Application of liquid digestate (LD), a by-product derived from anaerobic digestion of organic materials, was optimized for lettuce cultivation in closed plant production system (CPPS). LD can be dried to reduce transportation cost but ammonium, a major source of nitrogen in LD, is substantially lost during the process. In Experiment 1, it was shown that mixing of LD with lime juice at the ratio of 7:3 before drying was most effective in preventing ammonium loss. This redissolved mixture (RM) was used for fertigation in subsequent experiments. In Experiment 2, lettuce plant fertigated with RM had lower growth than those fertigated with chemical fertilizer when both treatments had the same nitrogen concentration. In Experiment 3, fertigation of RM resulted in lettuce plant with lower growth and higher accumulation of malondialdehyde than those fertigated with redissolved LD added with nitrate suggesting that growth suppression in the plant received RM could be attributed to ammonium toxicity. Reduction of light intensity causes an increasing of fresh and dry weight of lettuce plants in all treatments. Results from this study showed that RM can be used for lettuce cultivation in CPPS and condition of low light intensity with prolonged photoperiod can improve growth of lettuce plant.

　To investigate the effects of different types of irradiation on the growth and morphological characteristics of leaf lettuce (Lactuca sativa L. var. crispa “Greenwave”), a quantitative analysis of the leaf contour using an elliptic Fourier descriptor (EFD) was carried out together with conventional measurement methods. Two experiments were conducted to test the different treatments. Experiment 1 investigated the effects of monochromatic/alternating/simultaneous red/blue irradiation, and Experiment 2 determined the effects of random variations in photosynthetic photon flux density (PPFD) compared with that of constant light. The growth and morphological characteristics in Experiment 1 were consistent with those of previous studies, where the shoot fresh weights in monochromatic and alternating irradiations were larger than those in simultaneous irradiations. EFD showed that the leaf length and petiole under monochromatic and alternating irradiation were longer and more apparent than those under simultaneous irradiation. In Experiment 2, both the conventional measurement methods and EFD could hardly detect any differences in leaf lettuce growth and morphological characteristics under constant PPFD. These results suggested that fluctuating PPFD within certain limits in a PFAL may have little effect on the leaf lettuce growth.

　This study aimed to evaluate that the effect of the biomass and the vinblastine precursor concentrations in Catharanthus roseus before ultraviolet A (UV-A) light irradiation on vinblastine accumulation in the leaves for commercial vinblastine production in a plant factory with artificial light (PFAL). C. roseus seedlings were cultivated under monochromatic red lights with different photosynthetic photon flux densities of 150 (low) and 300 (high) μmol m^-2 s^-1 for 28 d and then were irradiated 5 W m^-2 UV-A light with monochromatic red lights with their different intensities for 5 d. The leaves dry weight was higher in high intensity treatments compared to low intensity treatments. After UV-A irradiation, the vinblastine concentration were approximately two times higher in the low intensity treatment than in the high intensity treatment. However, the vinblastine yield, a product of leaves dry weight and vinblastine concentration, did not have the great difference between the low and high intensity treatments. This study suggested that a suitable method to produce vinblastine using the PFAL was to apply the low intensity of monochromatic red light before UV-A light irradiation because the light use efficiency of vinblastine production was higher in the low intensity treatment than in high intensity treatment.

　Deficit irrigation can be used to improve tomato fruit quality. The semi-determinate tomato behaves like a bush tomato, with lateral shoots providing additional vegetative growth, but the response to deficit irrigation and the suitable training method have not been properly understood. Therefore, we clarify the combined effect of a training method (non-training, which omits manual plant management such as lateral shoot removal) and deficit irrigation (30–36% of field capacity) on yield, growth, and fruit quality of semi-determinate cherry tomato. Although deficit irrigation influenced non-training plants more than single-training plants (a conventional method by removing all lateral shoots) owing to the lowest midday leaf water potential, both plants showed the same levels of maximum quantum efficiency of photosystem II and fruit yield under deficit irrigation. Furthermore, non-training plants produced the highest levels of total soluble solids, glucose, fructose, citric acid, malic acid, and ascorbic acid under deficit irrigation. These observations indicated that the increased concentrations of the abovementioned components occurred as a result of water shortage in the fruit when compared with single-training plants. We conclude that non-training is suitable for semi-determinate cherry tomato cultivation under deficit irrigation, and that this method can produce high-quality fruits while mitigating manual plant management.