To drive LEDs for plant cultivation using an alternating-current (AC) power supply, full-wave rectification (FWR) is a reasonable method to supply a unidirectional forward current to LEDs because of the simple configuration and low energy loss of the rectification circuit. We grew cos lettuce hydroponically using a white LED light source that emitted continuous light, 100 Hz square-wave (SW) pulsed light, or pulsed light generated with FWR of 50 Hz sine-wave AC with the same averaged photosynthetic photon flux density of 150 µmol m^-2 s^-1. The results showed that shoot fresh weight, shoot dry weight, leaf area, and number of leaves did not differ significantly among the treatments. Plants grown under FWR pulsed light showed similar net photosynthetic rates under continuous light and SW pulsed light. Shoot fresh weight per power consumption was estimated to be significantly greater with FWR pulsed light than with continuous light, and we concluded that the use of FWR pulsed light without elaborated transformation to a flat waveform direct current is a promising lighting method to reduce the lighting cost.

　Tropospheric ozone (O₃) is known to harm crops by intrinsically affecting photosynthesis and other functions during crop growth. In staple crop production bases in the North China Plain (NCP) and Yangtze River Delta (YRD) regions, food security, especially food production, has been reported to be threatened by high O₃ concentrations. Studies have been conducted in the NCP or YRD to understand tropospheric O₃ and its precursor gases; however, the need to understand the effect of O₃ on crops in conjunction with the contributions of precursor gases (VOCs and NO_x) to O₃ formation using a fine-scale model remains. In this study, the combined Weather Research and Forecast with Chemistry (WRF-Chem) model was used to evaluate the impact of surface O₃ on reduced grain yield in China in 2010, covering the crop-growing seasons of single rice, double late rice, and winter wheat. The relative yield loss due to O₃ damage was evaluated using the accumulated O₃ exposure over a threshold of 40 ppb (AOT40) and a mean 7-hour O₃ mixing ratio (M7). The validation showed that the gas-phase chemistry mechanism Model for Ozone and Related chemical tracers, version 4 (MOZART-4), coupled with the Goddard Chemistry Aerosol Radiation and Transport (GOCART) aerosol module registered in WRF-Chem, can simulate O₃ fairly in the NCP and YRD. The aggregated average rice (wheat) relative yield losses throughout NCP and YRD were estimated to be 5.9% (27.1%) for AOT40 and 2.2% (9.6%) for M7, whereas aggregated rice (wheat) production losses were 2,345 kt (13,947 kt) for AOT40 and 999 kt (3,753 kt) for M7. In addition, reducing anthropogenic emissions of Volatile Organic Compounds (VOCs) from the energy and transport sectors is effective in reducing the surface O₃ concentration. The results provide important scientific evidence for achieving sustainable food production in China.

　To enhance the study of sunburn and fruit surface temperature (FST) prediction in domestic fruit trees, we examined the spatiotemporal characteristics of FST and the predominant factors influencing FST on clear summer days by measuring the FST of detached apple and satsuma mandarin fruits, and monitoring ambient summer meteorological condition. With respect to the diurnal variation in FST, we found that the maximum FST of fruit (FST_max) occurred on the surface facing southwest to west, approximately 2 h post-meridian transit time, thereby indicating that compared with other orientations, the surface of fruit facing these directions is at higher risk of sunburn. Our observations also revealed that under clear conditions, the FST_max of apple and satsuma mandarin fruits can be at least 15°C above the daily maximum air temperature (AT_max). We also established that in addition to AT_max, fruit size plays a key role in determining FST. Furthermore, comparative black globes measurements also revealed that under clear conditions, a large black globe warmed to a greater extent than a similar smaller globe. Our findings in this study indicate that FST appears to be influenced by both fruit size and meteorological factors, using the data of which will enable precise FST predictions.

　In this study, we developed a method for evaluating the heat insulation capacity of breathable thermal screens. Heat transfer through breathable thermal screens involves radiation, convection, conduction, and ventilation. Of these, ventilation heat transfer is unique to breathable thermal screens, and warrants further understanding. Therefore, we evaluated the heat insulation capacity of aluminized (Screen_Al) and polyester (Screen_Poly) thermal screens. Ventilation heat transfer coefficient (k_ven), heat transfer coefficient of the nonventilated part of the thermal screen (k), and heat transfer coefficient including all heat transfer forms (k_all) were measured via a hot-box with heat balance analysis. The k_ven of Screen_Al (1.5 W m^-2 °C ^-1) was higher than that of Screen_Poly (1.3 W m^-2 °C^-1) because the ventilation rate of Screen_Al (4.2 m³ m^-2 h^-1) was higher than that of Screen_Poly (3.8 m³ m^-2 h^-1). The k of Screen_Al (4.1 W m^-2 °C ^-1) was lower than that of Screen_Poly (6.0 W m^-2 °C ^-1) because of the higher longwave radiation reflectance of Screen_Al. Finally, the k_all of Screen_Al (5.7 W m^-2 °C ^-1) was lower than that of Screen_Poly (7.2 W m^-2 °C ^-1). In conclusion, we successfully demonstrated a method by which the heat insulation capacity of breathable thermal screens can be evaluated.