Photosynthesis is an important physiological response for determination of CO₂ fertilization in greenhouses and estimation of crop growth. In order to estimate the whole plant photosynthetic rate, it is necessary to investigate how light interception by crops changes with environmental and morphological factors. The objectives of this study were to analyze plant light interception using a three-dimensional (3D) plant model and ray-tracing, determine the spatial distribution of the photosynthetic rate, and estimate the whole plant photosynthetic rate of Irwin mango (Mangifera indica L. cv. Irwin) grown in greenhouses. In the case of mangoes, it is difficult to measure actual light interception at the canopy level due to their vase shape. A two-year-old Irwin mango tree was used to measure the whole plant photosynthetic rate. Light interception and whole plant photosynthetic rate were measured under artificial and natural light conditions using a closed chamber (1 × 1 × 2 m). A 3D plant model was constructed and ray-tracing simulation was conducted for calculating the photosynthetic rate with a two-variable leaf photosynthetic rate model of the plant. Under artificial light, the estimated photosynthetic rate increased from 2.0 to 2.9 μmolCO₂·m⁻²·s⁻¹ with increasing CO₂ concentration. On the other hand, under natural light, the photosynthetic rate increased from 0.2 μmolCO₂·m⁻²·s⁻¹ at 06:00 to a maximum of 7.3 μmolCO₂·m⁻²·s⁻¹ at 09:00, then gradually decreased to −1.0 μmolCO₂·m⁻²·s⁻¹ at 18:00. In validation, simulation results showed good agreement with measured results with R² = 0.79 and RMSE = 0.263. The results suggest that this method could accurately estimate the whole plant photosynthetic rate and be useful for pruning and adequate CO₂ fertilization.

Mushroom cultivation generates a large amount of CO₂ that can be used sustainably. The objective of this study was to use actual cultivation and simulation to find a sustainable cultivation method that uses the CO₂ generated by king oyster mushrooms for the production of romaine lettuces. A closed cultivation system consisting of one mushroom chamber, three lettuce chambers, and one gas-mixing chamber was used. Two cultivation conditions, non-continuous and continuous, were analyzed. The non-continuous system cultivated 15 lettuces and 12 mushroom bottles at a time every 25 and 16 days, respectively. The continuous system cultivated three lettuces and mushroom bottles every five and four days, respectively, so that each chamber contained mushrooms or lettuces at each growth stage. The CO₂ concentrations in the lettuce and mushroom chambers were stably maintained above 1000 μmol∙mol⁻¹ and below 2000 μmol∙mol⁻¹ in the continuous system. Mathematical models were developed to analyze the CO₂ concentration in each chamber. The shoot dry weight of lettuces grown in the mixed cultivation were 48.0%, 21.9%, 19.7%, and 18.1% at 10, 15, 20, and 25 days after transplanting, respectively, higher than those in the lettuce-only cultivation. Compared to mushroom-only cultivation, mixed cultivation reduced the accumulated CO₂ emissions into the air by 80.6%. Thus, using CO₂ from mushrooms to cultivate lettuce in a continuous cultivation system could reduce CO₂ emissions into the air and enable mixed cultivation of mushrooms and lettuces, achieving sustainable agriculture.

Climate change has a considerable impact on human life and ecosystems, as well as on agricultural ecosystems. The two main factors of future climate change, CO 2 concentration, and temperature should be tracked, and changes in crop yield and quality due to these environmental factors should be identified. The objective of this study was to analyze the growth, fruit quality, and leaf characteristics of apple trees (Malus domestica Borkh. 'Fuji') grown under different elevated CO 2 and temperature conditions for extended periods. Four different CO 2 concentrations and temperature treatments for the cultivation of apple trees were applied as follows: ambient CO 2 concentration and temperature (CON), elevated CO 2 concentration and ambient temperature (ECAT), ambient CO 2 concentration and elevated temperature (ACET), and elevated CO 2 concentration and elevated temperature (ECET). Tree shoot length and fruit fresh weight were measured over nine consecutive years. The soluble solids content, titratable acidity, firmness, Hunter 'a' value, and ethylene and CO 2 emissions of harvested fruits from 9-year-old trees were measured. Elevated CO 2 concentrations promoted shoot growth and average fruit fresh weight but reduced fruit yield at the early stage of development, with more than eight years of recovery. Elevated temperature decreased shoot growth, average fruit fresh weight, and fruit yield, as it caused a decrease in the leaf photosynthetic rate. However, under all climate change conditions, it was predicted that the fruit quality would decrease, thus, the marketability of apples would decrease. In the future, as climate change continues, this study can identify the type of cultivation and management practices needed to maintain the fruit quality of apples.

Reclaimed land used as arable land can improve low food self-sufficiency or export competitiveness through large-scale controlled-environment agriculture. However, high salinity in reclaimed land can cause diseases and decrease yields during crop cultivation. This study was conducted to understand the growth characteristics of bell pepper and tomato hydroponically cultivated in rockwool and coir media reflecting changes in electrical conductivity (EC) and NaCl concentrations in the raw water of reclaimed lands. For bell pepper, Machai varieties (C. annuum L. cv. Machai) were used. For tomatoes, TY TRUST varieties (S. lycopersicum L. cv. TY TRUST) were used. NaCl was supplemented into the nutrient solution once a week to construct a treatment group based on EC. For bell pepper and tomato, NaCl was supplied at the following levels: none (CON), EC 4.0 (T1), EC 4.5 (T2), EC 5.0 (T3), and EC 5.5 dS•m-1 (T4). The plant height, leaf area, leaf fresh weight, leaf dry weight, stem fresh weight, stem dry weight, and fruit yield of bell pepper and tomato were investigated as indicators of growth characteristics of crops. For bell peppers, the growth index decreased with an increase in the stage as the NaCl concentration was increased, regardless of the type of media used. The use of coir media could secure bell pepper production yields without a significant effect of the NaCl concentration at the levels used in this study. However, for tomatoes, the leaf area was significantly decreased when NaCl concentrations were applied compared to that of the control group. Also, most other growth indicators were significantly decreased at NaCl concentrations above T2. The effects of the NaCl concentration were reduced when tomatoes were cultivated in coir media instead of rockwool media. Therefore, for hydroponically cultivated bell peppers and tomatoes, if raw water containing NaCl is supplied, it may be possible to maintain the crop yield if coir media are used.

In recent years, light-emitting diode (LED) technology has been applied to improve crop production and induce targeted biochemical or physiological responses in plants. This study investigated the effect of different ratios of blue 450 nm and red 660 nm LEDs on the overall plant growth, photosynthetic characteristics, and total triterpenoid production in the leaves of Hedyotis corymbosa in vitro plants. The results showed that a high proportion of blue LED lights had a positive effect on enhancing photosynthesis and the overall biomass. In addition, blue LED lights were shown to be more effective in controlling the production of the total triterpenoid content compared with the red LED lights. Moreover, it was also found that plants grown under a high proportion of red LEDs exhibited reduced photosynthetic properties and even induced damage to the photosynthetic apparatus, which indicated that the blue or red LED lights played contrary roles in Hedyotis corymbosa.