.59 trillion in 2020. The total geographical distribution pattern of ESV was unstable, with a medium level of aggregation (0.02–0.06 trillion) in the northern districts and counties and a high level of aggregation (0.06–0.08 trillion) in the southwest and southeast on the grid scale of 1 km × 1 km. ESV had a highly significant synergistic relationship with annual precipitation (AP), but it showed pronounced trade-offs with population density (PD), comprehensive index of land use degree (LUI) and annual mean surface temperature (AMT). Simultaneously, there were profound synergies between the value of regulating, supporting, and cultural services. ESV was primarily positively governed by AP extremely negatively regulated by the synergistic effect of LUI and PD, the optimal regulatory thresholds of LUI, PD and AP for ESV levels of ≥0.06 trillion on the grid scale of 1 km × 1 km were 260, 30,000–50,000 people km−2, and 400–520 mm, respectively. Essentially, controlling the land use degree, expanding farmland and water areas, and stimulating climate humidification were crucial synergistic/trade-off strategies for further balancing and enhancing the value of various ecosystem service functions in sustainable ecological restoration of Yan'an.

Forest landscape restoration and ecosystem of Loess Plateau have enhanced prominently, since the policy implementation (1999) of the Grain for Green Project in China. Land ecological security (LES) performs an extremely critical function for protecting vulnerable land resources and sustaining forest ecosystem stability. Predecessors’ studies substantially concentrate on biophysical and meteorologic variables using numerous grounded methodologies, little research has been launched on systematic natural-socio-economic-ecological relationships and how these contributions and regulations for LES evaluation. Here, pressure-state-response (PSR) model was used to establish the evaluation system of LES in regional-scale, and LES was classified into five levels measured by ecological security index (S), including high (S ≥ 0.75), medium−high (0.65 ≤ S < 0.75), medium (0.55 ≤ S < 0.65), medium−low (0.45 ≤ S < 0.55), and low (S < 0.45) level, for systematically analyzing its spatiotemporal distribution characteristic and response mechanism to explanatory variables in Yan’an, northwest China, from 2000 to 2018. The results demonstrated that: (1) LES status was mainly characterized by medium−high level and medium level, and maintained profound stability. (2) zone with medium−high LES level was mainly concentrated in western and southern regions, continuously expanding to northeast regions, and possessed the largest territorial area, accounting for 37.22–46.27% of the total area in Yan’an. (3) LES was primarily susceptible to normalized differential vegetation index, vegetation coverage, and land surface temperature with their optimal impacting thresholds of 0.20–0.64, 0.20–0.55, and 11.20–13.00 °C, respectively. (4) Normalized differential vegetation index and vegetation coverage had a significant synergistic effect upon LES based on their interactive explanation rate of 31% and had significant variation consistency (positive and negative) with LES, which were powerfully suggested to signal the intensification of the regional eco-security level in the persistent eco-greening process.

Water shortage threatens agricultural sustainability in Horqin Sandy Land, northeast China. To explore the effects of various surface mulching patterns with micro-spray irrigation on the yield, water consumption (ETc), and water-saving potential of maize (Zea mays L.), we used three treatments: straw mulching (JG), organic fertilizer mulching (NF), and no mulching (WG; control). In each treatment, plants were supplied with 500 mm of total water (irrigation plus precipitation) during the entire growing season and were irrigated with the amount of total water supply minus precipitation. Yield and water use efficiency (WUE) showed a significant negative correlation with water saving potential per unit yield (Py) and water saving potential per unit area (Sp), which were also consistent with their relationships in the function model. Meanwhile, a remarkably positive correlation occurred between yield, WUE, and net economic profit, respectively. The JG treatment, which was mainly affected by light and temperature production potential (Yc), grain yield, and ETc, showed the lowest Py (0.16 m3 kg−1) and Sp (2572.31 m3 hm−2), and the maximum increase in yield, WUE, and net economic profit, extending to 16,178.40 kg hm−2, 3.25 kg m−3, 17,610.09 yuan hm−2, respectively, which were significantly higher than those in NF and WG, (p y and Sp, which were together responsible for lower WUE.

The availability of water is the critical factor driving plant growth, physiological responses, population and community succession in arid and semiarid regions, thus a precipitation addition-reduction platform with five experimental treatments, was established to explore the growth and physiology of two psammophytes (also known as psammophiles) to precipitation manipulation in Horqin Sandy Land. Changes in coverage and density were measured, and antioxidant enzymes and osmoregulatory substances in both of the studied species were determined. Investigation results showed that the average vegetation coverage increased with an increasing precipitation, and reached a maximum in July. Under the −60% precipitation treatment, Tribulus terrestris accounted for a large proportion of the area, but Bassia dasyphylla was the dominant species in the +60% treatment. T. terrestris was found to have higher a drought stress resistance than B. dasyphylla. From days 4 to 7 after rainfall, B. dasyphylla under precipitation reduction showed obvious water stress. The malondialdehyde (MDA) content of B. dasyphylla was higher than that of T. terrestris, but that of B. dasyphylla had the lower relative water content (RWC). The MDA content in the precipitation reduction treatments of the two studied species was higher than that in the precipitation addition treatments from days 4 to 10. Peroxidase (POD) and superoxide dismutase (SOD) activity and the soluble proteins and free proline content of T. terrestris were higher than those of B. dasyphylla. The free proline content of T. terrestris and B. dasyphylla increased with increasing drought stress. Our data illustrated that T. terrestris had a higher drought stress resistance than B. dasyphylla, which was correlated with the augmentation of some antioxidant enzymes and osmoregulatory substance. The adaptive mechanism provides solid physiological support for an understanding of psammophyte adaptation to drought stress, and of community succession or species manipulation for desertified land restoration.

Water scarcity threatens the sustainability of irrigated agriculture in semi-arid regions, and ridge-furrow planting systems (RFPS) can be a prospective rainwater harvesting approach. In this study, we aimed to develop a promising water-saving strategy to boost maize productivity and water use efficiency (WUE). In 2017, we carried out a field experiment to study the effects of various RFPS with multiple irrigation levels on the yield-water relationship of maize (Zea mays L.). Eleven treatments were set up: RFPS with film mulching on both ridges and furrows and without water supply after seed emergence, abbreviated as QF; RFPS with film mulching on continuous ridges, abbreviated as MD, including SMD, MMD, and LMD (S, M, and L—three water supply (irrigation plus precipitation) levels of 650 mm, 500 mm, and 350 mm during the whole growing season); RFPS without film mulching, abbreviated as DD, including SDD, MDD, and LDD; conventional flat planting with no film mulching, abbreviated as GG, including SGG, MGG, and LGG; localized full irrigation (actual amount of irrigation excessively exceeding the quantity needed), abbreviated as NM. A positive linear relationship (R2 = 0.95–1), a quadratic curve, and a negative linear relationship were observed between the irrigation water level and actual crop evapotranspiration (ETc), grain yield, and WUE, respectively. The ETc of QF (292 mm) was substantially lower than that of the other treatments (p < 0.01), saving 649 mm of irrigation water and increasing the yield by 2.24% compared with those of NM. Meanwhile, the WUE and irrigation water use efficiency (IWUE) of QF reached maximums of 6.3 and 47.36 kg m−3, respectively, which were significantly higher than those of other treatments (p < 0.001). The results showed that planting in an RFPS with film mulching on both ridges and furrows (a ridge-to-furrow ratio of 50:30, with a 38 mm irrigation level) is suitable for maize to obtain high yield and reduce irrigation water use significantly.

To understand how germinating psammophyte seeds adapt to drought stress in China's Horqin Sandy Land, we examined how the seedling growth and physiological properties of Agriophyllum squarrosum (L.) and Setaria viridis (L.) respond to drought. Results showed that Agriophyllum squarrosum had stronger drought stress resistance compared with Setaria viridis. The seed germination rate, plumule length, single-seed fresh weight, and seed water content of both species decreased under drought. At a water potential of-0.30 MPa, seed germination of A. squarrosum was 15. 7% and that of S. viridis was only 2. 7%. Mild and moderate drought increased radicle length and superoxide dismutase (SOD) activity of A. squarrosum and S. viridis, the soluble proteins and soluble sugars contents of A. squarrosum and catalase (CAT) activity of S. viridis, but severe drought decreased these values. The radicle length of A. squarrosum was highest at -0.09 MPa (at 45.8% greater than in the control), and was significantly larger than in other treatments. With prolonged drought stress, the SOD and CAT activities and the soluble sugars and proteins contents of A. squarrosum were higher than those of S. viridis. However, the free proline content of A. squarrosum was lower than that of S. viridis when the water potential was higher than -0.30 MPa. Our results demonstrate different physiological adaptability to drought for the two species, and will support more effective vegetation restoration in the Horqin Sandy Land. [ABSTRACT FROM AUTHOR]

The planting structure of crops and the sustainability of the water resources should be reasonably planned to alleviate the overexploitation of groundwater in Inner Mongolia. Therefore, the variations of precipitation, surface water and groundwater from 2000 to 2017, planting area and yield of maize from 1947 to 2917 was analyzed in our study. Main results showed that precipitation steadily increased with years, and significantly affected the surface water and groundwater (R²>0.85). Presently, the total water resource was 30.993 billion m³, the agriculture irrigation water was 12.085 billion m³, and the water consumption of groundwater was 8.533 billion m³. In recent years, the amount of water used for agriculture irrigation decreased markedly, mainly relying on groundwater. With the gradual increase of the area of water saving irrigation, the irrigation area using sprinkler irrigation and drip irrigation technology increased significantly, reaching up to 1.4445 million hm² in 2017, compared with the other irrigation patterns. Although the planting area of food crops in the proportion of the planting area of total crops seriously decreased, but maize, as the primary food crops and economic crops in the local region, its planting area in the proportion of planting area of all food crops continuously increased, and yield of maize also continued to increase. By 2017, the planting area of maize was up to 3,716,300 hm², yield of maize was 6,720kg hm-2, which was positively correlated with water storage in reservoirs. Therefore, it was necessity to adopt the planting pattern of high efficiency and water saving for improving the water use efficiency, reducing the use of groundwater, and achieving water saving agriculture and sustainable development of water resources. [ABSTRACT FROM AUTHOR]

A field trial was designed by five mulching approaches (TS, coarse sand mulching; TJ, straw mulching; TBJ, straw mulching with white plastic film; THJ, straw mulching with black plastic film; TK, no mulching) for determination of main physiological factors affecting greenhouse grape berries, and mastery of how the grape berry was influenced particularly by antioxidant enzymes. Main results showed that: (1) the first eigenvalues of the three main factors in all treatments were above 1, which corresponded with the vanance ratio of TK>TJ>TS>TBJ>THJ, wherein TK was up to 95.634%, and THJ was 91.567%. In TS, higher load of 0.926, 0.834, and 0.638 occurred in catalase (CAT), Pro content in leaves and superoxide dismutase (SOD) activity of berries, of which correlation coefficient in principal component expression was 0.542, 0.526, and 0.618, respectively, serving as main component factors; (2) determination coefficient (R²) of berry diameter was in range of 0.970- 0.970, with high reliability. Based on linear regressions between the berry diameter and principal component factors, the interpretation degree of these principal components factors to the grape berry was 82.90%, 78.40%, 66.60%, 77.00% and 70.30% in TS, TJ, TBJ, THJ and TK, respectively. Our conclusions suggested that under coarse sand mulching, the high level of CAT activity reduced the effect of variational proline (Pro) content and SOD activity on grape berry. The complementary synergy effect of CAT, SOD and Pro promoted the grape berry growth; after straw mulching, the Pro content in grape leaves and berries kept at an unstable status in the middle phase of growing season, weakened the ability of maintaining leaf osmotic potential, led to grape berry was controlled by the malondialdehyde (MAD) accumulations; under straw mulching with black film, combining the higher SOD activity which was not affected by the growing season with more Pro content maintained the defensive capability of membrane system, furthermore, MAD with a gentle decrease in earlier growing season enhanced the resistance of grapevines. [ABSTRACT FROM AUTHOR]

In regions with sandy soil texture and water scarcity, it is little to know the coupling effect of deficit irrigation with fertilization on soybean growth. The three combined effects of deficit irrigation (DI) and nitrogen fertilization (NF) on the leaf-level physiological and morphological parameters were identified. Irrigation was started once soil water content (SWC) was below 60% (T1), 50% (T2), 40% (T3), or 70% (CK) of field capacity (FC), respectively; meanwhile, 54 kg N ha-1 (T1), 67.5 kg N ha-1 (T2), or 81 kg N ha-1 (T3) was assigned at the beginning of the blooming stage. The results showed that the net photosynthetic rate (PN) and leaf water use efficiency (LWUE) was highest in T3. The leaf area (LA), plant height (SH), and leaf fresh mass (LFM) of T1, T3 increased by 32.69%, 16.05%, 29.10%, 14.93%, 62.49%, 71.43%, respectively, in comparison to CK. Relative water content (RWC, including leaf and pod) was lower in T1, T3 than in CK significantly, which was negative linear relationship with leaf water potential (ψw), and decreased continuously across growth stage. Ultimately, the average pod dry mass (PDM) in T3, T1 was up to 1.93g, 1.85g, CK just was 0.26g. Our results suggested that combination of 324mm irrigation and 54 kg N ha-1 optimally elevated VG, and 81mm water combining with 81 kg N ha-1 coupling most favoured RG and dry matter accumulation (DM) in comparison to single 405mm irrigation, maximizing the use efficiency of water, nitrogen and increasing vegetative growth (VG) and reproductive growth (RG). [ABSTRACT FROM AUTHOR]

Water is not only a limiting factor, but also one of the most important mediators of grape berry compositions in semi-arid land. Differences in superoxide dismutase (SOD), catalase (CAT), proline (Pro), malondialdehyde (MDA), and wine grape berry composition were investigated under water stress with drip irrigation. Merlot vines were proposed to the three levels of irrigation threshold (70-75%, 60-65% and 50-55% of field capacity (FC)) at the stage of germination, flowering and enlargement. The sweet taste and the favorable aromatic flavor were improved significantly from the germination to the enlargement stage to which slight water stress (60-65% of FC) was applied, wherein an optimal berry composition was achieved at the flowering stage which was mostly responsible for a positive relationship with high SOD activity. Such as, sugar-acid ratio, total sugar, tannins, total phenols, and anthocyanins of berries increased by 183.85%, 47.79%,66.67%, 100%, 57.52% in comparison to normal irrigation threshold (70-75% of FC), respectively. When Merlot vines were stressed at 50-55% of FC from germination to flowering stage, berry composition, diameter and cluster mass were higher than in normal irrigation (70-75% of FC), resulted from the linear positively correlations between berry diameter, dry matter and Pro content, activities of SOD, CAT observed. [ABSTRACT FROM AUTHOR]