Comparing decentralized participatory breeding with on-station conventional sorghum breeding in Nicaragua: I. Agronomic performance

Few studies have assessed the effective gains achieved by collaborative decentralized participatory breeding, in terms of yield and other agronomic traits, in comparison with centralized conventional breeding using the same breeding schemes. Our study concerned an experience of participatory improvement of tortillero sorghum for low-input cropping systems in northern Nicaragua. It set out to compare the effect of two breeding schemes simultaneously managed on-station and on-farm. Two synthetic populations were used as sources of genetic variability. The study was designed to distinguish between three “selection modes”: farmers’ selection on-farm (FoF), breeder’ selection on-station (BoS) and breeder's selection on-farm (BoF). After two selection cycles, we found that FoF selection reduced phenotypic variability as much as BoS selection. In general, BoS selection produced higher-yielding lines under the target on-farm conditions. But FoF selection was more effective in promoting lines with higher values for an index of agronomic suitability (IAS), expressing a better balance between earliness, plant height, grain size and yield. Such genotypes might cope more easily with local environmental constraints and farmers’ preferences. BoF selection did not prove to be effective for either yield or IAS. This research shows the need for close collaboration between farmers and breeders as well as complementarities between the selection phases managed on-farm and on-station, to make breeding for difficult environments fully efficient.     

水稻杂种后代籽粒直链淀粉含量选择与品质和产量性状的关系

 选用4个稻米直链淀粉含量有显著差异的粳稻品种配制两个杂交组合（系选1号×通769和东农423×藤系180）,研究其杂交后代籽粒直链淀粉含量选择对品质和产量性状的影响。结果表明,籽粒直链淀粉含量选择对杂种后代蒸煮食味品质和产量相关性状有不同程度的影响,其影响程度因杂交组合及性状不同而异;在蒸煮食味品质性状中,淀粉黏滞性谱的崩解值和消减值受直链淀粉含量选择的影响较大,而在产量相关性状中抽穗期、单株有效穗数、结实率、单株粒重等受直链淀粉含量选择的影响相对较大;通过直链淀粉含量的连续定向选择可以从杂种后代中分出直链淀粉含量不同的后代,粳稻杂种后代低直链淀粉含量的定向选择效果优于高直链淀粉含量的选择效果,更容易得到超低亲的变异类型;直链淀粉含量的选择对杂种后代产量性状的影响较复杂,存在有利或不利的影响,低直链淀粉含量的选择将会导致单株粒重的下降。     

Agronomic performance of rice breeding lines selected based on plant traits or grain yield

Selection for yield per se has greatly contributed to yield improvement in many crops. It is expected that selection based on plant traits is more effective in increasing crop yield potential. This study was conducted to compare the effectiveness of trait-based and yield-based selection in increasing rice yield and to determine whether lines with ideotype traits have the potential to express higher yield under optimal crop management conditions. Lines were selected based on plant traits or on grain yield measured in a breeder's replicated yield trial. The main target traits for selection were plant height, leaf and panicle morphology, grain size, total dry weight, and grain-filling percentage. Yield performance of trait-based selection was compared with that of yield-based selection in an agronomic trial with optimum crop management for three seasons. Trait-based selection increased leaf area index and total dry weight but reduced spikelet number per m² and harvest index compared with yield-based selection. Consequently, selection based on plant traits did not increase grain yield compared with selection based on yield per se. In one of the three seasons, yield of trait-based selection was significantly lower than that of yield-based selection. Among all tested breeding lines, maximum yield was produced by yield-based selection and minimum yield came from trait-based selection. These results suggest that lines with ideotype traits did not express higher grain yield than lines selected based on yield per se under optimal crop management conditions, and yield-based selection was as effective in increasing rice grain yield as trait-based selection in the late generations of the breeding cycle.     

Genetic gain of Al tolerance and contribution of agronomic traits on Al tolerance in the early stage of sorghum breeding program

ABSTRACT

Genetic gain (GG), heritability and contribution of the agronomic traits on Al tolerance are precious information for selection strategy in the breeding of Al-tolerant sorghum. The objectives of this study were (i) to estimate the GG of Al tolerance in sorghum and (ii) to determine the direct effect of agronomic traits on Al tolerance through path analysis. Evaluation of agronomic characters used F₂, and F₃ sorghum progenies in field experiment and screening of Al tolerance used the hematoxylin-staining method. Three sorghum populations showed the low GG of Al tolerance (GG = 0.558–1.108). This result indicates that high allocation of progenies in the early stages of the Al-tolerant breeding program and high selection differential (sd) of Al tolerance should be applied to obtain a higher gain of Al tolerance. Selection pressure for early maturity (sd = ?2.942) and short plant height (PH) (sd = ?38.165) resulted in lower improvement of GG for Al tolerance. The high dry weight and tall PH provided a more genetic contribution to the advancement of Al tolerance. Based on the overall path analysis data, the increase of plant biomass, the significant number of progenies in the early stage of breeding and strong sd of Al tolerance would be more appropriate to improve the Al tolerance in sorghum.     

水稻粒型基因克隆研究进展及育种应用展望

水稻的育种目标包括高产和优质等。粒型是指籽粒的三维结构,是决定水稻产量的重要因素之一,也是影响稻米品质的重要性状。目前已经克隆了超过60个与水稻粒型相关的基因,但应用于育种的粒型基因尚无完整统计。本文综述了已克隆的水稻粒型基因特别是数量性状基因座的研究进展,归纳总结了可应用于水稻高产及优质分子育种的重要粒型基因的功能标记,介绍了粒型基因的育种应用现状,并对前景作了展望,以期为水稻育种家提供可直接利用的分子育种信息。     

Research Progress and Breeding Prospects of Grain Size Associated Genes in Rice

The breeding objectives of rice include high yield and good quality. Grain size is the three-dimensional structure of seeds, which is one of the key traits determining grain yield and quality in rice. To date, more than 60 genes associated with grain size have been cloned, but the application of grain size genes in rice breeding has not been summarized. This review covers the current advances which can deepen our understanding, such as the key genes for grain size, genetic mechanism behind this trait, breeding application of cloned genes, functional markers for molecular breeding and prospects for future study, which will provide information of molecular breeding for rice breeders.     

水稻粒形遗传与长粒型优质粳稻育种进展

水稻粒形遗传机制和粒形育种一直是水稻品质和产量研究的重要领域。在粳稻品种选育中,对长粒形遗传种质的选择,已经成为近年来一种新的育种趋势。我们在总结粒长及其相关性状的遗传研究进展和已知粒长相关基因功能的基础上,系统地介绍了南方稻区长粒粳稻的育种历程及其选育策略。同时,对以品种嘉禾218为代表的南方长粒晚粳稻系列品种农艺性状和品质特性进行了比较,在阐明长粒粳稻优质、高产的品种特点的同时,提出长粒晚粳育种中选择粒形、兼顾株型、保产提质的选育思路。     

Collaborative breeding with farmers can be effective

Plant breeding efficiency is increased by better taking into account the needs of the clients. This can sometimes be helped by involving farmers in selection in the segregating generations. We describe a rice-breeding programme in Nepal where the use of simple breeding methods optimised the benefits from such collaboration. Farmers grew in their fields large populations that were bulks derived from the F₂ generations of single crosses. They selected within them starting in a generation where selfing was sufficiently advanced for the between-plant heritability to be high. Poorer bulks were soon rejected by farmers. A high proportion selected within the bulks and a significant proportion did so over several generations. An increasing number of farmers grew the best of the selected bulks because they spread from farmer to farmer without the need of intervention from scientists. Varieties selected from these bulks were preferred by farmers in on-farm trials and had a superior combination of yield and maturity compared with the later breeders’ selection from the same bulk. Levels of participation were higher with the better performing bulks and even when training was not provided, provided the germplasm performed acceptably well sufficient farmers selected in the bulks to make collaborative breeding cost effective. Collaborative breeding can be successful but demands different types of resources than those for on-station breeding so its cost effectiveness will vary with circumstances. It can be used to increase the probability of selecting segregants that perform well across environments by using methods that pool bulks selected by different farmers and it is also extremely useful for decentralising breeding programmes.     

Breeding for micronutrient density in edible portions of staple food crops: conventional approaches

Current and past efforts in breeding for industrial quality (processing, malting, baking, extruding, etc.), as opposed to yield, are reviewed as a prelude to discussion of the criteria that need to be met in breeding programs to improve the nutritional quality of crops for human consumption. In field crops, almost no attempts to improve nutritional value have been made. Recent studies in fact indicate that most criteria can be easily satisfied: existence of sufficient genetic variation, suitable selection methods and markers, workable heritabilities, and compelling reasons for doing so. However, establishing the efficacy in deficient human populations of elite material chosen by simple selection criteria is a major challenge that requires collaboration with human nutritionists. In some cases, developing marketing strategies for nutritionally superior types that may not – by color or other characteristics – appeal to target communities is also an issue breeders must bear in mind. Nevertheless, the fact recently established that desirable traits can be combined with high yield overcomes many obstacles. The widely demonstrated acceptance of new cultivars by farmers, in developing as well as industrialized countries, will ensure high impact of worthwhile improvements in nutritional value. To combine these new traits with high yield will increase the cost of breeding programs considerably, but the benefit–cost ratio is likely to be larger also.     

基于多元线性回归的辽宁省中熟玉米品种产量相关性分析

[目的]明确影响中熟玉米品种产量的主要因素,为辽宁省中熟玉米品种选育和生产提供参考。[方法]根据2019年参加辽宁省中熟玉米区域试验种植的9个玉米新品种相关的农艺性状数据,利用多元线性回归法对玉米新品种的主要性状进行相关性分析,揭示其变化规律,为玉米农艺性状的选择提供参考。[结果]辽宁省中熟玉米品种与产量密切相关的农艺性状是百粒重、行粒数、出籽率、空秆率和穗长等;百粒重和行粒数是辽宁省中熟玉米杂交种选育的主要影响因素。[结论]在选育中熟玉米品种时,要在保证适当百粒重和果穗长度的前提下,注重选育出籽率高、空秆率低的品种。在高产玉米品种选育中应增强抗倒性、降低空秆率、提高出籽率,适当增加百粒重和穗粗,降低穗位高。     

Genotypic variation for grain and stover yield of dryland (rabi) sorghum in India: 1. Magnitude of genotype × environment interactions

Grain and stover yield are key traits for the improvement of rabi sorghum varieties and hybrids in India. Large genotype-by-environment interactions (GEI) were identified for both grain and stover yield based on 10 years’ data available from the All India Coordinated Sorghum Improvement Program (AICSIP) experiments conducted from 1986/87 to 1996/97. From the estimates of the genotypic, GEI and residual components of variance for the four traits, a multi-environment testing strategy based on 15–20 locations, 2–3 years, and two replicates per trial would be required to achieve estimates of repeatability of approximately 0.70 for grain yield, 0.45 for stover yield, 0.70 for flowering time, and 0.85 for plant height.     

不同生态类型大麦品种(系)杂交后代主要农艺性状的分析

为了解不同生态类型大麦品种(系)杂交后代主要农艺性状的分离规律,以美国引进的优质啤酒春大麦品系ABI 18-152为母本、江苏主推冬啤酒大麦品种扬农啤7号为父本配制的杂种F1、F2群体及亲本为材料,测定株高、穗长、穗下节间长、单株穗数、主穗粒数、千粒质量、单株产量、粒长、粒宽、粒长宽比10个农艺性状,对各性状的杂种优势及分离规律进行分析。结果表明:除主穗粒数和粒宽在亲本间差异不具统计学意义,其余8个性状在亲本间均具有统计学意义(P<0.05)或高度统计学意义(P<0.01)。杂种F1的10个性状大多存在正向中亲优势和负向高亲优势,优势大小在性状间存在较大差异。株高类性状和单株产量性状在杂种F2群体内变异程度高,变异系数均在10%以上,单株产量的变异系数最大(58.65%);籽粒粒型性状在杂种F2群体内的变异程度较低,其变异系数在5%左右,粒长的变异系数最小(4.52%)。降低单株株高,对影响单株产量的性状加强选择,可实现矮秆高产品种的选育。     

Agronomic performance and quality of oat (Avena sativa L.) genotypes of worldwide origin produced under Central European growing conditions

One hundred and twenty oat (Avena sativa L.) genotypes of worldwide origin were evaluated for agronomic and grain quality characters in three replicated field experiments in Austria and one in Germany. Panicle emergence, plant height and lodging severity were evaluated under field conditions, and grain yield, thousand kernel weight, hectolitre weight, screenings percentage > 2 mm, and groat percentage were measured after harvesting. Substantial genetic variation and high heritability were observed for all traits. The highest yielding entries were improved cultivars from European breeding programs. Groat yield and grain yield were highly correlated. For agronomic traits such as earliness and plant height, and quality traits such as groat percentage, several of the overseas genotypes, mostly from the USA and Canada, showed better performance than the European cultivars. Selected lines from the North American breeding programs appear to be valuable resources for European oat breeding programs, especially for the improvement of physical grain quality traits.     

黑龙江省不同生态区玉米杂交种主要农艺性状的遗传相关与通径分析

运用SPSS18.0对不同生态区玉米杂交种产量与主要农艺性状中的生育期、株高、穗位高、穗长,穗粗、秃尖长、穗行数、行粒数、百粒重和出籽率关系进行逐步回归分析和通径分析。结果表明,根据积温、地理和气候条件,黑龙江省试验二区在品种选育上应着重选择粗穗、长穗、行多和出籽率高的品种;黑龙江省试验四区在品种选育上应着重选择生育期适当、低穗位高和适当提高株高的品种;黑龙江省试验五区在品种选育上应着重选择粗穗、长穗、出籽率高和封顶性好的品种;黑龙江省试验六区在品种选育上应着重选择中长穗和封顶性好的品种。     

The role of physiological understanding in plant breeding; from a breeding perspective

The role of physiological understanding in improving the efficiency of breeding programs is examined largely from the perspective of conventional breeding programs. Impact of physiological research to date on breeding programs, and the nature of that research, was assessed from (i) responses to a questionnaire distributed to plant breeders and physiologists, and (ii) a survey of literature abstracts. Ways to better utilise physiological understanding for improving breeding programs are suggested, together with possible constraints to delivering beneficial outcomes. Responses from the questionnaire indicated a general view that the contribution by crop physiology to date has been modest. However, most of those surveyed expected the contribution to be larger in the next 20 years. Some constraints to progress perceived by breeders and physiologists were highlighted. The survey of literature abstracts indicated that from a plant breeding perspective, much physiological research is not progressing further than making suggestions about possible approaches to selection. There was limited evidence in the literature of objective comparison of such suggestions with existing methodology, or of development and application of these within active breeding programs. It is argued in this paper that the development of outputs from physiological research for breeding requires a good understanding of the breeding program(s) being serviced and factors affecting its performance. Simple quantitative genetic models, or at least the ideas they represent, should be considered in conducting physiological research and in envisaging and evaluating outputs. The key steps of a generalised breeding program are outlined, and the potential pathways for physiological understanding to impact on these steps are discussed. Impact on breeding programs may arise through (i) better choice of environments in which to conduct selection trials, (ii) identification of selection criteria and traits for focused introgression programs, and (iii) identifying traits for indirect selection criteria as an adjunct to criteria already used. While many breeders and physiologists apparently recognise that physiological understanding may have a major role in the first area, there appears to be relatively little research activity targeting this issue, and a corresponding bias, arguably unjustified, toward examining traits for indirect selection. Furthermore, research on traits aimed at crop improvement is often deficient because key genetic parameters, such as genetic variation in relevant breeding populations and genetic (as opposed to phenotypic) correlations with yield or other characters of economic importance, are not properly considered in the research. Some areas requiring special attention for successfully interfacing physiology research with breeding are discussed. These include (i) the need to work with relevant genetic populations, (ii) close integration of the physiological research with an active breeding program, and (iii) the dangers of a pre-defined or narrow focus in the physiological research.     

On-farm evaluation of the ‘push–pull’ technology for the control of stemborers and striga weed on maize in western Kenya

The ‘push–pull’ technology is a novel pest management strategy developed for control of stemborers and striga weed, Striga hermonthica, in maize-based farming systems in eastern Africa, where maize is intercropped with desmodium, a forage legume, and Napier grass is planted as a border crop. Desmodium repels stemborer moths while Napier grass attracts them. Desmodium also suppresses the parasitic striga weed through a series of mechanisms ranging from shading to allelopathy through the root system. The technology is currently being disseminated among smallholder farmers in eastern Africa and adoption rates are rising. Our on-station studies have reported efficacy of this technology against the two pests resulting in increased grain yields. The current study was conducted between 2003 and 2006 in 14 districts in western Kenya to assess effectiveness of the technology under farmers’ own conditions. Twenty farmers from each district, who had adopted the technology, were randomly selected for the study. Each farmer had a set of two plots, a ‘push–pull’ and a maize monocrop. Seasonal data were collected on percentage of maize plants damaged by stemborers, the number of emerged striga, plant height and grain yields. Similarly, farmers’ perceptions on the benefits of the technology were assessed using a structured questionnaire. Stemborer damage and striga counts to maize plants were significantly lower in the ‘push–pull’ plots than in the maize monocrop plots. Similarly, maize plant height and grain yields were significantly higher in the former. Farmers rated the ‘push–pull’ technology significantly superior in having reduced stemborers and striga infestation rates and increased soil fertility and grain yields. These results demonstrate that the technology is equally effective in controlling both pests with concomitant yield increases under farmers’ conditions in the districts studied.     

玉米氮高效组合杂种优势分析

在氮高效自交系筛选工作的基础上,利用NC-Ⅱ设计的材料进行杂种优势分析,同时探讨氮高效育种中亲本选配等问题。研究结果表明:氮高效类型中氮高效的生理机制各有特点,试验结果可以分为以吸收效率为主和以利用效率为主的两种杂交组合。总结亲本组成规律,氮高效组合的组配可分两大类型:①主要决定于母本的吸收和利用效率;②父母本的吸收效率和利用效率互补。所以,在氮高效育种中,要注重对母本氮效率性状的选择,尤其是氮吸收效率的选择以及亲本间氮效率性状的优势互补。在低氮条件下,注重选择母本穗粒重、行粒数、出籽率,父本的穗粒重、百粒重、穗粒数、株高、棒三叶叶面积等性状,同时考虑亲本的综合农艺性状,使氮高效组合的稳定性和适应性更强。     

Comparisons of tetraploid progenies of potato dihaploids,their chromosome-doubled derivatives and second generation dihaploids

Summary Comparisons were made between tetraploid progenies obtained by crossing dihaploid and chromosome doubled dihaploid potatoes with tetraploids. Dihaploids obtained from a doubled dihaploid produced some progenies from 2xx4x crosses which were as high yielding and had as good tuber characteristics as control progenies produced by intercrossing heterozygous tetraploids. It was found that there was a slight reduction in tuber yield associated with inbreeding but selection could be made among highly inbred material for useful parents. Other characters were little affected by inbreeding. It was concluded that haploidisation and chromosome doubling could be used to produce homozygous clones for use by breeders without greatly depressing the agronomic value of their offspring.     

Farmers’ perceptions,knowledge and management of aflatoxins in groundnuts (Arachis hypogaea L.) in India

Aflatoxins, produced by the fungi Aspergillus flavus Link ex Fries and Aspergillus parasiticus Speare, are the major toxins affecting the quality of groundnuts (Arachis hypogaea L.) meant for human consumption. Groundnuts can be infected with aflatoxin-producing fungi pre-harvest, at harvest and post-harvest. This survey was conducted in Gujarat province in India in order to assess farmers’ and other stakeholders’ (extension staff and traders) perceptions and knowledge of aflatoxin contamination of groundnuts and to evaluate the agronomic and market practices used to manage it. The survey investigated the effects of the socioeconomic background of the farmers. The results showed that the socioeconomic and psychological characteristics, viz. education, caste, farm size, social participation, extension participation, market orientation, economic motivation, innovativeness and perception had positive and significant associations with farmers’ knowledge. The extension staff and traders had a good understanding of the problem and of the importance of managing aflatoxin contamination but farmers did not. Farmers’ who practised effective crop husbandry in order to increase production were unwittingly managing aflatoxin contamination to some extent. Their marketing practises showed that the problem of aflatoxin contamination was neglected at both the production and marketing stages. We suggest that extension agencies need to train farmers in the use of biological control agents, post-harvest management and identification of aflatoxin contamination. Partnerships need to be forged between research institutions, the departments of agriculture of various states, marketing agencies, NGOs, farmers’ groups, consumer groups, agrochemical manufacturers and other stakeholders in order to develop strategies for addressing the problem of aflatoxin contamination.     

引进甘蔗种质资源杂交后代适应性评价

通过对引进甘蔗种质资源24个杂交后代的的10个农艺性状进行主成分分析、回归分析与通径分析,科学评价引种甘蔗种质资源在广西本地的农艺性状表现,探究各农艺性状间的协同制约关系,为甘蔗种质资源的精准评价和杂交育种材料的科学选配提供理论依据。结果表明:(1)主要农艺性状变异系数为6.79%~29.44%,24个甘蔗种质在分蘖和蔗糖产量上有较大的遗传改良潜力。(2)主成分分析将这10个农艺性状凝聚成4个主成分,分别为产量因子、有效茎因子、糖分因子和出苗因子,贡献率分别是35.2%、16.5%、15.3%、12.1%,累计贡献率达到79.1%;(3)通径分析中各性状对糖产量的直接通径系数大小依次为:蔗茎产量(0.927)>蔗糖分(0.399)>单茎重(0.039)。表明:甘蔗品种(系)GUC23-1、GUC15-2、GUC23、GUC34、GUC25在广西的丰产性最优,在甘蔗引种和选育中,考虑将蔗茎产量、蔗糖分、单茎重作为主要选择性状。