[Effects of low light on photosynthetic characteristics of tomato at different growth stages]

Taking low light tolerance tomato strains 02S02 and 02S32 and sensitive strains 02S52 and 02S57 as test objects, this paper studied their leaf photosynthetic characteristics at seedling stage, flowering-fruit-setting stage, and fruit-inflating stage under effects of low light. The experiment was carried out in a low light environment, a plastic tunnel covered with black shading nets, with the light intensity being about 50% of that in normal plastic tunnel (average light intensity 800 micromol x m(-2) x s(-1) at sunny morning 9:00-11:00). For the four test tomato strains, their leaf photosynthetic rate in low light environment had a slight increase, but decreased greatly when the light intensity increased, with the change trends being similar but the change degree differed with strains and growth stages. The light compensation point and dark respiration rate decreased gradually with plant growth, and the decrement was larger for low light tolerance strains than for sensitive strains. The light saturation point, maximum photosynthetic rate, and apparent quantum yield decreased at all the growth stages, but the decrements differed with growth stages and were not consistent with the low light tolerability of test strains.