The effects of shade on the growth, leaf photosynthetic characteristics, and chlorophyll (Chl) fluorescence parameters of Lycoris radiata var. radiata were determined under differing irradiances (15, 65, and 100% of full irradiance) within pots. The HI plants exhibited a typical decline in net photosynthetic rate (P N ) during midday, which was not observed in MI-and LI plants. This indicated a possible photoinhibition in HI plants as the ratio of variable to maximum fluorescence (F v /F m ) value was higher and the minimal fluorescence (F 0 ) was lower in the , and LI plants. Diurnal patterns of stomatal conductance (g s ) and transpiration rate (E) were remarkably similar to those of P N at each shade treatments, and the intercellular CO 2 concentration (C i ) had the opposite change trend. Under both shading conditions, the light saturation point, light compensation point and photon-saturated photosynthetic rate (P max ) became lower than those under full sunlight, and it was the opposite for the apparent quantum yield (AQY). The higher the level of shade, the lower the integrated daytime carbon gain, stomatal and epidermis cell densities, specific leaf mass (SLM), bulb mass ratio (BMR), leaf thickness, and Chl a/b ratio. In contrast, contents of Chls per dry mass (DM), leaf area ratio (LAR), leaf mass ratio (LMR), leaf length, leaf area and total leaf area per plant increased under the same shade levels to promote photon absorption and to compensate for the lower radiant energy. Therefore, when the integrated daytime carbon gain, leaf area and total leaf area per plant, which are the main factors determining the productivity of L. radiata var. radiata plant, were taken into account together, this species may be cultivated at about 60~70% of ambient irradiance to promote its growth.

The diurnal trends of gas exchange and chlorophyll fluorescence parameters in four Lycoris species (L. houdyshelii, L. aurea, L. radiata var. pumila and L. albiflora) were determined and compared with a portable photosynthesis analysis system. Our study revealed that L. houdyshelii had the lowest light compensation point (LCP), while the other three species had higher LCP (12.37-14.99 μmol m -2 s -1 ); L. aurea had the highest light saturation point (LSP) (1,189 μmol m -2 s -1 ), and L. houdyshelii and L. albiflora had lower LSP with the values being 322 and 345 μmol m -2 s -1 , respectively, and L. radiata var. pumila showed the intermediate LSP. Both the species L. houdyshelii and L. albiflora exhibited a typical and obvious decline in net photosynthetic rate (P N ) during midday, which was not observed in L. aurea. This indicated a possible photoinhibition in L. houdyshelii and L. albiflora as the ratio of variable to maximum fluorescence (F v /F m ) values were higher in these two species. The minimal fluorescence (F 0 ) values were lower in L. aurea and L. radiata var. pumila. The diurnal changes of transpiration rate (E) in all four species presented only one peak, appearing between 11:00 h or 13:00 h. By using simple correlation analyses, it was observed that the environmental factors affecting P N were different among four species and the main factors were photosynthetic photon flux density (PPFD) and relative humidity especially for L. aurea and L. radiata. The results of studying indicated that the four species could be divided into two groups. The species L. radiata var. pumila and L. aurea were more adapted to a relatively high irradiance, and L. houdyshelii and L. albiflora could be grown in moderate-shade environment in order to scale up their growth and productivity. Abbreviations: AQY -apparent quantum yield; C i -intercellular CO 2 concentration; Chl -chlorophyll; E -transpiration rate; F 0 -minimal fluorescence of dark adapted state; F v /F m -ratio of variable to maximum fluorescence; g s -stomatal conductance for CO 2 ; LCP -light compensation point; LSP -light saturation point; P max -photon-saturated photosynthetic rate; P N -net photosynthetic rate; PPFD -photosynthetic photon flux density; T air -air temperature.

Growth, photosynthetic characteristics, chlorophyll (Chl) fluorescence parameters, and peroxidation of membrane lipid of Cryptotaenia japonica were studied under differing irradiances (15, 35, 60, and 100 % of full irradiance). At full irradiance, C. japonica exhibited a typical decline in net photosynthetic rate (P N ) at midday, which was not observed in the other irradiance treatments. This indicates a possible photoinhibition for C. japonica at the high irradiance. Diurnal patterns of stomatal conductance (g s ) were remarkably similar to those of P N in each irradiance treatment, and the intercellular CO 2 concentration (c i ) had the opposite trend. C. japonica growing under 60 % of the full irradiance exhibited the highest plant height, stem diameter, leaf area, and biomass. The initial fluorescence (F 0 ) value was lowest at 60 % of the full irradiance. Maximal fluorescence (F m ), potential activity of photosystem II (PS II) (F v /F 0 ), and maximal photochemical efficiency of PS II (F v /F m ) values were highest at 60 % of full irradiance and lowest at 15 % of the full irradiance. The malondialdehyde (MDA) content in 15 % and 100 % of the full irradiance were higher than under the other irradiances. During the treatment, catalase, peroxidase, and superoxide dismutase activities firstly increased and then declined under 15 % and 100 % of the full irradiance and were steadily low under 60 % of the full irradiance, indicating a low production of reactive oxygen species. Therefore, C. japonica thrived best under 60 % of the full irradiance.