Towards a better understanding of atmospheric water harvesting (AWH) technology.

Atmospheric water harvesting (AWH) technology is an emerging sustainable development strategy to deal with global water scarcity. To better understand the current state of AWH technology development, we conducted a bibliometric analysis highlighting three water harvesting technologies (fog harvesting, condensation, and sorption). By comprehensively reviewing the research progress and performing a comparative assessment of these technologies, we summarized past achievements and critically analyzed the different technologies. Traditional fog collectors are more mature, but their efficiency still needs to be improved. External field-driven fog harvesting and active condensation need to be driven by external forces, and passive condensation has high requirements for environmental humidity. Emerging bio-inspired fog harvesting and sorption technology provide new possibilities for atmospheric water collection, but they have high requirements for materials, and their commercial application is still to be further promoted. Based on the key characteristics of each technology, we presented the development prospects for the joint use of integrated/hybrid systems. Next, the water-energy relationship is used as a link to clarify the future development strategy of AWH technology in energy driving and conversion. Finally, we outlined the core ideas of AWH for both basic research and practical applications and described its limitless possibilities for drinking water supply and agricultural irrigation. This review provides an essential reference for the development and practical application of AWH technologies, which contribute to the sustainable utilization of water resources globally.

Mitigation of greenhouse gas emissions and improved yield by plastic mulching in rice production.

Soil mulching technologies are effective practices which alleviate non-point source pollution and carbon emissions, while ensuring grain production security and increasing water productivity. However, the lack of comprehensive understanding of the impacts of mulching technologies on rice fields has hindered progress in global implementation due to the varying environments and application conditions under which they are implemented. This study conducted a meta-analysis based on 2412 groups of field experiment data from 313 studies to evaluate the effects of soil mulching methods on rice production, greenhouse gas (GHG) emissions and water use efficiency. The results show that plastic mulching, straw mulching and no mulching (PM, SM and NM) have reduced CH4 emissions (68.8 %, 61.4 % and 57.2 %), increased N2O emissions (84.8 %, 89.1 % and 96.6 %), reduced global warming potentials (50.7 %, 47.5 % and 46.8 %) and improved water use efficiency (50.2 %, 40.9 % and 34.0 %) compared with continuous flooding irrigation. However, PM increased rice yield (1.6 %), while SM and NM decreased yield (4.3 % and 9.2 %). Furthermore, analysis using random forest models revealed that rice yield, GHG emissions and WUE response to soil mulching were related to climate, soil properties, fertilizer and rice varieties. Our findings can guide the implementation of plastic mulching technology in priority areas, contribute to agricultural carbon neutrality and support the development of practical guidelines for farmers.

Wheat genotypes with higher yield sensitivity to drought overproduced proline and lost minor biomass under severer water stress.

To clarify the differences in growth and yield responses to drought stress among genotypes contrasting in environmental background, dryland and irrigated genotypes, as well as the underlying biochemical mechanism would provide valuable information for developing superior dryland cultivars. Pot experiments for the whole life cycle in fifteen genotypes and comparative metabolomics analysis for seedlings between two drought tolerant (DT) dryland genotypes and two drought sensitive (DS) irrigated ones were carried out. The DT dryland genotypes suffered heavy biomass loss during severer drought but showed minor yield loss ultimately, while the DS irrigated ones showed minor biomass loss but greater yield loss. Additionally, the superior DT dryland genotypes showed better yield performance under both drought stress and well-watered conditions, indicating their possessing both drought tolerance and high yield potential traits. Suffering severer drought stress, seedling leaves of the DS irrigated genotypes increased some amino acids and organic acids to maintain cell metabolism and accumulate more biomass. Proline in particular was overproduced, which might cause toxicity to cell systems and lead to enormous yield loss ultimately. In contrast, DT dryland genotypes increased the beneficial amino acid and phenolic acids to enhance cell self-protection for alleviating drought damage and efficiently minimized yield loss ultimately.

Plastic Film Mulching Improved Maize Yield, Water Use Efficiency, and N Use Efficiency under Dryland Farming System in Northeast China.

This 2-year field study analyzed plastic film mulching (PFM) effects on nitrogen use efficiency (NUE), and soil N pools under rainfed dryland conditions. Compared to no-mulching (NM, control), maize yields under PFM were increased by 36.3% (2515.7 kg ha−1) and 23.9% (1656.1 kg ha−1) in the 2020 and 2021 growing seasons, respectively. The PFM improved (p < 0.01) the water use efficiency (WUE) of maize by 39.6% and 33.8% in the 2020 and 2021 growing seasons, respectively. The 2-year average NUE of maize under the PFM was 40.1, which was 30.1% greater than the NM. The average soil total N, particulate organic N, and microbial biomass N contents under the PFM soil profile were increased by 22.3%, 51.9%, and 35%, respectively, over the two growing seasons. The residual 15N content (%TN) in soil total N pool was significantly higher (p < 0.05) under the PFM treatment. Our results suggest that PFM could increase maize productivity and sustainability of rainfed dryland faming systems by improving WUE, NUE, and soil N pools.

Substitution of Chemical Fertilizer with Organic Fertilizer Affects Soil Total Nitrogen and Its Fractions in Northern China.

The impact of chemical to organic fertilizer substitution on soil labile organic and stabilized N pools under intensive farming systems is unclear. Therefore, we analyzed the distribution of soil total N (STN), particulate organic N (PON), microbial biomass N (MBN), dissolved organic N (DON), and mineral N (NO3- and NH4+) levels down to 100 cm profile under wheat-maize rotation system in northern China. The experiment was established with four 270 kg ha-1 N equivalent fertilizer treatments: Organic manure (OM); Organic manure with nitrogen fertilizer (OM + NF); Nitrogen fertilizer (NF); and Control (CK). Results found that the OM and OM + NF treatments had significantly higher STN, PON, MBN, DON, and NO3- contents in 0-20 cm topsoil depths. Conversely, the NF treatment resulted in the highest (p < 0.01) DON and NO3- depositions in 40-100 cm subsoil depths. The NH4+ contents in selected profile depths were significantly highest (p < 0.01) under OM treatment. The correlations between STN and its fractions were positively significant at 0-10 and 10-20 cm topsoil depths. Our results suggest that partial substitution of chemical fertilizer with organic manure could be a sustainable option for soil N management of intensive farming systems.

Update on the Roles of Polyamines in Fleshy Fruit Ripening, Senescence, and Quality.

Ripening of fleshy fruits involves complex physiological, biochemical, and molecular processes that coincide with various changes of the fruit, including texture, color, flavor, and aroma. The processes of ripening are controlled by ethylene in climacteric fruits and abscisic acid (ABA) in non-climacteric fruits. Increasing evidence is also uncovering an essential role for polyamines (PAs) in fruit ripening, especially in climacteric fruits. However, until recently breakthroughs have been made in understanding PA roles in the ripening of non-climacteric fruits. In this review, we compare the mechanisms underlying PA biosynthesis, metabolism, and action during ripening in climacteric and non-climacteric fruits at the physiological and molecular levels. The PA putrescine (Put) has a role opposite to that of spermidine/spermine (Spd/Spm) in cellular metabolism. Arginine decarboxylase (ADC) is crucial to Put biosynthesis in both climacteric and non-climacteric fruits. S-adenosylmethionine decarboxylase (SAMDC) catalyzes the conversion of Put to Spd/Spm, which marks a metabolic transition that is concomitant with the onset of fruit ripening, induced by Spd in climacteric fruits and by Spm in non-climacteric fruits. Once PA catabolism is activated by polyamine oxidase (PAO), fruit ripening and senescence are facilitated by the coordination of mechanisms that involve PAs, hydrogen peroxide (H2O2), ABA, ethylene, nitric oxide (NO), and calcium ions (Ca2+). Notably, a signal derived from PAO5-mediated PA metabolism has recently been identified in strawberry, a model system for non-climacteric fruits, providing a deeper understanding of the regulatory roles played by PAs in fleshy fruit ripening.

Stomatal conductance bears no correlation with transpiration rate in wheat during their diurnal variation under high air humidity.

A good understanding of the response of photosynthesis rate (P N) and transpiration rate (Tr) to stomatal alteration during the diurnal variations is important to cumulative photosynthetic production and water loss of crops. Six wheat genotypes were studied for 2 years with pot cultivation in rain-shelter. Among different genotypes, stomatal conductance (g s) was significantly correlated with both P N and Tr. But for each genotype, though g s was significantly correlated with P N regardless of relative air humidity (RH) status and it was also significantly correlated with Tr under lower RH (LRH, 15.4%) and moderate RH (MRH, 28.3%), it was not correlated with Tr under higher RH (HRH, 36.7%) during the diurnal changes. The conditional correlation between g s and Tr of wheat evoked new thinking on the relationships among g s, P N and Tr. Path analysis was further carried out to clarify the correlations of g s with the four atmospheric factors, that of Tr with g s and the four factors and the direct and indirect effects of the factors, during their diurnal dynamic variation. The effects of these factors on g s or Tr were related to RH. All the four factors had a much higher correlation with g s under HRH than that under LRH and MRH. Air temperature (T) had a rather higher direct effect than RH and photosynthetically active radiation (PAR). Also, the other factors had a much higher indirect effect on g s through vapor pressure deficit (VPD) and T. Transpiration rate was highly correlated with g s under LRH and MRH, with g s having a higher direct effect on it. In comparison, Tr was not correlated with g s under HRH but highly correlated with the atmospheric factors, with T, RH, and PAR having a higher indirect effect through VPD.

Dynamic changes in membrane lipid composition of leaves of winter wheat seedlings in response to PEG-induced water stress.

BACKGROUND: Membrane lipid composition associates closely with membrane stability and fluidity under water stress. In this study, lipidomic analyses based on electrospray ionization mass spectrometry (ESI-MS/MS) were carried out to explore dynamic changes of membrane lipids in term of molecular species caused by PEG (Polyethylene glycol-6000)-induced water stress in wheat seedlings. RESULTS: Among the main phospholipids, phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylglycerol (PG) are primary degradation targets, and PC was degraded in the largest degree. Membrane ion leakage dramatically increased later than the significant reduction of these phospholipids, indicating that the loss of membrane integrity lagged behind severe phospholipid degradation. Monogalactosyldiacylglycerol (MGDG) increased firstly and decreased later, while digalactosyldiacylglycerol (DGDG) ratcheted up with stress. DGDG/MGDG increased after stress for 3 days, and unsaturation of DGDG was promoted with stress. Variation trends of galactolipids differed among molecular species. The time when MGDG (34:3), DGDG (34:3) began to decline approached to the time when non-stomatal limitation impaired photosynthesis. While the two predominant molecular species MGDG (36:6) and DGDG (36:6) began to decline later. So we speculated that MGDG (34:3), DGDG (34:3) might be key components in photosynthesis apparatus and participate in photosynthesis directly. While the two predominant molecular species, MGDG (36:6) and DGDG (36:6) might locate in thylakoid lipid bilayer matrix and play roles in stabilizing the membrane. The research provides new insights into the dynamic response of lipid metabolism to PEG-induced water stress. CONCLUSION: In wheat plants under water stress, the major molecular species of PC, PE and PG were degraded, MGDG and DGDG molecular species had differing degradation time courses.

iTRAQ-Based Quantitative Analysis of Responsive Proteins Under PEG-Induced Drought Stress in Wheat Leaves.

Drought is an important abiotic stress that seriously restricts crop productivity. An understanding of drought tolerance mechanisms offers guidance for cultivar improvement. In order to understand how a well-known wheat genotype Jinmai 47 responds to drought, we adopted the iTRAQ and LC/MS approaches and conducted proteomics analysis of leaves after exposure to 20% of polyethylene glycol-6000 (PEG)-induced stress for 4 days. The study identified 176 differentially expressed proteins (DEPs), with 65 (36.5%) of them being up-regulated, and 111 (63.5%) down-regulated. DEPs, located in cellular membranes and cytosol mainly, were involved in stress and redox regulation (51), carbohydrate and energy metabolism (36), amino acid metabolism (24), and biosynthesis of other secondary metabolites (20) primarily. Under drought stress, TCA cycle related proteins were up-regulated. Antioxidant system, signaling system, and nucleic acid metabolism etc. were relatively weakened. In comparison, the metabolism pathways that function in plasma dehydration protection and protein structure protection were strongly enhanced, as indicated by the improved biosynthesis of 2 osmolytes, sucrose and Proline, and strongly up-regulated protective proteins, LEA proteins and chaperones. SUS4, P5CSs, OAT, Rab protein, and Lea14-A were considered to be important candidate proteins, which deserve to be further investigated.

Comparisons of WUE in twelve genotypes of winter wheat and the relationship between δ 13C and WUE.

Twelve winter wheat (Triticum aestivum) genotypes were examined for differences in grain yield, water use efficiency (WUE), and stable carbon isotope composition (δ13C) in flag leaves. The plants were subjected to rain-fed treatment and supplemental irrigation at the jointing and anthesis stages, during the 2015-2016 and 2016-2017 winter wheat growing seasons. The relationships between δ13C with grain yield and WUE were analyzed under two different water environments. The results indicated that there were significant differences in δ13C, grain yield, and WUE among wheat genotypes both under rain-fed and supplemental irrigation conditions. The δ13C values increased with grain-filling proceeding, the δ13C being lower under supplemental irrigation treatment than that under rain-fed treatment. The relationships between the average of δ13C with grain yield and WUE were significantly positive during three measurement periods (R2 = 0.5785 - 0.8258), whether under rain-fed or irrigation environments. This suggests that δ13C might be associated with the grain yield and WUE in winter wheat under rain-fed and supplemental irrigation conditions in the climate region of the northwest Huang-Huai-Hai Plain of China.

Polyamines Regulate Strawberry Fruit Ripening by Abscisic Acid, Auxin, and Ethylene.

Polyamines (PAs) participate in many plant growth and developmental processes, including fruit ripening. However, it is not clear whether PAs play a role in the ripening of strawberry (Fragaria ananassa), a model nonclimacteric plant. Here, we found that the content of the PA spermine (Spm) increased more sharply after the onset of fruit coloration than did that of the PAs putrescine (Put) or spermidine (Spd). Spm dominance in ripe fruit resulted from abundant transcripts of a strawberry S-adenosyl-l-Met decarboxylase gene (FaSAMDC), which encodes an enzyme that generates a residue needed for PA biosynthesis. Exogenous Spm and Spd promoted fruit coloration, while exogenous Put and a SAMDC inhibitor inhibited coloration. Based on transcriptome data, up- and down-regulation of FaSAMDC expression promoted and inhibited ripening, respectively, which coincided with changes in several physiological parameters and their corresponding gene transcripts, including firmness, anthocyanin content, sugar content, polyamine content, auxin (indole-3-acetic acid [IAA]) content, abscisic acid (ABA) content, and ethylene emission. Using isothermal titration calorimetry, we found that FaSAMDC also had a high enzymatic activity with a Kd of 1.7 × 10-3 m In conclusion, PAs, especially Spm, regulate strawberry fruit ripening in an ABA-dominated, IAA-participating, and ethylene-coordinated manner, and FaSAMDC plays an important role in ripening.

Ecosystem respiration and its components in a rainfed spring maize cropland in the Loess Plateau, China.

We estimated ecosystem respiration (Re) and its components in a rainfed spring maize field in the Loess Plateau, China, during the growing seasons of 2012, 2013, and 2014 using measurements of eddy covariance and soil respiration (Rs). The multi-factor equation, which included photosynthetic active radiation, 5-cm soil temperature, 10-cm soil water content, and green leaf area index (GLAI), had goodness-of-fit values of between 0.81 and 0.94 for Re, autotrophic respiration (Ra), and above-ground autotrophic respiration (Raa), and goodness-of-fit values of between 0.50 and 0.67 for Rs, below-ground autotrophic respiration (Rab), and heterotrophic respiration (Rh). The highly significant linear correlations between gross primary production (GPP) and Re and its components indicate that GPP had a strong influence on Re and its components. The growing season Re was dominated by Ra (64-71%), which in turn was dominated by Raa (63-73%). Although Rs was mainly made up of Rh (56-61%), Rs resembled Rab more closely than Rh. The relationships between GLAI and Ra/Re and between GLAI and Rab/Rs were described by logarithmic equations with goodness-of-fit values of between 0.88 and 0.89 and between 0.77 and 0.84, respectively, indicating that GLAI controlled Ra/Re and Rab/Rs.

Carbon budget of a rainfed spring maize cropland with straw returning on the Loess Plateau, China.

Assessing the carbon budget of rainfed agricultural ecosystems is a vital component in the process of estimating the global carbon balance. We used eddy covariance techniques combined with soil respiration measurements to estimate the carbon budget of a rainfed spring maize field where straw returning was practiced, on the Loess Plateau, China, during 2012-2014. Carbon fluxes and their components (except heterotrophic respiration, Rh) exhibited single-peak seasonal patterns, and linear relationships were found between daily gross primary productivity (GPP) and net ecosystem exchange (NEE), and between daily GPP and ecosystem respiration (Re), with goodness of fit value of 0.96 and 0.85, respectively. The green leaf area index was the most important factor controlling seasonal variations in daily NEE, Re, and GPP during the growing season, followed by photosynthetically active radiation and air temperature (Ta). Daily Re was mainly controlled by air temperature during the non-growing season, when Re accounted for only ~17% of the annual Re due to winter temperatures. Growing season plant respiration (Rp) was the most important source of carbon emissions from the maize field, with aboveground plant respiration being the major part of Rp. Rh accounted for ~60% of total soil respiration. Only ~60% of the annual GPP was lost as Re, resulting in an average annual net CO2 uptake of 509gCm-2. Taking into account carbon exported (483gCm-2) and carbon imported (10gCm-2), the average annual net biome productivity was 37gCm-2, indicating that the spring maize field with straw returning on the Loess Plateau was a weak carbon sink.

Warmer and Wetter Soil Stimulates Assimilation More than Respiration in Rainfed Agricultural Ecosystem on the China Loess Plateau: The Role of Partial Plastic Film Mulching Tillage.

Effects of agricultural practices on ecosystem carbon storage have acquired widespread concern due to its alleviation of rising atmospheric CO2 concentrations. Recently, combining of furrow-ridge with plastic film mulching in spring maize ecosystem was widely applied to boost crop water productivity in the semiarid regions of China. However, there is still limited information about the potentials for increased ecosystem carbon storage of this tillage method. The objective of this study was to quantify and contrast net carbon dioxide exchange, biomass accumulation and carbon budgets of maize (Zea maize L.) fields under the traditional non-mulching with flat tillage (CK) and partial plastic film mulching with furrow-ridge tillage (MFR) on the China Loess Plateau. Half-hourly net ecosystem CO2 exchange (NEE) of both treatments were synchronously measured with two eddy covariance systems during the growing seasons of 2011 through 2013. At same time green leaf area index (GLAI) and biomass were also measured biweekly. Compared with CK, the warmer and wetter (+1.3°C and +4.3%) top soil at MFR accelerated the rates of biomass accumulation, promoted greater green leaf area and thus shortened the growing seasons by an average value of 10.4 days for three years. MFR stimulated assimilation more than respiration during whole growing season, resulting in a higher carbon sequestration in terms of NEE of -79 gC/m2 than CK. However, after considering carbon in harvested grain (or aboveground biomass), there is a slight higher carbon sink (or a stronger carbon source) in MFR due to its greater difference of aboveground biomass than that of grain between both treatments. These results demonstrate that partial plastic film mulched furrow-ridge tillage with aboveground biomass exclusive of grain returned to the soil is an effective way to enhance simultaneously carbon sequestration and grain yield of maize in the semiarid regions.

Long-term effect of manure and fertilizer on soil organic carbon pools in dryland farming in northwest China.

An understanding of the dynamics of soil organic carbon (SOC) as affected by farming practices is imperative for maintaining soil productivity and mitigating global warming. The objectives of this study were to investigate the effects of long-term fertilization on SOC and SOC fractions for the whole soil profile (0-100 cm) in northwest China. The study was initiated in 1979 in Gansu, China and included six treatments: unfertilized control (CK), nitrogen fertilizer (N), nitrogen and phosphorus (P) fertilizers (NP), straw plus N and P fertilizers (NP+S), farmyard manure (FYM), and farmyard manure plus N and P fertilizers (NP+FYM). Results showed that SOC concentration in the 0-20 cm soil layer increased with time except in the CK and N treatments. Long-term fertilization significantly influenced SOC concentrations and storage to 60 cm depth. Below 60 cm, SOC concentrations and storages were statistically not significant between all treatments. The concentration of SOC at different depths in 0-60 cm soil profile was higher under NP+FYM follow by under NP+S, compared to under CK. The SOC storage in 0-60 cm in NP+FYM, NP+S, FYM and NP treatments were increased by 41.3%, 32.9%, 28.1% and 17.9%, respectively, as compared to the CK treatment. Organic manure plus inorganic fertilizer application also increased labile soil organic carbon pools in 0-60 cm depth. The average concentration of particulate organic carbon (POC), dissolved organic carbon (DOC) and microbial biomass carbon (MBC) in organic manure plus inorganic fertilizer treatments (NP+S and NP+FYM) in 0-60 cm depth were increased by 64.9-91.9%, 42.5-56.9%, and 74.7-99.4%, respectively, over the CK treatment. The POC, MBC and DOC concentrations increased linearly with increasing SOC content. These results indicate that long-term additions of organic manure have the most beneficial effects in building carbon pools among the investigated types of fertilization.

[Arsenic accumulation in different agricultural soils in Shouguang of Shandong Province].

The study on the soil arsenic (As) accumulation under different types of agricultural use in Shouguang of Shandong Province showed that farmland soils had an average As content of 9. 63 mg x kg(-1) , with the highest being 15. 15 mg x kg(-1) . Compared with the local background value (9. 3 mg As x kg(-1)) , 53. 1% of soil samples was detected as As enrichment. The soil As content was high in the west, east and north parts of Shouguang, relatively lower in the middle part, and the lowest in the south part. Different agricultural use had an obvious effect on the soil As content, which was decreased in the order of wheat/maize land > cotton field > protected vegetable land > uncovered vegetable land. Such a difference in soil As content was mainly affected by agricultural activities. With the increasing year of vegetable planting, soil As content had an increasing trend, because the As input from pig dung and chicken feces was the main source of soil As in protected vegetable land. Soil As enrichment could be reduced to some degree by applying soybean cake fertiliz-

[Evapotranspiration of winter wheat field in North China Plain].

By using eddy covariance and remote sensing techniques, the relationships between winter wheat soil moisture content and farmland evapotranspiration or canopy temperature were analyzed at field scale under various environmental conditions in the North China Plain. The results showed that when the soil moisture content was below 65% of field capacity, the evaporative fraction under full canopy was low and stable during the middle part of clear days. Under clear sky condition, there was a good non-linear correlation between latent heat flux and crop canopy temperature with diurnal and seasonal patterns. The temperature difference between crop canopy and air as well as the relative evapotranspiration had a close link to the relative moisture content of 0 - 100 cm soil layer. Based on the in situ measurements of daily evapotranspiration amount (ET(d)), daily net radiation flux (Rn(d), mm), average canopy temperature (T(e), degrees C) from 13 : 30 to 14: 00, and daily maximum air temperature (T(a max), degrees C) during the field experiment, the parameters of simplified estimation model for daily evapotranspiration were established.