Study On Screening Of Drought Resistant Maize And Drought Resistant Mechanism

In this paper, we study the growth,development physiological and biochemical characteristics of 38 types maize under drought stress at the seedling stage, analysis the drought resistance of 38 types by fuzzy administering function and principal component analysis. Preliminary screening three different types of drought resistance,then screen two types of highly resistant varieties, two types of non-resistant varieties, one of medium resistant varieties in all of this.Drought them in different level and study the impact of drought on different drought resistence maize growth and development,Photosynthetic physiological characteristics,phytohormone and hardiness physiological characteristics to analysis the mechanisms of drought resistance. The main conclusions are as follows:1. Analysis the drought resistance of 38 types by fuzzy administering function and principal component analysis, divided the 38 types of maize to three levels by their drought resistance from weight to weak. Highly resistant varieties:Chuandan428,Zhenghong311,Beiyu16,Lianyu15,Chendan30,Miandan12,Nonghua7,Kemao918; Medium resistant varieties:Chuandan418,Guoyu518,ZH532,Miandan8,Gaoyu79,Luyu13,Zhenghong102,Shanchuan907,Zhengxing3,Nongda95,Dongdan88,Zhongjin368,Zhenghong212,Shudan2,Zhenghong6,Shenlongyu3,Denghai11,Longdan9,Yongfeng16,Zhenghong505,Chendanqinkel,Qianbei2,Non-resistant varieties:Yayu2,Haihel,Pudan6,Changyul9,Longdan8,Chuandanl3,Xuyu4188,Aoyu28. By principal component analysis, in the seven evaluation indexs of drouht-resistence, the plant length,leaf area,DMA,relative water content,and MDA have more contribution rate and the five of its are the most important evaluation indexs of drouht-resistence.2. Analysis of the mechanisms of drought resistance declared:compare with the contrast,the plant length, root length and leaf area of each type was declined, the growth of plant fresh weight and dry matter weight also inhibited. And the inhibition degree was increased by the drought stress level, the inhibition degree of Highly resistant varieties was lower.3. Under drought stress, the Highly resistant varieties has higher relative water content, lower MDA and relative electric conductivity, this shows that the highly resistant varieties can maintain better water physiology environments, and the damage of their membrane system by drought was lower. With the time of drought stress, POD activity and SOD activity performance a trend of increasing, the Proline content firstly increasing and then decreasing, the soluble sugar was increasing.The SOD activity,POD activity,Proline content and soluble sugar of Zheng hong 311 and Cheng dan 30 was higher than other types. This shows that the highly resistant varieties have higher enzymatic scavenging activity and osmotic adjustment ability, and that's of non-resistant varieties was lower, because it's enzymatic scavenging activity was weak, and the damage of membrane system was greater, the osmotic adjustment ability was weaker4.With the level of drought stress increased, the ABA content and IAA content have increasing trend, the ZR content firstly increasing and then decreasing, the GA content has decreasing trend. The Physiological processes adjusting ability of endogenous hormones in highly resistant varieties were higher than that of non-resistant varieties.5. In drought stress, the Chlorophyll a and Chlorophyll a/b in maize leaf was decreased, Chlorophyll b firstly increased and then decreased, the decline of Chlorophyll a content was bigger than Chlorophyll b, this suggests that the damage of Chlorophyll a by drought is more serious than Chlorophyll b. The relative quickly damage of Chlorophyll a and decrease of Chlorophyll a/b can cause the ratio of reaction center pigments and light pigment imbalanced, which lead the decreasing of photosynthetic rate. The general Chlorophyll content in highly resistant varieties was higher than that of non-resistant varieties.With the level of drought stress increased, the Pn,Gs,Ci,Tr in maize have decreasing trend. Compared to non-resistant varieties, the highly resistant varieties have higher Gs,Ci,Tr which made these types maintain higher photosynthetic rate and accumulate more organics.