Effects of drought stress on soybean stomatal characteristics and photosynthetic parameter.

The effects of different degrees water stress on soybean stomatal and photosynthetic characteristics were investigated based on watering experimentation in self-made pot.The results showed that with the increasing of water stress intensity,soybean stomatal length,width,perimeter,and area all decreased,while the stomatal density showed an increasing trend.Under slight water stress,the average daily value of soybean leaf blade Pn was higher,while under sufficient irrigation,its Fv/Fm value was higher.There were no significant differences between chlorophyll contents by different water stress treatment.Under different water stress,no significant correlationship was found between the net photosynthetic rate and stomatal conductivity.While there was no significant correlationship between stomatal conductivity and single stomatal characteristics,indicating that the stomatal conductivity was one of the factors limiting soybean photosynthetic ability.In this experiment,the optimum soil relative moisture content was 60%~65%.The falling of photosynthesis rate is brought by stomatal limitation.When soil relative moisture content is below 60%,the non-stomatal limitation emerged.When the relative soil moisture content was 35%~40%,the non-stomatal limitation gradually became a dominant factor in declining soybean leaf blade photosynthesis ability,which could lead to harm of photosynthesis organ.