Grouping genotypes and test environments by some cluster methods regarding genotype × environment interaction in multi-environment trials

Lentil (Lens culinaris Medik.) is an important source of protein and carbohydrate food for people of developing countries and is popular in some developed countries where they are perceived as a healthy component of the diet. Ten lentil genotypes were tested for grain yield in five different environmental conditions, over two consecutive years to classify thes genotypes for yield stability. Seed yield of lentil genotypes ranged from 989.3 to 1.367 kg ha-1 and the linear regression coefficient ranged from 0.75 to 1.18. The combined analysis of variance showed that the effect of environment (E) and genotype by environment (GE) interaction were highly significant while the main effect of genotype (G) was significant at 0.05 probability level. Four different cluster procedures were used for grouping genotypes and environments. According to dendograms of regression methods for lentil genotypes there were two different genotypic groups based on G plus GE or GE sources. Also, the dendograms of ANOVA methods indicated 5 groups based on G and GE sources and 4 groups based on GE sources. According to dendograms of regression methods for environments there were 5 different groups based on G plus GE sources while the dendograms of ANOVA methods indicated 9 groups based on G and GE sources and 3 groups based on GE sources. The mentioned groups were determined via F-test as an empirical stopping criterion for clustering. The most responsive genotypes with high mean yield genotypes are G2 (1145.3 kg ha-1), G8 (1200.2 kg ha-1) and G9 (1267.9 kg ha-1) and could be recommended as the most favorable genotypes for farmers

Principal coordinate analysis of genotype × environment interaction for grain yield of bread wheat in the semi-arid regions

Multi-environmental trials have significant main effects and significant multiplicative genotype × environment (GE) interaction effect. Principal coordinate analysis (PCOA) offers a more appropriate statistical analysis to deal with such situations, compared to traditional statistical methods. Eighteen bread wheat genotypes were grown in four semi-arid regions over three year seasons to study the GE interaction and yield stability and obtained data on grain yield were analyzed using PCOA. Combined analysis of variance indicated that all of the studied effects including the main effects of genotype and environments as well as the GE interaction were highly significant. According to grand means and total mean yield, test environments were grouped to two main groups as high mean yield (H) and low mean yield (L). There were five H test environments and six L test environments which analyzed in the sequential cycles. For each cycle, both scatter point diagram and minimum spanning tree plot were drawn. The identified most stable genotypes with dynamic stability concept and based on the minimum spanning tree plots and centroid distances were G1 (3310.2 kg ha-1) and G5 (3065.6 kg ha-1), and therefore could be recommended for unfavorable or poor conditions. Also, genotypes G7 (3047.2 kg ha-1) and G16 (3132.3 kg ha-1) were located several times in the vertex positions of high cycles according to the principal coordinates analysis. The principal coordinates analysis provided useful and interesting ways of investigating GE interaction of barley genotypes. Finally, the results of principal coordinates analysis in general confirmed the breeding value of the genotypes, obtained on the basis of the yield stability evaluation

Canopy Temperature and Chlorophyll Content are Effective Measures of Drought Stress Tolerance in Durum Wheat

Durum wheat (Triticum durum L.) is used for the preparation of multiple food products, including pasta and bread. Its production is restricted due to diverse environmental stresses i.e. drought and heat stress. Here, comparative analysis of durum wheat varieties was done by studying canopy temperature depression (CTD) and chlorophyll content (CHL), yield and yield contributing traits to evaluate their performance under stress and low stress conditions. Twelve durum wheat genotypes were studied under stressful and low-stress conditions in Gachsaran region of Iran. CTD and CHL were measured at two stages, from the emergence of fifty percent of inflorescence (ZGS 54) to watery ripe stage (ZGS 71). According to stress tolerance index (STI), mean productivity (MP) and geometric mean productivity (GMP) indices, genotype G10 exhibited the most, while genotype G6, the least relative tolerance, respectively. Based on MP and GMP, genotype G10 was found to be drought tolerant, while genotype G2 displayed the lowest amount of MP and GMP. Therefore these genotypes are recommended to be used as genitors in artificial hybridization for improvement of drought tolerance in other cultivars. All indices had high correlation with grain yield under stress and non-stress condition, indicating more suitability of these indices for selection of resistant genotype. Results of the present study showed that among drought tolerance indices, harmonic mean (HM), GMP, CTD and modified STI index (K2STI) can be used as the most suitable indicators for screening drought tolerant cultivars

Yield stability of performance in multi-environment trials of barley (Hordeum vulgare L.) genotypes

Fourteen new breeding lines obtained from the barley breeding programs, cultivar Izeh and one local check genotype were evaluated for yield stability at eleven environments. The combined analysis of variance indicated the significance of the environments, genotypes and genotype by environment interaction. According to the environmental variance (EV) and coefficient of variation (CV), genotypes G2, G12, G13 and G14 while based on Wi, P, PP and SH parameters genotypes G4, G10 and G12 were the most stable ones. Regarding both PI and MSPI parameters, genotypes G2, G10 and G11 were the most stable. According to coefficients of three linear regression models, genotypes G1, G6 and G8 were more responsive and had specific adaptability to favorable environments. Considering most of stability parameters, genotypes G4 (3 393 kg ha−1) G12 (3 440 kg ha−1) can be recommended as the most stable genotype with regard to both stability and yield. In this study, high values of DI were associated with high mean yield, but the other stability methods were not positively correlated with mean yield. The results of principal component analysis and correlation analysis indicated that EV, CV, ER, and DI stability parameters would be useful for simultaneously selecting for high yield and stability

Using additive main effect and multiplicative interaction model for exploration of yield stability in some lentil (Lens culinaris Medik.) genotypes

The additive main effect and multiplicative interaction (AMMI) analysis has been indicated to be effective in interpreting complex genotype by environment (GE) interactions of lentil (Lens culinaris Medik.) multi- environmental trials. Eighteen improved lentil genotypes were grown in 12 semiarid environments in Iran from 2007 to 2009. Complex GE interactions are difficult to understand with ordinary analysis of variance (ANOVA) or conventional stability methods. Combined analysis of variance indicated the genotype by loca- tion interaction (GL) and three way interactions (GYL) were highly significant. FGH1 and FGH2 tests indicated the five  significant  components; FRatio  showed  three significant  components  and F-Gollob detected  seven significant components. The RMSPD (root mean square predicted difference) values of validation procedure indicated seven significant components. Using five components in AMMI  stability parameters (EVFI, SIP- CFI, AMGEFI and DFI) indicated that genotypes G5 and G6 were the most stable genotypes while consider- ing three components in of AMMI stability parameters (EVFII, SIPCFII, AMGEFII and DFII) showed that genotypes G8 and G18 were the most stable genotypes. Also genotypes G2, G5 and G18 were the most stable genotypes according to AMMI stability parameters which calculated from seven components  (EVFIII, SIP- CFIII, AMGEFIII and DFIII). Among these stable genotypes, only genotypes G2 (1365.63 kg × ha-1), G11 (1374.13 kg × ha-1) and G12 (1334.73 kg × ha-1) had high mean yield and so could be regarded as the most favorable genotype. These genotypes are therefore recommended for release as commercial cultivar

Sequential Path Analysis for Determination of Relationship Between Yield and Yield Components in Bread Wheat (<i>Triticum aestivum</i>.L.)

An experiment was conducted to evaluate 295 wheat genotypes in Alpha-Lattice design with two replications. The arithmetic mean and standard deviation of grain yield was 2706 and 950 (kg/ha),respectively. The results of correlation coefficients indicated that grain yield had significant and positive association with plant height, spike length, early growth vigor and agronomic score. Whereas there were negative correlation coefficients between grain yield and days to physiological maturity and canopy temperature before and during anthesis. Path analysis indicated agronomic score and plant height had high positive direct effects on grain yield, while canopy temperature before and during anthesis, and days to maturity, wes another trait having negative direct effect on grain yield. The results of sequential path analysis showed the traits that accounted as a criteria variable for high grain yield were agronomic score, plant height, canopy temperature, spike length, chlorophyll content and early growth vigor, which were determined as first, second and third order variables and had strong effects on grain yield via one or more paths. More important, as canopy temperature, agronomic score and early growth vigor can be evaluated quickly and easily, these traits may be used for evaluation of large populations

Sequential Path Analysis for Determination of Relationship Between Yield and Yield Components in Bread Wheat (<i>Triticum aestivum</i>.L.)

</p><p>An experiment was conducted to evaluate 295 wheat genotypes in Alpha-Lattice design with two replications. The arithmetic mean and standard deviation of grain yield was 2706 and 950 (kg/ha),respectively. The results of correlation coefficients indicated that grain yield had significant and positive association with plant height, spike length, early growth vigor and agronomic score. Whereas there were negative correlation coefficients between grain yield and days to physiological maturity and canopy temperature before and during anthesis. Path analysis indicated agronomic score and plant height had high positive direct effects on grain yield, while canopy temperature before and during anthesis, and days to maturity, wes another trait having negative direct effect on grain yield. The results of sequential path analysis showed the traits that accounted as a criteria variable for high grain yield were agronomic score, plant height, canopy temperature, spike length, chlorophyll content and early growth vigor, which were determined as first, second and third order variables and had strong effects on grain yield via one or more paths. More important, as canopy temperature, agronomic score and early growth vigor can be evaluated quickly and easily, these traits may be used for evaluation of large populations.</p

Model selection in additive main effect and multiplicative interaction model in durum wheat

The study included data set of 20 durum wheat genotype across 15 rain-fed environments. A combined analysis of variance showed that the genotypes differed significantly for seed yield and GE (year × location) interaction. Cross validations procedure and four various F-tests including FGollob, FRatio, FGH1 and FGH2 are used for testing the GE interaction principal component analysis (IPCA) axes and indicated that two, four, six or seven axes could be significant. According to EV1, D1, AMGE1 and SIPC1 parameters, genotypes G3, G7 and G17 were the most stable genotypes while based on EV4, D4, SIPC4 and AMGE4 parameters, genotype G13 was the most stable genotype. The hierarchical clustering showed that the twenty one studied the AMMI stability parameters and mean yield could be divided into four distinct groups. Group III contains mean yield, SIPC4, SIPC6 and SIPC8 which were computed from four, six or eight IPCAs. In conclusion, G13 (DON-MD 81- 36) was found to be the most stable genotype as well as high mean yield performance (2592.45 kg ha-1) and so is recommended for commercial release in semi-arid areas of Iran. Also, the SIPC-based stability parameters of the AMMI model was found to be useful in detecting the yield stability of the genotypes studied