西南玉米杂交种及其亲本自交系萌芽期抗旱性分析

Drought resistance of maize hybrids and their parent inbred lines during germination stage in southwestern China

  • 摘要: 【目的】研究干旱对热带亚热带玉米杂交种及其亲本自交系萌芽期农艺性状和生理生化指标的影响,为西南地区抗旱玉米自交系的种质利用和抗旱新品种选育提供参考。【方法】以桂单686(GML9616×ZNC442)、桂单689(GML1003×CML2020)和桂单662(桂A10341×GML906)及其亲本自交系为试验材料,采用20%聚乙二醇6000(PEG-6000)溶液模拟干旱胁迫,以等量灭菌蒸馏水处理为对照,分析干旱胁迫对玉米萌芽期主要农艺性状和生理生化指标的影响,通过抗旱系数、隶属函数法评价不同玉米品种及其亲本自交系的抗旱性差异,并通过杂种优势分析探明玉米杂交种与其亲本自交系抗旱性的关系。【结果】方差分析结果显示,各农艺性状和生理生化指标在处理间和材料间的差异均达极显著水平(P<0.01,下同),除胚芽长和胚芽干重外,其余指标间在处理与材料互作中的差异均达极显著水平。干旱胁迫整体上会导致玉米品种及其亲本自交系萌芽期的发芽势、发芽率、萌芽指数、胚根长、胚芽长、胚根干重、胚芽干重、贮藏物质转运率和超氧化物歧化酶(SOD)活性降低,丙二醛(MDA)、可溶性糖和可溶性蛋白含量及过氧化物酶(POD)和过氧化氢酶(CAT)活性增加。玉米萌芽期农艺性状指标和生理生化指标的变异系数范围分别为6.08%~34.05%和30.73%~64.65%,隶属函数评价权重系数之和分别为38.16%和61.84%。隶属函数评价结果显示,桂单689和桂A10341、GML9616、ZNC442、GML2020和GML1003的综合隶属函数D值在0.5~0.7,属于抗旱品种或自交系;桂单686和桂单662的D值在0.4~0.5,属于中等抗旱品种;GML906的D值小于0.4,属于弱抗旱自交系;未见D值大于0.7的强抗旱性品种或自交系。杂种优势分析结果显示,桂单686、桂单689和桂单662抗旱系数表现高亲优势的指标均较少,分别仅有1个、5个和5个。【结论】萌芽期干旱胁迫打破了玉米细胞内的氧化还原平衡,使膜脂过氧化加剧,阻碍物质生成,抑制生长活力,最终导致发芽能力下降,发芽势和发芽率降低。在西南玉米播期常遇干旱的地区,可选择种植抗旱性品种桂单689,以提高种子干旱适应能力;在抗旱玉米品种选育中,应重视西南热带亚热带种质如桂A10341、GML9616和ZNC442等的利用与改良,进一步创制抗旱性突出的新种质。同时,在育种实践中,玉米杂交种抗旱性杂种优势不能简单通过亲本抗旱性来预测。

     

    Abstract: 【Objective】To study the effects of drought on agronomic traits and physiological and biochemical indexes of tropical and subtropical maize hybrids and their parent inbred lines during germination stage,which could provide theoretical reference for the germplasm utilization of drought resistant maize inbred lines and breeding of drought resistant new varieties in southwestern China. 【Method】The study used maize hybrid varieties Guidan 686(GML9616×ZNC442),Guidan 689(GML1003×CML2020),Guidan 662(GuiA10341×GML906) and their parent inbred lines as experimental materials. 20% polyethylene glycol(PEG-6000)solution was used to simulate drought stress, with an equal amount of sterilized distilled water treatment as control, to analyze the effects of drought on the main agronomic traits and physiological and biochemical indexes during the germination stage. The drought resistance differences of different maize varieties and their parent inbred lines were evaluated by drought resistance coefficient and membership function method, and the relationship between drought resistance of maize hybrids and their parent inbred lines was explored through heterosis analysis. 【Result】The analysis of variance results showed that the differences in various agronomic traits and physiological and biochemical indexes between treatments and materials were extremely significant(P<0.01, the same below). Except for plumule length and plumule dry weight, the differences in other indexes between treatments and materials were extremely significant. Drought stress simulated by PEG solution led to a decrease in germination energy,germination rate,germination index,radicle length, plumule length,radicle dry weight, plumule dry weight,storage material transfer rate and superoxide dismutase(SOD) activity in maize varieties and their parent inbred lines. Meanwhile,malondialdehyde(MDA),soluble sugar and soluble protein content,peroxidase(POD) and catalase(CAT)activity increased. The coefficient of variation of agronomic traits and physiological and biochemical indexes during germination stage of maize ranged from 6.08% to 34.05% and 30.73% to 64.65% respectively,accounting for 38.16% and 61.84% of the total weight coefficient of membership function evaluation respectively. The evaluation results using the membership function method showed that the comprehensive membership function D values for Guidan 689 and Gui A10341,GML9616,ZNC442,GML2020 and GML1003 were 0.5-0.7,belonging to drought resistant varieties or inbred lines. The D values of Guidan 686 and Guidan 662 were 0.4-0.5,belonging to medium drought resistant varieties. The D value of GML906 was less than 0.4,belonging to the weak drought resistant inbred line. No strong drought resistant varieties or inbred lines with D values greater than 0.7 were found. The analysis of heterosis showed that the number of drought resistance coefficient indexes with high parent advantage for Guidan 686,Guidan 689 and Guidan 662 were only 1,5 and 5 respectively. 【Conclusion】Drought stress during germination stage disrupts the redox balance within maize cells,exacerbates lipid peroxidation of membranes,hinders the generation of substances,suppresses growth vitality,and ultimately leads to a decline in germination capacity,with reduced germination energy and germination rate. In southwestern region of China,where maize sowing often encounters drought,drought resistant varieties such as Guidan 689 can be selected for planting to improve the adaptability of seeds to drought. In the breeding of drought resistant maize varieties,attention should be paid to the utilization and improvement of southwestern tropical and subtropical germplasms such as Gui A10341,GML9616 and ZNC442,and further create new germplasms with outstanding drought resistance. Meanwhile,in breeding practice,the heterosis of drought resistance of maize hybrids can not be simply predicted based on the drought resistance of their parents.

     

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