Limited contribution of water availability in genotype-by-environment interaction in sugarcane yield and yield components

Water deficit is an important abiotic stress factor limiting sugarcane production. Understanding the effect of water deficit on cane yield, yield components and genotype × environment (G × E) interaction can aid in selecting genotypes that are adapted to water deficit conditions. In this study, response of cane yield and yield components of 10 sugarcane genotypes grown under 3 irrigation treatments—fully irrigated, semi-irrigated and rainfed—was examined across 3 locations and 3 crop-years within each location. Cane yield reduced by 32% and 9% in the rainfed and semi-irrigated treatments, respectively, compared to the fully irrigated treatment. Genotypic variation was highly significant for cane yield and yield components in all three irrigation regimes. Cane yield in the rainfed treatment showed significant genetic correlation with stalk diameter (r_g = 0.68), leaf number (r_g = 0.64), node number (r_g = 0.67) and stalk number (r_g = 0.68). Genotype × irrigation variance was negligible compared to genotype, genotype × location and genotype × crop-year variances. Commercial genotypes had higher yield in most environments except in low-yield potential environments, which caused a significant genotype × location × irrigation effect, suggesting opportunities for improving sugarcane productivity in these environments.     

Genotype × environment interaction for yield and reaction to leaf spot infections in groundnut in semiarid West Africa

Capitalizing on the yield potential in available groundnut germplasm, and high stability of kernel yield are important requirements for groundnut producers in semiarid environments. Forty-seven groundnut genotypes were evaluated from 2003 to 2005 at 4 locations representative of the Guinea and Sudan savanna ecologies in Ghana. The objectives were to assess genotypic differences in reaction to early and late leaf spot infections under natural field conditions, assess the extent of genotype × environment (G × E) interaction for kernel yield, and determine the relationship between yield potential and yield stability. Genotypes differed significantly in their reaction to leaf spot infections indicated by the area under disease progress curve (AUDPC). Genotypic AUDPC was negatively correlated with maturity period (P < 0.01), with kernel yield (P < 0.05) at each of the 3 locations in the Guinea savanna ecology but not in the Sudan savanna ecology and with each of four stability parameters (P < 0.05). High or low yielding genotypes were grouped based on Dunnett’s test at P < 0.10. High yielding groups had significantly low AUDPC, high biomass, high partitioning of dry matter for kernel growth, and were later in maturity compared to low yielding genotypes. Significant G × E interaction effect for kernel yield was dominated mainly by the lack of correlation among environments variance (76–78%) relative to the heterogeneity of genotypic variance component (22–24%). Stability of yield assessed through the among-environment variance, Wricke’s ecovalence, and Finlay-Wilkinson regression coefficient revealed that genotypes in the higher yielding group were relatively unstable compared to the low yielding group. Indicated by the Kataoka’s index of yield reliability, however, relatively unstable genotypes in the high yielding group are expected to be more productive even under assumptions of high risk aversion (P = 0.75–0.95) compared to the more stable, low yielding genotypes. The findings indicate that deploying these recently developed germplasm in semiarid regions in West Africa provides a better match to farmers’ risk-averse strategies compared with the use of existing earlier maturing cultivars.     

Multi-attribute responses of maize inbred lines across managed environments

In maize (Zea mays L.) breeding programs, selection among and within segregating progenies is based mainly on indirect selection criteria. A better understanding of the environment influence on physiological attributes of maize inbred lines is important to the identification and selection of superior inbred lines as well as to successful hybrid seed production. In this study, the size and form of genotype (G) and genotype × environment (G × E) interaction effects for plant grain yield (PGY) and several physiological attributes were examined for 12 maize inbred lines grown in four managed environments, represented by two seasons (Y) and two nitrogen levels. Mixed model analysis revealed that the G effect was relatively high for attributes related to light capture, phenology, early biomass production, and numerical components of PGY. The G × E interaction effect explained most of the variability for PGY, harvest index (HI), and biomass production at maturity. Three-mode principal component analysis allowed us to: (1) describe the associations among multiple attributes across environments, (2) reveal the form of the main patterns of G × E interaction, (3) establish the importance of the genotype × year (G × Y) interaction for kernel number, HI, and biomass at maturity in determining PGY, (4) identify promising genotypes of high-PGY across environments, and (5) detect genotypes of similar response patterns for PGY but with a contrasting relative behavior for other attributes, which may permit the simultaneous selection for grain yield and desired secondary traits. Such selection results would contribute greatly in the identification of superior inbreds than selecting for grain yield alone.

White lupin (Lupinus albus) variation for adaptation to severe drought stress

This study aimed to reduce the gap of knowledge on white lupin drought tolerance variation, by assessing the grain yield of 21 landraces from major historical cropping regions, one variety and two breeding lines in a large phenotyping platform that imposed controlled severely stressed or moisture‐favourable conditions after an initial stage of favourable growth. Drought stress reduced grain yield by 79%. Genetic correlation coefficients indicated moderate consistency of genotype responses across conditions for grain yield (r_g = 0.76), fairly high consistency for straw yield (r_g = 0.85) and harvest index (r_g = 0.91), and high consistency for flowering time (r_g = 0.99). However, low genetic correlation for yield (r_g = 0.31) occurred among a subset of genotypes with early phenology. Specific adaptation to either condition implied significant (p = 0.05) genotype × condition interaction of crossover type between well‐performing genotypes. Early flowering was an important stress escape mechanism, but intrinsic drought tolerance could be inferred from responses of a few genotypes. Various landraces out‐yielded the improved germplasm under stressed or favourable conditions.     

257份菊芋种质资源表型性状的遗传多样性

为有效利用我国菊芋种质资源的遗传多样性,分析了257份菊芋种质资源,表明12个数量性状的变异系数(CV)在6%～50%之间,平均为24.75%,单株块茎重的变异系数最大(50%),生育期的变异系数最小(6%),多样性指数(H')分布在1.24～1.53之间,平均为1.44,单株块茎数的多样性指数最高(1.53),叶宽的多样性指数最低(1.24);8个质量性状的多样性指数在0.85～1.08之间,平均为0.98,以块茎习性最大,块茎整齐度最小,大部分性状表现出丰富的遗传多样性; 257份菊芋资源的隶属函数均值介于0.12～0.58之间,其中JA1095材料最高(0.58),其花数和单株块茎重具有明显优势。菊芋资源12个数量性状的相关性分析表明,茎粗、叶长、花和花盘大小可作为今后选育高产菊芋品种的指导目标性状;主成分分析结果表明,7个主成分因子的累计贡献率达66.794%,其中花数量、单株块茎数量、块茎毛根量、块茎表皮光滑程度4个性状是构成菊芋种植表型差异的主要因素;以20个性状为基础的聚类分析将257份种质材料分为5类,其中,第I类和第II类占总资源量的85%。本研究结果为菊芋种质资源的利用及品种选育等提供了重要参考。     

Effect of environmental variables on performance of Jerusalem artichoke (<Emphasis Type="Italic">Helianthus tuberosus</Emphasis> L.) cultivars in a long term trial: a statistical approach

Tuber yield, together with tuber number and size are the basic agronomic and breeding traits in Jerusalem artichoke and can be significantly affected by environmental factors. We report the results of a long term trial on the performance of 20 Jerusalem artichoke cultivars. The random model for means with restricted maximum likelihood (REML) procedure was used to estimate the overall effects of the genotype, environment and genotype by environment interaction on traits. The partial least square regression (PLSR) model was used for modeling genotype by environment interaction variance components with a set of available correlated environmental variables. The REML variance component estimates model revealed that tuber number and yield are more dependent on GE interaction which allowed identification of best genotypes for specific environments. The PLSR model revealed that the most important climatic variables for optimal emergence, canopy development, high tuber number and yield are adequate soil and air temperatures in April. For larger tuber mass, precipitation variables and even distribution of rainfall were the most important factor, together with soil and air temperature in June when tuber growth is initiated. The knowledge obtained in this study is valuable for the identification and understanding of key environmental factors that contribute to the performance of Jerusalem artichoke.     

Comparison of shifted multiplicative model,rank correlation,and biplot analysis for clustering winter wheat production environments

Categorization of locations with similar environments helps breeders to efficiently utilize resources and effectively target germplasm. This study was conducted to determine the relationship among winter wheat (Triticum aestivum L.) yield testing locations in South Dakota. Yield trial data containing 14 locations and 38 genotypes from 8 year were analyzed for crossover genotype (G) × environment (E) interactions according to the Azzalini-Cox test. G × E was significant (P < 0.05) and contributed a small proportion of variation over the total phenotypic variation. This suggested that for efficient resource utilization, locations should be clustered. The data were further analyzed using the Shifted Multiplicative Model (SHMM), Spearman’s rank correlation and GGE biplot to group testing locations based on yield. SHMM analysis revealed four major cluster groups in which the first and third had three locations, with four locations in each of the second and fourth groups. Spearman rank correlations between locations within groups were significant and positive. GGE biplot analysis revealed two major mega-environments of winter wheat testing locations in South Dakota. Oelrichs was the best testing location and XH1888 was the highest yielding genotype. SHMM, rank correlation and GGE biplot analyses showed that the locations of Martin and Winner in the second group and Highmore, Oelrichs and Wall in the third group were similar. This indicated that the number of testing locations could be reduced without much loss of grain yield information. GGE biplot provided additional information on the performance of entries and locations. SHMM clustered locations with reduced cross-over interaction of genotype × location. The combined methods used in this study provided valuable information on categorization of locations with similar environments for efficient resource allocation. This information should facilitate efficient targeting of breeding and testing efforts, especially in large breeding programs.     

Genetic variability and interrelationships of seed yield and yield components in switchgrass

Information on the genetic variability of seed yield and yield components is limited and no information is available on correlations among seed yield and yield components and direct and indirect effects of the yield components on seed yield in switchgrass, Panicum virgatum L. Accordingly, we conducted replicated experiments at Chickasha and Perkins, OK, in 1998 involving 11 lowland type switchgrass populations to assess genetic variation for seed yield and yield components, quantify interrelationships among them, and determine direct and indirect effects of yield components on seed yield through path coefficient analysis to identify traits for indirect selection of seed yield. Significant (P ≤ 0.01) variation existed among the 11 populations over locations for percent seed set and 100-seed weight. Seed yield/plant and the seed yield components panicle number/plant, spikelet number/panicle, and seed number/panicle had significant (P ≤ 0.05) population × location interactions, indicating substantial environmental influence on these traits for these populations. Accordingly, data for these traits were analyzed separately for each location revealing significant (P ≤ 0.01) differences among populations at both locations for each of these traits. Phenotypic correlation between seed yield/plant and seed number/panicle was positive (r = 0.76** at Chickasha and r = 0.72** at Perkins). Path coefficient analyses revealed that seed number/panicle had the highest positive direct effect on seed yield at both locations. Ample genetic variability was present among the switchgrass populations studied to allow breeding improvement of seed yield. Selection for increased seed number/panicle would be the most effective means of indirectly selecting for higher seed yield within this germplasm. Correlation and path coefficient analyses among biomass yield, seed yield, and harvest index indicated that, at least within the switchgrass germplasm studied, it would be possible to breed switchgrass cultivars with enhanced biomass yielding ability and sufficient seed production capability for their commercial propagation.     

Yield stability studies of soybean (Glycine max (L.) Merrill) under rhizobia inoculation in the savanna region of Nigeria

Soybean (Glycine max (L.) Merrill) production is expanding into temperate and tropical environments. Yield stability studies under rhizobia inoculation were investigated in 24 soybean genotypes over two successive growing seasons at three agro‐ecological zone of Nigeria, during the 2015–2016 rainy seasons. Treatments were arranged in a split‐plot design and replicated three times. Treatments were 24 soybean genotypes and three levels of rhizobia inoculation. Results indicated that the variation of genotypes and inoculation on percentage emergence, height, number of leaves, number of branches per plant, total biomass yield, above‐ground biomass and seed yield was significant (p = .05). The effects of genotypes (G), environment (E) and G × E interactions on seed yield were also significant. Two soybean genotypes (TGx 1989‐45F and TGx 1990‐110FN) were identified as the most promising in relation to yield stability. Of the three locations, Abuja produced the least interaction effects followed by Igabi and may be most appropriate environments for large‐scale soybean production. Appropriate inoculation of soybean with inoculants (LegumeFix and or NoduMax) should be encouraged in farmer's field.     

Genotypic and bio-agronomical characterization of an early Sicilian landrace of globe artichoke

In Sicily, the increasing use of exotic globe artichoke germplasm is eroding the presence of autochthonous landraces, including the long established ‘Violetto di Sicilia’. Ten clones have emerged from a clonal selection programme in this landrace, and here we describe the variation that they capture both at the level of AFLP-based genotype and phenotypically with respect to key productivity traits, on the basis of two seasons of field evaluation. The clonal selections yielded, on average, 8.9 heads per plant (equivalent to a fresh weight yield of 1.28 kg). Two clones yielded particularly well in both growing seasons (10.6 heads, equivalent to 1.46 kg per plant), while another pair produced particularly large heads (on average 165 g) and a high receptacle incidence (on average 19.3 g 100 g⁻¹ fresh weight). Both the number of days to first harvest and the quantity of head dry matter were subject to a significant degree of ‘clone × year’ interaction. Yield, the number of heads per plant and receptacle incidence were associated with a moderate (0.30–0.53) broad sense heritability, indicating that these traits could be successfully improved by phenotype-based clonal selection. AFLP fingerprinting was able to discriminate between all the clones, based on only three primer combinations. A principal component analysis based on the AFLP fingerprints was used to compare the selected clones with a set of individuals chosen on the basis of maximum genetic diversity. This comparison suggested that the new clone set was representative of the genetic variation present in ‘Violetto di Sicilia’, because the diversity captured by the two sets was largely overlapping, confirming the possibility of carrying out clonal selection in this globe artichoke landrace without compromising its preservation in situ.     

Genetic Variability for Mineral Concentration in the Forage of Jerusalem Artichoke Cultivars

Summary One of the potential uses of Jerusalem artichoke (Helianthus tuberosus L.) is as a forage crop. Information on inherent differences in forage nutritional quality is essential if the quality of the forage is to be improved through breeding. The objectives of this study were to determine the genotypic variability among and within forage of Jerusalem artichoke cultivars for the concentration of N, P, Ca, Mg, K and the Ca/P ratio at flowering, to determine if selection among and within cultivars is feasible, to estimate the magnitude of the genotype × environment interaction, and to examine the relationships among mineral concentrations in the forage. Ten cultivated Jerusalem artichoke cultivars grown in an irrigated field nursery at Bushland, TX were evaluated for N, P, Ca, Mg, K, and the Ca/P ratio in the forage at flowering over a 2-yr period. Cultivars, cultivar × year, and error variances were estimated to calculate the phenotypic variance. Estimates of the within-population variances were also determined. The adequacy of Jerusalem artichoke forage at flowering for maintenance of a ruminant animal was classified as follows: N, Ca, Mg, K as adequate, P inadequate, and the Ca/P ratio as excessive. There were genotypic differences among the ten cultivars for N, P, Ca, Mg, K, and the Ca/P ratio for both years and averaged across years. The magnitude of the genotypic variance components indicated that a substantial proportion of the total variation for these elements was due to cultivar, indicating the possibility of improving these elements. However, further studies on heritability and response to selection will be required before conclusions can be reached concerning the likelihood of successfully breeding for these traits.     

Effect of recombination in the maize breeding population with exotic germplasm on the yield stability

A little knowledge exists about the probability that recombination in the parental maize populations will enhance the chances to select more stable genotypes. The synthetic parent maize population ((1601/5 × ZPL913)F₂ = R₀) with 25% of exotic germplasm was used to assess: (i) genotype × environment interaction and estimate stability of genotypes using nonparametric statistics; (ii) the effect of three (R₃) and five (R₅) gene recombination cycles on yield stability of genotypes; (iii) relationship among different nonparametric stability measures. The increase of mean grain yield was significant (P < 0.01) in the R₃ and R₅ in comparison to the R₀, while it was not significant between R₃ and R₅. Analysis of variance showed significant (P < 0.01) effects of environments, families per set, environment × set interaction, family × environment interaction per set on grain yield. The non-significant noncrossover and significant crossover (P < 0.01) G × (E) interactions were found according to Bredenkamp procedures and van der Laan-de Kroon test, respectively. The significant (P < 0.01) differences in stability were observed between R₀-set 3 and R₅-set 3 determined by S_i⁽³⁾ S_{i}^{(3)} , R₃-set 1 and R₅-set 1 determined by S_i⁽³⁾ S_{i}^{(3)} (P < 0.05), and R₀-set 3 and R₅-set 3 determined by S_i⁽⁶⁾ S_{i}^{(6)} (P < 0.05). The significant parameters were those which take into account yield and stability so the differences could be due to differences in yield rather than stability. Findings can help breeders to assume the most optimum number of supplementary gene recombination to achieve satisfactory yield mean and yield stability of maize genotypes originating from breeding populations.     

Genetic analysis and genotype × environment (G × E) for grey leaf spot disease resistance in elite African maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) germplasm

Maize grey leaf spot (GLS) disease remains an important foliar disease in sub-Saharan Africa accounting for more than 25% yield losses in maize. Information on inheritance of GLS resistance of germplasm adapted to African environments is required in new sources being identified. Therefore, hybrids generated from a 10 × 10 half-diallel mating of tropical advanced maize inbred lines were evaluated in six environments to determine combining ability, genotype × environment interaction (G × E) and the impact of GLS disease on grain yield. General combining ability effects were highly significant and accounted for 72 and 68% of the variation for GLS resistance and grain yield, respectively. Significant specific combining ability effects associated with reduced disease levels were observed in some hybrids when one parent was resistant, and these may be exploited in developing single cross maize hybrids. Regression analysis showed a 260–320 kg ha^?1 decrease in maize grain yield per each increase in GLS disease severity score, and significant associations (r = ?0.31 to ?0.60) were observed between grain yield and GLS severity scores. This showed the potential of GLS disease to reduce yield in susceptible varieties grown under favourable disease conditions, without control measures. Genotype and genotype × environment biplots and correlation analysis indicated that the significant G × E observed was not due to changes in hybrid ranking, implying absence of a significant crossover interaction. Therefore, predominance of additive gene effects imply that breeding progress for GLS disease resistance would be made through selection and this could be achieved at a few hot-spot sites, such as Baynesfield and Cedara locations in South Africa, and still deploy the resistant germplasm to other environments in which they are adapted.     

Changes in the concept of genotype × environment interactions to fit agriculture diversification and decentralized participatory plant breeding: pluridisciplinary point of view

The standardization of environments (E) encouraged by modern society and by the productivist model of agriculture has resulted in the standardization of genotypes (G) thereby reducing G × E interaction. New societal values call for the diversification of agriculture to fit contrasted environments. This process can be depicted by four models defined by two axes, one socio-economic (individual logics versus collective governance), and the other agro-ecological (reductionist versus systemic approaches). These models differ in (i) their objectives (from improvement in yield to the empowerment of farmers), (ii) their specific expectations with respect to genotypes (from inherited genetic resources to varieties that represent genetic, ethical and social progress), (iii) their specific representations of the environment (E) (from a simple interaction between the bio-physical environment (B) and the crop management (C), to a complex interaction including the competences of the actors (A), outlets (O), regulations (R), society (S)), (iv) their particular relations between G and E (from G × E to G × B × C × A under evolving constraints represented by R × O × S). Taking this diversity into account changes the way plant improvement is considered. Thus, depending on the model, the order, interest and status of the five classic stages of plant improvement (setting objectives, creating variability, selecting, evaluating and disseminating) may be called into question. Between the existing analytical model (Model I) and a holistic model (Model IV) which remains to be developed, lies the challenge of ensuring the sustainability, efficiency and acceptability of plant breeding and resulting innovations. From a simple “statistical parameter” that we, as plant breeders, attempt to reduce, the G × E interaction is becoming an “objective” that we try to predict and valorize. Structuring the different components of E, G and G × E, enables us to extend the basic concept of representivity to both the cultivation conditions and the relational socio-economic positions of the actors involved.

Relationship between the first and second crops and estimation of genetic parameters of the second crop on the nutritive value of timothy (<Emphasis Type="Italic">Phleum pratense</Emphasis> L.)

Improvement of the nutritive value of timothy (Phleum pratense L.) through breeding should result in enhanced livestock productivity. This study investigated the extent of genotype × crop interaction (G × C) between the first and second crops, and the extent of genotype × year interaction (G × Y) and narrow-sense heritability (h _N²) of the second crop of the nutritive value of timothy. Twenty-six clones were used to evaluate these interactions in 2007 and 2008, and 17 clones and their half-sib progeny were used to evaluate the h _N² in 2010 in Kunneppu, Japan by analyzing their nutritive value. The content of water-soluble carbohydrate (WSC) was significantly correlated between the two crops in 12 clones with many internode elongation stems (IES) in the second crop and the 2 years, with non-significant effects of G × C in these clones and G × Y. However, the low-digestible fiber (Ob) content and the ratio of Ob to organic cell wall showed weak to medium correlations between the two crops, regardless of IES ratio or the elapsed time of 2 years, with significant effects shown for the two interactions. The h _N² of the three traits was medium to high. These results suggest that, in the second crop, selections for WSC content through the first crop in genotypes with many IES in the second crop, and under multiple environments in other traits are potentially useful; and that recurrent selection which utilizes an additive genetic variance is likely to be effective for the three traits.     

Diallel analysis of grain yield and resistance to seven diseases of 12 African maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) inbred lines

Maize (Zea mays L.) is grown on 15 million ha in eastern and southern Africa. Several diseases are of common occurrence in the region and regularly result in significant yield losses. A collaborative regional disease nursery (REGNUR) project was initiated in 1998 to identify and increase access to disease resistant germplasm, generate and disseminate information on disease and insect resistance sources, and facilitate the development of resistant cultivars by project partners. A diallel among 12 elite inbred lines was formed with the specific objective of evaluating the combining ability of these inbred lines for grain yield and resistance to seven diseases. The trial was grown at six sites in 2001. Results showed that both general (GCA) and specific combining ability effects were significant for most diseases. On the average, GCA accounted for 69% of resistance to diseases and only 37% of variation for grain yield. Correlations between GCA effects for disease scores were generally non-significant, implying that it is possible to pyramid genes for disease resistance in inbred lines. This underscores the need for screening for resistance to prevailing diseases using artificial inoculation or reliable hot-spots. Based on GCA effects for grain yield and across diseases, P12 and P6 were the best inbred lines. The crosses P4 × P9 (6.7 t ha⁻¹) and P4 × P12 (6.9 t ha⁻¹) were the best hybrids in the earlier maturity group, while P3 × P9 (8.3 t ha⁻¹) and P2 × P8 (7.4 t ha⁻¹) were the best hybrids in the late maturity group.     

半干旱地区菊芋品系植株表型与光合特性分析

为了加快半干旱地区的新型资源作物菊芋品种的选育进程,探讨菊芋产量及相关性状表型和光合生理基础是必要的。选用本课题组收集和培育的4个品系( 2个高产,2个低产品系),设置随机区组试验,比较菊芋高产和低产品系与产量形成相关的生物量累积、植株表型和光合特性的差异。结果表明,高产菊芋品系的地上生物量、块茎产量及根生物量显著高于低产品系;高产品系整体表现出明显的生长优势,其株高、基径、叶面积和叶片数均显著高于低产品系。气体交换参数分析表明,高产品系的光补偿点和暗呼吸速率显著小于低产品系,而其他各项参数差异不显著。相关性分析表明,菊芋块茎产量与株高、基径、叶面积、叶片数、地上生物量和根生物量呈显著正相关,而与光补偿点和暗呼吸速率呈显著负相关。建议多的叶片数、大的叶面积和发达的根系作为半干旱地区菊芋高产品系田间选育指标,而低的光补偿点和暗呼吸速率在高产品系选育中也具参考价值。     

Coagulable protein in potato: Screening method and prospects for breeding

Summary From tubers of 34 varieties of Solanum tuberosum, extracts were prepared and analysed for crude protein and coagulable protein by the Kjeldahl method. Content of coagulable protein was 0.37–1.24%. From the same material, juice was prepared with a juice centrifuge and analysed for coagulable protein by the Kjeldahl and microbiuret method. The average amount of coagulable protein in the juice was 81.8% of the total coagulable protein. The correlation coefficient between coagulable protein in the juice and total coagulable protein was 0.956. The correlation coefficient between Kjeldahl and microbiuret data for coagulable protein in the juice was 0.956. Analysis of tuber juice by the microbiuret method is recommended as a rapid screening technique for coagulable protein.Relationships between protein data of the 34 varieties and earliness, yield and content of dry matter were analysed statistically. Content of coagulable protein in fresh material correlated with content of dry matter (rs=–0.756), yield of fresh potatoes (r=–0.615) and earliness (r=–0.361) but not significantly with yield of dry matter (rs=–0.309). Coagulable protein in dry matter correlated with fresh yield (r=–0.525), but not significantly with content of dry matter (r=–0.260), yield of dry matter (r=–0.131) and earliness (r=–0.054). Path coefficient analysis showed that 67% of the variation in coagulable protein in fresh material was statistically determined by earliness, content of dry matter, fresh yield and content of uncoagulable protein in fresh material, whereas only 34% of the variation in content of coagulable protein in dry matter was determined by these components. A high content of coagulable protein in fresh or dry matter can be combined with early maturity and with high yield of dry matter. Coagulable protein in dry matter seems to be a more suitable criterion of selection than coagulable protein in fresh material.     

Mineral bioavailability in grains of Pakistani bread wheat declines from old to current cultivars

Estimating variation in grain mineral concentration and bioavailability in relation to grain yield and the year of cultivar release is important for breeding wheat with increased content of bioavailable minerals. The grain yield and yield components, grain phytate concentration, and concentration and bioavailability of minerals (zinc Zn, iron Fe and calcium Ca) in wheat grains were estimated in 40 wheat cultivars released in Punjab (Pakistan) during the last five decades. Mean grain Zn and Ca concentrations in current-cultivars were significantly lower (≥14%) than in obsolete cultivars released during the Green Revolution (1965–1976). Much of this variation was related to increased grain weight in current-cultivars. There was a positive correlation among minerals (r = 0.39 or higher, n = 40) and minerals with phytate in wheat grains (r = 0.38 or higher, n = 40). The tested cultivars varied widely in grain yield and grain phytate-to-mineral molar ratios (phytate:mineral). Compared to obsolete cultivars, the current-cultivars had a higher phytate:mineral ratio in grains, indicating poor bioavailability of minerals to humans. The study revealed a non-significant relationship between grain yield and phytate:mineral ratios in grains. Therefore, breeding for lower phytate:mineral ratios in wheat grains can ensure increased mineral bioavailability without significant reduction in the yield potential. Future breeding should be focused on developing new genotypes suitable for mineral biofortification and with increased mineral bioavailability in grains.     

Identification of QTL underlying the filling rate of protein at different developmental stages of soybean seed

Seed protein content at the harvest stage is the sum of protein accumulation during seed filling. The aim of our investigation was to identify loci underlying the filling rate of seed protein at different developmental stages. To this end, we used 143 recombinant inbred lines (RILs) derived from the cross of soybean cultivars ‘Charleston’ and ‘Dongnong 594’ and composite interval mapping with a mixed genetic model. The genotype × environment interactions of the quantitative trait loci (QTL) were also evaluated. Thirty-nine unconditional QTL underlying the filling rate of seed protein at five developmental stages were mapped onto 14 linkage groups. The proportion of phenotypic variation explained by these QTL ranged from 4.88 to 26.05%. Thirty-eight conditional QTL underlying the filling rate of seed protein were mapped onto 16 linkage groups. The proportion of phenotypic variation explained by these QTL ranged from 1.87 to 31.34%. The numbers and types of QTL and their genetic effects on the filling rate of seed protein were different at each developmental stage. A G × E interaction effect was observed for some QTL.