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Aerated subsurface drip irrigation is a new technology developed over the past decades to improve aeration in the root zone by mixing irrigation water with air bubbles to ameliorate the adverse effect of hypoxic on crops and boost crop yield and quality. The key to disseminate aerated subsurface drip irrigation is to understand its efficacy under different soil and cropping conditions to determine the rational aeration rate and the associated equipment. Based on the development in both research and application of subsurface drip irrigation and the associated aeration technologies, we systematically review the suitable aeration levels for improving oxygen in the root zone of crops to improve their growth. In particular, we focus on the development in technologies for mixing the irrigation water with gas bubbles and their application, the existing problems in aerated subsurface drip irrigation, and the potential applications of these technologies. This review aims to help those who are interested in aerated irrigation to understand the present state and research progress in aerated subsurface drip irrigation. Available results indicated that aerated subsurface drip irrigation indeed improves crop yield and quality considerably, but we also highlight the areas which need further research, including when the root zones need aeration, air - irrigation water - soil interaction, as well as how to improve efficiency of irrigated water and oxygen.

【Objective】 The functions of drip-irrigation systems depend on many factors and in this paper, we investigated the performance of the automatic flushing valve as impacted by layout of dripline. 【Method】 The experiment compared four flushing valves which were manufactured by 3D printing. They were then fixed at the end of the 0.5 m Φ16PE pipe (C1), a 48 m dripline (C2), and two 48 m long driplines connected in parallel (C3), respectively. The changes in flushing duration (FD), flushing water volume (FQ), flushing velocity (FV) and the minimum inlet pressure of the driplines required for the flushing valve automatic closing (H1min) under different layouts were measured and compared. 【Result】 The flushing velocity of the single dripline in C2 and C3 decreased from 0.82~1.03 m/s to 0.34~0.66 m/s, and the difference between the dripline inlet pressure H1 and flushing valve inlet pressure H2 was in the range of 0.114~0.132 MPa and 0.047~0.088 MPa, respectively. Compared with C2, C1 and C3 reduced H1min by 74.8% and 40.4% on average, respectively. When FD or FQ was the same, H1 required for the four flushing valves varied in the order of C2 > C3 > C1. When H2 < 0.05 MPa, FD decreased by 999.75 s/MPa on average, while when H2 > 0.05 MPa, FD decreased slowly by 164.7 s/MPa on average. Regardless of the dripline layouts, FD and FQ are quadratic functions of H2. 【Conclusion】 The FD and FQ are related to H2, and independent of the dripline layouts. When H2 > 0.05 MPa, FD changes steadily and the flushing effect is uniform. Fixing the flushing valve at the end of multiple driplines in parallel reduces the system pressure for automatic closing of the flushing valve. However, further work is needed to test if the flushing performance meets the requirements in the field.

The development of water-saving management relies on understanding the physiological response of crops to soil drought. The coordinated regulation of hydraulics and stomatal conductance in plant water relations has steadily received attention. However, research focusing on grain crops, such as winter wheat, remains limited. In this study, three soil water supply treatments, including high (H), moderate (M), and low (L) soil water contents, were conducted with potted winter wheat. Leaf water potential (Ψleaf), leaf hydraulic conductance (Kleaf), and stomatal conductance (gs), as well as leaf biochemical parameters and stomatal traits were measured. Results showed that, compared to H, predawn leaf water potential (ΨPD) significantly reduced by 48.10% and 47.91%, midday leaf water potential (ΨMD) reduced by 40.71% and 43.20%, Kleaf reduced by 64.80% and 65.61%, and gs reduced by 21.20% and 43.41%, respectively, under M and L conditions. Although gs showed a significant difference between M and L, Ψleaf and Kleaf did not show significant differences between these treatments. The maximum carboxylation rate (Vcmax) and maximum electron transfer rate (Jmax) under L significantly decreased by 23.11% and 28.10%, stomatal density (SD) and stomatal pore area index (SPI) under L on the abaxial side increased by 59.80% and 52.30%, respectively, compared to H. The leaf water potential at 50% hydraulic conduction loss (P50) under L was not significantly reduced. The gs was positively correlated with ΨMD and Kleaf, but it was negatively correlated with abscisic acid (ABA) and SD. A threshold relationship between gs and Kleaf was observed, with rapid and linear reduction in gs occurring only when Kleaf fell below 8.70 mmol m−2 s−1 MPa−1. Our findings demonstrate that wheat leaves adapt stomatal regulation strategies from anisohydric to isohydric in response to reduced soil water content. These results enrich the theory of trade-offs between the carbon assimilation and hydraulic safety in crops and also provide a theoretical basis for water management practices based on stomatal regulation strategies under varying soil water conditions. [ABSTRACT FROM AUTHOR]

【Objective】 Subsurface drip irrigation (SD1) is a water-saving technique but difficult to keep the surface soil moist to ensure seed germination in drought-prone areas. Alternate row planting (AP) combined with the raised bed has been developed as an effective cultivation to moisten the surface soil. The purpose of this paper is to experimentally investigate the suitable furrow depth to improve seedling emergence and sustain crop yield. 【Method】 We took spring maize as an example and used the variety Xuntian 1102 as the model plant. The field experiment was conducted from May 2018 to September 2018 in the National Water-saving Irrigation Engineering Technology Research Center at Daxing, Beijing. The depth of the furrows was 0 (CK), 10 cm (H10) or 15cm (H15). In all treatments, the seeds were drilled to 5 cm deep from the soil surface and the irrigation amount prior to seedling emergence was 30mm, same in all treatments. During the experiment, we measured the changes in soil moisture, seedling emergence and the ultimate yield in each treatment. 【Result】 Alternate row planting combined with the raised bed significantly increased soil moisture at the drilling points to facilitate seed germination. Compared to CK, irrigating 35 mm of water prior to seedling emergence in H10 and H15 increased soil moisture in the region proximal to the seeds by 18.2% and 25.7%, respectively. The improved soil moisture increased the seedling emergence rate to more than 88% in both treatments, equivalent to a14.6% (H10) or 16.3% (H15) increase over the CK (P

【Background and objective】 Emitter clogging is a problem facing drip irrigation and drip-line flushing is an effective anti-clogging technology. The aim of this paper is to study how key structural parameters of automatic flushing valve at the end of drip-line impact its hydraulic performance as well as the underlying mechanisms. 【Method】 Three structural parameters were examined: dentition length (L) and width (W), as well as the height of the bonnet (Z) in the valve. Overall, there were seven flushing valves with different structural parameters, which were made by a 3D printer. For each valve we tested how its hydraulic performance changed with the applied water pressure (H2), flushing time (T), flushing volumetric rate (Q) and flushing velocity (V). 【Result】 When H2 was in 0.038~0.096 MPa, T varied from 7.5 to 32.1 s, Q from 2 220 to 5 725 mL, and V from 0.87 to 1.53 m/s, depending on the valves. When H2≤0.058 MPa, T and Q were negatively correlated with H2, while when H2>0.058 MPa, H2 only negatively affected T and did not result in a noticeable change to Q. Both T and Q were positively correlated with L, W and Z; the minimum flow area in the labyrinth channel depended on L and W. The amount of water entering the upper cavity of the valve was affected by Z, and as a result, it impacted T and Q as well. The impact of the three structural parameters on T and Q was ranked in the order of W>L>Z. V was affected by H2 more than by the structural parameters. 【Conclusion】 T and Q are closely related to the velocity, the amount of water flowing into the upper cavity, and the distance between the elastomer and the water outlet. The air in the upper cavity within the valve is a key factor impacting on T and Q; V is affected predominantly by H2.

【Background】 Tomato is a vegetable grown widely across Ningxia in greenhouses with the soil mulched. Drip irrigation is the main irrigation for greenhouse crops, but excessive irrigation is common resulting in not only water waste but also environmental contamination due to agrochemicals leaching. Increasing water use efficiency and reducing detrimental impact of the mulching film is hence critical to sustaining tomato production in Ningxia. 【Objective】 The purpose of this study was to find an optimal drip-irrigation scheduling and film mulching in attempts to provide guidance for improving water use efficiency while in the meantime increasing yield of the greenhouse tomato in Ningxia. 【Method】 A two-year experiment was conducted in a solar greenhouse with the soil either not mulched (M) or mulched (NM) with plastic film. Added to these were three irrigation levels by keeping the soil moisture at 100% (W1), 80% (W2) and 70% of the field capacity respectively, with the irrigation used by local farmers (123% of the field capacity) taken as the control (CK). 【Result】 It was the film much rather than the irrigation amount that affected the growth of plant height and stem diameter from seedling stage to flowering and fruit setting stage at significant level (P

Background and aims Leaf shape in crops can impact light distribution and carbon capture at the whole plant and canopy level. Given similar leaf inclination, narrow leaves can allow a greater fraction of incident light to pass through to lower canopy leaves by reducing leaf area index, which can potentially increase canopy-scale photosynthesis. Soybean has natural variation in leaf shape which can be utilized to optimize canopy architecture. However, the anatomical and physiological differences underlying variation in leaf shape remain largely unexplored. Methods In this study, we selected 28 diverse soybean lines with leaf length to width ratios (leaf ratio) ranging between 1.1 and 3.2. We made leaf cross-sectional, gas exchange, vein density and hydraulic measurements and studied their interrelationships among these lines. Key results Our study shows that narrow leaves tend to be thicker, with an ~30 µm increase in leaf thickness for every unit increase in leaf ratio. Interestingly, thicker leaves had a greater proportion of spongy mesophyll while the proportions of palisade and paraveinal mesophyll decreased. In addition, narrow and thicker leaves had greater photosynthesis and stomatal conductance per unit area along with greater leaf hydraulic conductance. Conclusions Our results suggest that selecting for narrow leaves can improve photosynthetic performance and potentially provide a yield advantage in soybean. [ABSTRACT FROM AUTHOR]

Clarifying the components and regulatory mechanisms of evapotranspiration is essential for irrigation scheduling. In this study, straw mulching and non-mulching treatments were set up in a maize field with drip irrigation, where the water use and related factors were determined in 2014 and 2015. Straw mulching slightly reduced evapotranspiration by 2.6% on average for the two years. However, transpiration of straw mulching increased by 10.0% and 9.0% and soil evaporation decreased by 36.0% and 31.1%, compared to the non-mulching treatment for 2014 and 2015, respectively. Straw mulching decreased the average crop coefficients of the entire growth period (from 1.03 to 1.01) while increasing them in the mid-growth period (from 1.20 to 1.22). The net radiation above the canopy for straw mulching was 92.3%–96.3% of that for non-mulching treatment, which could explain the lower evapotranspiration of the mulching treatment. The daytime canopy conductance of straw mulching was 30% higher than that of non-mulching treatment, which could potentially result in higher biomass. This study provided essential parameters for water management of drip irrigation maize fields with straw mulching in similar areas. [ABSTRACT FROM AUTHOR]

Two- or multi-component hydrogels consisting of the three-dimensional network of polymer chains play more and more significant role in the field of biomaterials such as contact lens, burn dressing drug delivery systems etc or in some technical fields such as gel actuators, sensors, absorbents etc. In the work, a novel blend hydrogel composed of kappa-carrageenin (KC) and polyisopropylacrylamide (PNIPAAm) was prepared via gamma-radiation technology at room temperature. The main component of the hydrogels is a typical temperature sensitive polymer PNIPAAm. As the second component, KC is a kind of natural macromolecules. The properties of the gels, such as gel strength, and swelling behavior were investigated. The incorporation of relatively small content (up to 5 wt.%) of KC could obviously improve the mechanical properties and swelling capacity. 3% KC content in the blend hydrogel is preferable for better strength and swelling properties. On the other hand, as a kind of polysaccharide, KC would be degraded by Оі-rays; so suitable dose must be controlled carefully. Here the total dose used was controlled below 3 kGy. KC is soluble in water. If the hydrogels synthesized in the work were as usually extracted in water or other polar solvent such as methanol, the KC in hydrogels would be also washed out completely together with unreacted monomer and linear polymer, and the action of KC in the blend hydrogels would be disappeared. Otherwise, the results published before showed that the unreacted monomer and linear polymer in the hydrogels were very small, no more than 3-5%, which would not affect the properties of the hydrogels.