Supplemental lighting is common in northern countries or during winter greenhouse tomato production. We investigated the effect of supplemental lighting treatments on cherry tomato (‘Jun-Ama’) yield, productivity (light-use efficiency (LUE) and energy-use efficiency (EUE)), and fruit quality under high irradiance (average greenhouse daily light integral (DLI) = 14.5 mol m⁻² d⁻¹). Supplemental lighting treatments contained average DLIs of 2.7, 4.9, and 7.6 mol m⁻² d⁻¹ for interlighting, toplighting, and inter- + toplighting, respectively. Supplemental LED lighting increased fruit yield by 18, 41, and 40% with inter-, top-, and inter- + toplighting, respectively, compared with the control. Interlighting increased fruit number (+11%), and top- and inter- + toplighting also increased the fruit number (+26%, +27%) and weight (+10%, +10%), respectively. LUE and EUE were comparable between inter- and toplighting, while inter- + toplighting decreased LUE by 21 and 38%, and EUE by 38 and 31% compared with inter- and toplighting, respectively. All LED supplemental treatments significantly increased total soluble solids compared with the control. Total acidity and lycopene content were unchanged in all treatments. In conclusion, LED supplemental lighting with inter- or toplighting improved cherry tomato yield and quality, but inter- + toplighting was inefficient under high irradiation.

The objectives of this study were to evaluate the yield of different types of cucumbers from the perspective of yield components. The yield and yield components of nine cucumber cultivars (Beit Alpha, Greenhouse, and Japanese) grown hydroponically in a greenhouse were investigated. Fruit yield fresh weight in the Beit Alpha type was higher than that of the Japanese type, and the fruit yield fresh weight was significantly correlated with fruit yield dry weight, total dry matter (TDM), fraction of fruits, and number of fruits. However, the fruit yield fresh weight was not significantly correlated with intercepted light, light use efficiency (LUE), leaf area index, light extinction coefficient, and fruit dry matter content. High fruit yield dry weight was associated with a high TDM and the fraction of fruits. Moreover, the high TDM and fraction of fruits were associated with LUE and the number of fruits, respectively.

In this study, we aimed to estimate dry matter (DM) production and fresh fruit yield in “Fresco-dash” (FD) and “Project X” (PX) cucumber cultivars using an empirical model developed for tomatoes. First, we cultivated the two cucumber cultivars under a hydroponic system for about six months. Also, parameters related to DM production such as light use efficiency (LUE), light extinction coefficient (k), DM distribution of fruits (DMD), and fruit dry matter content (DMC) were measured via destructive measurements. The k, DMD and DMC values were 0.99 and 0.93, 46.0 and 45.2, 3.84 and 3.78 in “Fresco Dash” and “Project X”, respectively. Second, we cultivated cucumbers to estimate DM production and fruit fresh yield using the model without destructive measurement for about eight months and validated the model’s effectiveness. The predicted DM fell within the range of the observed DM ± standard error at 51 and 132 d after transplantation (DAT) in PX as well as 51 (DAT) in FD. The predicted and observed DM at 163 DAT were 2.08 and 1.82 kg m⁻², 2.09 and 1.87 kg m⁻² in “Fresco Dash” and “Project X”, respectively. The predicted and observed fruit yield at 200 DAT were 30.3 and 31.7, 30.5 and 29.1 in “Fresco Dash” and “Project X”, respectively, which were 4.4% lower than the observed fruit yield in FD and 4.9% higher than that in PX. These results suggest that the model applies to cucumbers in predicting dry matter production and fresh fruit yield.

Using organic fertilizer made from waste materials is beneficial for both the economy and the environment, promoting sustainability and reducing pollution. In hydroponics, decomposition converts these materials into fertilizer, with multiple parallel mineralization (MPM) enabling efficient nutrient conversion by microorganisms. The tomato cultivar “Momotaro Next” was cultivated hydroponically in order to determine whether organic fertilizer derived from soluble bonito fish waste (OF) through MPM could be used in tomato hydroponic cultivation compared with a chemical nutrient solution treatment (CF). In this study, ammonium (NH₄⁺) was generated through the OF decomposition process. During cultivation, the ammonium concentration tended to increase, while the nitrate (NO₃⁻) concentration tended to decrease. The total yield (TY), total dry matter (TDM), and leaf area index (LAI) were lower after OF treatment than after CF treatment. Notably, the TY, TDM, and LAI were 5.4 kg m⁻², 594 g plant⁻¹, and 1.7 for OF and 6.8 kg m⁻², 895 g plant⁻¹, and 3.8 for CF, respectively. The results of the tomato fruit qualities show no significant differences for total soluble solids (TSS) (%Brix), lycopene, glucose, fructose, or sucrose. However, significant differences were observed for gamma-aminobutyric acid (GABA), glutamate, aspartate, and citric acid. The lower yield and quality of the tomato crop with the OF treatment were caused by the high concentration of NH₄⁺ that occurred during cultivation due to a nonoptimal mineralization process. Therefore, a well-managed MPM process could improve crop quality by reducing the risk of high NH₄⁺.

Rejuvenation pinching is one of the training techniques for lowering cultivation of cucumber (Cucumis sativus L.), in which the harvesting shoot is regularly updated with a new axillary shoot stimulated by pinching. It is considered utilizable for managements of labor and fruit development; however, the ecophysiological effects of its repetition on cucumber growth and yield remain elusive. To address this, we analyzed the winter-spring greenhouse cultivations of 'S-27Z' conducted in 2021 and 2020 with and without rejuvenation, respectively, based on yield components. The cucumber plants undergoing rejuvenation exhibited a reduced fresh yield (23.3 kg・m-2) compared with those without rejuvenation (51.5 kg・m-2). Fruit abortions were not frequent with either cultivation. Total aboveground dry-matter production was also decreased in the rejuvenating cultivation, and the corresponding light-use efficiency was suppressed. It was suggested that the yield decrease was caused mainly by a reduction in the number of nodes and consequent decrease in fruit sets, which suppressed the dry-matter distribution to the fruits. Consistent with this, axillary shoot outgrowth after pinching was temporarily and continuously suppressed in winter and spring, respectively, with accompanying changes in the aboveground dry-matter partitioning. We propose that rejuvenation pinching is preferable on taking its negative effects on the yield and incidence of fruit abortions into account.