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As freshwater becomes an increasingly scarce and expensive natural resource, novel water-saving irrigation methods for dwarfing apple orchards are needed in the Loess Plateau. However, studies are lacking on the effects of novel root-zone irrigation technology on leaf-level photosynthesis, which directly determines the yield and survival ability of trees. In this study, the leaf gas characteristics and water status of five-year-old dwarfing apple trees in the Loess Plateau of China were monitored during the 2016–2017 growing seasons under water storage pit irrigation (WSPI) and surface irrigation (SI) treatments. Under WSPI, the leaf water potential (Ψm), net photosynthesis rate (Pn), stomatal conductance (gs), and chlorophyll content (Chl) were significantly higher than those under SI (by 12.21–28.36%), while non-photochemical quenching, superoxide dismutase, and sucrose were lower. Compared with SI, WSPI improved dwarfing apple yield by 25.4% and 26.7% in 2016 and 2017, respectively. WSPI increased the photosystem II (PSII) activity by increasing the chlorophyll fluorescence features (the potential quantum yield of PSII (Fv/Fm), actual quantum yield (ΦII), photochemical quenching (qP), and electron transport rate (ETR)). Principal component analysis showed that Ψm, Chl, the chlorophyll fluorescence features (qP, ΦII, and ETR), Pn, and gs could represent the leaf photosynthetic difference between WSPI and SI treatments. Results indicated that apple under WSPI could improve its yield through enhancing leaf photosynthetic performance, and water storage pit irrigation is an effective root-zone irrigation method for apple orchards on the Loess Plateau. [ABSTRACT FROM AUTHOR]

It is of great significance to explore the strategy of regulated deficit irrigation (RDI) under mulched drip irrigation to stabilize tomato yield and improve quality and efficiency. This experimental study was conducted on a drip-irrigated greenhouse in two consecutive years (2020 and 2021). Three deficit levels were set for the flowering and fruit development stage (Stage I), and three were set for the fruit-ripening stage (Stage II). As a combination evaluation method, the fuzzy Borda model was used to optimize the RDI strategy of greenhouse tomato. The results showed that the net photosynthetic rate, stomatal conductance, transpiration rate, and total shoot biomass of tomato decreased with an increase in the water deficit, while the intercellular CO2 concentration had an opposite trend. The mild and moderate water deficit at Stage I reduced tomato yield by 16–24% and 30–40% compared to full irrigation. The water deficit at Stage II was able to improve various quality parameters and the water-use efficiency of tomato; the irrigation water-use efficiency (32.8–33.9 kg/m3) and leaf water-use efficiency (3.2–3.6 μmol/mmol) were the highest when the soil water content was 70–90% θf (field capacity) at Stage I and 40–60% θf at Stage II (T3). Based on the fuzzy Borda combination evaluation model, T3 was determined as the treatment with stable yield, high quality, and efficient irrigation under the experimental conditions. The irrigation regime was as follows: irrigating 20–25 mm in the transplanting stage, no irrigation in the seedling stage, irrigating 193.2–220.8 mm at Stage I, and then irrigating 27.6 mm at Stage II. [ABSTRACT FROM AUTHOR]

The ridge–furrow mulching system with plastic film (RFMS) has been widely used in semi-arid areas in order to improve soil water and heat conditions, crop yields and water use efficiency. It is of practical significance to study the effect of mulching and ridge types on soil water and heat in order to optimize mulching measures and improve the effectiveness of the ridge and furrow system. To clarify the combined effect of soil water and heat beneath the system and the influence of ridge morphology on it, field experiments were conducted with three treatments, including conventional planting in bare land (CK), a ridge–furrow (wide ridge with 70 cm width and 10 cm height, narrow ridge with 40 cm width and 15 cm height) mulching system with complete plastic film (RFWN) and a ridge–furrow (equal ridge with 55 cm width and 15 cm height) mulching system with complete plastic film (RFE). An insufficient irrigation system was adopted and the two-dimensional numerical software HYDRUS-2D was used to simulate the soil water and heat flow under the experimental conditions. The model was calibrated and verified according to test data for the period of 2018 to 2019, which showed good agreement between the simulated and measured values. The simulation results revealed that the ground temperatures of RFWN and RFE were much higher than that of CK, and the average value of 0–25 cm during the growth period could increase by 2.29–4.61%. Compared with CK, RFWN and RFE reduced soil evaporation (84.71–93.73%) and field evapotranspiration (12.02–21.75%), while they increased root water uptake (25.87–40.98%) and T/ET (48.85–80.15%). Plastic film mulching and ridge morphologies affected the infiltration range and the direction of soil water movement, increased soil moisture when there was no rainfall or irrigation and reduced soil water and heat fluctuations, which was more conducive to crop growth, especially under the RFWN system. The simulation method proposed in this paper is an effective technique for calculating the soil water and heat dynamics under different ridge and furrow sections under the condition of film mulching, and it can be used for the optimal management of soil water and heat in this area. [ABSTRACT FROM AUTHOR]