High thermally stable deep red-emitting Sb^(3+),Ho^(3+)-codoped Cs_(2)NaScCl_(6) double perovskite for plant lighting

Lead-free halide double perovskite has received widespread attention due to its excellent optical performance.However,the lack of deep red light and poor heat quenching resistance severely limit its application in plant lighting field.In this work,Ho^(3+) was introduced into the thermally stable Cs_(2)NaScCl_(6)host,exhibiting a deep red emission of 660 nm.By constructing an energy transfer channel between Sb^(3+)and Ho^(3+),the photo luminescence quantum yield(PLQY) of Cs_(2)NaScCl_(6):1%Sb^(3+),40%Ho^(3+) rises up to53.8%,that is increased by 17 times,and its emission intensity can still be maintained by 80% at 423 K,exhibiting good heat quenching resistance.The obtained Cs_(2)NaScCl_(6):1%Sb^(3+),40%Ho^(3+) and Cs_(2)NaScCl_(6):1%Sb^(3+) with blue light emission were employed for fabricating a light-emitting diode(LED) device with a340 nm UV chip,and its emission spectrum matches well the absorption spectra of chlorophyll A and chlorophyll B with the high resemblance of 70% and 75%,making it suitable for use as an artificial light source to control the growth process of plants in the field of plant lighting.

Improvement of light uniformity by lighting arrangement for standardized crop production

In a commercialized, fully artificial plant factory, artificial luminaire is arranged in a unified way using a general illumination theory, an actual measurement, or an empirical methodology. However, with these methods, lightings are implemented without considering specific optical characteristics of lighting or material characteristics of each component that constructs a cultivation system, resulting in an amount of light that becomes irregular. The amount of lighting is closely related with the growth and quality of crops, and the deviation between points where cultivated crops are located causes quality difference in the produced crops, thus impairing the economic feasibility of a plant factory. In this regard, a simulation to figure out an optimum lighting layout was performed. Arrangements based on the spectrum distribution of light source and reflector materials were implemented to ascertain the distance between lighting and height of lighting and gather information in the pre-treatment process to improve the uniformity of light in the plant cultivation system. Improvement of around 15% in light uniformity is achieved compared with the existing system after the simulation is carried out. This result would reduce the deviation in crop growth to make uniform quality crop production possible.

Multi-site occupancies and dependent photoluminescence of Ca_(9)Mg_(1.5)(PO_(4))_(7):Eu^(2+) phosphors:A bifunctional platform for optical thermometer and plant growth lighting

Herein,we demonstrate an optical thermometer based on single Eu^(2+)doped Ca_(9)Mg_(1.5)(PO_4)_7 phosphors,which were prepared by traditional solid-state reaction technique under a reduction atmosphere.Considerations on the bond length obtained by the crystal structure refinement and the dependent photoluminescence performances allow to assign the two distinct emission bands to Eu^(2+)ions occupied Cal-Ca3 and Mg2 sites.Moreover,the blue and red emitting bands perfectly match with the photosynthetic action spectrum,which can enhance the indoor plant photosynthesis.The optimal doping content of Eu^(2+)ions in this Ca_(9)Mg_(1.5)(PO_(4))_(7)system is 3 mol%.The corresponding concentration quenching effect is verified as dipole-dipole interaction with the critical distance of 3.315 nm.Furthermore,by exploiting the fluorescence intensity technique,the optical thermal resistance properties of Ca_(9)Mg_(1.5)(PO_4)_7:Eu^(2+)are identified based on the temperature dependent emission spectra in a range of 303-523 K.In detail,the maximum absolute and relative sensitivity S_(a)and S_(r)of Ca_9Mg_(1.5)(PO_(4))_(7):Eu^(2+)thermometer are as high as 0.637%/K and 0.3155 K^(-1),respectively.Consequently,the Eu^(2+)doped Ca_(9)Mg_(1.5)(PO_(4))_(7)phosphors establish a bifunctional platfo rm for both optical the rmometer and plant growth lighting via multi-site occupancies.

Towards sustainable plant factories with artificial lighting (PFALs) for achieving SDGs

The challenges and opportunities for developing sustainable plant factories with artificial lighting(PFALs)are discussed.After examining the production cost and productivity of existing PFALs in Japan,the possibility of introducing a relatively new concept and methodology for considerably improving productivity are discussed in relation to environmental controllability and resource use efficiencies.The fundamental and potential characteristics of ideal or next-generation PFALs(n-PFALs)are then discussed with some suggestions for actualizing n-PFALs.Finally,perspectives of the n-PFALs and technologies to be integrated into the n-PFALs are presented in relation to the Sustainable Development Goals(SDGs)to be achieved by 2030.

Arbuscular mycorrhizal symbiosis facilitates apricot seedling(Prunus sibirica L.)growth and photosynthesis in northwest China

Arbuscular mycorrhizal(AM)fungi can successfully enhance photosynthesis(P_(n))and plants growth in agricultural or grassland ecosystems.However,how the symbionts affect species restoration in sunlight-intensive areas remains largely unexplored.Therefore,this study’s objective was to assess the effect of AM fungi on apricot seedling physiology,within a specific time period,in northwest China.In 2010,an experimental field was established in Shaanxi Province,northwest China.The experimental treatments included two AM fungi inoculation levels(0 or 100 g of AM fungal inoculum per seedling),three shade levels(1900,1100,and 550µmol m^(−2) s^(−1)),and three ages(1,3,and 5 years)of transplantation.We examined growth,Pn,and morphological indicators of apricot(Prunus sibirica L.)seedling performances in 2011,2013,and 2015.The colonization rate in mycorrhizal seedlings with similar amounts of shade is higher than the corresponding controls.The mycorrhizal seedling biomass is significantly higher than the corresponding non-mycorrhizal seedling biomass.Generally,P_(n),stomatal conductance(G_(s)),transpiration rate(T_(r)),and water use efficiency are also significantly higher in the mycorrhizal seedlings.Moreover,mycorrhizal seedlings with light shade(LS)have the highest Pn.WUE is increased in non-mycorrhizal seedlings because of the reduction in T_(r),while T_(r) is increased in mycorrhizal seedlings with shade.There is a significant increase in the N,P,and K fractions detected in roots compared with shoots.This means that LS had apparent benefits for mycorrhizal seedlings.Our results also indicate that AM fungi,combined with LS,exert a positive effect on apricot behavior.

Genomic basis for light control of plant development

Light is one of the key environmental signals regulating plant growth and development.Therefore,understanding the mechanisms by which light controls plant development has long been of great interest to plant biologists.Traditional genetic and molecular approaches have successfully identified key regulatory factors in light signaling,but recent genomic studies have revealed massive reprogramming of plant transcriptomes by light,identified binding sites across the entire genome of several pivotal transcription factors in light signaling,and discovered the involvement of epigenetic regulation in light-regulated gene expression.This review summarizes the key genomic work conducted in the last decade which provides new insights into light control of plant development.

Circadian clock component, LHY, tells a plant when to respond photosynthetically to light in nature

The circadian clock is known to increase plant growth and fitness, and is thought to prepare plants for photosynthesis at dawn and dusk; whether this happens in nature was unknown. We transformed the native tobacco, Nicotiana attenuata to silence two core clock components, NaLHY （irLHY） and NaTOC1 （irTOC1）. We characterized growth and light- and dark-adapted photosynthetic rates （Ac） throughout a 24 h clay in empty vector-transformed （EV）, irLHY, and irTOC1 plants in the field, and in NaPhyA-and NaPhyB1-silenced plants in the glasshouse. The growth rates of irLHY plants were lower than those of EV plants in the field. While irLHY plants reduced Ac earlier at dusk, no differences between irLHY and EV plants were observed at dawn in the field, irLHY, but not EV plants, responded to light in the night by rapidly increasing Ac. Under controlled conditions, EV plants rapidly increased Ac in the day compared to dark-adapted plants at night; irLHY plants lost these time-dependent responses. The role of NaLHY in gating photosynthesis is independent of the light-depen- dent reactions and red light perceived by NaPhyA, but not NaPhyB1. In summary, the circadian clock allows plants not to respond photosynthetically to light at night by anticipating and gating red light-mediated in native tobacco.

THE PIGMENT-PROTEIN COMPLEXES OF HIGHER PLANTS MIGRATION IN THYLAKOID AND THE REGULATION OF LIGHT ENERGY DISTRIBUTION BETWEEN PHOTOSYSTEMS

Appressed and non-appressed lamella membranes of Castor bean leaf chloroplasts were separated by non-ionic detergent Triton-X 100.Appressed membranes showed a high oxygen-evolving activity and low chl a/b ratio. Examining with SDS-PTGE and liquid nitrogen temperature fluorescence measurement showed that they contained only PSII and light-harvesting pigment-protein complexes (LHCP),and there was no detectable amount of PSI. Freeze-fracture electromicroscopic observation confirmed that this part was really an appressed lamella membrane. Through divalent cation Mg^(++), the thylakoid membranes were induced to unstack and restack.With the addition of Mg^(++), the fluorescence intensity was changed instantly. We realized that there existed two processes:One was a rapid process which was accomplished within 30 s. The other was a slow process of which the time duration was about 60 min. This dual effects of Mg^(++) had not been reported before.We had analyzed the change of F685/F730 and discussed the possible rneehanis ms of light energy distribution between photosystems.

A novel Li^(+)-doped MgLuGaO_(4)phosphor with stable white-light emission and long persistent luminescence

In recent years,white persistent luminescence materials have received extensive attention due to the potential application of white light in the field of plant growth lighting.The white persistent luminescence materials synthesized by traditional methods either have strict requirements on the concentration of doped ions or cannot produce white light continuously and stably due to different decay rates of various emission centers,which limits their further application.In our work,we successfully synthesized a novel Li^(+)-doped MgLuGaO_(4)phosphor with stable white-light emission and long persistent luminescence.The broadband emission of MgLuGaO_(4):Li^(+)is mainly located at 350-650 nm,which has no change at different decay time,showing stable white-light emission.The persistent luminescence intensity is increased by 3.8 times and the persistent luminescence time is extended from 24 h to more than 36 h by doping Li+ions.Stable white-light and long persistent luminescence emission make it promising to be used in plant growth lighting.