Effects of shading on the growth, photosynthetic characteristics and nutrient content of Aglaonema commutatum

The objective of this study was to investigate the effects of different shading treatments, CK (no shading), T₁ (25% shading), and T₂ (50% shading), on the growth, photosynthetic characteristics, chlorophyll fluorescence parameters, and nutrient accumulation of Aglaonema commutatum variety “Butterfly”. Therefore, screening suitable light environment conditions for the growth of “Butterfly” and clarifying its mechanisms of adaptation in response to different light regimes from the perspective of photosynthetic physiology can provide a theoretical basis for the efficient cultivation of “Butterfly”. The results showed that 1) with the increase of shading, the biomass of roots and shoots, root length, root surface area, total root volume, and average root diameter all displayed a first increasing then decreasing tendency, and reached their maximum at T1 treatment. 2) shading significantly promoted the accumulation of photosynthetic pigments in the leaves of “Butterfly” compared to CK, while no significant differences were observed for chlorophyll a/b among different treatments. 3) shading treatments significantly increased the maximum net photosynthetic rate P_n and decreased the dark respiration rate. Moreover, the apparent quantum yield in the T₁ treatment was significantly higher, and the light compensation point was significantly lower than that in CK. The opposite tendencies were observed in the T₂ treatment. These results suggested that proper shading can enhance the utilization capacity of leaves under low light conditions by increasing photosynthetic rate and reducing respiration consumption, which in turn promoted the accumulation of carbon assimilation products, and ultimately maintain the normal growth of plants. 4) With the increase of shading, initial fluorescence (F_o) decreased significantly, while PSⅡ maximal photochemical efficiency (F_v/F_m) and non-photochemical quenching coefficient increased, and the values of maximal fluorescence (F_m), variable fluorescence (F_v), PSⅡpotential efficiency (F_v/F_o), photochemical quenching coefficient, and actual maximum quantum yield all displayed first increasing then decreasing tendencies and arrived at their maximum with T₁ treatment. 5) T₁ treatment significantly promoted the translocation of Mg and K from roots to shoots, which in turn increased the contents of Mg and K in aboveground compared to CK. The opposite was also true for Ca; thus, Ca accumulation in shoots significantly decreased when compared with CK. Taken together, T₁ treatment (25% shading) is a more suitable light condition for the growth of “Butterfly”. Based on the above analysis, we suggested that 25% shading was conducive to the growth of “Butterfly”, which may be attributed to the promotion of maximum net photosynthetic rate, apparent quantum efficiency, PSⅡ photochemical efficiency and electron transfer rate.