Abstract:

The effect of colored plastic films on the photosynthetic characteristics and yield of spring
Chinese cabbage（Brassica campestris L. ssp. pekinensis）in plastic greenhouse were studied，with‘Jujin’
as material，and colorless plastic film as the control. The results showed that the purple film and red film
increased the air temperature，whereas reduces the humidity under the same photon flux density. Conversely，blue film and green film decreased the air temperature，but increased humidity. The daily
photosynthetic rate（Pn）of spring Chinese cabbage cultivated in plastic greenhouse varied in a single peak
curve. The Pn of purple film and red film plants were significantly higher than that of the control plants，
but no differences were observed in blue film，green film and the control plants. The light saturation point
（LSP）of Chinese cabbage were 1 133.4–1 217.5 μmol · m-2 · s-1，both significantly higher in purple film
and red film than in the control. No differences were found in light compensation point（LCP），apparent
quantum yield（AQY），CO2 compensation point and saturation point among different treatments. However，
the carboxylation efficiency（CE）of purple film was higher，while that of green film was lower，compared
with the control. During sunny days，the noticeable reduction in photorespiration（Pr），but the marked
enhancement in efficiency for solar energy utilization（LUE）were observed in red film and purple film
plants，compared to control plants. The red film and purple film treatments showed higher，while the green
film treatment revealed lower activities of ribulose-1,5-bisphosphate carboxylase（RuBCase），fructose-
1,6-bisphosphatase（FBPase），sedoheptulose-1,7-bisphosphatase（SBPase）and transketolase（TK）than
those of the control. The growth was higher in purple film and red film plants，lower in green film plants
than in the control plants，but no difference was observed between blue film and the control plants. In
comparison with the control，the economics yield of purple film and red film increased by 15.1% and 7.8%
respectively，but that of blue film and green film decreased by 6.4% and 15.5%. These data suggest that
purple film and red film increase the LUE and photosynthetic carbon assimilation，consequently facilitate
the growth and the yield of Chinese cabbage，however the green film showed the opposite result.

Key words: Chinese cabbage, colored plastic film, light quality, photosynthetic characteristic, yield