Effects of Nutrient Solution Application Rates on Yield, Quality, and Water-Fertilizer Use Efficiency on Greenhouse Tomatoes Using Grown-in Coir.

The yield, quality, and water-fertilizer use efficiency of crops are important parameters for assessing rational water and fertilizer management. For an optimal water and fertilizer system with respect to the nutrient solution irrigation of greenhouse tomatoes using cultivation substrates, a two-year greenhouse cultivation experiment was conducted from 2022 to 2023. Three drip fertigation treatments (T1, T2, and T3) were implemented in the experiment, where nutrient solutions were supplied when the substrate's water content reached 60%, 70%, and 80%. The frequency of nutrient solution applications is based on weighing coconut coir strips in the morning and evening at 7:00 to determine the daily water consumption of plants. Nutrient solutions were supplied when the substrate's water content reached the lower limit, and the upper limit for nutrient supply was set at 100% of the substrate water content. The nutrient solution application was carried out multiple times throughout the day, avoiding the midday heat. The nutrient solution formula used was the soilless tomato cultivation formula from South China Agricultural University. The results show that plant height and the leaf area index rapidly increased in the early and middle stages, and later growth tended to stabilize; the daily transpiration of tomatoes increased with an increase in nutrient solution supply, and it was the greatest in the T3 treatment. Between the amount of nutrient solution application and the number of years, the yield increased with the increase of the amount of nutrient solution, showing T3 > T2 > T1. Although the average yield of the T2 treatment was slightly lower than that of the T3 treatment by 3.65%, the average irrigation water use efficiency, water use efficiency, and partial fertilizer productivity of the T2 treatment were significantly higher than those of the T3 treatment by 29.10%, 19.99%, and 28.89%, respectively (p < 0.05). Additionally, soluble solid, vitamin C, and soluble sugar contents and the sugar-acid ratio of tomatoes in the T2 treatment were greater than those in the other two treatments (p < 0.05). Using the TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution) method, it was concluded that the nutrient solution application rate of 70% can significantly increase water and fertilizer use efficiency and markedly improve the nutritional and flavor quality of the fruit without a significant reduction in yield. This finding provides significant guidance for the high-yield, high-quality, and efficient production of coconut coir-based cultivated tomatoes in greenhouses.

Long-term saline water irrigation affected soil carbon and nitrogen cycling functional profiles in the cotton field.

Saline water irrigation (SWI) plays an important role in alleviating water resource shortages. At the same time, the salt input of irrigation water affects soil microorganisms which participate in various ecological processes of terrestrial ecosystems. However, the responses of soil microbial functional potential to long-term SWI remains unclear. Therefore, Metagenomics method was utilized in cotton fields under long-term SWI to reveal the microbial functional profiles associated with soil carbon and nitrogen cycles. Results indicated that SWI impacted the microbial functional profiles of soil carbon and nitrogen cycles in the cotton fields significantly. Especially, irrigation water salinity inhibited the relative abundances of sacC and vanB, which are soil carbon degradation genes. SWI also affected the functional gene abundance of nitrogen degradation, dissimilatory nitrate reduction, and nitrification. Moreover, SWI significantly increased the abundance of Candidatus_Cloacimonetes in both carbon and nitrogen cycles. In the discussion, we used person analysis found that soil salinity, pH, and ammonium nitrogen were important factors affecting the abundance of functional genes and microbial taxa. Overall, this study indicated that long-term SWI significantly influenced specific microbial functional genes and taxa abundance, which may lead to predictable outcomes for soil carbon and nitrogen cycling, and is of great importance in exploring the impact of SWI on soil environments.

Irrigation and Fertilization Scheduling for Peanut Cultivation under Mulched Drip Irrigation in a Desert-Oasis Area.

The aim of this study was to investigate the impact of water and nitrogen regulation on the characteristics of water and fertilizer demands and the yield, quality, and efficiencies of the water and nitrogen utilization of peanuts cultivated under mulched drip irrigation in a desert-oasis region. The experiment, conducted in Urumqi, Xinjiang, centered on elucidating the response mechanisms governing peanut growth, yield, quality, water consumption patterns, and fertilizer characteristics during the reproductive period under the influence of water and nitrogen regulation. In the field experiments, three irrigation levels were implemented, denoted as W1 (irrigation water quota of 22.5 mm), W2 (irrigation water quota of 30 mm), and W3 (irrigation water quota of 37.5 mm). Additionally, two nitrogen application levels, labeled N1 (nitrogen application rate of 77.5 kg·ha-1) and N2 (a nitrogen application rate of 110 kg·ha-1), were applied, resulting in seven treatments. A control treatment (CK), which involved no nitrogen application, was also included in the experimental design. The results indicate a direct correlation between the increment in the irrigation quota and increases in farmland water-related parameters, including water consumption, daily water consumption intensity, and water consumption percentage. The nitrogen harvest index (NHI) demonstrated a higher value in the absence of nitrogen application compared to the treatment with elevated nitrogen levels. The application of nitrogen resulted in an elevation in both nitrogen accumulation and nitrogen absorption efficiency within pods and plants. When subjected to identical nitrogen application conditions, irrigation proved to be advantageous in enhancing water-use efficiency (WUE), nitrogen partial factor productivity (NPFP), and the yield of peanut pods. The contribution rate of water to pod yield and WUE exceeded that of nitrogen, while the contribution rate of nitrogen to nitrogen-use efficiency (NUE) was higher. The total water consumption for achieving a high yield and enhanced water- and nitrogen-use efficiencies in peanuts cultivated under drip irrigation with film mulching was approximately 402.57 mm. Taking into account yield, quality, and water- and nitrogen-used efficiencies, the use of an irrigation quota of 37.5 mm, an irrigation cycle of 10-15 days, and a nitrogen application rate of 110 kg·ha-1 can be regarded as an appropriate water and nitrogen management approach for peanut cultivation under mulched drip irrigation in Xinjiang.

Carbon Amendments Shape the Bacterial Community Structure in Salinized Farmland Soil.

Practical, effective, and economically feasible salt reclamation and amelioration methods are in great demand in arid and semiarid areas. Energy amendments may be more appropriate than alternatives for improving salinized farmland soil because of their effects on soil microbes. We investigated the effects of biochar (Carbon) addition and desulfurization (noncarbon) on the soil bacterial community associated with Zea mays seedlings. Proteobacteria, Firmicutes, and Actinobacteriota were the dominant soil bacterial phyla. Biochar significantly increased soil bacterial biodiversity but desulfurization did not. The application of both amendments stimulated a soil bacterial community shift, and biochar amendments relieved selection pressure and increased the stochasticity of community assembly of bacterial communities. We concluded that biochar amendment can improve plant salt resistance by increasing the abundance of bacteria associated with photosynthetic processes and alter bacterial species involved in carbon cycle functions to reduce the toxicity of soil salinity to plants. IMPORTANCE Farmland application of soil amendments is a usual method to mitigate soil salinization. Most studies have concluded that soil properties can be improved by soil amendment, which indirectly affects the soil microbial community structures. In this study, we applied carbon and noncarbon soil amendments and analyzed the differences between them on the soil microbial community. We found that carbon soil amendment distinctly altered the soil microbial community. This finding provides key theoretical and technical support for using soil amendments in the future.

The effects of nitrogen application rate on the grain physicochemical properties of japonica rice under controlled and flooding irrigation.

BACKGROUND: In this study, we investigated the effects of water-nitrogen interaction on the grain quality of two varieties of japonica rice grown on the North China Plain, based on evaluations of grain biochemical components, starch X-ray diffraction properties, thermal and pasting characteristics, and particle size distribution. RESULTS: We found that, under controlled irrigation, increasing levels of nitrogen resulted in a reduction in grain starch content and an increase in protein content. Nitrogen fertilization, irrigation, and their interaction had significant effects on the particle size and size distribution of rice flour. Under both controlled and flooding irrigation, the lowest values of pasting parameters for cultivars Xindao22 and Xindao10 were observed in response to moderate and high nitrogen application, respectively. Under flooding irrigation, Xindao22 exhibited lower mean value of gelatinization onset, peak, and conclusion temperatures and enthalpy in response to control irrigation, whereas in Xindao10 these parameters were relatively stable with respect to nitrogen and irrigation treatments. However, we observed no significant effects of either nitrogen or irrigation on amylopectin chain length distribution or starch relative crystallinity. CONCLUSION: Nitrogen application rate and irrigation methods had distinct effects on the physicochemical properties of flour derived from treated rice plants. The findings will provide support for scientific irrigation and fertilization in order to improve rice grain quality. © 2020 Society of Chemical Industry.

[Diagnosis method of cotton water status based on infrared thermal imaging].

Canopy temperature is one of promising signals for evaluating crop water status. The infrared thermal imager can provide real-time temperature distributions over larger areas with high spatial resolution. The main factors (the observation orientation, angle and distance) controlling the accuracy of measuring canopy temperature with the infrared thermal imaging were investigated in a cotton field. Moreover, the correlation relationships between the crop water stress index (CWSI), which was observed using different methods, and soil water content (SWC), leaf water potential (LWP), and stomatal conductance (g(s)) of cotton in different water treatments were analyzed. Results indicated that the CWSI, which was measured in the opposite direction of the sun with the observation angle of 45°, was in good correlation with LWP, g(s) and SWC, indicating it was a suitable observing method of canopy temperature. The canopy temperature gradually decreased with the increasing observation distance, so the calibration was necessary for long-distance measurement. By analyzing the relationship between the temperature at the dry/wet reference surface and the canopy temperature, we developed a suitable and simplified model of CWSI for cotton in the North China Plain.