Effects of Drought Stress on Photosynthesis and Yield of Ramie

Ramie Chuanzhu 11 was planted in pots which were set 4 treatments(namely well-watered,mild-watered,moderate and severe drought stress) for 20 days in a rain-proof green-house,then photosynthesis and yield were analyzed.The results showed that drought stress led to a prominent drop in net photosynthetic rate(Pn),stomatal conductance(Gs) and transpiration rate(Tr).The severer the drought stress was,the quicker reduction of the three indexes was.However,drought stress led to a prominent increase in instantaneous water use efficiency(WUEi) and stomatal limits(Ls),both WUEi and Ls enhanced under mild and moderate drought stress,but subsequently dropped under severe drought stress.The observed gradually change in Pn,indicated that mild drought and moderate drought caused stomatal inhibition while severe drought caused non-stomatal inhibition.In addition,decreased photosynthetic activity inhibited the growth of plants and led to a noticeable decline of the stripped bast percentage and fiber yield.Nonetheless,ramie could withstand mild drought stress.In summary,drought stress decreased photosynthetic rate,growth and yield of ramie,and the extent of these variations was closely related with the intensity of the drought stress.Therefore,when the field soil is under a moderate drought condition,mitigation measures must be timely taken in order to ensure the normal growth of the plants.