玉米杂交组合主要农艺性状与产量的灰色关联度分析

为了探讨玉米杂交组合产量与其他主要农艺性状间关联的主次关系,应用灰色关联度分析法研究13个玉米杂交新组合8个农艺性状对产量的影响及各性状间的相互关系,结果表明与产量的关联度大小依次为单穗粒重>株高>穗位高>穗行数>百粒重>秃尖>生育期>穗长,在育种实践中,应注重对单穗粒重、株高和穗位高的选择,同时结合其余农艺性状的综合表现进行育种,将对产量有一个比较大的提升。     

贵州区试玉米组合主要性状分析及育种对策探讨

利用主成分分析法和回归分析法分析影响2007～2009年贵州省玉米区域试验109个优良组合产量的因子,结果表明,影响产量的主成分因子分别是单穗粒重、生育期、百粒重、株高、穗行数和海拔;利用各因子作为自变量,玉米产量作为因变量,进行逐步回归分析,建立-个产量回归方程.方程的相关系数(R)为0.756,各因子对生产量影响的大小为单穗粒重＞生育期＞海拔＞株高＞百粒重＞穗行数.玉米高产育种应加强种质的创新与改良,注重粒重、穗行数、生育期和株高的选择,并把遗传改良的重点放在单穗粒重上.     

超甜超高油兼用型玉米主要产量性状和品质性状研究

本试验通过测定9个超甜超高油兼用型玉米杂交组合的主要产量性状和品质性状,包括穗长、乳熟期的鲜苞重和可溶性总糖含量、完熟期的单穗粒重和含油率。结果表明,组合3的可溶性总糖含量最高,鲜苞较重,可作为超甜玉米推广。组合4的鲜苞重、单穗粒重较高,可溶性总糖含量、含油率较高;组合1的含油率最高,可溶性总糖较高,但单穗粒重、鲜苞重中等,这两个组合可作为超甜超高油兼用型玉米推广。     

玉米杂交种主要农艺性状的通径分析

文章对玉米10个主要农艺性状进行通径分析,结果表明:单穗粒重是提高籽粒产量的决定因素;株高、百粒重、生育期、穗行数、行粒数是影响产量的重要因素;穗长、穗粗与产量呈正相关,主要是通过单穗粒重和百粒重间接影响的,而穗位高虽与产量呈正相关,但主要是通过株高和单穗粒重的间接影响,对出籽率的直观选择,难以实现大的突破。因此,在选育优良玉米新品种考虑农艺性状时,不但要着眼于某一性状对产量的突出作用,更要重视研究其它性状对突破产量的综合效应。     

Golden Glow玉米群体的多育性和相关性状的遗传：Ⅰ．表型评价

人们从墨西哥玉蜀黍中驯化玉米时就已经开始对多育性（主茎发育穗枝的潜力）进行选择。因为单穗玉米有利于手工收获，所以直到20世纪早期的机械化前，人类的选择都偏爱单穗玉米。然而，多育性具有增强集约管理条件下胁迫耐性的潜能。本试验的研究目的是：（1）评价194个F3家系群体的多育性和15个相关形态性状的变异。这些F3家系来源于自交系A679和一个多育性强的S1植株的杂交后代，而该S1植株又来源于Golden Glow品种的23轮多育性混合选择；（2）弄清这些性状间的相关关系，并推断哪一些性状是由相似遗传因子控制。     

贵州省东部杂交玉米区试分析与评价

对2006~2009年贵州省东部组杂交玉米区域试验44个组合的数据进行产量分析。结果表明,4年间贵州省东部杂交玉米育种处于徘徊阶段,平均产量在600 kg/667 m2左右,没有突破性进展。对影响该组品种的产量因子进行相关和主成分分析后认为,以增加单穗粒重和穗行数(兼顾穗长)为核心增加单株产量,是贵州东部玉米高产育种的主要方向。保持一定的植株高度,控制适宜的生育期,有利于玉米的高产、稳产。     

春玉米主要产量性状的遗传分析

利用12个玉米自交系，按双列杂交模式设计组配66个杂交组合．分析了8个穗部性状的配合力和遗传参数。试验表明一般配合力在亲本间存在显著差异，各自交系的特殊配合力，在同一性状不同组合间及同一组合不同性状间也有显著差异，穗粗、容重、子粒行数等性状主要受加性效应控制，遗传力较高，可以在早代选择．而单穗粒重、产量、每行粒数等性状则遗传力较低。     

玉米品种鑫研218及高产栽培技术

鑫研218是山东鑫丰种业股份有限公司用SX1395与SX393杂交选育而成的玉米杂交种。2017-2018年分别通过了国家黄淮海夏播玉米区、东华北中晚熟玉米区和西北春玉米区审定。该品种具有高产性好、抗病抗倒性好、适宜机收、适应性广等突出特点。介绍了鑫研218的选育经过、特征特性、产量表现以及高产栽培技术要点。     

同一来源玉米DH系的性状分离分析

利用单倍体诱导系对遗传背景相近的玉米自交系MC1和MC2所组配的F1进行杂交诱导获得单倍体,经过自然加倍得181份纯系(DH系),分析DH系农艺性状的分离情况。结果表明:181个DH系株高、穗位高、穗长、秃尖长、穗行数、百粒重和单穗粒重等数量性状的次数分布符合正态分布;所得DH系各数量性状的变异类型丰富,且在产量性状上存在优于两亲本的分离;两亲本的21对SSR核心引物分子标记带谱在DH系中的分布都近似于1∶1比率,未出现偏分离。因此,通过遗传诱导的方法所得DH系类型多样,可以满足育种上的需要。单倍体育种是一种选育优良玉米纯系的有效方法。     

国审玉米新品种中地88的选育及创新思考

中地88是以自育系M 3-11为母本,自选系D 2-7为父本杂交育成的玉米单交种。2014—2015年参加西北春玉米品种区域试验,2年平均产量为15 943.5kg/hm2,比对照郑单958增产6.57%;2015—2016年参加黄淮海夏玉米品种区域试验,2年平均产量为10 395.0kg/hm2,比对照郑单958增产6.13%;2016年参加西北春玉米品种生产试验,平均产量为14 982.0kg/hm2,比对照郑单958增产6.65%;同年参加黄淮海夏玉米品种生产试验,平均产量为10 151.1kg/hm2,比对照郑单958增产5.15%。中地88对茎腐病、粗缩病、大斑病、小斑病、弯孢菌叶斑病等均有较高的抗性;籽粒品质达到普通玉米一等级国标、高淀粉玉米一等级国标、饲料用玉米二等级国标和青贮玉米一等级国标。中地88于2017年6月通过农业部国家农作物品种审定委员会审定,其主要特点是高产稳产、优质、抗逆性较强,适宜机械化籽粒直收,粮饲青贮兼用,适宜在西北春玉米区、东华北春玉米区和黄淮海夏玉米区及同一适宜生态区种植。     

豫麦16的选育特点及其产量潜力

豫麦１６的选育特点是：采用多抗源异地材料作亲本，扩大Ｆ２种植群体规模，Ｆ４选择特优系并配合抗条锈病、白粉病鉴定，Ｆ５进行多点产量试验。通过边试验，边繁殖、边提纯的方法。结合高产栽培试验和组织大面积高产示范，加快了育种进程与推广，初步明确了豫麦１６具有每公顷７５００－９０００ｋｇ的高产潜力，探讨了进一步选育高产品种的育种目标。     

东北不同生态条件对大豆杂交后代的选择效应

以５个大豆杂交组合的Ｆ２－Ｆ５代为材料，连续４年在东北三省８个试验点按当地的高产育种目标进行选择，于Ｆ５代每个地点从每一组合中决选出１个高产品系，各地共计决选出４０个优良品系，并在上术８上地点以同一方案进行两年生态试验，以便分析生产条件对大豆杂交后代的选择效应。试验结果表明，在不同生态条件下，各地都选出了适合当地生态条件的生育期类型；在不同肥力条件下，各地都选出了适合当地生态条件的百粒重和抗倒伏性     

东华北不同生态区玉米品种产量及相关性状差异研究

以10个中晚熟玉米品种为试验材料,在东华北的5个生态区进行种植试验,对产量、穗部性状、农艺性状、抗倒性、抗病性等进行了研究。结果表明：不同生态区对玉米产量潜力存在很大影响（F=13.53）,品种间也存在较大差异（F=22.93）;产量构成因素的相关系数为穗数>穗粒数>百粒重,穗部性状受不同生态区的影响程度为秃尖长>穗粒重>穗长>穗行数,秃尖长是不同生态条件下变化最为活跃的穗部性状,与产量呈极显著的负相关;不同生态区抗倒性变化较小,倒伏率变异系数的变幅仅为1.24%~2.43%;在玉米病害方面,山西是病害易发区,不同病害在各生态区的发病存在很大差异。总体上,参试的10个玉米品种在内蒙古和山西更有利于生产潜力的发挥,抗倒性弱的品种适合在内蒙古种植,抗病性弱的品种不宜在山西种植。根据不同生态区的温度、日照和降水量特点,合理调配播种时间、开花时节是提高玉米生态适应性的关键。     

玉米杂交种主要农艺性状对产量稳定性影响的研究

根据华北夏玉米区域试验材料,应用回归系数和性状相关的方法,研究了玉米杂交种7个农艺性状对其籽粒产量稳定性的影响。结果表明,大部分农艺性状与杂交种稳产性呈负相关,以穗行数和千粒重的影响最大,穗位高、穗长、株高和穗粒数的影响较小。在育种实践中,可加强对杂交种稳产性影响小而对籽粒产量影响大的性状进行选择,适当降低穗位高,增加穗粒数,有利于提高玉米杂交种产量的稳定性。     

Inbreeding and selection in swedes (Brassica napus ssp rapifera)

Summary The effect of inbreeding and selection within the old swede cultivar Scotia was examined. A decline in yield was shown by lines produced by selfing from the highest yielding progenies selected after open pollination. It is assumed that these progenies were from heterozygous plants. The yield of two groups of lines did not decline and from these, after a second generation of selfing, eight lines were selected with a mean dry matter yield 10 per cent higher than Scotia.Now part of Scottish Crop Research Institute, Dundee, Scotland.     

Improving the yield, processing quality and disease and pest resistance of potatoes by genotypic recurrent selection

A potato (Solanum tuberosum Gp Tuberosum) breeding programme is described and analysed in which resistances to late blight [Phytophthora infestans (Mont.) de Bary] and the white potato cyst nematode (Globodera pallida) have been combined with a modest increase in yield and acceptable fry colour for processing. It began in 1991 and has involved cycles of crossing, selection between from 120 to 145 progenies (full-sib families), and clonal selection within the selected progenies. We have shown that the breeding scheme can operate on a 3-year cycle with limited within progeny selection, and on a 5- or 6-year cycle with more extensive within progeny selection. Six years are required when resistance to late blight is assessed in the tubers as well as the foliage. The more extensive within progeny selection is recommended once genes have been combined from sufficient parents to achieve one’s objectives. The yield increase after three cycles of indirect selection through breeders’ visual preference was only modest because it was operating against a decrease which would occur in the absence of selection. A practical improvement in the scheme would be to increase the number of progenies assessed to over 200, given the moderate to high heritabilities of the progeny and clonal tests. But this would require a considerable effort because the success rate achieved with the potato pollinations was typical at just over 30%. In the fourth cycle we showed how new breeding objectives and germplasm could be accommodated whilst continuing to maintain progress, something that is important in any long term breeding strategy.     

Environment of selection and type of germplasm in barley breeding for low-yielding conditions

Summary Thee groups consisting of 332, 243 and 280 barley breeding lines (entries) of known selection history were evaluated in 10, 9 and 8 environments, respectively, to determine the relationship between grain yield in low yielding (LYE) or high yielding (HYE) environment, and selection history and type of germplasm. One cycle of selection in LYE produced on average five times more entries outyielding the best check in LYE than selection in HYE. A retrospective analysis indicated that the highest yielding lines in LYE were lower yielding (15%–28%) in HYE when compared with the best check, and by 20% and 38% compared with the best entries in HYE. In contrast, the highest yielding lines in HYE were lower yielding (4%–33%) in LYE when compared with the best check, and by 33% and 40% when compared with the best entries in LYE. The highest yielding lines in LYE did not differ consistently from the highest yielding lines in HYE for a number of morphological and developmental traits including days to heading. This suggests there are many paths to high yield in LYE and that analytical breeding based on individual traits may not be appropriate for variable environments. Only 0.07% of the highest yielding entries in LYE was selected for high yield in HYE conditions confirming previous results indicating that selection for high yield in HYE is an inefficient strategy for improving yield in low yielding conditions. This frequency is 28 times lower than the frequency of high yielding entries in LYE selected from landraces or crosses with landraces in low yielding conditions. The results imply that the most cost-effective strategy for barley breeding in low yielding conditions is to select repeatedly in low yielding conditions and to include adapted germplasm (landraces) in the breeding material.     

Choice of shrinkage parameter and prediction of genomic breeding values in elite maize breeding populations

Genomic selection (GS) is a promising alternative to marker‐assisted selection particularly for quantitative traits. In this study, we examined the prediction accuracy of genomic breeding values by using ridge regression best linear unbiased prediction in combination with fivefold cross‐validation based on empirical data of a commercial maize breeding programme. The empirical data is composed of 930 testcross progenies derived from 11 segregating families evaluated at six environments for grain yield and grain moisture. Accuracy to predict genomic breeding values was affected by the choice of the shrinkage parameter λ², by unbalanced family size, by size of the training population and to a lower extent by the number of markers. Accuracy of genomic breeding values was high suggesting that the selection gain can be improved implementing GS in elite maize breeding programmes.     

利用籼稻资源中的“隐蔽有利基因”提高粳稻苗期耐冷性

苗期低温是制约东北水稻生产的一个重要逆境因子,培育苗期耐低温的水稻品种是解决这一问题最有效的途径之一。以粳型恢复系C418为轮回亲本与7个来自不同地域的供体杂交和回交培育BC₂F₂群体，利用沈阳春季田间自然低温进行耐冷筛选，并对入选的177个苗期耐冷导入系后代在自然和人工气候室两种不同强度的低温胁迫条件下的苗期表现进行评价。结果表明，虽然供体亲本均为苗期耐冷性弱的品种，但在全部回交后代中均出现耐冷的超亲分离，表明这些供体亲本均携带对耐冷性有利的“隐蔽基因”, 不过组合间的耐冷性选择效率存在较大差异。以人工气候室低温胁迫后的存活率为耐冷性鉴定指标，导入系之间出现广泛分离，田间筛选入选比例高的BG300和中413导入系群体中出现存活率高的导入系后代比例较其它群体高，说明在同一轮回亲本遗传背景下回交后代的耐冷水平取决于供体。在室内严格低温条件下表现为强耐冷性的导入系在相对温和的自然低温胁迫下表现为苗高、苗干重较非胁迫条件生长抑制不明显，且能够促进根系生长。结果表明，大量的耐冷有利基因以“隐蔽”的形式存于水稻种质资源中。通过利用来源广泛的种质资源作为供体进行回交育种，对回交后代进行严格耐冷筛选，可有效选育高产耐冷水稻品种和有价值的育种材料。     

Farmers' highland maize (Zea mays L.) selection criteria: Implication for maize breeding for the Hararghe highlands of eastern Ethiopia

Despite the presence of large numbers of improved maize cultivars, farmers in the Hararghe highlands of eastern Ethiopia persistently grow local cultivars and are not benefiting from the varietal improvement program. By growing local cultivars farmers obtain an average yield of 1.2 t ^-1 whereas research has released cultivars yielding 5–11 t ^-1under on-station conditions. Recognizing this and the important role maize is playing in the livelihood system of farmers in eastern Ethiopia; Participatory Varietal Selection (PVS) was conducted for three consecutive seasons (1996–1998) in three locations. The objectives of the study were to identify farmers' cultivar selection criteria for future breeding, to enable farmers to assess the performance of improved cultivars under their management, to increase farmers' access to the cultivars of their preference by injecting source seed into the local seed system, and to investigate whether breeding for wide adaptation like for the Hararghe highlands has any drawbacks or not. The study indicated farmers' maize varietal selection criteria together with the differences in selection criteria across locations classified under the same adaptation zone. Though farmers selected some of the many improved cultivars tested, no improved cultivar had all the characteristics, which farmers want in a single cultivar. To be able to combine cultivar selection traits farmers considered cultivar combinations in all locations, but not the single `best' cultivar. Despite the yield advantage of hybrids, farmers selected Open Pollinated Varieties (OPVs) because they had more preferred traits. Farmers also preferred to retain their local cultivars despite their lower yield compared to most of the improved cultivars. Both situations confirmed how resource poor farmers' cultivar requirements are much more diverse than yield per se. Gender and social group-driven difference in cultivar preference was also observed. The study revealed the need for proper zoning of the Hararghe highlands as a prerequisite to developing better adapted maize cultivars to the varied agro ecological and socioeconomic niches. As shown in this study, proper zoning, due consideration to farmers' relevant selection traits and wider use of participatory approaches should be adapted to develop cultivars which can gain farmers acceptance. This revised version was published online in August 2006 with corrections to the Cover Date.