Light distribution in Chinese solar greenhouse and its effect on plant growth

Chinese solar greenhouse (CSG) is universally applied in northern China for producing horticultural products. CSG is characterized by the unbalanced structures with an arched front roof face to the south side and a thick wall as well as back roof in the north side. Such structures affect light distribution in the greenhouse. This study aims to investigate the light distribution properties in CSG from north to south sections, and to investigate tomato plant growth performance in the corresponding locations. Experiments were carried out in a CSG which was divided into three equal sections from north to south side. Tomato was grown in the greenhouse. Results showed that PAR intensity in the south and middle sections of CSG was permanently higher than the north section. This resulted in a distinct plant growth performance in CSG. Specifically, plants grown in the north section of CSG exhibited a shade avoidance response with stem elongation phenotype and leaf expansion. Furthermore, the north-plants showed lower leaf photosynthetic capacity which correlated with a lower total nitrogen and chlorophyll contents in comparison with the plants grown in the middle and south sections. Taken together, plants in the north section of CSG produced less total biomass than the middle and south section plants. We conclude that plant growth is not uniform in CSG due to heterogeneous light distribution which was caused by unbalanced greenhouse structures. This study may provide sound evidence for exploring a proper lighting strategy as well as fine crop management in CSG.