Optimal canopy structure and radiation thresholds for sustaining maize yield under low solar radiation

In Japan, most strawberries are grown by forcing culture, and fruit is harvested from November to June. Low temperature and solar radiation are major factors behind the unstable yield in winter. To clarify the effect of substrate heating and shading in winter in Japan, we investigated dry-matter production, fruit yield and causes of malformed fruit emergence in strawberry. We compared strawberry 'Mouikko' plants grown under combinations of substrate heating (25°C) and no heating, and 55% shading and no shading under forcing culture. Substrate heating and shading started on 8 December 2015. Total above-ground dry weight in the substrate-heating+no-shading treatment was significantly higher than that in other treatments, except on 15 January. In both shading and no shading treatments, substrate heating increased total above-ground dry weight significantly. There were significant differences in total above-ground dry weight as a result of substrate heating and shading. Leaf area showed a similar tendency to total above-ground dry weight. Total fresh-fruit yield was highest in substrate heating+no shading, and significantly lowest in no substrate heating+shading of the four treatments. On the other hand, the rate of malformed fruit was significantly highest in no substrate heating+shading and lowest in substrate heating+no shading. There were significant differences in the number of normal fruit, total number of fruit and malformed fruit rate in relation to substrate heating and shading. Fruit yields with substrate heating were significantly higher than those without substrate heating at the end of January and the beginning of April. These results show that, at low temperature and low solar radiation, emergence of malformed fruit may be influenced by lower levels of assimilation products caused by the decreased leaf area. Thus, substrate heating may decrease the rate of malformed fruit and increase fruit yield through an increase in total above-ground dry weight.

Experimental assessment of a CO2 direct-expansion solar-assisted heat pump operating with capillary tubes and air-solar heat source

Criticality and severity of adverse effects of the sun on performance of solar PV systems

Hot water is required for bathing and cleaning of utensils in the morning and evening hours in Indian homes. People in rural areas use fossil fuels, cooking gas and rarely electricity for hot water production. Present day solar collectors cannot help in instant hot water generation. A system involving a parabolic trough, an evacuated tube and Therminol D-12 oil is developed and studied for instant hot water generation. The developed system works satisfactorily during low incident solar radiation. Experiments on the developed new system show that Therminol D-12 helps to generate hot water at a temperature of 60°C within 10 minutes of time with low solar radiation.

Performance of a solar assisted solid desiccant dryer for kenaf core fiber drying under low solar radiation

Data linking solar radiation with fractures are lacking. We found that lower solar radiation was associated with higher hip fracture admission rates in men from Chile. This supports the idea that solar radiation, a surrogate of vitamin D, may be involved in the development of fractures in older population. INTRODUCTION : To explore the associations between solar radiation and latitude with hip fracture admission rates in people aged 65 years or older in Chile, the country with the greatest variation in solar radiation in the world. Methods In this ecological study, we investigated the associations between regional solar radiation and latitude with hospitalizations due to hip fracture in population aged 65 years or older, by reviewing national records between 2013 and 2018. We also evaluated the role of sociodemographic factors such as poverty, education, indigenous ethnicity, and rurality rates. Results Between 2013 and 2018, there were 44,328 admissions due to hip fracture in people aged 65 years or older; 77.5% were women and 65.1% were aged 80 years or older. The national admission rate was 389.3 per 100,000 inhabitants (95% CI: 382.4-396.2). The highest admission rate was registered in the Region IX (445.3 per 100,000, 95% CI: 398.3-492.4), which has the highest poverty rates, indigenous ethnicity rates, and rurality rates. We found a north-south increasing gradient of admission rates in men (β=1.5 [95% CI: 0 to 3], p=0.044) and a significant association between solar radiation and admission rates in men (β=-4.4 [95% CI: -8 to 0.8], p=0.02). Admission rates in men were also associated with sociodemographic variables such as poverty (β=2.4 [95% CI: 0 to 4.8], p=0.048) and rurality rates (β=1.2 [95% CI: 0.1 to 2.4], p=0.039). Conclusion Regional solar radiation and latitude were associated with hip fracture admission rates in men aged 65 years or older in Chile, with highest admission rates at higher latitudes and lower solar radiation.

Aechmea lindenii (E. Morren) Baker var. lindenii (Bromeliaceae-Bromelioideae) ocorre em restingas e Floresta Pluvial de Encosta Atlântica em Santa Catarina e Nordeste do Rio Grande do Sul, BR. Pode ser encontrada total ou parcialmente exposta à irradiação solar e em distintas formas de vida - terrícola, rupícola e epifítica. O objetivo deste trabalho foi comparar morfoanatomicamente às características de folhas de A. lindenii var. lindenii em distintas condições ambientais. Foram coletadas, na Ilha de Santa Catarina (Florianópolis, SC), folhas de plantas terrícolas em restinga herbácea (alta irradiação solar), rupícolas de costões rochosos (alta irradiação solar), terrícolas e epifíticas de sub-bosques (baixa irradiação solar) de restinga arbórea e rupícolas de sub-bosque (baixa irradiação solar) de Floresta Pluvial de Encosta Atlântica. Foram mensurados comprimento, largura, área da lâmina e bainha foliar, densidade estomática, comprimento e largura das células-guarda, espessura total e das estruturas constituintes na lâmina foliar. As características anatômicas qualitativas são semelhantes nas distintas condições analisadas. A baixa irradiação solar determina maior expansão da área foliar, decorrente do alongamento da lâmina. Lâmina e bainha foliares têm maior largura sob alta irradiação. A densidade estomática foi maior em folhas de plantas sob alta irradiação solar. A espessura total da lâmina foliar foi menor em plantas terrícolas sob alta irradiação, porém não mostrou diferenças estatísticas significativas entre as outras condições.

Solar updraft tower (SUT) power plant is a unique system using solar energy, which consists of three main parts: the chimney, turbine, and collector. In tropical climate conditions, especially in Malaysia, the application of solar chimney can be deemed more competitive compared to other renewable energy systems. In this study, one prototype with a dimension of 3.5 m in diameter for the collector and 5 m height for the chimney, was built in Melaka, Malaysia. Vital parameters such as temperature field, pressure, humidity, and air movement were measured using data logger and stored using non-volatile memory. The most exciting finding was that the temperature and pressure difference was significantly seen during the experiment along the day. There was a significant surge for the humidity in the morning with an average of above 95% and the ambient temperature was approximately 35 °C due to low solar radiation. The humidity kept decreasing after sunrise due to the greenhouse effect produced in the solar collector. With the collection of these critical parameters, a solar chimney power plant was adequate to function and generate power from solar radiation in a country such as Malaysia, which is based in the equatorial region. These studies are limited as the analysis focused mainly for high radiation and did not investigate efficiency during low solar radiation. The addition of heat storage underneath the collector with current techniques is another direction of research for continuous system operation, particularly during low solar radiation. It is proposed that the synthesis of these factors should be extensively explored in future studies coupled with the application of heat storage.

Comparative analysis of solar-air dual source heat pump system with different heat source configurations

High solar radiation from the sun in the heat outdoor may be impaired exercise capacity. This study aimed to compare the effects of different levels of solar radiation on exercise capacity and evaluate skin temperature responses in the heat. Seven male participants performed cycling exercise at 60% of their maximal oxygen uptake until volitional exhaustion in hot outdoor environments (approximately 33-35°C, 40-50% relative humidity) under both clear sky (high solar radiation trial: 1062±50 W/m2) and under thick clouds (low solar radiation trial: 438±52 W/m2). The time to exhaustion of the participants was shorter in the high solar radiation trial (32.0±12.4 min) than in the low solar radiation trial (39.2±18.0 min: P=0.045). Mean skin temperature was significantly higher in the high solar radiation trial than that in the low solar radiation trial (P<0.05); however, the rectal temperature did not differ significantly between the two trials. The high solar radiation trial had narrower core-to-skin temperature gradient, greater the body heat gain from the sun, and higher rating of perceived exertion than the low solar radiation trial. These results indicate that high solar radiation during outdoor exercise in the heat causes a greater increase in skin temperature and body heat gain from the sun than low solar radiation and consequently impairs exercise capacity.

Low solar radiation caused by industrial development and solar dimming has become a limitation in crop production in China. It is widely accepted that low solar radiation influences many aspects of plant development, including slender, weak stems and susceptibility to lodging. However, the underlying mechanisms are not well understood. To clarify how low solar radiation affects stem mechanical strength formation and lodging resistance, the japonica rice cultivars Wuyunjing23 (lodging-resistant) and W3668 (lodging-susceptible) were grown under field conditions with normal light (Control) and shading (the incident light was reduced by 60%) with a black nylon net. The yield and yield components, plant morphological characteristics, the stem mechanical strength, cell wall components, culm microstructure, gene expression correlated with cellulose and lignin biosynthesis were measured. The results showed that shading significantly reduced grain yield attributed to reduction of spikelets per panicles and grain weight. The stem-breaking strength decreased significantly under shading treatment; consequently, resulting in higher lodging index in rice plant in both varieties, as revealed by decreased by culm diameter, culm wall thickness and increased plant height, gravity center height. Compared with control, cell wall components including non-structural carbohydrate, sucrose, cellulose, and lignin reduced quite higher. With histochemical straining, shading largely reduced lignin deposition in the sclerenchyma cells and vascular bundle cells compared with control, and decreased cellulose deposition in the parenchyma cells of culm tissue in both Wuyunjing23 and W3668. And under shading condition, gene expression involved in secondary cell wall synthesis, OsPAL, OsCOMT, OsCCoAOMT, OsCCR, and OsCAD2, and primary cell wall synthesis, OsCesA1, OsCesA3, and OsCesA8 were decreased significantly. These results suggest that gene expression involved in the reduction of lignin and cellulose in both sclerenchyma and parenchyma cells, which attribute to lignin and cellulose in culm tissue and weak mechanical tissue, consequently, result in poor stem strength and higher lodging risks.Highlights:(1) Shading decreases the stem mechanical strength of japonica rice by decreasing non-structural carbohydrate, sucrose, lignin, and cellulose accumulation in culms.(2) The decrease of carbon source under shading condition is the cause for the lower lignin and cellulose accumulation in culm.(3) The expression of genes involved in lignin and primarily cell wall cellulose biosynthesis (OsCesA1, OsCesA3, and OsCesA8) at the stem formation stage are down-regulated under shading condition, inducing defective cell wall development and poor lodging resistance.

Operational performance of a novel heat pump coupled with mini-channel PV/T and thermal panel in low solar radiation

Sunflower inspired urban city pattern to improve solar energy utilization in low solar radiation countries

지구 온난화에 의한 미래의 기후변화는 감자의 생물 계절, 생육 및 수량에 지대한 영향을 미칠 것으로 예상되므로 그 영향을 평가하여 적응대책을 수립하여야 한다. 본 연구에서는 고온조건을 포함한 다양한 기상 조건에서 감자의 생육과 수량 변화를 확인하고자 하였다. 작기 이동 실험은 2014년과 2015년, 수원의 서울대학교 부속 실험농장에서 실시되었으며, 봄 실험에서는 조생종인 남작과 수미 그리고 중만생종인 대서를 세 번의 파종기에 걸쳐 재배하였다. 가을 실험에서는 수미와 대서를 두번의 파종기에 걸쳐 2014년에만 재배하였다. 괴경형성기는 품종과 파종기에 따라 출아 후 11일부터 22일까지 다양한 시기에 나타났다. 기상요인들이 괴경형성기에 미치는 영향을 분석한 결과, 현재 기후조건에서 괴경형성기는 기온 상승과 단일조건하에서 촉진되었다. 반면에 고온과 장일 조건에서 적은 일사량은 역시 괴경형성기를 지연시켰다. 공시 품종 모두 괴경형성 적온은 <TEX>$22-24^{\circ}C$</TEX> 내외로 추정되었으며, 기온, 일장 및 일사는 괴경형성에 상승적으로 상호작용하였다. 재배기간, 괴경 형성기와 기상요인이 수량에 미치는 영향을 확인하기 위한 능형회귀 결과 가장 큰 영향은 재배기간으로 나타났다. 남한에서 감자의 생육기간은 봄철의 장마와 늦가을의 서리로 제한된다. 이는 봄 작기 동안의 수원의 평균 기온이 감자 수량의 최적온도와 큰 차이를 보이지 않고 2014~2015년 마른장마로 인해 생육시기 동안 충분한 일사량이 확보되어 제한요인으로 작용하지 못하였기 때문이다. 앞당겨진 괴경형성기와 최저기온의 상승은 수량을 감소시켰다. <TEX>$17-22^{\circ}C$</TEX> 범위의 평균기온에서는 일교차만이 수량에 큰 영향을 주었다. 고온반응 실험은 2015년에 서울대학교 부속실험농장의 플라스틱 하우스 4개동에서 수행되었다. 대표 품종으로 수미가 이용되었으며, 4월 29일과 9월 17일에 외기온 프라스틱하우스와 외기온보다 <TEX>$1.5^{\circ}C$</TEX>, <TEX>$3.0^{\circ}C$</TEX>, <TEX>$5.0^{\circ}C$</TEX> 높게 조절되는 프라스틱 하우스에 각각 80주씩 파종하였다. 가을실험에서는 출아기와 괴경형성기만을 관측하였다. 괴경형성기는 장일효과로 인해 봄 실험에서 가을 실험에 비해 14일 가량 늦어졌으며, <TEX>$5.0^{\circ}C$</TEX> 온실에서는 고온, 저일사와 장일효과로 인해 괴경이 형성되지 않았다. 온도 상승에 따라 괴경 형성 초기의 괴경 숫자가 감소하여, 괴경으로 전류되는 동화산물과 수확기 괴경의 평균 생서중이 감소하였다. 잉여동화산물은 주로 줄기로 집적되어 왕성한 줄기신장을 보였다. 본 실험 결과에 따르면 이미 수원의 현재 기후는 감자재배의 적온 범위를 벗어나기 시작하였으며, 미래기후에서 고온피해는 더 심각하게 나타날 것이다. 하지만, 감자의 괴경 형성 및 비대에 대한 이해는 아직까지도 부족한 상태이므로 미래 기후 변화 영향을 평가하기 위해서는 고온 하에서 감자의 생리적 반응에 대한 구체적인 연구가 필요할 것으로 사료된다. Potato phenology, growth, and yield are projected to be highly affected by global warming in the future. The objective of this study was to examine the responses of potato growth and yield to environmental elements like temperature, solar radiation, and daylength. Planting date experiments under open field condition were conducted using three cultivars differing in maturity group (Irish Cobbler and Superior as early; Atlantic as mid-late maturing) at eight different planting dates. In addition, elevated temperature experiment was conducted in four plastic houses controlled to target temperatures of ambient temperature (AT), <TEX>$AT+1.5^{\circ}C$</TEX>, <TEX>$AT+3^{\circ}C$</TEX>, and <TEX>$AT+5^{\circ}C$</TEX> using cv. Superior. Tuber initiation onset was found to be hastened curve-linearly with increasing temperature, showing optimum temperature around <TEX>$22-24^{\circ}C$</TEX>, while delayed by longer photoperiod and lower solar radiation in Superior and Atlantic. In the planting date experiments where the average temperature is near optimal and solar radiation, rainfall, pest, and disease are not limiting factor for tuber yield, the most important determinant was growth duration, which is limited by the beginning of rainy season in summer and frost in the late fall. Yield tended to increase along with delayed tuber initiation. Within the optimum temperature range (<TEX>$17^{\circ}-22^{\circ}C$</TEX>), larger diurnal range of temperature increased the tuber yield. In an elevated temperature treatment of <TEX>$AT+5.0^{\circ}C$</TEX>, plants failed to form tubers as affected by high temperature, low irradiance, and long daylength. Tuber number at early growth stage was reduced by higher temperature, resulting in the decrease of assimilates allocated to tuber and the reduction of average tuber weight. Stem growth was enhanced by elevated temperature at the expense of tuber growth. Consequently, tuber yield decreased with elevated temperature above ambient and drop to almost nil at <TEX>$AT+5.0^{\circ}C$</TEX>.

Techno-economic study of compound parabolic collector in solar water heating system in the northern hemisphere