Seed germination and seedling growth of invasive weed Ipomoea cairica under drought stress.

Ipomoea cairica is an invasive weed that is seriously harmful for natural ecosystem,agriculture and forestry in Eastern Guangdong.Some indexes such as seed germination ratio,seed germination index,chlorophyll relative content,water potential,biomass and activity of antioxidant enzyme,etc.were determined and compared by treating with PEG-6000,and the effects of drought stress on seed germination and seedling growth were studied,which will be able to provide some informations for research of I.cairica drought resistance mechanism.The results showed that initial germination time of I.cairica seeds was delayed with increasing drought stress degree,germination ratio and germination index significant also reduced.The seeds can not germinate absolutely along with rotten phenomenon at severe drought stress(30% PEG-6000).The chlorophyll relative content,biomass and water potential were much lower than that of control groups,and root/shoot ratio was much higher than that of control group.The activity of SOD and content of MDA continuously ascended,CAT was continued to decline,and POD was steady without change at light drought stress(0~10% PEG-6000),increased at moderate drought stress(10%~20% PEG-6000),and declined at severe drought stress(20%~30% PEG-6000).The research found that drought stress could inhibit I.cairica seed germination and seedling growth to a certain extent.At the same time,I.cairica can active adapt to drought stress environment by changing some biological and physiological indexes.