Correlation and path-cofficient analysis of seed yield and yield related trait in Iranian confectionery sunflower populations

This study was undertaken in order to determine the association among yield components and their direct and indirect effects on the seed yield of confectionery sunflower. 36 confectionery sunflower populations originated from different regions of Northwest Iran were characterized using 11 agromorphological traits including: Days to 50% flowering, plant height, stem diameter, head diameter, number of leaves, leaf length, leaf width, petiole length, number of seeds per head, 100-seed weight and seed yield. Phenotypic correlations results show that seed yield per plant was positively and significantly associated with 100-seed weight, head diameter, number of seeds per head, stem diameter and plant height. Path coefficient analysis revealed that number of seed per head, 100-seed weight, and head diameter has positive direct effect on seed yield. Therefore, selection based on these characters would be more effective to improving seed yield in confectionery sunflower in breeding programs.Key words: Helianthus annuus L., direct effect, phenotypic correlation, indirect selection

Collection, evaluation and classification of Iranian confectionary sunflower (Helianthus annuus L.) populations using multivaraite statistical techniques

Characterization of confectionary sunflower germplasm resources is critical to their efficient collection and management as well as for breeding programs. Thirty six (36) confectionary sunflower populations originating from different regions of Northwest Iran were characterized using 15 agro-morphological traits. Among the studied traits, high coefficients of variation were observed for harvest index (48.36), seed yield (42.07) and petiole length (41.63). Cluster analysis using Ward's method classified the 36 populations into four groups. A large number of genotypes was placed in cluster III (16 genotypes) followed by cluster I (13), cluster IV (4) and cluster II (3). Clusters I, III and VI include genotypes from different sources indicating no association between clustering pattern and eco-geographical distribution of genotypes. The maximum inter-cluster distance of 9.03 was observed between clusters II and VI indicating the possibility of high heterosis if individuals from these two clusters are cross-bred. Principal component analysis resulted in the first four components with Eigen value greater than one accounting for 78% of the total variation. The results of PCA were closely in line with those of cluster analysis. These results can now be used by breeders to develop high yielding sunflower hybrids.Key words: Cluster analysis, confectionary sunflower, genetic variability, principal component analysis

Study on the resistance components in 33 commercial potato cultivars to Colorado potato beetle, Leptinotarsa decemlineata (Col.: Chrysomelidae)

Greenhouse and field experiments were conducted to evaluate the resistance components in 33 potato commercial cultivars to Colorado potato beetle, Leptinotarsa decemlineata (Say) in 2008. In a field choice test, the numbers of attracted beetles to the cultivars was determined as antixenosis index. To evaluate the antibiosis, potato tubers were planted in pots under greenhouse conditions and on each pot, one sleeve cage was set up, in which 15 first instar larvae were released and reared. The Larval weight after 12 days of releasing, mortality percentages of larvae and pupae and the durations of developmental stages were analyzed as the antibiosis indices. To study the level of tolerance of cultivars, the infested and non infested plots were isolated and arranged based on a randomized complete block design in field. In infested plots, each plant was infested by 40 medium larvae (second and early third instars) 15 days prior to the blooming of plants. At the end of the season, defoliation and yield loss among infested plots were determined and compared to non infested plots for each cultivar. Significant differences were observed in all studied traits. The cultivars Cardinal, Carlita and Sinja showed antixenosis effects with the least numbers of attracted beetles, whereas cultivars Carlita, Sinja, Delikat, Aparet and Bridjet showed antibiosis effects in comparison to the others. The cultivars Santana, Satina, Nicola and Bridjet showed tolerance to damage of the pest. Using cluster analysis, UPGMA procedure was based on Euclidean distance and 33 experimental cultivars were grouped in 7 distance groups

Molecular characterization and similarity relationships among sunflower (Helianthus annuus L.) inbred lines using some mapped simple sequence repeats

Information about the genetic diversity and relationships among breeding lines and varieties is not only useful for germplasm conservation and inbred line identification, but also for the selection of parental lines for quantitative trait loci (QTL) mapping as well as hybrid breeding in crops, including sunflower. In order to develop mapping populations, genetic distances among twenty eight sunflower genotypes were evaluated using simple sequence repeat (SSR) markers. One hundred and two markers were generated by 38 SSR loci and the mean for the number of allele per locus was 2.32. Polymorphism information content (PIC) values ranged from 0.09 (locus ha3555) to 0.62 (locus ORS598) with an average of 0.41. Jaccard's coefficient similarity matrix for the studied sunflower  genotypes varied from 0.25 to 0.9 indicating a broad genetic base. The maximum similarity (0.9) was observed between genotypes RT931 and ENSAT-R5, while the lowest similarity (0.25) was between genotypes LC1064C and LR64. Based on unweighted pair group method with arithmetic mean (UPGMA) clustering algorithm, the studied genotypes were clustered in four groups. However, some genotypes have the same specific characters that influence their clustering, and as a result, the results of the principal coordinate analysis (PCoA) largely corresponded to those obtained through cluster analysis.Key words: Cluster analysis, genetic diversity, principal coordinate analysis, sunflower, simple sequence repeat

Comparison of Resistance Index Some Potato Cultivars to the Colorado Potato Beetle, Leptinotarsa decemlineata (Say) (Col.: Chrysomelidae)

Introduction: Potato, Solanum tuberosum L. is an important crop with 5.24 million tons of production on 210,000 hectares of irrigated land in Iran. Several pests attack the potato crop which among them the Colorado potato beetle, Leptinotarsa decemlineata (Say), is the most important defoliating pest of potato throughout the world and Iran and considerably reduce crop yield. Growers rely on pesticides to control this pest in the field but this insect is well known for its rapid resistance development to pesticides, so that it has developed field resistance to nearly all insecticides used against it and it is now resistant to more than 40 chemical insecticides. The problems of insecticide resistance, combined with continuing environmental concerns associated with chemical pesticide use, have provided a considerable stimulus over the past 50 years for the development of alternative control methods. Host plant resistance is considered to be an important part of integrated pest management (IPM) system of this pest, which is compatible with sustainable control methods and can reduce the use of chemical insecticides .With the aim of identifying the existence of resistance resources, a study was conducted to evaluate and comparison the resistance index (PRI) of 33 potatocultivarsto the Colorado potato beetle. Detected resistant variety (ies) could be used as a resistance source for IPM programs of this pest. Materials and Methods: Greenhouse and field experiments were conducted to compare resistance index (PRI) of 33 potato cultivars to the Colorado potato beetle, Leptinotarsa decemlineata (Say), in Naghadeh region during 2007-2008. In a choice test, the numbers of attracted beetles to each cultivar was determined as antixenosis index in the field. Also, Percentage of larval and pupal mortality were determined and used as the antibiosis index under greenhouse conditions. To evaluate the tolerance index, infested and non infested plots were planted and arranged based on a randomized complete block design under field conditions. In infested plots, each plant was infested by 40 medium larvae (second and early third instars) 15 days prior to the blooming of plants. At the end of season, yield loss in infested plots were determined and compared with non infested plots for each cultivar and used as the tolerance index. Normalized values for each category were computed on a zero-to-one scale by dividing the mean value of each variety evaluated by the maximum mean value of all entries. Normalized tolerance values were calculated as percent reductions of plant biomass relative to a non-infested control. Normalized indices for antibiosis (X), antixenosis (Y) and tolerance (Z) were used to calculate PRI in the formula: PRI = 1/(XYZ) (Inayatullah et al., 1990). Results and Discussion: Combined analysis of variance showed that interactive effect of cultivar × year was significant for all of the indices at P=0.01. The cultivars Sinja, Bridjet and Cardinal with the least antixenosis index (Y), had the highest antixenosis resistance to the Colorado potato beetle in 2007, also the cultivars Cardinal, Carlita and Elles with the least antixenosis index (Y), had the highest antixenosis resistance to the pest in comparison to other cultivars in 2008. The highest antibiosis (X) resistance was observed in the cultivars Delikat, Carlita, Armada and Sinja with the least antibiosis index, in two studied years. The cultivars Satina, Cardinal, Santana and Nicola with the least tolerance index (Z), had the highest tolrence to the Colorado potato beetle in comparison to the other cultivars during 2007-2008. The cultivars Delikat,Bridjet and Cardinal ere the most resistant cultivars with 52.63, 36.30 and 29.87 PRI, respectively in 2007. In this year, the cultivars Diamont, Aparet and Velox were the most sensitive cultivars with 1.90, 2.06 and 2.26 PRI, respectively in comparison to other cultivars. In 2008, the cultivars Santana, Bridjet and Sinja were the most resistant cultivars with 48.56, 28.36 and 25.80 PRI, respectively and the cultivars Velox, Agria and Bright were the most sensitive cultivars with 1.90, 2.71 and 3.20 PRI, respectively in comparison to the other cultivars in 2008. Conclusion: Significant positive correlation was observed between the plant resistance indices (PRI) in two study years (r= 0.499, P= 0.01). Results of this research revealed that the cultivars Bridjet, Delikat, Cardinal, Carlita, Sinja and Nicola with the highest PRI were the most resistant cultivars to the Colorado potato beetle in comparison to other cultivars during 2007-2008, suggesting that these cultivars can be used in the IPM program of the pest and resistance transfer to high yield varieties through plant breeding programs

Correlations between yield and fruit quality characteristics of fresh market tomatoes Correlações entre caracteres de produção e qualidade de frutos de tomate de mesa

Genotypic, phenotypic and environmental correlations were estimated for all possible pairs among eleven characters of tomatoes. Fifteen treatments including five parents and ten hybrids of Instituto Agronômico (IAC) tomato breeding program were evaluated using a randomized complete block experimental design, with tree replications in Itatiba, São Paulo state, Brazil, during 2005/2006. The following traits were evaluated: fruit yield per plant (FP), fruit number per plant (FN), average fruit weight (FW), cluster number per plant (CN), fruit number per cluster (FC), number of locules per fruit (NL), fruit length (FL), fruit width (WI), fruit wall thickness (FT), total soluble solids (SS), and total titratable acidity (TA). The genotypic (rG), phenotypic (rF) and environmental correlations (rA) for two pairs of plant traits were estimated using the Genes© program. High similarity was found among the estimates of genotypic and phenotypic correlations. Positive and high phenotypic and genotypic correlations were observed between FP and the traits FN, FW and FT, and these associations contributed for yield increasing. FW and FT contributed to yield increase and should be considered together as primary yield components in tomato. Positive values of the genotypic and phenotypic correlations revealed that FP influenced FN with high direct effect and significant positive correlation. These traits may be included as the main selection criteria for tomato yield improvement.<br>Correlações fenotípica, genotípica e ambiental foram estimadas entre todos os possíveis pares de onze caracteres de tomate de mesa. Quinze tratamentos, incluindo cinco parentais e dez híbridos do programa de melhoramento de tomate do Instituto Agronômico (IAC) foram testados no delineamento em blocos casualizados completos, em Itatiba-SP, em 2005/2006. Os seguintes caracteres foram avaliados: produção (FP), número (FN) e peso médio do fruto (FW), número de pencas por planta (CN), número de frutos por penca (FC), número de lóculos por fruto (NL), comprimento do fruto (FL), largura do fruto (WI), espessura da parede do fruto (FT), sólidos solúveis totais (SS) e acidez titulável total (TA). Os coeficientes de correlação genotípica (rG), fenotípica (rF) e ambiental (rA) para cada par de caracteres foram estimados pelo programa Genes©. Houve grande similaridade entre as estimativas das correlações genotípicas e fenotípicas estudadas. As correlações genotípica e fenotípica entre FP e os caracteres FN, FW e FT foram positivas e altas, contribuindo para o aumento da produção. FW e FT devem ser considerados, em conjunto, como componentes primários na produção de tomate. Os valores positivos das correlações genotípicas e fenotípicas revelaram que FP influenciou FN com efeito direto e alta correlação positiva e significativa. Esses caracteres podem ser incluídos como principais critérios de seleção para aumento da produtividade em tomateiro