Overview of modelling techniques for greenhouse microclimate environment and evapotranspiration

The most important biotic stress factor impacting tomato crop biophysical, biochemical, physiological, and morphological features is water stress. A pot experiment was undertaken in a greenhouse to study the drought responsiveness of tomato (Solanum lycopersicum) yield and quality indices in sandy loam and silty loam soils. For both sandy loam and silty loam soils, the water supply levels were 70–100% FC, 60–70% FC, 50–60% FC, and 40–50% FC of ET_o (crop evapotranspiration) from the vegetative stage to the fruit ripening stage, calculated using the Hargreaves–Samani (HS) model compared to the time-domain reflectometer (TDR) values calibrated using volumetric water content (VWC). The experiment was conducted as a 2 × 4 factorial experiment, arranged in a completely randomized block design, with four treatments replicated four times. In this study, we examined how sandy loam and silty loam soils at different % FC affect the total marketable yield and quality components of tomatoes, concentrating on total soluble solids (Brix), fruit firmness, dry fruit mass, pH, titratable acid (TA), ascorbic acid (Vit. C), and carotenoid composition. Lycopene and β-Carotene were estimated using the UV spectroscopy method, with absorption spectra bands centered at 451 nm, 472 nm, 485 nm, and 502 nm. The results revealed that even though there were some limitations, TDR-based soil moisture content values had a strong positive correlation with HS-based evapotranspiration, with R² = 0.8, indicating an improvement whereby TDR can solely be used to estimate soil water content. Tomato plants subjected to 40–50% FC (ET_o) water stress in both sandy loam and silty loam soils recorded the highest total soluble solids, titratable acidity, ascorbic acid content, and β-carotene content at an absorption peak of 482 nm, and lycopene content at an absorption peak of 472 nm, with lower fruit firmness, fruit juice content, and fruit juice pH, and a reduced marketable yield. Similarly, tomato plants subjected to 60–70% FC throughout the growing season achieved good fruit firmness, percent juice content, total soluble solids, titratable acidity, ascorbic acid content, and chlorophyll content (SPAD), with minimum fruit juice pH and high marketable yield in both soil textural types. It is concluded that subjecting tomato plants to 60–70% FC (ET_o) has a constructive impact on the marketable yield quality indices of tomatoes.

This study examined the impact of varying biochar application rates on soil characteristics and the growth of Amaranthus caudatus in Ghana. Corn cob biochar, produced at a temperature of 550 °C, was applied at different rates (0, 2.5, 5.0, 7.5, and 10.0 t/ha) in a Randomized Complete Block Design with three replications. The findings demonstrated a notable enhancement in soil characteristics as the biochar application rates increased. The soil pH rose from 5.45 in the control group to 6.16 with the application of 7.5 t/ha. The 10 t/ha rate resulted in a significant increase of up to 24.3% in organic carbon content. The 10 t/ha treatment resulted in a 60% rise in total nitrogen, whereas accessible phosphorus exhibited an 80% increase. The water retention ability was significantly enhanced, with the application of 7.5 t/ha resulting in the greatest increase (11.7% compared to 10.8% in the control). Biochar application had a favorable impact on plant growth metrics. The application of 10 t/ha resulted in the highest plant height, measuring 17.17 cm, which is a 100% increase compared to the control group. The 7.5 t/ha treatment had the highest number of leaves, with 11.54 leaves, representing a 15% increase compared to the control. The stem circumference also increased, with the application rate of 7.5 t/ha resulting in the widest stems measuring 21.1 mm. The application of biochar significantly increased the yield of fresh matter in Amaranthus caudatus. The 10 t/ha rate resulted in the highest yield of 1722 kg/ha, closely followed by the 7.5 t/ha rate with a yield of 1676 kg/ha. These rates showed yield increases of 183 and 176% respectively, compared to the control yield of 608 kg/ha. This study showcases the capacity of biochar to enhance soil fertility and increase crop yield in tropical soils when used as a soil supplement. The findings indicate that applying biochar at rates ranging from 7.5 to 10 t/ha could be the most effective in improving soil characteristics and promoting the growth of Amaranthus caudatus in comparable circumstances. The consequences of these discoveries are significant for the sustainable management of soil and the security of food in tropical countries.

The use of plant-based indicators and other conventional means to detect the level of water stress in crops may be challenging, due to their difficulties in automation, their arduousness, and their time-consuming nature. Non-contact and non-destructive sensing methods can be used to detect the level of water stress in plants continuously and to provide automatic sensing and controls. This research aimed at determining the viability, efficiency, and swiftness in employing the commercial Workswell WIRIS Agro R infrared camera (WWARIC) in monitoring water stress and scheduling appropriate irrigation regimes in mandarin plants. The experiment used a four-by-three randomized complete block design with 80–100% FC water treatment as full field capacity and three deficit irrigation treatments at 70–75% FC, 60–65% FC, and 50–55% FC. Air temperature, canopy temperature, and vapor pressure deficits were measured and employed to deduce the empirical crop water stress index, using the Idso approach (CWSI_(Idso)) as well as baseline equations to calculate non-water stress and water stressed conditions. The relative leaf water content (RLWC) of mandarin plants was also determined for the growing season. From the experiment, CWSI_(Idso) and CWSI were estimated using the Workswell Wiris Agro R infrared camera (CWSI_W) and showed a high correlation (R² = 0.75 at p < 0.05) in assessing the extent of water stress in mandarin plants. The results also showed that at an altitude of 12 m above the mandarin canopy, the WWARIC was able to identify water stress using three modes (empirical, differential, and theoretical). The WWARIC’s color map feature, presented in real time, makes the camera a suitable device, as there is no need for complex computations or expert advice before determining the extent of the stress the crops are subjected to. The results prove that this novel use of the WWARIC demonstrated sufficient precision, swiftness, and intelligibility in the real-time detection of the mandarin water stress index and, accordingly, assisted in scheduling irrigation.

Rapid and onsite determination of the soil status and quality parameters holds a brighter potential for improving food security, and minimizing waste of the excessive application of soil amendments hence reducing environmental pollution. In this study, a pocket‐sized shortwave NIR spectroscopy (740–1070 nm) and multivariate statistics were used to classify soil from different land‐use types and simultaneously predict nitrogen (N), phosphorus (P), potassium (K), calcium (Ca²⁺), magnesium (Mg²⁺), and pH in Ghana. Different Algorithms. Linear discriminant analysis (LDA), support vector machine (SVM), and partial least squares algorithms (full‐range partial least square, FrPLS; interval partial least squares, IPLS; synergy interval partial least squares, Si‐PLS) were attempted for building a suitable classification and quantification model. The models were assessed by the classification rate, coefficient of determination (R_p²), and root mean square error of prediction (RMSEP) in the prediction set. A total of 110 soil samples from 0 to 15 cm, 15 to 30 cm, and 30 to 45 cm layers were collected from the field of different land‐use cropping systems. The results obtained showed that SVM had a 98.61% classification rate of the soil from the cropping system. While Si‐PLS was superior in predicting N, P, K, Mg²⁺, Ca²⁺, and pH. The performance of the Si‐PLS model for N, P, K, Mg²⁺, Ca²⁺, and pH were 0.571, 0.779, 0.910, 0.778, 0.826, and 0.904 for R_p² and 0.033%, 0.738 mg·kg⁻¹, 0.117 cmol·kg⁻¹, 0.654 cmol·kg⁻¹, 3.0219 cmol·kg⁻¹, and 0.4760 pH unit for RMSEP, respectively. The results revealed that the portable NIR spectroscopic technique could be used to measure the soil status and some quality parameters. However, further studies are needed to proof its application. This could lead to improving the yield and saving the cost of fertilizer application.

The Subsurface self-regulating, Low-Energy, Clay-based Irrigation (SLECI) system is a recently developed irrigation method. The SLECI system supplies water directly to the crop root zone by utilising the potential difference established between its permeable interior and exterior radial walls. In this study, we investigated the effect of the SLECI emitter’s operating pressure head and burial depth on the water flow characteristics in sandy loam soil. The results show that the developed COMSOL-2D model accurately predicted water flow characteristic under SLECI. The operating pressure head significantly influenced the water flow characteristics. As the operating pressure head increased, emitter discharge increased, and the wetted soil area was extended. The burial depth had a minimal effect on the emitter discharge but notably affected the advancement and time at which wetting fronts reached the soil surface and bottom boundaries. Operating the SLECI emitter at a higher operating pressure head and shallower burial depth could degrade irrigation water application and water use efficiencies. Based on a multi-objective optimisation algorithm, we recommend that the SLECI emitter be operated at a 125 cm pressure head and buried at 40 cm for crops with a root zone depth of 100 cm. Our study is expected to provide a greater understanding of the SLECI system and offer some recommendations and guidelines for its efficient deployment in sandy loam for enhanced water use efficiency in crop production.