Genetic Structure of Three Open-Pollinated Faba Bean Varieties (Vicia faba L.)*

To study the genetic structure of open-pollinated faba bean varieties, three sets of genotypes were generated from each of the varieties ‘Minica’, ‘Kristall’, and ‘Deiniol’: (1) inbred lines developed by single-seed descent in bee-proof isolation cages, (2) intravanetal and (3) intervarietal F₁-hybrids produced by controlled hand crossing. In 1989 and 1990, a total of 144 entries, including the three open-pollinated source varieties, were grown in single-row plots with two replications at two locations in Western Germany. Performance data of the inbred lines revealed relatively large genotypic variability within each variety, for all the characters studied, which was greater in ‘Deiniol’ and ‘Kristall’ than in ‘Minica’. An average yield heterosis of 20 %, 39 % and 57 %, respectively, was found for the intravarietal hybrids, whereas that of the intervarietal hybrids varied between 70 and 73 %. Compared to the mean yield of the inbred lines the superiority of the open-pollinated source variety was small and not significant in ‘Minica’ (6 %), but it was large and highly significant in ‘Kristall’ (22 %) and ‘Deiniol’ (37 %). The present investigation revealed in faba bean that similar performance levels of open-pollinated varieties may result from either high per se performance under inbreeding with low heterosis values or from lower per se performance but with high heterosis values.     

Combining ability,heterosis and genetic diversity in tropical maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) under stress and non-stress conditions

Drought and low soil fertility are considered the most important abiotic stresses limiting maize production in sub-Saharan Africa. Knowledge of the combining ability and diversity of inbred lines with tolerance to the two stresses and for those used as testers would be beneficial in setting breeding strategies for stress and nonstress environments. We used 15 tropical maize inbred lines to (i) evaluate the combining ability for grain yield (GY), (ii) assess the genetic diversity of this set of inbred lines using RFLP, SSR, and AFLP markers, (iii) estimate heterosis and assess the relationship between F₁ hybrid performance, genetic diversity and heterosis, and (iv) assess genotype × environment interaction of inbred lines and their hybrids. The F₁ diallel hybrids and parental inbreds were evaluated under drought stress, low N stress, and well-watered conditions at six locations in three countries. General combining ability (GCA) effects were highly significant (P < 0.01) for GY across stresses and well-watered environments. Inbred lines CML258, CML339, CML341, and CML343 had the best GCA effects for GY across environments. Additive genetic effects were more important for GY under drought stress and well-watered conditions but not under low N stress, suggesting different gene action in control of GY. Clustering based on genetic distance (GD) calculated using combined marker data grouped lines according to pedigree. Positive correlation was found between midparent heterosis (MPH) and specific combining ability (SCA), GD and GY. Hybrid breeding program targeting stress environments would benefit from the accumulation of favorable alleles for drought tolerance in both parental lines.     

转双抗虫棉纯合系的杂种优势及其产量性状的配合力

采用NCⅡ设计，利用4个生产上推广应用的棉花品种与9个转两类抗虫基因（Cry1Ae和API）纯合系进行杂交组配，对36个组合的F1产量性状的杂种优势和配合力进行分析，结果表明：大多数组合的竞争优势明显，各产量性状均具有竞争优势，但子指的优势为负值；皮棉和子棉的产量均具有较大的竞争优势，两者分别为17．2％和7．9％，皮棉和子棉产量的竞争优势率分别达到86．1％和80．6％。产量性状的优势大小依次为衣分、铃重和单株铃数，分别为4．1％，2．1％和0．7％。对组合的配合力方差进行分析，结果显示：9个转基因抗虫棉纯合系各产量性状的一般配合力差异较大，4个母本中的两抗虫棉的皮棉和子棉的产量的一般配合力优于两非抗虫棉。对这些组合特殊配合力进行分析，发现有6个组合具有较高的特殊配合力。因这9个纯合系的受体均为冀合321，所以这种配合力的差异是由外源基因作用的差异造成。     

Hybrid performance and AFLP- based genetic similarity in faba bean

Successful prediction of heterosis and performance of F₁-hybrids from the genetic similarity of their parents based on molecular markers has been reported in several crops and can be very helpful in hybrid breeding. The relationship between genetic similarities based on amplified fragment length polymorphism (AFLP) of 18 European faba bean lines and their hybrid performance and heterosis was investigated. Parental lines, 62 F₁-hybrids and their F₂-progenies were evaluated in field trials in four environments in Germany for seed yield, 1,000-seed weight and plant height. Results clearly demonstrated a stable superiority of the hybrids over their inbred parents and elite check cultivars, and showed a marked and varying amount of heterosis. Parental seed yield and F₂-hybrid yield were promising as predictors for F₁-hybrids. AFLP analysis of the 18 inbred lines using 26 EcoRI/MseI primer combinations resulted in 1202 polymorphic fragments. Cluster analysis based on genetic similarity estimates unambiguously identified pedigree-related inbred lines. No clear separation of the 18 inbred lines into subgroups was detected. Correlation coefficients between genetic similarity estimates and either heterosis or F₁-hybrid performance were small and not useful. Also correlations between specific genetic similarity and specific combining ability were too small for all traits to be of predictive value. Results showed that AFLP-based genetic similarities are not useful to predict the performance of hybrids or heterosis within the elite European faba bean gene pool.     

不同来源玉米自交系及杂交组合杂交当代子粒性状的差异分析

玉米杂种优势的研究对于提高玉米产量和品质有重要意义。对2013年海南三亚种植收获的89份温带自交系、59份热带/亚热带自交系和由这148份自交系随机组配的179份杂交组合进行当代子粒性状的测定。分析了温带玉米与热带/亚热带玉米自交系子粒性状的多样性与差异性,同时依据亲本来源的不同,探索了不同组合的杂交当代子粒性状的差异性。结果表明：温带来源的玉米自交系粒长和百粒重比热带/亚热带材料的粒长和百粒重显著偏长偏重;不同来源的自交系组配的杂交当代F₁,母本来源于温带的杂交当代F₁粒长显著长于母本来源于热带/亚热带材料;杂种优势分析结果说明,杂交当代F₁在粒厚和百粒重性状上表现的相对高亲和相对中亲优势强于粒长和粒宽。     

Ga糯玉米自交系的配合力分析与评价

摘要：利用不完全双列杂交NCⅡ设计,以3个经遗传改良的Ga糯玉米自交系为父本,与8个糯玉米自交系进行杂交。对24个杂交组合进行农艺性状鉴定,分析Ga糯玉米自交系主要农艺性状的配合力效应。结果表明,父、母本各性状的一般配合力和特殊配合力效应均达极显著差异。Ga糯玉米自交系具有良好的配合力,其中,CM327的一般配合力效应比较高,其组配的杂交种在产量、穗长、行粒数等性状上具有明显优势,具有很好的杂优利用潜力。Ga糯玉米自交系的选育利用,有助于糯玉米种质的扩增与杂种优势的利用。     

Combining ability and heterosis of elite drought-tolerant maize inbred lines evaluated in diverse environments of lowland tropics

Estimates of combining abilities and heterosis of inbred lines are imperative for selection of suitable parents of maize hybrids. This study examined the combining ability of 24 drought-tolerant maize inbred lines, 12 each from International Centre for Maize and Wheat Improvement (CIMMYT) and International Institute of Tropical Agriculture (IITA). The lines were allotted into six groups each comprising four lines. The four lines in one group were used as females and crossed to the four lines in another group as males in six different sets using a North Carolina Design II mating scheme to generate 96 hybrids. The hybrids were evaluated together with four checks across six environments in the rainforest and savannah agro-ecologies of Nigeria between 2011 and 2012. The parental inbred lines were also evaluated in separate trial in each location. Significant hybrids × environment interaction was observed for grain yield and other measured traits. GCA effects accounted for 83.3% of the variation for grain yield at Bagauda, 78.1% at Saminaka, and 77.7% at Ikenne. GCA also contributed 91.1 and 80.0% to the variation observed for plant height and ear aspect, respectively, across the environments. Significant SCA × environment interaction detected for grain yield suggests that hybrids were not stable across test environments. Prediction of grain yield in hybrids using midparent values resulted in a R ² value of 0.13. Midparent heterosis for grain yield varied from 80 to 411%, with the top 36 hybrids recording >200%. Four CIMMYT (EXL02, EXL06, EXL04 and EXL16) and three IITA (ADL33, ADL41, and ADL32) inbred lines had positive and significant GCA effects for grain yield across environments. The novel alleles present in the CIMMYT lines will improve the adapted IITA germplasm in a new population for extracting new set of more productive inbred lines for developing adapted high yielding drought-tolerant maize hybrids.     

转基因抗虫棉核不育系配合力及杂种优势分析

为了分析转基因抗虫棉不育系的配合力和杂种优势。采用6×6NCⅡ交配设计,分析了6份转基因抗虫核不育系与6份陆地棉亲本杂交后,9个性状杂种F1的超父本优势、竞争优势和配合力。结果表明,籽棉产量超父本优势的平均值为19.44%,22个组合具正向的杂种优势;竞争优势的平均值为-8.36%,16个组合出现正向竞争优势。单株铃数的杂种优势最为明显。父本值与F1平均值的相关关系表明,8个性状F1代平均值与父本值的相关性达到极显著水平。经配合力分析,A1、A4、B1、B5等亲本的GCA较好;SCA效应显著的6个性状中,A1×B6、A3×B3等组合的SCA效应均为正值。     

Studies on a diallel cross and double-cross hybrids among various Brassica oleracea types

Summary Three unrelated pairs of inbred lines from marrow-stem kale (A), thousand headed kale (B), and Scotch curled kale (C), together with 3 lines from Chou Fourrager Jaune (D), Brussels sprouts (E), and January King cabbage (F) were used to produce a diallel cross.Study of the F₁ generation revealed that general combining ability was highly significant for all yield components studied and specific combining ability was also significant for all but at a much lower level. Greater heterosis for leaf yield, but not for stem yield, was indicated in the inter-type hybrids as compared with intra-type hybrids.Double-crosses made among F₁ from the paired inbred lines did not reveal consistent effects of order of combining the inbred lines on yield characters, but the large differences in plant-to-plant uniformity showed that only the (X₁×X₂)×(Y₁×Y₂) combination is likely to be of practical significance.     

Genetic Analysis of Grain Yield and Other Traits of Early‐Maturing Maize Inbreds under Drought and Well‐Watered Conditions

Maize (Zea mays L.) is an important staple food crop in West and Central Africa (WCA). However, its production is constrained by drought. Knowledge and understanding of the genetics of hybrid performance under drought is invaluable in designing breeding strategies for improving maize yield. One hundred and fifty hybrids obtained by crossing 30 inbreds in sets using the North Carolina Design II plus six checks were evaluated under drought and well‐watered conditions for 2 years at three locations in Nigeria. The objectives of the studies were to (i) determine the mode of gene action controlling grain yield and other important agronomic traits of selected early inbred lines, (ii) examine the relationship between per se performance of inbreds and their hybrids and (iii) identify appropriate testers for maize breeding programmes in WCA. General combining ability (GCA) and specific combining ability (SCA) mean squares were significant (P < 0.01) for grain yield and other traits under the research environments. The GCA accounted for 64.5 % and 62.3 % of the total variation for grain yield under drought and well‐watered conditions, indicating that additive gene action largely controlled the inheritance of grain yield of the hybrids. Narrow‐sense heritability was 67 % for grain yield under drought and 49 % under well‐watered conditions. The correlations between traits of early‐maturing parental lines and their hybrids were significant (P < 0.01) under drought, well‐watered and across environments. Mid‐parent and better‐parent heterosis for grain yield were 45.3 % and 18.4 % under drought stress and 111.9 % and 102.6 % under well‐watered conditions. Inbreds TZEI 31, TZEI 17, TZEI 129 and TZEI 157 were identified as the best testers. Drought‐tolerant hybrids with superior performance under stress and non‐stress conditions could be obtained through the accumulation of favourable alleles for drought tolerance in both parental lines.     

Retrotransposon-related genetic distance and hybrid performance in sunflower (Helianthus annuus L.)

Heterosis is a main force leading the development of the hybrid seed industry in sunflower. The purpose of this study is to evaluate if heterosis effects for morphological traits among sunflower hybrids can be related to differences in the repetitive component of the genome of parental lines. The assumption is that, at least for certain traits, heterosis results from mutations in the cis-regulatory elements of genes, largely related to retrotransposon insertions and/or removals. Our experimental approach consists of a correlation study between hybrid performance and retrotransposon-related genetic distances between inbreds. Six sunflower inbred lines of different origin were crossed in a half diallel fashion; comparing parental lines and hybrids, mid parent heterosis of F₁ hybrids was evaluated for six traits. We estimated the parental genetic distances between the six inbreds on data gathered by the inter-retrotransposon-amplified-polymorphism (IRAP) protocol. Different retrotransposons previously isolated in sunflower were targeted by 11 primer pairs designed on conserved LTR domains. As a control, genetic distances were also calculated using 86 genic SNPs. We analysed the correlation between the mid-parent heterosis for each of the six traits analysed and the genetic distance (calculated on data obtained by SNP or IRAP analyses) between the parental lines. Differences between parents showed to be largely related to variations in the retrotransposon component of the genome. Retrotransposon-related genetic distance between parents resulted to be larger than that related to genic SNPs, and significantly correlated to seed yield and, at a lesser extent, to plant height and stem diameter in hybrids. The hypothesis that variations in the repetitive component of the genome, especially LTR-retrotransposons, affect the displaying of heterosis is discussed.     

玉米不同基因型气孔特征和叶温差的研究

为了探讨玉米不同基因型和杂种优势在气孔及蒸腾上的特征，对3个高产杂交种(农大108、农大103和中原单32)及其所有亲本进行了气孔形态、气孔频率和叶温差的观察与测量。结果表明，3个玉米杂交种在气孔特征及叶温上都表现出显著的杂种优势，其中农大108和农大103的杂交种气孔长度都表现正向超亲，杂种优势率分别为10．55％和9．30％，但气孔频率为负向超亲(杂种优势率分别为39．25％和20．43％)；中原单32的杂交种在气孔长度和气孔频率都表现正向超亲，杂种优势率分别为9．47％和16．48％；但从3个杂交种组合均值看，气孔长度为正向超亲，气孔频率为负向超亲。3个玉米杂交种的叶温差都表现正向超亲。相关分析表明，气孔长度与气孔频率呈显著负相关(r=-0．6460^*)；气孔长度与叶温差呈正相关，而气孔频率与叶温差呈负相关，但都不显著。     

Combining ability and gene action for maturity and agronomic traits in different heterotic groups of maize inbred lines and their diallel crosses

Combining ability information is necessary for selection of suitable advanced lines for hybridization and identification of promising hybrids for development of improved varieties. A number of 14 maize (Zea mays L.) inbred lines and 91 related crosses were evaluated over two years, 2008 and 2009, in a temperate-zone of Iran. The objectives of the study were to identify the best general and specific combiners, heterosis and type of gene actions responsible for agronomic traits. Except for grain yield and growing degree day to milky, significant general (GCA) and specific (SCA) combining ability were observed for all traits. The Baker ratio for plant height (0.15), ear height (0.26), growing degree day to milky stage (0.04), and grain yield (0.002) showed the predominance of non-additive gene effects in the expression of these traits. The heterosis observed for grain yield, grain number, pollination period, ear and plant height was considerably higher than that observed for other traits. The correlations (r) of F₁ means and SCA effects were positive and significantly higher than that of r (F₁, mid-parents) and r (F₁, heterosis) for all the traits except cob percent, growing degree days to silking, and physiological maturity. MO17, K3547/5, and K3615/2 had negative GCA effects for growing degree day to milky stage and maturity. Among hybrids, MO17 × K3653/2, B73 × K3651/2, and K3545/6 × K3493/1 with positive SCAs for pollination period and grain yield had also negative SCA effects for degree day to silking and milky stages. Therefore, the use of these inbred lines and hybrids increases the response to selection for increasing grain yield and early maturity in maize.     

西南骨干玉米自交系主要农艺性状和产量正反交杂优效应分析

为了比较玉米自交系主要农艺性状和产量的正反交杂优效应,以9份西南地区骨干玉米自交系组配的72份单交种为材料,采用随机区组试验,对自交系及其正反交杂种F1代主要农艺性状和产量进行比较研究。结果表明,正反交效应对不同玉米自交系杂种F1代主要农艺性状和产量的影响不同;T检测表明,大多数玉米自交系正反交杂种F1代主要农艺性状和产量差异不显著。玉米自交系海9-21、5003、478正反交杂种F1代在穗粗、百粒重、单穗粒重、穗下茎节强度及穗位高等性状上差异显著或极显著。由此得出,不同自交系正反交杂种F1代在主要农艺性状和产量上具有不同的杂种优势,其中穗位高/株高具有负向杂种优势。由于玉米穗位高/株高具有负向杂种优势,即杂种F1代穗位高/株高值较自交系有所降低,因此在自交系选育时,不宜对亲本材料过分追求低的穗位高/株高。     

Heterosis breeding in Indian mustard (Brassica juncea L. Czern & Coss): Analysis of component characters contributing to heterosis for yield

Summary Divergence of 25 accessions of Brassica juncea of Indian, CIS (Commonwealth of Independent States, former USSR) and synthetic origin was studied by D² analysis. On the basis of divergence, ten accessions were selected and crossed in a diallel fashion without reciprocals to study the combining ability and heterosis. None of the accessions was found to be a good general combiner for all the nine quantitative characters that were studied. Significant heterosis over better parent for single plant yield was recorded in CIS x Indian and synthetic x CIS crosses (5 each) followed by Indian x synthetic types (3). The analysis of component characters showed that the mean performance of the majority of hybrids was intermediate for five out of six yield attributing traits, thus exhibiting dominance or partial dominance effect. To estimate the contribution of such yield attributing traits towards heterosis for yield, a comparison was made among three parameters viz. heterosis over mid parent (MP), better parent (BP) and better yielding parent (BYP) of the concerned hybrid. It was observed that estimation of heterosis from BYP was a more accurate method to determine the contribution of component characters towards yield heterosis than the analysis based on MP and BP. From the component character analysis, it was concluded that characters like number of primary and secondary branches, number of siliqua per plant and siliqua density contributed significantly towards heterosis in yield. Plot level yield trials of two selected hybrids (Skorospieka II x RH30 and Donskaja IV x Varuna) over two growing seasons revealed 29.4 to 91.8% heterosis over BYP.     

11份玉米自交系单株产量等性状的配合力与遗传参数研究

旨在研究玉米自交系单株产量等性状的配合力、遗传力及反交效应,为玉米自交系的选育和杂交种的组配提供依据。以11份玉米自交系为试材,按Griffing Ⅲ完全双列杂交法组配110个组合,观测杂交种的单株产量、株高、穗位高、雄穗分支数、雄穗主轴长、抽丝期和开花期等7个性状的表型数据,并对上述性状的一般配合力、特殊配合力、广义遗传力、狭义遗传力和反交效应进行估算。供试材料除雄穗主轴长的特殊配合力差异不显著外,其余性状的一般配合力和特殊配合力差异均达到极显著水平。JZ3和JZ6两个自交系单株产量的一般配合力为极显著正值,两对组合JZ9×JZ2和JZ2×JZ9、JZ6×JZ3和JZ3×JZ6的单株产量具有最大的正向SCA效应值,分别为40.68 g和35.24 g。单株产量的反交效应差异极显著,部分自交系的反交效应方差较大。7个性状的广义遗传力从大到小依次为,雄穗分支数、株高、开花期、穗位高、抽丝期、单株产量和雄穗主轴长;狭义遗传力从大到小依次为,雄穗分支数、株高、穗位高、开花期、雄穗主轴长、抽丝期和单株产量。试验结果表明单株产量性状的显性遗传方差占比最大,狭义遗传力最小,易受环境条件的影响,对该性状的选择适宜在晚代进行;单株产量性状具有显著的反交效应,故部分自交系需严格控制正反交方式。     

Genetic analysis of drought tolerance in adapted × exotic crosses of maize inbred lines under managed stress conditions

Introduced maize (Zea mays L.) germplasm can serve as sources of favorable alleles to enhance performance in new maize varieties and hybrids under drought stress conditions. In the present study, the combining abilities of 12 exotic maize inbred lines from CIMMYT and 12 adapted maize inbred lines from IITA were studied for grain yield and other traits under controlled drought stress. The inbred lines from each institution were separated into groups using SSR-based genetic diversity and were intercrossed using a factorial mating scheme to generate 96 hybrids. These hybrids were evaluated under both controlled drought stress and well-watered conditions at Ikenne in Nigeria in 2010 and 2011. Average mean yields of hybrids under drought stress represented 23 % of the average yield of hybrids under full irrigation. General combining ability (GCA) effects accounted for 49–85 % of the observed variation for several traits recorded under both well-watered and drought stress conditions. Specific combining ability effects for grain yield, though positive in most hybrids, were not significant under drought stress conditions. All the twelve exotic and nine adapted lines had positive GCA effects (female, male, or both) for grain yield under either drought stress or full irrigation, or both environments. EXL03 and EXL15 that had positive and significant female and male GCA effects for grain yield under both environments can be used to improve their adapted counterparts for grain yield and drought tolerance. Normalized difference vegetation index had weak but significant correlation with grain yield.     

Heterosis in landrace-based topcross hybrids of pearl millet across arid environments

This study quantified the magnitude of heterosis in pearl millet (Pennisetum glaucum) topcross hybrids produced by crossing 16 diverse landraces and three high yielding open-pollinating varieties on two homozygous male-sterile lines. Hybrids and pollinators were grown in 12 year ×;location combinations in India that were grouped into three zones. Genetic components of variance quantifying the differences among these hybrids were estimated. The hybrids showed a conspicuous heterosis for grain yield, earliness and biomass yield but not for straw yield. The level and direction of heterosis for time to flowering depended strongly on the earliness of the male-sterile line. In the terminal drought stress zone hybrids made on the early maturing male-sterile line 843A had the highest level of heterosis for grain yield (88%). This was partly due to escape from terminal stress. In the other two zones the heterosis for grain yield was on average 30%. Heterosis for biomass yield and biomass yield per day was on average also positive in all three zones. For all traits, except time to flowering and biomass yield per day, pollinator effects were the only significant source of variation. Differences between hybrids were mostly caused by additive genetic effects. Significant amount of heterosis observed in landrace-based topcross hybrids for grain yield and other productivity-related traits suggested that substantial improvement in pearl millet productivity in and environments can be obtained by topcrossing locally adapted landraces on suitable male-sterile lines. This revised version was published online in July 2006 with corrections to the Cover Date.     

转Bt抗虫棉与常规棉品种间配合力分析及杂种优势研究

 利用6个抗虫棉品种作母本,4个常规品种作父本,按NCⅡ设计,对24个组合的杂种F₁进行了分析。结果表明,杂种F₁具有明显的优势,所研究的13个性状全部具有中亲优势,9个性状具有高亲优势,11个性状具有竞争优势。配合力分析的10个性状中单株铃数、铃重、纤维长度、纤维伸长率和麦克隆值主要受基因的加性效应控制,而子棉产量和皮棉产量主要受基因的非加性效应影响。鲁棉研17是优良的抗虫棉亲本,而冀棉12 是良好的非抗虫棉亲本,组合鲁棉研17×中棉所12在重要农艺性状上优势明显,相对而言纤维品质的改良较难。     

标记型柱头外露种质系与陆地棉亲本间杂种优势与配合力分析

采用ＮＣⅡ遗传交配设计,对５份标记型柱头外露种质系和３份陆地棉亲本交配后,杂种Ｆ１的１１个性状的杂种优势和配合力进行了分析。结果表明,主要产量性状霜前皮棉产量,超高优势的幅度为－２８．８８％～１３．１７％,平均为－３．０６％,６个组合具正向的杂种优势;中亲优势的幅度为１８．１４％～８０．１２％,平均为５３．０８％,１５个组合均具有正向的中亲优势;竞争优势的幅度为－１５．３２％～４６．４３％,平均为１１．２７％,１０个组合具有正向的竞争优势。其它产量性状中单株铃数的杂种优势最为明显。纤维品质性状,２．５％跨长和比强度的优势明显,麦克隆值的负向优势明显。高亲值、中亲值和低亲值与Ｆ１平均值的相关关系表明,多数产量性状Ｆ１代平均值与高亲值相关性密切,因此在组合筛选时应注意对常规亲本的选择。配合力上,ＧＣＡ效应显著的性状,中棉所１９和石３２１分别在产量、品质性状方面表现较优,９６－１、９６－６７、９６－３３等３份标记型柱头外露种质系表现较优;ＳＣＡ效应显著的８个性状中,Ａ１Ｂ２８个性状的ＳＣＡ效应值均为正,Ａ２Ｂ２和Ａ４Ｂ１均有７个性状的ＳＣＡ效应为正。文中对标记型柱头外露种质及亲本选配等问题进行了讨论。