Root morphology and its components’ behavior could show a considerable response under multiple water application points per plant to help the ultimate effect of fruit yield and fruit quality. In this study, a comparison of a single emitter per plant was made with two, three, and four emitters per plant under drip irrigation and two irrigation levels (full irrigation 100% and deficit irrigation 75% of crop evapotranspiration) to investigate their effects on physiological parameters, root, yield, and their associated components for potted cherry tomato under greenhouse conditions in Jiangsu-China. The experimental results showed that the plants cultivated in the spring-summer planting season showed significantly higher results than the fall-winter planting season due to low temperatures in the fall-winter planting season. However, the response root length, root average diameter, root dry mass, leaf area index, photosynthetic rate, transpiration rate, fruit unit fresh weight, the number of fruits, and pH were increased by multiple emitters per plant over a single emitter per plant, but total soluble solids decreased. Besides, a decreasing trend was observed by deficit irrigation for both planting seasons, and vice versa for the case for tomato total soluble solids. Due to an increase in measured parameters for multiple emitters per plant over a single emitter per plant, the yield, water use efficiency, and water use efficiency biomass significantly increased by 18.1%, 17.6%, and 15.1%, respectively. The deficit irrigation caused a decrease in the yield of 5% and an increase in water use efficiency and water use efficiency biomass of 21.4% and 22.9%, respectively. Two, three, and four emitters per plant had no significant effects, and the obtained results were similar. Considering the root morphology, yield, water use efficiency, water use efficiency biomass, and fruit geometry and quality, two emitters per plant with deficit irrigation are recommended for potted cherry tomato under greenhouse conditions. The explanation for the increased biomass production of the plant, yield, and water use efficiency is that two emitters per plant (increased emitter density) reduced drought stress to the roots, causing increased root morphology and leaf area index and finally promoting the plant’s photosynthetic activity.

The spatial distribution of root systems in the soil has major impacts on soil water and nutrient uptake and ultimately crop yield. This research aimed to optimize the root distribution patterns, growth, and yield of cherry tomato by using a number of emitters per plant. A randomized complete block design technique was adopted by selecting eight treatments with two irrigation regimes and four levels of emitters under greenhouse conditions. The experiment results showed that the root distribution extended over the entire pot horizontally and shifted vertically upwards with increased emitter density. The deficit irrigation resulted in reduced horizontal root extension and shifted the root concentrations deeper. Notably, tomato plants with two emitters per plant and deficit irrigation treatment showed an optimal root distribution compared to the other treatments, showing wider and deeper dispersion measurements and higher root length density and root weight density through the soil with the highest benefit–cost ratio (1.3 and 1.1 cm cm⁻³, 89.8 and 77.7 µg cm⁻³, and 4.20 and 4.24 during spring–summer and fall-winter cropping seasons, respectively). The increases in yield and water use efficiency (due to increased yield) were 19% and 18.8%, respectively, for spring–summer cropping season and 11.5% and 11.8%, respectively, for fall–winter cropping season, with two emitters per plant over a single emitter. The decrease in yield was 5.3% and 4%, and increase in water use efficiency (due to deficit irrigation) was 26.2% and 27.9% for spring-summer and fall-winter cropping seasons, respectively, by deficit irrigation over full irrigation. Moreover, it was observed that two, three, and four emitters per plant had no significant effects on yield and water use efficiency. Thus, it was concluded that two emitters per plant with deficit irrigation is optimum under greenhouse conditions for the cultivation of potted cherry tomatoes, considering the root morphology, root distribution, dry matter production, yield, water use efficiency, and economic analysis.

Crop models are instrumental in simulating resource utilization in agriculture, yet their complexity necessitates extensive calibration, which can impact the accuracy of yield predictions. Machine learning shows promise for enhancing yield estimations but relies on vast amounts of training data. This study aims to improve the pakchoi yield prediction accuracy of simulation models. We developed a stacking ensemble learning model that integrates three base models—EU-Rotate_N, Random Forest Regression and Support Vector Regression—with a Multi-layer Perceptron as the meta-model for the pakchoi dry matter yield prediction. To enhance the training dataset and bolster machine learning performance, we employed the EU-Rotate_N model to simulate daily dry matter yields for unsampled data. The test results revealed that the stacking model outperformed each base model. The stacking model achieved an R² value of 0.834, which was approximately 0.1 higher than that of the EU-Rotate_N model. The RMSE and MAE were 0.283 t/ha and 0.196 t/ha, respectively, both approximately 0.6 t/ha lower than those of the EU-Rotate_N model. The performance of the stacking model, developed with the expanded dataset, showed a significant improvement over the model based on the original dataset.

Sucrose is the main constituent of assimilation transport from source to sink. In order to study the transport mechanism of sucrose, the sucrose at stem was taken as a research object and the sucrose flow field in tomato stem was analyzed using CFD ANSYS FLUENT simulation. The results showed that the sucrose pressure distribution was lower at bottom node and higher at middle node. The velocity of sucrose at different nodes was higher at the bottom node and lower at middle node and assimilation flow direction of the first, second, and third leaf from the bottom was towards the roots. The result of verification experiment showed that sucrose content measured at different nodes was higher at middle node than that of bottom node. Results of this study confirmed that ANASYS FLUENT can better simulate sucrose migration in greenhouse tomato stem. This study provides a new method for studying the partitioning mechanism of tomato assimilates in greenhouse. Keywords: greenhouse tomato, sucrose flow field, computational fluent dynamic, rule of distribution DOI: 10.25165/j.ijabe.20221501.6061 Citation: Ni J H, Dong J T, Ullah I, Mao H P. CFD simulation of sucrose flow field in the stem of greenhouse tomato seedling. Int J Agric & Biol Eng, 2022; 15(1): 111–115.

To pursue high yields, the excessive application of nitrogen (N) fertilizer has been reported in high-residual soil nitrate levels, excessive nitrate leaching, and nitrate contamination of groundwater. In this study, tomato crops (Lycopersicon esculentum Mill.) were subjected to various nitrogen treatments, and the nitrate nitrogen content, soil water content at different soil layers, dry matter, and yield were measured. A mechanistic model, EU-Rotate_N, was used to simulate the aforementioned indexes in a region of Jiangsu province with a relatively higher water table. The predicted values of soil moisture and soil nitrate content at various soil depths agree well with the measured values during tomato growth. The statistical index of soil water content ranged from 0.367 to 0.749, 0.856 to 0.947, and the statistical index of soil nitrate nitrogen content ranged from 0.365 to 0.698, and 0.869 to 0.932, for Autumn-Winter (AW) and Spring-Summer (SS) crops, respectively. Moreover, the dry weight and yield simulation effects of the tomato are also in good agreement with the actual measured values. The results show that the EU-Rotate_N model is effective in simulating soil water content, nitrate nitrogen content, dry matter quality, and yield in Jiangsu province, with little underestimation in soil water content at a soil depth of 20–30 cm during SS, which might be improved further considering the high water table of the region.