Soil compaction easily causes root hypoxia stress, resulting in poor root growth and the absorption of soil water and nutrients. We hypothesized that aerated irrigation (AI) could enhance nutrient uptake and utilization, thus unlocking the high yield potential by increasing soil aeration and root morphology indicators compared with that in the non-aeration treatment. A greenhouse experiment was conducted to investigate the effect of soil aeration and root morphology on the yield of greenhouse cucumbers. The dissolved oxygen (DO) in irrigation water at 10 mg L⁻¹ (A₁), 20 mg L⁻¹ (A₂), and non-aeration treatment (A₀) were applied via a subsurface drip irrigation system. The soil respiration rates, DO in soil water, root morphology, and crop yield were measured. The results showed that AI could significantly improve the soil respiration rate, DO in soil water, and root morphology compared with non-aeration treatment. The A₂ significantly increased soil respiration rate by 11.63% and 11.93%, respectively, compared with the A₁ and A₀ treatments. Under A₁ and A₂, the DO in soil water increased by 20.01% and 18.02%, respectively, compared with the A₀. Moreover, during the flowering and fruit set, the mature, and the late stages, the root surface area, root volume, root tip number, root forks, and root dry weight in the A₂ treatment significantly increased than that in the A₀ treatment. The soil respiration rate, DO in soil water, root length, and root forks were the main indexes correlated to the yield, respectively. The DO in soil water and root forks number significantly influenced the yield. The cucumber yield and economic benefits in A₂ peaked at 53.04 t ha⁻¹ and 3.95 × 10⁴ USD ha⁻¹, increased by 7.86% and 7.30% compared with that in the A₀ treatment, respectively (p < 0.05). The results could provide technical support and scientific knowledge for regulating greenhouse cucumbers under AI.

The current study was undertaken to investigate the dynamic characteristics of the tomato crop, such as its plant height and leaf area index (LAI), based on the effective cumulative temperature. This was assessed under aerated drip irrigation (ADI) conditions and the application of a specific nitrogen (N) dose, and their relationship with the yield of the crop was formulated. The study was conducted in a greenhouse located in Zhengzhou, Henan province, China. The assessment conditions were the two irrigation methods, ADI and conventional drip irrigation (CK), and the three N application rates, i.e., 0, 140, and 210 kg ha⁻¹. The logistic and Richards models were used to fit dynamic equations for plant height and LAI under the different treatments to quantify the characteristic parameters and understand their relationship with yield. The results revealed that the growth of the tomato plant fitted well with the logistic and Richards model at R² > 0.98 (p < 0.01), regardless of the treatments. ADI and N application were found to significantly increase the maximum growth rate and average growth rate over the rapid growth period based on the tomato plant height and LAI. They were also noted to reduce the effective cumulative temperature at which plant height entered the rapid growth period (p < 0.05), thereby increasing the time spent in the nutritional growth phase. This is an essential precursor for the better development of subsequent reproductive organs. Tomato yields also confirm it: the highest yield of 85.87 t ha⁻¹ was obtained with 210 kg N ha⁻¹ for the ADI treatment, with an increase of 13.8%, 12.2%, and 39.6% compared to the CK–210 kg N ha⁻¹, ADI–140 kg N ha⁻¹, and ADI–0 kg N ha⁻¹ treatments, respectively (p < 0.05). Grey correlation analysis showed that the characteristic parameters closely related to yield were all from the ADI and N application treatments. Furthermore, it was observed that the effective cumulative temperature and the maximum growth rate of the LAI at which the LAI entered the slow growth phase were the key growth characteristic parameters affecting tomato yield. This study provides a scientific basis for regulating the growth dynamics and yield of vegetables in greenhouse facilities under ADI and N application.

In order to study the soil nitrogen (N) distribution pattern in the root zone of chili peppers under aerated drip irrigation (ADI) conditions and analyze the relationship between soil N distribution and crop growth, two irrigation methods (conventional drip irrigation and ADI) and three N levels (0, 140, and 210 kg hm⁻²) were set up in this experiment. Soil samples were collected by the soil auger method at the end of different reproductive periods, and the uniformity coefficient of soil N in the spatial distribution was calculated by the method of Christiansen’s coefficient. The growth status and soil-related indices of pepper were determined at each sampling period, and the relationships between soil N distribution and chili pepper growth were obtained based on principal component analysis (PCA). The results showed that the spatial content of soil nitrate-N (NO₃⁻-N) fluctuated little during the whole reproductive period of chili peppers under ADI conditions, and the coefficient of uniformity of soil NO₃⁻-N content distribution increased by 5.29~37.63% compared with that of conventional drip irrigation. The aerated treatment increased the root length and surface area of chili peppers. In addition, the ADI treatments increased the plant height, stem diameter, root vigor, and leaf chlorophyll content to some extent compared with the nonaerated treatment. The results of PCA showed that the yield of chili peppers was positively correlated with the uniformity coefficient of soil NO₃⁻-N, root vigor, and root length. ADI can significantly improve the distribution uniformity of soil NO₃⁻-N and enhance the absorption and utilization of N by the root system, which in turn is conducive to the growth of the crop, the formation of yields, and the improvement of fruit quality.

In order to provide a theoretical basis for the rational application of nitrogen fertilizer for tomatoes under aerated drip irrigation, a model of the critical nitrogen dilution curve was established in this study, and the feasibility of the nitrogen nutrition index (NNI) for the real-time diagnosis and evaluation of the nitrogen nutrient status was explored. The tomato variety “FENOUYA” was used as the test crop, and aerated drip irrigation was adopted by setting three levels of aeration rates, namely, A1 (dissolved oxygen concentration of irrigation water is 5 mg L⁻¹), A2 (dissolved oxygen concentration of irrigation water is 15 mg L⁻¹), and A3 (dissolved oxygen concentration of irrigation water is 40 mg L⁻¹), and three levels of nitrogen rates, namely, N1 (120 kg ha⁻¹), N2 (180 kg ha⁻¹) and N3 (240 kg ha⁻¹). The model of the critical nitrogen concentration dilution of tomatoes under different aerated treatments was established. The results showed that (1) the dry matter accumulation of tomatoes increased with the increase in the nitrogen application rate in a certain range and it showed a trend of first increase and then decrease with the increase in aeration rate. (2) As the reproductive period progressed, the nitrogen concentration in tomato plants showed a decreasing trend. (3) There was a power exponential relationship between the critical nitrogen concentration of tomato plant growth and above-ground biomass under different levels of aeration and nitrogen application rate, but the power exponential curves were characterized by A1 (Nc = 15.674DM^−0.658), A2 (Nc = 101.116DM^−0.455), A3 (Nc = 119.527DM^−0.535), N1 (Nc = 33.819DM^−0.153), N2 (Nc = 127.759DM^−0.555) and N3 (Nc = 209.696DM^−0.683). The standardized root mean square error (n-RMSE) values were 0.08%, 3.68%, 3.79% 0.50%, 1.08%, and 0.55%, which were less than 10%, and the model has good stability. (4) The effect of an increased nitrogen application rate on the critical nitrogen concentration dilution curve was more significant than that of the increase in aeration rate. (5) A nitrogen nutrition index model was built based on the critical nitrogen concentration model to evaluate the nitrogen nutritional status of tomatoes, whereby 180 kg ha⁻¹ was the optimal nitrogen application rate, and 15 mg L⁻¹ dissolved oxygen of irrigation water was the optimal aeration rate for tomatoes.

A vegetable water production function has been one of the most significant parameters to improve the use efficiency and economic benefit of agricultural water in the greenhouse. Meanwhile, aerated irrigation unlocks the high yield potential for greenhouse crop production. Thus, water, fertilizer and air coupled production function is proposed for the optimization of the irrigation scheme during the greenhouse tomato growth period. Two seasons of greenhouse tomato experiments were conducted under aerated subsurface drip irrigation (ASDI). There were three nitrogen application rates (N₁, 120 kg ha⁻¹; N₂, 180 kg ha⁻¹; N₃, 240 kg ha⁻¹) and three aeration rates with dissolved oxygen (DO) in irrigation water (A₂, 15 mg L⁻¹; A₃, 40 mg L⁻¹ and A₁, 5 mg L⁻¹ in the non-aeration treatment) in the first crop season, while three irrigation rates of soil moisture content (W₁, 50–60% field capacity; W₂, 60–70% field capacity; W₃, 70–80% field capacity) and two aeration rates with DO in irrigation water (25 mg L⁻¹ and 5 mg L⁻¹) in the second crop season. The potential yield function of tomato was constructed, and the water sensitivity index was resolved. The production function of greenhouse tomato under water, fertilizer, and air coupled irrigation was established based on the Jensen function. The water allocation scheme under multiple irrigation quotas was optimized by the dynamic programming (DP) method. The results showed that with the elapse of crop growth stages, the cumulative curve of the water sensitivity index showed an S-shaped curve, which first rose slowly and then fast, and eventually tended to be stable. The optimized irrigation increased the yield by 4.25% averagely compared with the irrigation method of fixed moisture content interval, while the crop yield in the optimized ASDI increased by 26.13% compared with non-aeration treatment. In summary, the optimal combination was the aeration rate DO of 24.55mg L⁻¹ in irrigation water and nitrogen application rate of 281.43 kg ha⁻¹, and the irrigation quota of 420 mm. The net yield increased by 11,012 USD ha⁻¹ in a single crop season when compared with the non-aeration treatment. The results would provide a reference method for the optimization of technical parameters of water—fertilizer—air coupled irrigation.

China is one of the regions with the most frequent drought disasters and serious social and economic losses. Agricultural drought is the most serious natural disaster. Due to climate change, the regional agricultural drought risk assessment has always been the focus of the academic circle. This study takes Zunyi City as an example, which is the most typical city of karst landform development. The monthly precipitation data set of ground meteorological observation stations in Zunyi City from 1956 to 2020 was selected, and the drought characteristic variables were extracted by the coupled use of the precipitation anomaly percentage (Pa) index and the theory of runs. A copula function was applied to establish the joint distribution model of characteristic variables, obtaining the drought frequency and drought return periods. Combined with the Jensen model, the agricultural drought loss rate under different drought return periods in the target year (2020) was calculated and evaluated. The results showed that the Gumbel-Hougaard copula function was suitable for the joint distribution of drought joint variables in Zunyi City. From 1956 to 2020, fewer droughts occurred in Zhengan and Wuchuan, and the most droughts took place in Fenggang, Meitan, and Yuqing. The average drought duration in each county was about 1.5 months, and the average drought severity was about 0.35 in spatial distribution. Crop loss rate caused by drought increased and the affected area expanded with the increase of drought return periods (5, 10, 20, 50, and 100 years) in temporal distribution. Meanwhile, the drought disaster was most drastic in the eastern region, followed by the south, north, west, and central area. The results were highly consistent with the historical drought in Zunyi City, which verified the validity of the model. This study could provide scientific knowledge for drought resistance and reasonable mitigation programing for the security of the regional agricultural production and the sustainability of social and economic development.