【作者】 孙琦；

【导师】 张世煌；

【作者基本信息】 中国农业科学院 ， 作物遗传育种， 2012， 博士

【摘要】 玉米（Zea mays L.）是中国第一大粮食作物，也可用于饲料、工业原料与再生能源，在国民经济中占有重要地位。近几年由于干旱频繁发生，病虫害日益加重，严重威胁了玉米生产。因此需要设定新的育种目标及方案改善玉米的抗病虫能力，适应恶劣环境的能力。以美国为代表的玉米种业发达国家的经验表明，对推广品种的回顾性研究可以为进一步开发新品种遗传产量潜力以及提高产量能力提供有益的依据和指导。因此，本研究试图通过对我国玉米主产区1950-2000年间主要推广品种的耐旱与抗病鉴定试验，探讨：（1）主推玉米品种耐旱性的变化趋势。（2）主推玉米品种在干旱与正常浇水条件下产量、农艺性状及其杂种优势效应的变化趋势。（3）主推玉米品种抗病性的演变趋势。探索今后进一步提高产量潜力的育种策略，为高产育种实践提供理论依据。本研究所采用的试验材料均为玉米主产区大面积推广的品种，包括1950年代的农家种，1960年代的双交种以及1970-2000年代的单交种共35个。2010年在旱棚内进行苗期耐旱鉴定试验。2010-2011年在新疆和海南进行开花期耐旱鉴定试验。2010年在北京、济宁、吉林等地开展病害鉴定试验。通过以上试验，主要结果结论如下：1、主推玉米品种的苗期耐旱性随年代的变化趋势缓慢下降,其中20世纪50到60年代快速提高,60年代以后呈下降趋势。70年代以来的单交种苗期耐旱性随年份变化是呈下降趋势。70年代以来的27个单交种可分为3类,耐旱性强的杂交种为鲁单50、群单105、农大108、掖单13、掖单4号、郑单2号;耐旱性弱的杂交种为农大3138、农大60、沈单16;其余为中间类型。今后育种工作的重点之一就是在自交系选育中加大苗期水分胁迫，进而为培育耐旱杂交种奠定基础。2、干旱条件下，主推玉米品种产量较灌溉条件下降。在灌溉与干旱条件下，我国玉米主推品种的产量与年代呈线性上升趋势。在海南试验点的灌溉条件下产量的遗传增益为85.8Kg.ha^-10.year^-1（R²=0.96），干旱条件下的遗传增益为53.88Kg.ha^-1.year^-1（R²=0.94）。在新疆试验点，灌溉条件下产量遗传增益为94.3Kg.ha^-1.year^-1（R²=0.97），干旱条件下的遗传增益为61Kg.ha-.1year^-1（R²=0.99）。在水浇条件下产量的遗传增益高于干旱条件。主推玉米品种的耐旱系数随着年代更替而下降，即我国玉米主推品种的耐旱性呈下降趋势。虽然玉米育种家一直比较重视品种的耐旱性，但是在干旱严重的情况下，主推玉米品种的耐旱性呈现下降趋势。因此在今后自交系选育与杂交种比较试验中应当加大干旱胁迫的选择压力，才能进一步提高品种的耐旱性。在干旱条件下，1950-2000年代农家种及骨干杂交种被改良的植株性状为，ASI，叶夹角、雄穗分枝数、空秆率、最大绿叶数。光合速率和叶片卷曲度没有得到改良。被改良的穗部性状为穗长、穗粗、穗粒数、百粒重、秃尖长。出籽率没有改良。耐旱性上升的主要植株性状为株高、穗位高、最大绿叶数，叶夹角与空秆率的耐旱性在下降。干旱条件下ASI、雄穗大小、光合速率与产量的相关性较高。因此得出，我国主推玉米品种的大部分农艺性状都得到了改良，但要提高品种的耐旱性需要继续提高干旱条件下的光合速率，减小雄穗，减少空秆率，减小秃尖，提高出籽率等方面的工作，选择叶片卷曲的基因型。3、亲本自交系的产量均随着年代而直线上升。大体趋势是1960-1980年代自交系产量迅速升高，1990年代下降，2000年代又有所回升。亲本自交系的耐旱系数随着年代更替呈上升趋势，2000年代出现下降。这说明我国骨干自交系的耐旱性在逐渐提高，但近十年出现倒退。今后需要拓宽种质基础，加大自交系选育中干旱的选择压力，进一步提高自交系的耐旱性。干旱条件下，亲本自交系被改良的植株性状为ASI、株高与穗位、雄穗分支数、叶夹角、空秆率、最大绿叶数。果穗性状都得到了改良。主要农艺性状的耐旱性上升的为株高、空秆率、穗长、穗粗、穗粒数，下降的为穗位高、百粒重。因此得出，玉米骨干自交系大部分农艺性状的耐旱性得到了很好的改良，下一步要加强干旱条件下百粒重的改良。4、干旱条件下的绝对杂种优势低于灌溉条件。这说明干旱引起杂交种的减产幅度大于其亲本自交系。绝对杂种优势均随着年代延伸而增加。在干旱条件下玉米杂交种绝对杂种优势增加速度低于灌溉条件。干旱条件下相对杂种优势较正常水浇条件没有明显差异。在所有灌溉条件中，1970-2000年代杂交种的相对杂种优势总体保持稳定。因此可以认为，杂交种产量的提高，并不是来源于逆境条件下杂种优势的提高，而是由于抗逆性得到改良。5、随着年代更替玉米品种对矮花叶病与瘤黑粉病的抗性总体呈上升趋势，杂交种对这两种病害的抗性远远高于农家品种。品种对丝黑穗病的抗性随年代更替而上升，但是1970年代单交种的出现，对丝黑穗病的抗性大大降低，1980年代以后，玉米杂交种对丝黑穗病的抗性迅速升高。因此1980年代以后通过针对性的育种途径，品种对丝黑穗病的抗性得到了较好的改良。本试验中1950-2000年代的35个时代品种都不抗粗缩病。因此选育抗粗缩病品种是生产上亟需解决的问题。更多还原

【Abstract】 Maize（Zea mays L.）is the first food in China. It is also used as fodder, industry material andrenewable energy and is very important in national economy. Corn production was affected severelybecause drought frequently occurred and pests and diseases aggravated increasingly. Therefore, newbreeding objective and scheme were needed to establish to improve diseases resistance and adaption tosevere environment. Experience of the nations with developed seed industries indicated thatretrospective study could afford useful advice and instruction for improving yield ability. Identificationexperiments on drought tolerance and disease resistance were carried out for spreading cultivars from1950to2000. The aim was to discover:（1）trend of drought tolerance of Chinese spreading cultivars,（2） trend of yield, plant trait and heterosis of spanning cultivars in full irrigation and drought stressenvironments in China,（3） trend of disease resistance of spreding cultivars. The research can explorenew breeding strategies to further improve yield potential in the future and also offord theory basis forhigh yield breeding.The material of the research was mainly spanning cultivars in maize central production region from1950to2000, including the4OPVs in1950s,4double-cross hybrids in1960s and27single-crosshybrids after1970s. Evaluation of drought tolerance in seedling stage was carried out in dry house in2010. Identification of drought tolerance in the flowering stage was developed in Xinjiang and Hainanin2010and2011. Evaluation on diseases resistance was lunched in Beijing, Jining and Jilin in2010.From these experiments, the results were acquired as follows:1. Drought tolerance in seedling stage slowed down along with the decades. It increased rapidlyfrom1950to1960and decreased after1960. It also declined with released years for single-crosshybrids after1970. Twenty seven single-cross hybrids were clustered into three categories, hybrids withbetter tolerance to drought including Ludan50, Qundan105, Nongda108, Yedan13, Yedan4, Zhengdan2;worse tolerant hybrids comprising Nongda138, Nongda60, Shendan16; the rest belonging to middletype. One of emphasis in maize breeding is to strengthen water stress in seedling stage, whichestablishes the basis for breeding new hybrids tolerant to drought.2. The change between grain yield of cultivars and decades was linear increase in full irrigation anddrought stress treatments. The yield gain was85.8Kg.ha^-1.year^-1（R²=0.96）in full irrigation and53.88Kg.ha^-1.year^-1（R²=0.94）in drought stress at Hainan location。At Xinjiang location, it was94.3Kg.ha^-1.year^-1（R²=0.97）in full irrigation and61Kg.ha^-1.year^-1（R²=0.99）in drought stress.The yield gain was higher in full irrigation treatment than in drought stress treatment. Thecoefficient of drought tolerance （Cd） of cultivars decreased with decades, that is to say, the droughttolerance declined with decades. Although the breeders always attached importance to the droughttolerance of cultivars, it declined in severe stress environments. Therefore, drought stress should bestrengthened in breeding progress including inbred lines and hybrids in the future for further improvingthe ability of adaption to stress environments.In drought treatments, improved agronomic traits included that ASI, leaf angle, tassel branches number, green leaves number, empty ear rate, ear length, ear diameter, kernel number per ear, weightper hundred kernels, barren tip length. The traits with no improvements included that photosynthesis,leaf rolling and shell percentage. The traits with decreased drought tolerance were comprised of leafangle and empty ear rate.The next tusk emphasized on diminishing tassel, empty ear rate and barren tip length, andimproving photosynthesis and shelling percentage in drought tolerance breeding in maize.3. The grain yield of inbred lines increased linearly with decades. The yield increased from1960to1980, decreased in1990, and then increased in2000. The grain yield of inbred lines in droughttreatment reduced comparative with full irrigation treatment. The yield gap of new inbred lines waslarger than that of old one. The Cd of inbred lines decreased with decades, but declined in2000.Therefore, the drought stress tolerance of inbred lines increased step by step, but backward in2000. Weshould introduce new germplasm and strengthen drought pressure in breeding lines in the future.In drought treatments, improved agronomic traits included ASI, plant and ear height, leaf angle,tassel branches number, empty ear rate, green leaves number and all the ear traits. The traits whosedrought tolerance declined were comprised of ear height and weight per hundred kernels.Therefore, most agronomic traits of parental lines and their drought tolerance were improved. Andwe should further improve weight per hundred kernels for breeding new inbred lines tolerance todrought.4. The absolute heterosis in drought stress was less than that of full irrigation. It indicated that theyield reduction range of hybrid was higher than parental lines. Absolute heterosis increased withdecades from1970to2000in drought stress and in full irrigation treatments. The relative heterosisdeclined from1970to2000slowly, so it kept steady generally. No obvious difference exists betweenrelative heterosis in drought stress and full irrigation treatments. Thus we can conclude that theimprovement of hybrids was impertinent to relative heterosis in drought stress.5. The resistance to maize dwarf mosaic virus （MDMV） and common smut disease （CSD）increased with decades. The resistance of hybrids was better than OPVs to the two diseases. Theresistance to head smut disease （HSD） increased from1950to1960, decreased in1970, and increasedagain from1980to2000. So the HSD resistance decreases in1970because of single hybrid occurrence.But it was improved from1980as the result of purposive breeding strategies. All of the entries werehighly susceptible to maize rough dwarf virus （MRDV）. Therefore, breeding new varieties resistant toMRDV is a key problem to solve.更多还原