Evaluation of U.S. and Yugoslavian Maize Populations as Sources of Favorable Alleles

Abstract

Choice of an appropriate donor of alleles for use in reselection programs of existing inbred lines of maize (Zea mays L.) is crucial to the success of such programs. Well‐adapted local populations or exotic improved populations might be used as donors to improve a target genotype. The objectives of this study were to: (i) evaluate U.S. and Yugoslav maize populations as donors of favorable alleles for improvement of two single cross hybrids, (ii) estimate Dudley's relationship values to determine which inbred parent should be improved, and (iii) compare four estimators of the value of populations: Dudley's minimally biased estimators (Lplμ*), minimum upper bound (UBND), predicted three‐way cross (PTC), and net improvement (NI). Lplμ*, UBND, PTC, and NI showed significant differences among donors for grain yield. The highest values of favorable alleles were detected in populations, which had already undergone some type of family‐based recurrent selection for grain yield. The evaluation of Dudley's relationships between donors and parents of elite hybrids generally agreed with pedigree information. The improvement of both hybrids should be done with populations EP1, BS12C8, BS26, and ZPSyn1. The population EP1 can be used for comparative improvement of all three traits in the hybrid B73 × Mo17. Simultaneous improvement of grain yield and ear length in the hybrid A82/9 × L155 can be achieved with several donor populations. Rank correlations among applied estimators were positive and generally highly significant. The largest correlation values for grain yield were detected between Lplμ* and PTC.

Breeding Potential of Exotic Maize Populations to Improve an Elite Chinese Hybrid

“…Trifunovic et al (2001) used the estimators Lpl μ′, UBND, PTC, and NI to designate four Yugoslav and U.S. populations as the best donors for improving grain yield, ear length, and grain moisture of two Yugoslav hybrids, B73 × Mo17 and A82/9 × L155, representing the Stiff‐Stalk × Lancaster heterotic pattern. Using Dudley’s method, Taller and Bernardo (2004) found four exotic and synthetic populations with favorable alleles for grain yield that were absent in LH 227 × LH 295, a hybrid derived from the BSSS × Non‐BSSS heterotic pattern of the northern Corn Belt.…”

“…Furthermore, the efficiency of these statistics to identify populations with favorable alleles absent in target hybrids has also been compared, and high correlations were found between Lpl μ′, UBND, PTC, and NI, with each estimator possessing specific advantages (Pfarr and Lamkey, 1992; Revilla et al, 1998; Trifunovic et al, 2001). These quantitative phenotype‐based methods are appropriate tools for initial selection of the most promising germplasm for genotyping and improvement of elite populations (Rodriguez et al, 2007).…”

Analysis on breeding potential of eight synthetic populations to improve a Chinese maize hybrid Zhengdan 958

“…Keywords: Zea mays L.; synthetic populations; germplasm improvement; hybrid 黄 淮 海 是 我 国 玉 米 主 产 区 , 播 种 面 积 占 全 国 33% [1,2] 。 自 20 世纪 70 年代单交种应用以来, 杂交种 的推广应用对我国玉米生产起到了积极推动作用 [3] 。 优良杂交种郑单 958(PA×四平头杂优模式)以高产、 多抗、广适性等优点, 连续成为黄淮海夏玉米区和 我国推广面积最大的品种 [4] , 但近年来也表现出产 量潜力需要进一步提升、商品品质不佳等不足 [5] 。 通过玉米种质创新, 改良杂交种的不良性状对提高 其生产应用价值具有重要意义 [6,7] Dudley 等 [12] 、Kraja 等 [13] 、Taller 和 Bernardo [14] 等学 者评价了美国合成群体改良玉米带杂交种 FRB73 × FRMo17、FR1064 × LH185、LH 227 × LH 295 的产 量和抗倒性; Stojsin 和 Kannenberg [15] 利用加拿大合 成群体改良当地杂交种 CG28 × CO265、CGKX86 × CO265 的产量和株型性状; Rodriguez 等 [16] 利用西班 牙合成群体改良当地杂交种 EP80 × F7、EP80 × Z78007 的耐冷性; Trifunovic 等 [17] 利用南斯拉夫群 体改良当地杂交种 A82/9 × L155 的产量和穗部性状;…”

“…系 [8] 。采用 Falconer 和 Mackay 模型 [22] 估计供试群 因 [13] 。在某一生态区, 优良杂交种具有较多有利等 位基因 [8] , 但个别性状表现不佳, 通过进一步改良, 有望在此基础上选育出农艺性状改良的杂交种。 [17,18] ; 通过估计 Lplμ'、NI 等参 数明确改良西班牙杂交种的合成群体 [16] [23] , 因此选用其作 为衡量商品品质的指标。 通过估计 4 个遗传参数, 仅 有东农群体、辽旅综、中综 3 号等 3 个合成群体不 能确定 Lplμ'估计值。一方面, 由于估计的 q j 和 q k 上下限, 无法确定计算 Lplμ'参数的公式。另一方面, 籽粒容重性状遗传性较复杂, 会影响到 Dudley 参数 的估计。Helm 等 [24] 认为籽粒容重是由多基因控制, 以加性效应为主; 丁俊强等 [23] 利用郑 58 和昌 7-2 建 立的 F 2:3 群体分析籽粒容重的遗传效应, 发现加性 和上位性效应同时存在。Dudley 理论假设只存在完 全显性效应, 忽略上位性 [8] , 但其余 3 个遗传参数没…”

Maize Populations as Sources of Favorable Alleles to Improve Cold‐Tolerant Hybrids

“…Several statistics were developed based on Dudley's theory; some of them offer specific contributions—particularly NI (net improvement) (Bernardo, 1990) is appropriate for choosing donor populations for direct production of improved inbreds, and PNG ceg (probability of a net gain of favorable alleles when partial dominance or complementary epistasis is prevalent) (Metz, 1994) for nondominant gene effects. These statistics were widely used to estimate the potential improvement of field and sweet maize hybrids (Dudley, 1988; Cartea et al, 1996; Kraja and Dudley, 2000; Trifunovic et al, 2001). This method was originally proposed for using exotic populations as a source of new favorable alleles.…”