One-year-old Robinia pseudoacacia saplings were subjected to 70% of field capacity (control) and progressive drought stress (treatment) to study the effects of drought stress on non-structural carbohydrates (NSCs) of R. pseudoacacia saplings at the end of the growing season. While leaf biomass

stomatal conductance and net photosynthetic rates of saplings under control generally exhibited no significant differences throughout the experiment (P＜0.05)

those under treatment decreased with the intensification of drought stress (P＜0.01). Soluble sugar concentrations and the ratios of soluble sugars to starch in different tissues under treatment all increased with drought progression

but were significantly higher than those under control (P＜0.05). Contrarily

starch and NSC concentrations in each tissue under treatment all decreased with drought progression (P＜0.05). Except NSC in leaves and fine roots

starch and NSC concentrations under treatment were all lower than those under control (P＜0.05). NSC concentrations in branches

stems and coarse roots were 96.6%

70.5%

and 78.2% of those under control

respectively. At the whole sapling level

NSC concentrations under treatment decreased throughout the experiment

and were significantly lower than those under control (P＜0.05)

and were 84.0%

79.0%

76.3% and 67.5% of those under control on the 6th

9th

12th and 15th days

respectively. Soluble sugar

starch and NSC concentrations and the ratios of soluble sugars to starch in different sapling tissues

except NSC concentrations in branches and fine roots

and NSC concentrations at the whole sapling level were all significantly correlated with soil water content

leaf biomass

stomatal conductance and net photosynthetic rates. Our results suggested that the premature defoliation and decrease of photosynthetic rate of R. pseudoacacia saplings resulted from drought stress at the end of the growing season could facilitate the transformation of starch to soluble sugars and then decrease the accumulation of starch

as a result

would induce the premature consuming of NSC

which would mainly occur to stems and coarse roots.