In order to explore the photosynthetic physiological differences of oat ear organs and flag leaves under drought stress， a pot experiment was conducted using Avena sativa L.‘Kona’ as the experimental material. Drought stress was initiated after the first flower bloomed. Chlorophyll contents， photosynthetic enzyme activities， soluble sugar and starch contents in flag leaves and ear organs were measured at 0， 7 and 14 days after drought stress treatment. The results showed that the chlorophyll content in the glumes was higher than that of the flag leaves， while the chlorophyll content of the lemmas was lower. Drought stress significantly reduced the enzyme activities of Rubisco， PEPC， and PEPCK in the flag leaves， while it had no significant influence on the activities of Rubisco in glumes and PEPCK， NADP-ME， NAD-ME activities in both ear organs. In addition， the activities of Rubisco， PEPC and PEPCK in the glumes were significantly higher than those in the flag leaves. Drought stress significantly increased the soluble sugar and starch contents in the flag leaves， while had no significant influence on sugar contents in both ear organs. To sum up， the flag leaves of ‘Kona’ oats responded more sensitively to drought stress， while the ear organs， especially the glumes， maintained better stability.

Oat  /  Ear Organs  /  Drought stress  /  Photosynthetic physiology  /  Sugar content