In China, alfalfa (
L.) often grows in marginal land with poor soil fertility and suboptimal climate conditions. Alfalfa production cannot meet demands both in yield and quality. It is necessary to ...apply fertilizers to achieve high yields and produce high-quality alfalfa in China. However, there is no understanding on the impact of fertilizer application on alfalfa production and the possible optimal application rates across China.
We conducted a meta-analysis to explore the contribution of fertilizer application to the yield and quality of alfalfa based on a dataset from 86 studies published between 2004 and 2022.
The results showed that fertilizer application not only increased alfalfa yield by 19.2% but also improved alfalfa quality by increasing crude protein (CP) by 7.7% and decreasing acid detergent fibre by 2.9% and neutral detergent fibre by 1.8% overall compared to the non-fertilizer control levels. The combined nitrogen (N), phosphorus (P) and potassium (K) and combined NP fertilizer applications achieved the greatest yield and CP concentration increases of 27.0% and 13.5%, respectively. Considering both yield and quality, the optimal rate of fertilizer application ranged from 30 to 60 kg ha
for N, 120 to 150 kg ha
for P and less than 120 kg ha
for K. Meta-analysis further showed that the effect of fertilizer application on yield was greater in low soil organic matter (SOM) soils than in high SOM soils. In conclusion, fertilizer application is an effective strategy to improve the yield and quality of alfalfa in China, especially that grown in low SOM soils. This study is helpful for optimizing fertilization schedules of alfalfa in China.
Phosphorus (P) fertilizer is critical to maintain a high yield and quality of alfalfa (Medicago sativa L.). There are several fertilizer types and soil types in China, and the application of a single ...type of P fertilizer may not be suitable for present-day alfalfa production.
In order to select the optimal combination of alfalfa and soil type and fertilizer type for improving P utilization efficiency. We conducted a greenhouse pot experiment, calcium superphosphate (SSP), diammonium phosphate (DAP), ammonium polyphosphate (APP), potassium dihydrogen phosphate (KP), and no-fertilizer control treatments were applied to alfalfa in sandy and saline-alkali soils. The response of alfalfa root morphology and rhizosphere processes to different P fertilizers was investigated.
The results showed that shoot biomass of alfalfa was slightly higher in sandy soil than in saline-alkali soil. Shoot biomass of alfalfa increased by 223%-354% in sandy soil under P treatments compared with the control, and total root length increased significantly by 74% and 53% in DAP and SSP treatments, respectively. In saline-alkali soil, alfalfa shoot biomass was significantly increased by 229% and 275% in KP and DAP treatments, and total root length was increased by 109% only in DAP treatment. Net P uptake of alfalfa in DAP treatment was the highest in both soils, which were 0.73 and 0.54 mg plant
, respectively. Alfalfa shoot P concentration was significantly positively correlated with shoot and root biomass (
< 0.05, 0.01 or 0.001) whereas negatively correlated with acid phosphatase concentration (
< 0.05). Improvement of plant growth and P uptake induced by P fertilizer application was greater in sandy soil than in saline-alkali soil. DAP and KP was the most efficient P fertilizers in both sandy soil and saline-alkali soil.
In China, alfalfa (
L.) is often grown on marginal land with poor soil fertility and suboptimal climate conditions. Soil salt stress is one of the most limiting factors for alfalfa yield and quality, ...through its inhibition of nitrogen (N) uptake and N fixation.
To understand if N supply could improve alfalfa yield and quality through increasing N uptake in salt-affected soils, a hydroponic experiment and a soil experiment were conducted. Alfalfa growth and N fixation were evaluated in response to different salt levels and N supply levels.
The results showed that salt stress not only significantly decreased alfalfa biomass, by 43%-86%, and N content, by 58%-91%, but also reduced N fixation ability and N derived from the atmosphere (%Ndfa) through the inhibition of nodule formation and N fixation efficiency when the salt level was above 100 mmol Na
SO
L
. Salt stress also decreased alfalfa crude protein by 31%-37%. However, N supply significantly improved shoot dry weight by 40%-45%, root dry weight by 23%-29%, and shoot N content by 10%-28% for alfalfa grown in salt-affected soil. The N supply was also beneficial for the %Ndfa and N fixation for alfalfa with salt stress, and the increase reached 47% and 60%, respectively. Nitrogen supply offset the negative effects on alfalfa growth and N fixation caused by salt stress, in part through improving plant N nutrition status. Our results suggest that optimal N fertilizer application is essential to alleviate the loss of growth and N fixation in alfalfa in salt-affected soils.
Background Desert steppe ecosystems are prone to drought stress, which influences the ecological balance and sustainable development of grasslands. In addition to directly restrict plant growth, ...drought stress indirectly impacts plant fitness by altering the diversity and function of root-associated microbiomes. This begs the question of whether the functional microbiome of forage plants, represented by synthetic microbial communities (SynComs), can be leveraged to mitigate drought stress in desert steppes and promote the ecological restoration of these fragile ecosystems. Methods A pot experiment was conducted to evaluate the role of SynComs in improving the plant growth and drought stress resistance of Neopallasia pectinata (Pall.) Poljak in desert steppe in Inner Mongolia, China. Six SynComs were derived from the rhizosphere and root endosphere of 12 dominant forage species in the desert steppe. Each SynCom comprised two to three bacterial genera ( Bacillus , Protomicromonospora , and Streptomyces ). We examined the capacities of different SynComs for nutrient solubilization, phytohormone secretion, and enzymatic activity. Results Under no water stress (75% soil water holding capacity, WHC), single strains performed better than SynComs in promoting plant growth in terms of stem diameter, root length, and plant dry weight, with the greatest effects observed for Streptomyces coeruleorubidus ATCC 13740 ( p < 0.05). However, under mild to moderate drought stress (55% and 35% WHC), SynComs outperformed single strains in enhancing plant biomass accumulation and inducing the production of resistance-related substances ( p < 0.05). No significant effect of single strains and SynComs emerged under extreme drought stress (20% WHC). Conclusion This study underscores the potential of SynComs in facilitating forage plants to combat drought stress in desert steppe. Mild to moderate drought stress stimulates SynComs to benefit the growth of N. pectinata plants, despite a soil moisture threshold (21% WHC) exists for the microbial effect. The use of SynComs provides a promising strategy for the ecological restoration and sustainable utilization of desert steppes by manipulating the functional microbiome of forage plants.
We explored the migration and distribution of heavy metal pollution in a dry and windy area in northern China. We collected soil, atmospheric deposition, and water samples, and measured heavy metal ...concentrations. Cu, Zn, As, and Pb in the 0–10 cm soil layer had a fan-shaped distribution, consistent with their atmospheric deposition fluxes. This indicates that the distribution of these heavy metals was driven by strong winds. The concentration of Cd in the river increased from 0.257 mg/L upstream to 0.460 mg/L downstream, resulting in the same distribution trends as soil near the river. Surface runoff may therefore drive Cd migration. The concentration of Pb in the river exceeded the pollution threshold, resulting in accumulation in the 5–10 cm soil layer. Atmospheric deposition fluxes were consistent with the soil distribution results, and principal component analysis showed that the contribution of surface runoff was high. This suggests that the migration of Pb and Cr is driven by both wind and surface runoff. Six heavy metals showed different migration behaviors, suggesting specific control strategies should be implemented for individual heavy metals.
We propose a super-resolution method for microwave front-looking imaging, which takes advantage of the signal bandwidth to enhance the resolution of imaging. Via spatial spectrum shifting, the ...distortion introduced by broadband imaging is eliminated. Therefore, the resolution of our method can surpass the Rayleigh diffraction limit defined by the angular aperture. A numerical study shows that, in the case of an angular aperture of 0.22, our method can reach 6 mm for a target located 10 km away without imaging distortion. It is equivalent to the resolution of an angular aperture of 1.38 We derive the relationship between the resolution and the signal bandwidth, which illustrates that our method makes it possible to use the bandwidth dimension for improving front-looking imaging resolution. The proposed method will promote the development of ultralong-distance precision imaging and wide-range microwave surveillance.
We propose and demonstrate a high-resolution single-antenna three-dimensional (3-D) microwave imaging scheme. Combining the spatial decoupling capabilities of Hadamard modulation, and the broadband ...characteristics of optical receivers, our scheme can achieve high-resolution 3-D imaging resolution with one receiving antenna without scanning. It has been experimentally demonstrated that an unmanned aerial vehicle-shaped target can be successfully imaged in 3-D. According to the measurement, the resolution of the 3-D image can obtain a resolution of better than 4 cm in all three dimensions. We believe that our method will greatly promote the application of high-resolution microwave 3-D imaging in complex and changing scenarios with limited equipment.
We propose and demonstrate a high-resolution single-antenna 3D microwave imaging scheme. Combining the spatial decoupling capabilities of Hadamard modulation, and the broadband characteristics of ...optical receivers, our scheme can achieve high-resolution 3D imaging resolution with one receiving antenna without scanning. It is experimentally demonstrated that an unmanned aerial vehicle-shaped target can be successfully imaged in 3D. According to the measurement, the resolution of the 3D image can obtain a resolution of better than 4 cm in all three dimensions. We believe that our method will greatly promote the application of high-resolution microwave 3D imaging in complex and changing scenarios with limited equipment.
Acid‐sensing ion channel (ASIC) serves important roles in the transmission of nociceptive information. To confirm the analgesic mechanism of dragon's blood resin, patch–clamp technique, in vivo ...animal experiments, and immunohistochemical staining were used to observe the effects of the three flavonoids (loureirin B, cochinchinemin A, and cochinchinemin B) isolated from dragon's blood resin on ASIC. Results showed that the three flavonoids exerted various inhibitory effects on ASIC currents in rat dorsal root ganglion (DRG) neurons. The combination of the three flavonoids with total concentration of 6.5 μM could decrease (53.8 ± 4.3%) of the peak amplitude and (45.8 ± 4.5%) of the sustained portion of ASIC currents. The combination of the three flavonoids was fully efficacious on complete Freud's adjuvant (CFA)–induced inflammatory thermal hyperalgesia at a dose of 6.5 mM similar with amiloride at 10 mM. The analgesic effects of the combination could be weakened by an ASIC activator 2‐guanidine‐4‐methylquinazoline. CFA‐induced hyperalgesia was accompanied by c‐Fos up‐regulation in DRG neurons, and the combination rescued thermal hyperalgesia through down‐regulation of c‐Fos and ASIC3 expression in CFA‐induced inflammation. These collective results suggested that the flavonoids isolated from dragon's blood resin could be considered as the chemical compounds that exert analgesic effects on inflammatory thermal pain due to action on ASIC.
PDF
