In order to clarify the regulation effect of humic acid (HA) on the photosynthetic characteristics of oat leaves under drought stress,the oat variety Yanke 2 was used as the experimental material,and the pot water was used to set normal water supply (75% field water holding capacity) and moderate drought stress (60% field water holding capacity and severe drought stress (45% field water holding capacity). HA and equal water (CK) were sprayed under three water conditions. Changes in photosynthetic pigment content,photosynthetic characteristics,dry matter accumulation and yield of oat leaves were analyzed. The results showed that with the decrease of soil moisture,chlorophyll a content,chlorophyll b content,carotenoid content,photosynthetic rate,stomatal conductance,the transpiration rate,intercellular CO2 concentration,dry matter accumulation,yield and its components all showed a downward trend. The differences of index values between normal water supply conditions and spraying HA under drought stress was not significant. Under drought stress,compared with CK,the indices increased after spraying HA,and the increase was significant under severe drought stress. This indicates that spraying HA under drought stress improved the photosynthetic performance of oat leaves,promoted dry matter accumulation and increased yield,with a most obvious effect under severe drought stress. |