Nitrogen (N) application can improve drought tolerance and water use efficiency (WUE) in crops. Previous studies have shown that aerated irrigation improves crop N absorption and utilization. However, the mechanisms behind the interaction of water and N under aerated drip irrigation and its impact on crop WUE remain unclear. This study conducted a two-year greenhouse experiment with spring-summer and autumn-winter tomato crops to investigate the effects of water and nitrogen coupling on leaf carbon (C) and N content, photosynthetic characteristics, dry matter accumulation, yield, and WUE. The experiment included three irrigation levels (W1, 50% ET c; W2, 75% ET c; W3, 100% ET c) and three N application rates (N1, 0 kg ha –1; N2, 150 kg ha –1; N3, 250 kg ha –1). The results showed that increased N application and irrigation levels significantly increased leaf C and N content, net photosynthetic rate (P n), and stomatal conductance (G s) ( P < 0.05). Under deficit irrigation, N application increased leaf C content by 2.17% and N content by 9.34%, improving leaf photosynthetic capacity and increasing P n by 15.57% and G s by 19.32%. The W2 treatment demonstrated the most pronounced improvements compared to W1. The W3N3 treatment produced the highest dry matter accumulation for both tomato types, with no significant difference from W2N3 ( P > 0.05). The W2N3 treatment produced the highest yield, 8.67–9.13% higher than W3N3. The highest WUE occurred in W2N3 for spring–summer tomato and W1N3 for autumn–winter tomato. Although W1N3 had 1.02% higher WUE than W2N3, it had a 15.25% lower yield. Thus, W2N3 is recommended as the optimal water–nitrogen management strategy for greenhouse tomato production. Correlation analysis revealed that leaf C and N contents positively correlated with P n, dry matter accumulation, and yield, while the leaf ratio of C and N (C/N) negatively correlated with WUE, suggesting that leaf C and N contents regulate tomato WUE. N application under deficit irrigation enhanced leaf C and N contents, improving photosynthetic capacity (P n, G s), dry matter accumulation, yield, and WUE. Regression models suggest that the optimal water and N application rates for greenhouse tomatoes are 192.30–225.67 mm and 205.93–243.43 kg ha -1 for spring-summer tomato, and 162.00–181.18 mm and 194.98–237.73 kg ha -1 and for autumn-winter tomato crops. These findings provide a theoretical basis for water-efficient agricultural practices and sustainable greenhouse tomato production.
Abstract To quantitatively evaluate the anti‐clogging performance of labyrinth channel emitters, literary data were used to study the clogging of different emitters under different conditions. The results showed that the emitter clogging comprehensive evaluation index ( I a ) can be used as an inherent property of labyrinth flow channel emitters, denoted as the anti‐clogging ability characterization index, which is affected by flow channel structure parameters and dimensions. The larger I a is, the more likely it is for the emitter to be clogged and for clogging to be more serious. The emitter anti‐clogging ability is affected by the emitter discharge ( Q ), flow path length ( L ), width ( W ), depth ( D ), cross‐sectional area ( A , which equals W × D ), minimum sectional size (min( D , W )), etc. The I a value with Q , W , D , A and min( D , W ) increases first decreases and then increases, and with L increases first increases and then decreasing, and a critical threshold range exists. I a can be estimated by Q , W , D , A and min( D , W ) and can be used as an effective indicator to quickly estimate emitter anti‐clogging ability and emitter configuration in drip irrigation systems. In practical applications, an emitter with x < 0.47 (flow index) should be selected, and an emitter with I a < 0.45 has a better hydraulic performance and anti‐clogging ability. To obtain a better anti‐clogging ability, Q , W , D , A and min( D , W ) should be 1.33–2.13 L/h, 0.71–0.90 mm, 0.55–0.71 mm, 0.33–0.68 mm 2 and 0.60–0.75 mm, respectively. When L is 26.47–58.31 mm, the emitter anti‐clogging ability is relatively low.
Mounting evidence has suggested that α-adducin and G-protein β3 (GNB3) genes are logical candidates for salt-sensitive hypertension. Some, but not all, studies have reported that α-adducin G460T and GNB3 C825T polymorphisms may influence the risk of the disease. To comprehensively address this issue, we performed a meta-analysis to evaluate the influence of these two polymorphisms on hypertension and potential biases in Chinese.Data were analyzed using Stata (v11.0) and random-effects model was applied irrespective of between-studies heterogeneity, which was evaluated via subgroup and meta-regression analyses. Study quality was assessed in duplicate. Publication bias was weighed using Egger's test and funnel plot.36 study populations totaling 9042 hypertensive patients and 8399 controls were finally identified. Overall, in allelic/genotypic/dominant/recessive models, no significant association was identified for both G460T and C825T polymorphisms (P>0.05) and there was possible heterogeneity (I(2)>25%). Subgroup analyses by study design indicated that the magnitude of association in population-based studies was marginally significantly strengthened for α-adducin G460T allelic model (OR = 1.12; 95% CI: 1:00-1.25; P = 0.043). Moreover, subgroup analyses by geographic distribution indicated comparison of 825T with 825C yielded a marginally significant increased risk in southern Chinese only (OR = 1.48; 95% CI: 1.01-2.16; P = 0.045). Further meta-regression analyses showed that geographic regions were a significant source of between-study heterogeneity for both polymorphisms. There was a possibility of publication bias for G460T, but not for C825T.Our overall results suggest null association of α-adducin G460T and GNB3 C825T polymorphisms with hypertension in Chinese but indicate local marginal significance of C825T, as a putative salt-sensitive switch, in southern Chinese.
Abstract The influence of aeration on the emitter clogging of Yellow River water drip irrigation was evaluated, and reasonable measures to slow down the emitter clogging were investigated. A short‐cycle intermittent irrigation test and sediment settlement test were performed under the conditions of aeration and no aeration. The results showed that aeration accelerated the settlement of sediment at the inlet of the flow channel, increased the clogging rate of the flow channel inlet and exacerbated the clogging of the emitter. With the decrease of sediment particle size, aeration increased sediment deposition and emitter clogging. With the increase fencing inlet area, the effect of aeration on sediment settlement and emitter clogging decreased. Under aeration conditions, the upward position of the emitter outlet significantly reduced the mass of emitter blockage and increased the emitter flow compared with the downward positioning of the outlet. Thus, the recommendation is to select an emitter with a large area of fencing inlet, and the outlet of the emitter should be positioned upwards in order to improve the anticlogging performance of the emitter for Yellow River water aerated drip irrigation.
Irrigation is a common practice in agriculture to increase crop yield. However, the impacts of irrigation on microbial-mediated processes that influence soil carbon (C) pools and crop yield remains largely unknown. Therefore, we conducted a 2-year field experiment to investigate the effects of low (I1, 80% field capacity, 80%FC), medium (I2, 90%FC), and high (I3, 100%FC) irrigation upper limits on rhizosphere soil bacterial community, soil organic carbon (SOC) content, and wheat yield. The results showed that as the irrigation upper limit increased, the α-diversity of the bacterial community decreased. The bacterial community structure significantly differed across various irrigation upper limits. As the irrigation upper limit increased from low (80%FC) to medium (90%FC) or high (100%FC), the abundance of copiotrophic taxa (Proteobacteria, Actinobacteria, Bacteroidetes) decreased, and oligotrophic taxa (Acidobacteria) increased, enhancing the decomposition of persistent C pools. In the second year of the irrigation experiment, the I2 and I3 treatments significantly decreased microbial biomass carbon (MBC), SOC content (by 4.62–7.30%), and the microbial quotient (MQ) compared to I1. Wheat straw biomass and grain yield also decreased as the irrigation upper limit increased from 80%FC to 100%FC, with key bacterial taxa (Proteobacteria, Actinobacteria, and Chloroflexi) and functional processes (glycan biosynthesis and metabolism; folding, sorting, and degradation; translation; transport, and catabolism) playing key roles in wheat grain formation. Our findings indicate that adjusting irrigation levels affects the rhizosphere soil bacterial communities, and that the lowest upper limit of irrigation application (80%FC) is associated with maximum crop yield and microbial diversity.
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