Effects Of Cadmium Stress On Reactive Oxygen Metabolism In Wheat At Different Developemental Stages

In recent years, because of over-exploitation of mineralresources and excessive use of agrochemical, the soil's more and moresever pollution has became one of the important factor Influencingcontinuable agriculture and ecological environment, we studied theeffects of Cd²⁺ stress on reactive oxygen metabolism in wheat at differentdevelopemental stages, the capability of NO to act as antioxidant agentin wheat leaves undergoing oxidative stress caused by Cd²⁺ treatment andthe Effect of Chlamydomonas sajiao Lewin on the Seed Germination andGrowth of Wheat under Cd²⁺ stress.1. The effects of Cd²⁺ stress on reactive oxygen metabolism in wheatat different developemental stages. When wheat was treated with Cd²⁺ ofdifferent concentrations, the changes in enzymatic and non-enzymaticantioxidative system at jointing, heading, early filling and middlefilling stage was studied. The result showed that the level of O_2·^-,H₂O₂, MDA progressively increased and the increase rate at earlydevelopemental stages were significantly higher. The change inactioxidative enzymes and antioxidant were also unbalanced: fromjointing stage to heading stage, Enzymatic antioxidative system playedan important role on ROS scavenging because of the increase in SODactivity and stability in CAT activity; at filling stage, the activity of SOD and CAT evidently decreased respect to the controls, but theactivity of APX and GR, content of AsA and GSH were stabe aftersignificant decrease. These results indicated, the mechanism ofantioxidative system in wheat was diverse at different developemetalstages. Cd²⁺stress can induce the increase of ROS content, cause oxidativestress, accelerate the floral consenescence, seriously impair yield andquality of wheat. Furthermore, wheat can adapt and tolerate the damageunder Cd²⁺stress, and this ability grew stronger and stronger along withthe deveopemental process.2. The capability of NO to act as antioxidant agent in wheat leavesundergoing oxidative stress caused by Cd²⁺ treatment. Spraying twice ofAsA and NANO₂ as miscible liquids, a NO donor, at 0.1mmol/L once 12hours, the changes in antioxidative system at jointing, heading, earlyfilling and middle filling stage was studied under Cd²⁺ treatment. Theresult showed that, during four developmental stages, the NO canenhance the activity of SOD, CAT and APX induced by Cd²⁺ stress, the levelof O_2·^-, H₂O₂, MDA progressively increased and restored to the levels inthe control. It is postulated that NO can alleviate Cd²⁺-induced oxidativestress, strength the adaptability.3. The Effect of Chlamydomonas sajiao Lewin on the Seed Germinationand Growth of Wheat under Cd²⁺stress. Presoaking wheat seed with img/L,10mg/L, 100mg/Lçš„Cd²⁺ solution, The effects of Germination percentage,germination potential, germination index, simple vigorous indexes ofwheat were studied. The results showed that Cd²⁺ stress can inhibiteGermination percentage, germination potential, germination index, simplevigorous indexes of wheat, and with the increase of Cd²⁺ concentration, theinhibiting effect is enforced. Cd2+with different concentrations allcan inhibit the growth of buds and roots significantly ,and has strongerinhibition on root than on bud. Adding different concention ofChlamydomonas sajiao Lewin to Cd²⁺ The results showed that Chlamydomonassajiao Lewin can stimulate Germination percentage, germination potential, germination index, simple vigorous indexes of wheat and the length ofroot,bud.