Studies On The Effects Of Drought On The Photosynthesis And Cold Tolerance In Common Wild Rice (Oryza Rufipogon Griff)

The photosynthetic gas exchange parameters, chlorophyll fluorescence parameters, and photosynthetic pigment contents of common wild rice were measured after drought using cultivated rice as control, and the relative electronic conductivity and the photosynthetic parameters of common wild rice accessions, which were treated by drought, were also measured after cold in order to investigate the effects of drought on photosynthesis and cold tolerance in common wild rice, and then to provide theoretical support for their application. Preliminary results are as follows:1) After drought treatment, the net photosynthetic rate of Dongxiang wild rice was not significantly changed, while that of Hepu wild rice, Hainan wild rice and Zhonghua 11 (cultivated rice variety as control) was decreased significantly by 24.3%～27.3%. After drought treatment, the apparent quantum yield of Hainan wild rice was significantly decreased, however, that of other materials was not changed significantly. After drought treatment, the carboxylation efficiency of the 3 common wild rice was not obviously changed, but that of Zhonghua 11 was significantly decreased. After drought treatment, the stomatal conductance of all materials decreased significantly.2) The total chlorophyll content of 3 common wild rice (CWR) after drought treatment was not obviously changed compared to that of CWR without drought, but the aboved pigment decreased obviously in Zhonghua 11 after drought. There was no significant difference in carotenoid content in all materials.3) After drought treatment, photochemical efficiency (PhiPS2) and electron transfer rate (ETR) did not change significantly in Hepu wild rice and Hainan wild rice,but decreased significantly in Dongxiang wild rice and Zhonghua 11. There are no significant changes of other chlorophyll fluorescence parameters for all materials.4) After drought pretreatment+natural low temperature stress, the leaf color of Hainan wild rice, Zhonghua 11 and Brazil upland rice were significantly green than that without the drought pretreatment of the same material (control), the leaf rolling degree is slighter than that of the control. However, there was no significant difference of the leaf color and leaf rolling degree in Dongxiang wild rice, Chaling wild rice, Liujiang wild rice and Hepu wild rice compared with the control.5) After drought pretreatment+natural low temperature stress, except for Hepu wild rice, chlorophyll content and carotenoid content of the remaining 4 wild rice and 2 cultivated rice were all higher than those of the control, especially Hainan wild rice and Zhonghua 11.6) After drought pretreatment+natural low temperature stress, Except for Dongxiang wild rice and Chaling wild rice, the relative electrical conductivity of the other 4 materials were significantly lower than that of the control.7) After drought pretreatment+natural low temperature stress, The gas exchange parameters of Maximum photosynthetic rate (Amax), stomatal conductance (Cond), apparent quantum yield (AQY) and the efficiency of carboxylic acid (CE) in Hainan wild rice, Zhonghua 11and Brazil upland rice were higher than those of the control, but those of the other materials were not significantly changed.8) After drought pretreatment+natural low temperature stress, the chlorophyll fluorescence parameters of Fv’/Fm’, PhiPS2, ETR, photochemical quenching destroy (qP) in Hainan wild rice, Zhonghua 11 and Brazil upland rice were higher than that of the control, however, the other materials were not significantly changed compared with the control.The aboved preliminary results suggest that:① the affection of drought on photosynthesis of Dongxiang wild rice was smller than that of cultivated rice Zhonghua 11, Hainan CWR and Hepu CWR, and the affection of drought on photosynthetic pigment content and carboxylation efficiency of common wild rice were smaller than that of Zhonghua 11. ② Drought pretreatment significantly enhanced cold tolerance in Zhonghua 11, Brazil upland rice and Hainan wild rice,while the effects of the other tested wild rice materials are not obvious under low temperature stress in this study, it may be of their strong cold tolerance.