Diallel analysis over two environments for blossom-end scar size in tomato

Summary To investigate genetic regulation of blossom-end scar size in tomato (Lycopersicon esculentum Mill.), a half diallel cross including 10 parents was grown under warm fall conditions in Bradenton, Florida, and cool winter conditions in Hazeva, Israel. The parents were a random sample representing all available fresh market tomato breeding lines commercially grown under subtropical field conditions. A randomized, complete block design with three replications was used and the blossom-end scar index (BSI), a measure for scar size relative to truit size, was measured on 40 and 25 fruits per plot in Bradenton and Hazeva, respectively. Analysis of variance for BSI indicated highly significant (P=0.001) variation among parents and among F1's in both environments. In Bradenton and Hazeva both, the difference in average BSI between parents and F1's was not significant suggesting insignificant overall dominance effects. Further partitioning of variation within F1's indicated that general combining ability (GCA) effects were highly significant in both environments, whereas specific combining ability (SCA) effects were significant at P=0.001 in Bradenton, but only at P=0.05 in Hazeva. Estimated variance components for GCA and SCA effects indicated that BSI inherited mainly additively in both environments. Analysis combined over environments indicated that variation in sensitivity to environments was 5-fold higher among parents than among F1's. The genotype x environment variance component was not large enough to justify testing over more than one environment for population improvement purposes and early testing of hybrids. Evaluation of inbred lines, however, may have to be done in more than one environment, especially for Suncoast-derived material. Under temperatures in Hazeva, genotype differences were more pronounced and heritabilities higher than under high temperatures in Bradenton. The estimated overall single plot heritability was 0.63. Breeding lines with a pointed blossom-end morphology (e.g. NC 8276 and NC 140 in this study) generally had small blossom-end scars, and intercrossing of these lines or crossing with non-pointed, moderately smooth breeding lines generally resulted in smooth hybrids.     

Studying the effect of environmental variables on the genotype × environment interaction of tomato

Genotype × environment interaction (GEI) affects marketable fruit yield and average fruit weight of both hybrid and open-pollinated (OP) tomato genotypes. Cultivars vary significantly for marketable fruit yield, with hybrid cultivars having, on average, higher yield than OP cultivars. However, information is scanty on environmental factors affecting the differential response of tomato genotypes across environments. Hence, the aim of this research was to use factorial regression (FR) and partial least squares (PLS) regression, which incorporate external environmental and genotypic covariables directly into the model for interpreting GEI. In this research, data from an FAO multi-environment trial comprising 15 tomato genotypes (7 hybrid and 8 OP) evaluated in 18 locations of Latin America and the Caribbean were analyzed using FR and PLS. Environmental factors such as days to harvest, soil pH, mean temperature (MET), potassium available in the soil, and phosphorus fertilizer accounted for a sizeable portion of GEI for marketable fruit yield, whereas trimming, irrigation, soil organic matter, and nitrogen and phosphorus fertilizers were important environmental covariables for explaining GEI of average fruit weight. Locations with relatively high minimum and mean temperatures favored the marketable fruit yield of OP heat-tolerant lines CL 5915-223 and CL 5915-93. An OP cultivar (Catalina) and a hybrid (Apla) showed average marketable fruit yield across environments, while two hybrids (Sunny and Luxor) exhibited outstanding marketable fruit yield in high yielding locations (due to lower temperatures and higher pH) but a sharp yield loss in poor environments. Two stable hybrid genotypes in high yielding environments, Narita and BHN-39, also showed high and stable yield in average and low yielding environments.     

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.     

Analysis of the genotype-by-environment interaction of spring barley tested in the Nordic Region of Europe: Relationships among stability statistics for grain yield

Variation in agronomic and quality characteristics was investigated in 220 Nordic spring barley cultivars across distinct environments (6 locations during 3 years) in the Nordic Region of Europe. The objectives of this research were to determine the importance of the genotype by environment interaction in all characteristics evaluated and to establish the relationship among different stability statistics for grain yield. Combined analysis of variance across locations indicated that both environments and genotype by environment interactions influenced significantly the cultivar phenotypes for all characteristics, irrespective of their type (row number) or earliness. The first two interaction principal component axes of the additive-main-effects-and-multiplicative-interaction (AMMI) model accounted together between 35% and 75% of the total genotype-by-environment interaction for all characteristics. Grain yield was, on average, higher in 2-row than in 6-row cultivars, which were significantly earlier in heading and grain maturity than the former. However, in some of the most northern locations, 6-row barley cultivars significantly outyielded on average 2-row barley lines. The genotype by location interaction variance (σ² _GL) accounted by each genotype was significantly associated to the deviation from regression (Tai's λ) while the coefficient of regression (β) was significantly correlated to the IPCA1 and IPCA2 of the AMMI model in 2-row, 6-row and early barley cultivars. This revised version was published online in August 2006 with corrections to the Cover Date.     

Parametric and nonparametric measures of phenotypic stability in linseed (Linum usitatissimum L.)

A combined analysis with three parametricand two nonparametric measures to assess G × E interactions and stability analyses toidentify stable genotypes of linseed across18 environments in Ethiopia wereundertaken. The combined analysis ofvariance for environments (E), genotypes(G) and G × E interaction was highlysignificant (p<0.01), suggestingdifferential responses of the genotypes andthe need for stability analysis. Theparametric stability measures ofcoefficient of variability and thestability variance showed that R12-N10D wasthe most stable genotype, whereascultivars' superiority measure indicatedChilalo to be the most stable cultivar.Like most of the parametric methods, thenon-parametric measures revealed thatR12-N10D had the smallest changes in ranksand thus was the most stable genotype incontrast to R12-D24C, which was unstableand the lowest yielder. A comparison of thefive stability measures showed that thecoefficient of variability, stabilityvariance and variance of ranks were similarin assessing the relative stability of thegenotypes, whereas cultivars' superioritymeasure deviated from the others. Thestability variance and variance of rankswere significantly rank correlated, andwere the best in determining thecomparative stability of linseed genotypes.The coefficient of variability was alsorelatively better than the cultivar'ssuperiority measure. Further studies ofrepeatability tests are, however, needed todetermine the best methods. The stabilitystatistics generally identified R12-N10D,followed by Chilalo, as the most stablevarieties, whereas R12-D24C and R11-M20Gwere the least stable varieties.     

Heat stress affects vegetative and reproductive performance and trait correlations in tomato (<Emphasis Type="Italic">Solanum lycopersicum</Emphasis>)

High ambient temperature has adverse effects on plant vegetative and reproductive development and reduces crop yield. To better understand the importance of male and female fertility for tomato fruit set ability under high temperature conditions and to test whether heat tolerance levels among and between reproductive and vegetative traits of genotypes correlate with each other, 13 tomato cultivars were subjected to long-term moderate heat (LTMH) or short-term heat shock (STHS), depending on the trait that was evaluated. LTMH caused significant decrease in performance of nearly all reproductive traits, i.e. pollen viability, pollen number, female fertility, seeded-fruit set and flower number per inflorescence, but not in inflorescence number. Considerable variation was found among cultivars, both under control and LTMH conditions. The cultivars Nagcarlang, Saladette and Malintka 101 produced a higher percentage of viable pollen under LTMH. For fruit set under LTMH condition, only cultivars that had been previously reported as being heat-tolerant produced fruits with seeds. STHS negatively affected vegetative traits concerning seedling survival and membrane stability. Correlation analysis revealed relationships between various traits within the control and heat treatments, but not between the two. Under heat stress fruit set was positively correlated with pollen viability, as well as with flower number per inflorescence. However, no significant correlations were found between vegetative and reproductive traits. Our data highlight the prominent role of pollen viability for tomato fertility under LTMH growth conditions. The observed variation in thermotolerance among different cultivars offers the possibility to decipher underlying physiological and genetic mechanisms.     

Influence of environmental productivity levels and yield stability on selection strategies in soybean

Summary Yield data were collected for soybean (Glycine max (L.) Merr.) lines in maturity groups III and IV in 14 environments from 1985 to 1989. The lines in each maturity group were subdivided into three different groups based on the mean yield over all environments, and the genotype × environment interactions were studied for each group. Yield stability of the lines was determined. Effectiveness of selection based on different types of environments was examined.Productivity level of the environment did not influence the relative ranking of the lines. Significant rank correlations occurred between mean yields in most environments and the overall mean yield, but few similarities occurred in the line rankings among individual environments. High-yielding lines contributed a significantly smaller proportion to the genotype × environment interaction than medium- and low-yielding lines.A small proportion of the lines were below or above average stability. Significant correlations occurred among stability, overall mean yield, and mean yield in high- and low-yielding environments. However, few significant correlations occurred between individual environment yields and stability in high- or low-yielding environments. Maturity groups differed in yield and stability relationships. Stability in high- and low-yielding environments did not adequately predict stability for each other.Contribution No. 93-445-J from the Kansas Agricultural Experient Station     

Genetic variation,genotype × environment interaction,and selection for tipburn resistance in lettuce in multi-environments

Tipburn is a calcium related and environmentally induced physiological disorder causing economic damage in all lettuce (Lactuca sativa L.) production regions. The objectives of this research were to determine (1) the genetic variation for tipburn incidence, (2) the genotype (G) × environment (E) interaction (GE) for tipburn incidence, and (3) the efficiency of field selection for tipburn resistance. Tipburn incidence was recorded over 2 years in Salinas, CA, and Yuma, AZ, for 55 romaine, crisphead, green leaf, and red leaf type cultivars, and over 3 years in Quebec for 15 romaine cultivars. Analysis revealed that G, E, and GE affected tipburn incidence, including crossover interactions that were not repeatable over years. This indicates that cultivar/breeding line evaluations should be based on mean performance and stability over multiple environments. Among lettuce types, only crisphead had significant genetic variability for tipburn resistance, reflecting the greater breeding effort applied to this type compared romaine, green and red leaf types. Analysis of a dataset with five romaine cultivars in eight environments in California, Arizona, and Quebec for 2 years revealed that Yuma in 2006 and Saint-Blaise in 2005 were highly correlated (r = 0.923, P < 0.05), and were the most discriminating and most representative environments for tipburn evaluation. Single plant selection for tipburn resistance in three F₂ romaine populations was ineffective. Further, the degree of head closure was significantly associated with tipburn incidence. Identification and selection of morphological characters associated with resistance in conjunction with direct selection against tipburn may be an effective method for genetic improvement of tipburn resistance.     

Inheritance of resistance to fruit rot (Phytophthora parasiticaDast.) in tomato (Lycopersicon esculentum Mill.)

Summary Fruit rot disease caused by Phytophthora parasiticaDast. is a limiting factor in tomato production in Himachal Pradesh. 30 to 60 per cent fruits are damaged by this disease. Crosses were made between EC 54725 (Lycopersicon pimpinellifolium), a small tyuited type, resistant to fruit rot and four highly susceptible tomato commercial cultivars (Gola, Sioux, S12, and Lalmani). Studies of F₁'s, F₂'s and back crosses indicated that EC 54725 carries a dominant gene imparting resistance to fruit rot.     

GGE叠图法─分析品种×环境互作模式的理想方法

本文介绍一种分析作物区域试验结果的方法－ＧＧＥ叠图法。首先，将原始产量数据减去各地 点的平均产量，由此形成的数据集只含品种主效应Ｇ和品种－环境互作效应ＧＥ，合称为ＧＧＥ。对ＧＧＥ 作单值分解，并以第一和第二主成分近似之。按照第一和第二主成分值将各品种和各地点放到一个平 面图上即形成ＧＧＥ叠图。借助于辅助线，可以直观回答以下问题：（１）什么是某一特定环境下最好的 品种；（２）什么是某一特定品种最适合的环境；（３）任意两品种在各环境下的表现如何；（４）试验中品 种×环境互作的总体模式是怎样的；（５）什么是高产、稳产品种；（６）什么是有利于筛选高产、稳产品 种的环境。     

GGE双标图在湖南省棉花品种区域试验中的应用

为研究2013年湖南省棉花品种区域试验B组中参试品种与环境的互作关系,科学评价参试品种与试点,从而为品种审定、品种在生产中的有效利用及试点遴选提供理论依据。采用具有直观分析农作物两向数据的GGE双标图软件对参试品种的丰产性与稳定性、理想品种选择、品种适宜种植区域划分、各试点的代表性和鉴别力及理想试点选择等方面进行了分析。结果表明：2013年湖南省棉花品种区域试验B组各品种（系）皮棉产量的基因型、环境（试点）、基因型与环境互作效应均达极显著水平,其中环境主效（试点）、基因型主效及基因型与环境互作效应分别占处理变异平方和的57.99%、13.54%、28.48%;丰产性最好的品种是B3,稳产性最好的品种是B5,但最理想的品种是B3;大通湖管理区、君山和湖南省棉花科学研究所试点为最理想试点。     

Genotype and environmental interaction for fruit quality traits in vintage tomato varieties

Tomato (Solanum lycopersicum L.) is the second most highly consumed vegetable in the world after potato. Traits including physicochemical (lycopene, total titratable acid (TTA), total soluble solids (TSS) and vitamin C), morphological (fruit shape and size) and colors contribute to the overall fruit quality of tomato. The primary objective of the present study was to evaluate vintage tomato varieties representing a wide genetic background for fruit quality including physicochemical, morphological and color traits in multiple environments and to analyze consistency of their performances across locations. In order to achieve this objective, we acquired 44 vintage tomato varieties and evaluated them in five environments (NC, NY, OH in 2009, and NC and OH in 2010). Analysis of the data revealed that there was a significant (p < 0.01) difference among genotypes and environments for all quality traits, Genotype × Environment interaction was significant (p < 0.01) for all quality traits except for TSS. Broad-sense heritability of physicochemical traits ranged from 5.8 % (lycopene) to 35.7 % (TTA) whereas that for morphological traits ranged from 8.1 % (proximal eccentricity) to 97.3 % (fruit shape index external 1), and color from 69.0 % (a*-value) to 99.3 % (b*-value). Pearson’s correlation analysis indicated that estimated lycopene content was negatively correlated with the other physicochemical traits whereas vitamin C, TSS and TTA were positively correlated with each other. Principal component analysis (PCA) based on phenotypic data identified five components explaining at least 82 % of the total variation. Cluster analysis based on phenotypic data revealed the clusters of vintage tomato varieties were not distinct whereas single nucleotide polymorphism data revealed three distinct populations. This information including heritability and correlation coefficients from the present study may be useful to tomato breeding programs to choose germplasm, improve the response to selection and simultaneously improve multiple traits for tomato fruit quality.     

Variation of resistance to broomrape (Orobanche ramosa) in tomatoes

Summary Twenty five tomato cultivars and one accession of wild tomato were evaluated for their resistance to branched broomrape (Orobanche ramosa) infestation. Tomato cultivars were found different in their resistance to Orobanche based on different growth parameters. Total Orobanche number, haustoria development and number of emerged Orobanche shoots were all different between tomato cultivars. Differences in the growth and fruit yield among tomato cultivars were also found in response to Orobanche infestation. Ranking tomato cultivars for Orobanche resistance indicates the existence of different resistance mechanisms in these cultivars. Relatively high to moderate levels of resistance were obtained in Tiny Tim, Acora, Castler, Pomodora, Orient, Red Alert and the accession LA 1478 of L. pimpinellifolium. The cultivar Tiny Tim showed the highest level of resistance for all measured parameters and in all experiments.     

Genotype-by-environment effects on the performance of recombinant inbred lines of Virginia-type peanut

Peanut (Arachis hypogaea L.) is known to be sensitive to genotype-by-environment interaction (GEI) effects. While previous studies have reported strong GEI effects on peanut yield, most of those studies involved a relatively small number of unrelated genotypes. We examined the extent of GEI effects in elite Virginia-type peanut using a large population of recombinant inbreed lines (RILs). Two-hundred-sixty-six F₇ RILs derived from different cultivars were grown in three environments. Net pod yield (NPY) was evaluated along with 11 other traits. ANOVA revealed that genotype and environment affected all of the examined traits, except for the triplet trait. The substantial influence of the environment was also demonstrated in a genetic-parameter analysis, in which the phenotypic variation coefficients were almost double those for genotypic variation. Still, relatively high heritability and genetic gain values were found for pod weight and NPY. Since NPY is the main target for selection, it was analyzed further. Path analysis showed that NPY is most directly influenced by pod weight and the shelling ratio. A significant GEI effect on NPY was identified using an AMMI model that described 42.7% of the total variation. This GEI component was subjected to a principal components analysis, which confirmed that the variability due to the different environments was greater than the variability that could be attributed to the different genotypes. Yet, several lines had stable yields across environments. These results demonstrate the importance of multi-location phenotyping for QTL analyses and crop improvement in peanut.     

Assessing the agronomic potential of linseed genotypes by multivariate analyses and association mapping of agronomic traits

High prices of fish oil make linseed attractive for aquaculture and animal feed. To ensure a constant supply of linseed, the development of stable cultivars is of strategic importance. In this study, 35 linseed genotypes were evaluated in five Chilean environments (E) from 2009 to 2012. The additive main effect and multiplicative interaction analysis (AMMI), genotype (G) plus genotype by environment (GE) interaction (GGE) biplot analysis and three stability parameters were tested with the aim of identifying adapted genotypes for the development of linseed cultivars. An association mapping (AM) analysis was also conducted for four agronomic traits and the stability of the associated markers was evaluated using the QQE (QTL main effect and QTL by environment interaction) approach. Combined analysis of variance for yield, seeds per boll (SPB), plant height (PH) and days to flowering (DTF) were significant for G, E and GE (P < 0.001). The combined stability analysis identified some Canadian, Argentinean and Chilean accessions to be the best adapted and highest yielding genotypes. Coancestry analysis indicated that crossing Canadian and Chilean genotypes could maximize transgressive segregation for yield. Significant associations for DTF, PH and SPB explained up to 59 % of the phenotypic variation for these traits. The QQE and AM analyses were consistent in identifying marker LGM27B as the most stable and significant across all environments with the largest effect in reducing DTF. The combined application of the stability, AM and QQE analyses could accelerate the development of marketable linseed cultivars adapted to Southern Chile.     

Genotype × environment interaction and yield stability in a cowpea-based cropping system

Twenty-four cowpea genotypes were evaluated under sole cropping or additive series intercropping with sorghum from 2004 to 2005 at four sites representative of the Guinea and Sudan savannah ecologies in Ghana. The aim was to determine whether cowpea breeding programs that emphasize selection under sole-crop conditions have the potential to produce cultivars that are effective under additive series intercropping. Genotype × cropping systems interaction was significant for days to 50% flowering but not for grain yield, biomass and other studied traits. Genotypic yield reaction to cropping systems indicated that bridging the yield gap between sole cropping and intercropping systems is best addressed by agronomic interventions that reduce stress on intercrop cowpea rather than by selecting for specifically adapted genotypes for intercropping. Significant genotype × environment interactions were observed for all traits when data was pooled over cropping systems. Partitioning of the genotype × environment interaction variance indicated that days to 50% flowering was dominated by heterogeneity of genotypic variance, whereas genotype × environment interactions for grain yield and biomass was mainly due to imperfect correlations. Large differences in genotypic yield stability were observed as estimated by the among-environment variance, regression of yield on the environmental index, Kataoka’s index, and by partitioning of genotype × environment interaction sum of squares into components attributable to each genotype. The results suggest that in regions where genotype × environment interaction for yield frequently causes re-ranking across environments, genotypes with the least contribution to the interaction sum of squares are likely to be most productive. On the whole, the results support the contention that breeding under sole-crop conditions has the potential to produce cultivars effective under intercropping conditions.     

Genotype by environment interaction for disease resistance and other important agronomic traits supporting the indication of common bean cultivars

The present work aimed to study the genotype by environment interaction for nine important agronomic traits as a support for the indication of common bean cultivars for the Southern region of Brazil, identifying cultivars that possess high adaptability/stability. We carried out 25 field trials, in the rainy and dry sowing seasons, at different locals in the states of Paraná and Santa Catarina, from 2008 to 2010. The trials included 17 cultivars. Data were obtained for agronomic traits and subjected to variance analyses, and to adaptability and stability analyses according to the Nunes method. The genotype by environment interaction is important for different agronomic traits. There is genetic variation among cultivars and it was identified a different number of superior cultivars for each trait. Considering the means and adaptability and stability scores, 88% of the cultivars were superior for rust, 53% for anthracnose, 41% for grain yield, plant architecture and cycle, 30% for fusarium wilt and lodging, and 18% for angular leaf spot and common bacterial blight. For some of these traits, like angular leaf spot, common bacterial blight, fusarium wilt and lodging, it is necessary to intensify the efforts to provide more cultivars with high resistance or tolerance level, adaptability and stability. BRS Esplendor, a black-seeded cultivar, CNFC 10431 and BRS Sublime, both carioca-seeded cultivars, presented superiority for six of nine traits, being indicated to be used in the Southern region of Brazil. Other cultivars presented advantages for fewer traits and must be used in environments which these traits present greater importance.     

Non-parametric measures of phenotypic stability in chickpea genotypes (<Emphasis Type="Italic">Cicer arietinum</Emphasis> L.)

Multi-environment trials (MET) play an important role in selecting the best cultivars and/or agronomic practices to be used in future years at different locations by assessing a cultivar's stability across environments before its commercial release. Objective of this study is to identify chickpea (Cicer arietinum L.) genotypes that have high yield and stable performance across different locations. The genotypes were developed by various breeders at different research institutes/stations of Iran and the International Center for Agricultural Research in Dray Areas (ICARDA), Syria. Several statistical methods were used to evaluate phenotypic stability of these test chickpea genotypes. The 17 genotypes were tested at six different research stations for two years in Iran. Three non-parametric statistical test of significance for genotype × environment (GE) interaction and ten nonparametric measures of stability analyses were used to identify stable genotypes across the 16 environments. The non-parametric measures (Kubinger, Hildebrand and Kroon/Van der) for G × E interaction were highly significant (P < 0.01), suggesting differential responses of the genotypes to the test environments. Based on high values of nonparametric superiority measure (Fox et al. 1990) and low values of Kang's (1988) rank-sum stability parameters, Flip 94-123C was identified as the most stable genotype. These non parametric parameters were observed to be associated with high mean yield. However, the other nonparametric methods were not positively correlated with mean yield and were therefore not used in classifying the genotypes. Simple correlation coefficients using Spearman’s rank correlation, calculated using ranks was used to measure the relationship between the stability parameters. To understand the nature of relationships among the nonparametric methods, a hierarchical cluster analysis based on non weighted values of genotypes, was performed. The 10 stability parameters fell into three groups.     

Inheritance of characters determining growth and development of tomato (Lycopersicon esculentum Mill.) under low energy conditions

Summary Diallel crosses were made between 15 tomato genotypes with varying performance under a low energy regime. It appeared that differences between genotypes for 11 vegetative and generative plant characters are determined mainly by additive genetic variation. For breeding cultivars adapted to low energy conditions, crossing genotypes with a high GCA for weight of trusses and fruits (WTF) and genotypes with a high GCA for weight of vegetative plant parts (WVP) seems most promising. Complications may arise from the negative correlation between GCA values for WTF and WVP, and the strong positive correlation between GCA values for fruit number and WTF, causing small fruits.