Effects Of Low Temperature And Acid Rain Combined Stress On Seedling Growth Of Forage Rice

Zhuliangyou 819 has high yield,high protein content and high roughness,which meets the requirements of "three high" feed rice variety.It is widely promoted in Hunan Province as the main feed rice varieties.In the south of China,the phenomenon of "cold spell in spring" often occurs,when the temperature decreases with continuous rain.Hunan is a major rice producing province in China,but the acidification of rainwater greatly affects the growth,yield and quality of the feed rice.In this study,rice pot experiment was carried out in the temperature-controlled plant growth room of rice plant of Hunan Agricultural University.The effects of combined stress of low temperature and acid rain on the growth traits,photosynthetic characteristics and antioxidant system of Zhuliangyou 819 were studied by spraying simulated acid solution with different acidity at different temperatures(Note: CK is sprayed water at 25 °C,C1 is a simulated acid solution sprayed pH4.5 at 25 °C,C2 is a simulated acid solution sprayed pH3.5 at 25 °C,C3 is sprayed water at 10 °C,and C4 is a simulated acid solution sprayed pH4.5 at 10 °C,Simulated acid solution of pH3.5 sprayed at 10 °C by C5).The effects of low temperature and acid rain on the growth traits,photosynthetic characteristics and antioxidant system of Zhuliangyou 819 were also discussed.The paper also explores the physiological mechanism of low temperature and acid rain affecting the growth of forage rice,which provides reference for the application and popularization of forage rice in Hunan.The results of the experiments are as follows:(1)The treatment period No.5d,compared with the control(CK),the seedling height,the fresh weight in the upper ground,the fresh weight in the underground,the dry weight in the upper ground,and the dry weight in the underground were all reduced,followed by CK > C1 > C2 > C3 > C4 > C5;During the recovery period,No.5d,the seedlings under the combined stress of low temperature and low temperature acid rain died,C1 and C2 were all less than CK,followed by CK > C1 > C2.(2)Processing period 5d,compared with control(CK),each processing FO,Ci rise,followed by C5 > C4 > C3 > C2 > C1 > CK,Chlorophyll,Fm,Fv/Fm,Fv/FO,Pn,Cond,and Tr are reduced,followed by CK > C1 > C2 > C3 > C4 > C5.Recovery period 5d,the seedlings under the combined stress of low temperature and low temperature acid rain died,C1,C2 parameters change with treatment period 5d.(3)Treatment period 5d,compared with control(CK),the content of seedlings ’leaves and roots MDA increased,followed by C5 > C4 > C3 > C2 > C1 > CK.In the single acid rain treatment,the content of SOD and POD in the leaves and roots of seedlings increased,followed by C2 > C1 > CK.The content of SOD and POD in leaves and roots of seedling decreased after single low temperature treatment.Under the low temperature acid rain compound stress,compared with C3,the content of SOD and POD in leaves and roots of seedlings increased,followed by C5 > C4 > C3.During the recovery period,No.5d,the seedlings under combined stress of low temperature and low temperature acid rain died,SOD,POD,MDA rose,followed by C2 > C1 > CK.In conclusion,low temperature and acid rain can inhibit photosynthesis of forage rice and greatly affect the antioxidant effect of plant leaves and roots,resulting in irreversible damage to seedlings,thus affecting the growth and development of rice seedlings.What’s more,the effect of low temperature on forage rice is greater than that of acid rain on forage rice,the combined stress of low temperature and acid rain at pH 3.5 caused the most serious damage to the growth of forage rice seedlings.Continuous stress of low temperature or low temperature combined with acid rain would cause more serious impact on seedlings and even cause seedlings to die.