A study of typical plant growth changes in response to drainage water and salt in ditch wetland in arid area.

Agricultural drainage significantly affected the changes of soil moisture and salinity in ditch wetlands. These changes can profoundly impact the spatial distribution and evolution of ditch wetland vegetation, thereby affecting the ecological environmental effects of these wetlands. Consequently, it is imperative to investigate the response of typical plant growth to drainage and soil salt in ditch wetlands in arid regions. Based on the classical metapopulation conceptual framework model (Levins model), this study established a new model of plant growth change in ditch wetlands, incorporating the key variables (water level and soil salinity) of arid area ditch wetlands. The application of the Gaussian model facilitates the resolution of species growth rates and mortality rates within this model. The study focused on the main drainage ditch (ditch M) and the drainage bucket ditch (ditch N) in the Lubotan saline-alkali land in Fuping, Shaanxi Province. The results revealed the following key findings: 1) the model effectively simulates the response of plant growth changes to water level and soil salinity in ditch wetlands in arid regions, particularly plants in the reed area and transition area disturbed by single factors such as water level and soil salinity; 2) the germination period of Phragmites australis in the reed area thrives in a shallow moisture environment, and adjusting the water level of the drainage ditch can maintain optimal growth conditions for Phragmites australis; 3) during the germination period of Suaeda salsa in the transition area, soil salinity should not be excessively high, though a moderate increase in soil salinity can promote the germination and growth of Suaeda salsa; and 4) Suaeda salsa in the symbiotic area has a higher adaptability to the soil salinity, with change in biomass consistent with plants in the transition area. The model provides an explanation and prediction for the growth changes of plant communities in ditch wetlands under drainage conditions. By integrating this model with the impact of farmland drainage on water level and soil salinity in drainage ditches, effective drainage management measures can be formulated, offering scientific support for the construction of ecological irrigation areas.

Optimizing Shade Cultivation Method and Irrigation Amount to Improve Photosynthetic Characteristics, Bean Yield, and Quality of Coffee in a Subtropical Monsoon Climate.

Reasonable water and light management technology can improve economic benefits, coffee yield, and quality. We used cluster analysis and principal component analysis to evaluate and optimize the water and light management technology with high coffee yield, quality, and economic benefits in a subtropical monsoon climate region of China. The experiment was arranged in a randomized complete block design with two factors (3 irrigation levels × 4 shade cultivation treatments) replicated four times during 2016-2017. The irrigation levels consisted of full irrigation (FI) and two deficit irrigations (DI L : 75% FI, DI S : 50% FI). The shade cultivation treatments consisted of no shade cultivation (S0) and three shade cultivation modes (S L : intercropping with four lines of coffee and one line of banana; S M : intercropping with three lines of coffee and one line of banana; S S : intercropping with two lines of coffee and one line of banana). The results showed that the effects of irrigation level and shade cultivation mode on growth, crop yield, most of the photosynthetic characteristics, and nutritional quality were significant (p < 0.05). Regression analysis showed that the leaf radiation use efficiency (RUE) showed a significant negative exponential relation or logistic-curve variation with photosynthetically active radiation (PAR). The bean yield increased with an increase of the shade degree when water was seriously deficient, whereas it first increased and then decreased with an increase of the shade degree under FI and DI L . Based on both cluster analysis and principal component analysis, the FIS S treatment resulted in the highest comprehensive quality of coffee, followed by the FIS M treatment; the DI S S0 treatment obtained the lowest quality. Compared with the FIS0 treatment, the FIS M treatment increased the 2-year average bean yield and net income by 15.0 and 28.5%, respectively, whereas the FIS S treatment decreased these by 17.8 and 8.7%, respectively. To summarize, FIS S treatment significantly improved the nutritional quality of coffee, and FIS M treatment significantly increased the dry bean yield and economic benefits of coffee. The results of the study could provide a theoretical basis for water-saving irrigation and shade cultivation management of coffee in a subtropical monsoon climate region of China.

Comprehensive Evaluation on the Yield, Quality, and Water-Nitrogen Use Efficiency of Mountain Apple Under Surge-Root Irrigation in the Loess Plateau Based on the Improved TOPSIS Method.

The purpose of this study was to know the controlling effects of water and nitrogen coupling on the yield, quality, and water-nitrogen utilization effectiveness of mountain apples under surge-root irrigation in the Loess Plateau. In order to optimize the water and nitrogen irrigation systems of superior quality and high yield, 7 years was selected for the mountain apple test material. The trial was designed with four tiers of irrigation, i.e., full irrigation (FI: 85-100% θ f , where θ f is the field capacity), light deficit irrigation (DIL: 70-85% θ f ), moderate deficit irrigation (DIM: 55-70% θ f ), and severe deficit irrigation (DIS: 40-55% θ f ) and three tiers of nitrogen, i.e., high nitrogen (NH: 600 kg ha-1), medium nitrogen (NM: 400 kg ha-1), and low nitrogen (NL: 200 kg ha-1). The subjective weight attained by the analytic hierarchy methods and the objective weight achieved by the enhanced coefficient of variation method were examined to find the comprehensive weight based on the notion of game hypothesis. Then, the weighted technique for order of preference by similarity to the ideal solution (TOPSIS) process was utilized to comprehensively assess the yield, quality, and water-nitrogen use efficiency of the apples, and a binary quadratic regression model was created between the comprehensive evaluation index and water-nitrogen inputs. The results showed that the effects of irrigation and nitrogen levels on the fruit yield, irrigation water use efficiency (IWUE), total water use efficiency (TWUE), nitrogen partial factor productivity (NPFP), and quality of mountain apples were significant (P < 0.05). The apple yield and TWUE first improved and then diminished with an escalating quantity of water-nitrogen inputs, the IWUE diminished with a boost in the irrigation quantity, the NPFP dwindled when the nitrogen amount was increased. The best water and nitrogen inputs for apple yield, quality, or water-nitrogen use efficiency were dissimilar. The best comprehensive evaluation index was DILNM treatment, and the worst comprehensive evaluation index was DISNL treatment, based on the TOPSIS system. The interval of irrigation and nitrogen attained from the mathematic model ranged in 95-115 mm and 470-575 kg ha-1, respectively. The outcome of this study may perhaps offer a theoretical basis for the scientific research of surge-root irrigation and the managing of mountain apple tree irrigation and fertilization in the Loess Plateau, China.

Effects of water-nitrogen coupling on photosynthetic characteristics, yield, water and nitrogen use efficiency for mountain apple trees under surge-root irrigation in Northern Shaanxi area of China.

Taking 7-year-old apple trees (Hanfu) as the test material, an experiment with three irrigation levels including high water (W1, 85%-100%θf, θf was the field water holding capacity), medium water (W2, 70%-85%θf) and low water (W3, 55%-70%θf), and three nitrogen application levels, high (N1, 600 kg·hm-2), medium (N2, 400 kg·hm-2) and low (N3, 200 kg·hm-2), was conducted to investigate the effects of water and nitrogen coupling on photosynthetic characteristics, yield and water and nitrogen utilization of apple trees in mountainous areas under surge-root irrigation (SRI). The results showed that the net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (gs), intercellular CO2 concentration (Ci), leaf instantaneous water use efficiency (WUEi) of apple trees leaves decreased with decreasing nitrogen application rates under the same irrigation amount, but Ci increased. Under the same nitrogen application rate, foliar Pn, Tr, gs and WUEi decreased with decreasing irrigation amount, but Ci increased. The daily average values of Pn and Tr under W1N1 treatment were the largest, while W2N2 treatment had the largest WUEi. Apple yield, irrigation water use efficiency (IWUE) and nitrogen partial productivity (NPFP) were significantly affected by irrigation and nitrogen application. The W2N2 treatment had the highest yield (26761 kg·hm-2). IWUE increased significantly with the decreasing irrigation and the increasing nitrogen application, while NPFP increased significantly with the increases of irrigation and the decreases of nitrogen application. Results of the regression analysis showed that the combination of irrigation and nitrogen application was closest to W2N2 treatment when yield and IWUE got the optimal solution. Therefore, W2N2 treatment was the best combination mode of water and nitrogen application for apple under SRI in Northern Shaanxi mountain area.

Development of "water-suitable" agriculture based on a statistical analysis of factors affecting irrigation water demand.

Water shortage has become a serious problem for the sustainable development of irrigated agriculture in arid regions. In these areas, the scale and planting structure of agriculture suitable for local water resources is particularly important. Irrigation water demand is a crucial indicator of water requirement in irrigation districts. In this study, Mann-Kendall method was used to analyze the temporal changes of climatic factors of the past 50 years and ArcGis to determine spatial changes in human activities. The path analysis was used to quantitative characterize direct and indirect effects of these factors on irrigation water demand and suggest how human activity can be altered to reduce irrigation water demand. The results show that temperature has risen significantly since the completion of the second-stage irrigation district, wind speed has dropped since the completion of the first-stage irrigation district, and cultivated land area has greatly expanded. The direct impact and comprehensive effect of planting area on irrigation water demand is the largest. Controlling for the total water intake, the maximum agricultural planting scale is 40,133 ha. Through adjustment of the planting structure, the scale of irrigated agriculture could increase by as much as 25.8%. Therefore, agricultural planting structures and planting scales suitable for local water resources should be put into action for future sustainable development of agriculture.