The purpose of this study was to clarify the plant growth and fruit quality of blueberry in a controlled room under artificial light. Cultivars used were a northern highbush 'Blueray', and two southern highbush, 'Misty' and 'Sharpblue'. A comparative study was carried out of growth characteristics, photosynthetic potential and fruit quality analysis in different growing environments, in particular focusing on plants growing in a glasshouse under natural sunlight and plants in a controlled room under artificial light. Environmental conditions of the controlled room under artificial light were 15 to 25°C, 50 to 70% humidity, 150 to 350 μmol·m −2 ·s −1 light intensity, and a 10-hour photoperiod from the primary experiment. In these growing environments, normal fruits developed from all the tested cultivars by successful growth without decreasing plant vigor and leaf photosynthetic ability until fruit harvesting time compared to the cultivars grown in the glasshouse under natural sunlight condition. Moreover, it was confirmed that high-quality fruits could be harvested in a controlled environment to increase fruit production with high SSC % and high anthocyanin content but low acid % in 'Blueray' and 'Misty', but not 'Sharpblue'. Finally, this report presents the possibility of high-quality blueberry production in a controlled environment under artificial light conditions with some cultivars.

Root-zone temperature (RZT) is closely related to nutrient transportation and biomass production. However, its influence on biomass production and dry matter distribution remains unknown, especially in year-long production greenhouses. We explore the potential of RZT as an environmental control method to promote spinach field production by quantifying the effects of RZT to increase spinach production. Three RZT treatments using a nutrient film technique (NFT) system quantified and evaluated the effects of spring, summer, and winter spinach cultivation. We investigated the growth characteristics, total aboveground dry matter, and fraction of dry matter distribution to the leaf and root (which corresponded with yield). The RZT effects on total aboveground dry matter varied with the average air temperature inside the greenhouse. The total aboveground dry matter correlated positively with RZT in optimal air temperature conditions (15–20 °C). The dry matter-to-leaves ratio of the spinach did not correlate significantly with RZT in suboptimal (5 °C < air temperature < 15 °C) or supraoptimal (20 °C < air temperature) conditions. Therefore, RZT can promote biomass accumulation. We suggest RZT provides a feasible method for controlling the dry matter distribution fraction. Further research into the functional role of RZT will support hydroponic growers in improving crop yield.

The development of models for yield prediction in greenhouse sweet peppers may help improve yield and labour productivity. We aimed to monitor the growth and yield of hydroponically grown sweet pepper plants without destructive sampling. First, we constructed a prediction model and validated it in a cultivation experiment. In the developed model, daily node appearance and light use efficiency were predicted from daily mean air temperature and daytime carbon dioxide (CO2) concentration. The daily light interception was obtained by non-destructive leaf area estimation. Second, we validated the model through the cultivation experiment. The predicted total dry matter production at 200 days after transplanting (DAT), 1,379 g/m2, fell within the range of the observed value, 1,353 ± 46 g/m2 (mean ± SE). The predicted and observed yields at 200 DAT were 7.90 kg/m2 and 7.73 ± 0.82 kg/m2, respectively. We approximately predicted node appearance, total dry matter production, and fruit yield, while partially succeeding in predicting leaf area index and dry matter partitioning to fruit. Our non-destructive prediction model can be an effective tool for growers and to improve the yield of sweet pepper production.