Showing 6 results for Indirect Selection
R. Shiravand , M. M. Majidi,
Volume 3, Issue 8 (6-2013)
Abstract
Littele is known about the relationships of different traits in safflower using wild and cultivated species. In this study, 46 safflower genotypes from five different species were evaluated under normal and deficit irrigation and the relationship of traits was assessed. Results showed that water stress had significant effect on head yield per plant, number of seeds per head, head diameter and 1000-seed weight but didn’t have significant effect on other traits. Positive and significant phenotypic correlations were observed among seed yield per plant with oil percent, number of heads per plant, head diameter, head yield per plant and number of seeds per head for both irrigation regimes, which were confirmed by genetic correlations. Based on stepwise regression, number of seeds per head justified the majority of seed yield variation for both stress and non-stress conditions. However, under normal conditions, the number of traits entered into the model and the justified variation was more than moisture stress conditions. Path analysis showed that number of heads per plant had the highest direct effect on seed yield in non-stress conditions and can be used to indirectly improve seed yield in safflower. Under stress conditions, number of seeds per head had the highest direct effect on seed yield. Factor analysis revealed four factors which explained more than 82 and 85 percent of variance in non-stress and stress conditions, respectively. These factors were named the sink, plant morphology, oil and economical factor in non-stress conditions. Under stress conditions, the factors were named the economical factor, plant morphology, sink and seed weight. The relationships between traits discussed in this study can be exploited in indirect selection to improve the important traits of safflower (such as seed yield and oil content) economically, through traits with higher heritability, with emphasis on wild germplasm.
F. Rashidi, M. M. Majidi,
Volume 6, Issue 19 (5-2016)
Abstract
In this study 36 canola genotypes from seven different species including Brassica. napus, B. rapa, B. oleracea, B. juncea, B. carinata, B. nigra and B. friticulosa were evaluated under non-stressed, moderate and sever drought stress conditions during 2011-2012 in a field experiment. The relationships among different traits were assessed. Results of analysis of variance (ANOVA) indicated high variation among genotypes for most of the studied traits. Cultivar by environment interaction was significant for most of the traits, suggesting differential genotypic responses to moistures conditions. The correlation results for the three B. napus, B. rapa and B. oleracea were divided in three levels of watering regime and the coefficients were found to be species-specific but overall correlation coefficients showed that there was significant and positive correlations between grain yield and number of pods per plant and 1000 grain weight, irrespective of watering regime. Results of stepwise regression were suggestive of species and watering-specificity. Under non-stress conditions the greatest direct effect on grain yield belonged to pod length for B. napus and number of pods per plant for B. rapa and B. oleracea. Results indicated that in order to improve grain yield indirectly, breeding strategies should be specific for each Brassica species.
P. Eynizadeh, H. Dehghani, M. Khodadai,
Volume 10, Issue 4 (1-2021)
Abstract
Tomato (Solanum lycopersicum L.) is one of the important horticultural crop species world-wide. Identifying superior genotypes with a high yield and acceptable fruit quality can pave the way for breeding programs. In order to identify the best tomato cultivars for some of fruit quality and yield related traits, a 3-replicate experiment with 20 commercial tomato hybrids in randomized complete block design was conducted in research field of Tarbiat Modares University in Tehran, in 2017. The examined traits included number of days to flowering, number of days to first fruit-set, plant height, number of primary branches, number of primary clusters, number of fruits per plant, fruit yield per plant, leaf chlorophyll index, fruit juice acidity, fruit electrical conductivity, water salinity, total dissolved solids, percentage of brix and fruit lycopene content. Hybrids were compared by two methods of the heatmap clustering and the analytical hierarchy process as a multivariate indicator. Among the 14 tested traits, four traits including number of days to flowering, leaf chlorophyll index, water salinity, and total dissolved solids, indicated low heritability and genotypic/phenotypic correlation with fruit yield and hence were denied for multivariate analysis. Hybrids Hypeel 108 and Queenty were superior to the other hybrids in fruit lycopene content and fruit yield, respectively, and both hybrids had an acceptable fruit juice acidity for processing in the food industry. Hybrids Queenty, Adora, Berlina, and Hypeel 108 indicated the highest AHP values and the highest genetic distances. Thus, they were found to be the most suitable genotypes for cultivating in areas with similar climatic conditions and formation of next breeding generation. These hybrids were superior to other hybrids, not only in fruit yield but also in a great majority of the traits.
E. Shadan, Mr H. Najafi Zarrini, B. Alizadeh, Gh. Ranjbar, Gh. Kiani,
Volume 11, Issue 4 (1-2022)
Abstract
Due to the increasing need of the country to imported edible oil and rapeseed importance among oilseeds, efforts to increase its grain yield and oil content are of high importance. Therefore, recognizing the traits that increase grain yield of rapeseed has an important role in the success of breeding programs. Thus, sixteen rapeseed genotypes were evaluated in a randomized complete block design with three replications in three regions with different climatic conditions in Iran, including Karaj, Isfahan, and Hamadan in 2016-2017. Traits such as number of pods per plant, number of seeds per pod, grain yield, 1000-grain weight, plant height, height of the first branch, stem diameter, oil percent, number of days to flowering, number of days to the end of flowering, duration of flowering, and number of days to maturity were measured. Stepwise regression analysis showed that number of grain/pod, number of days to maturity and number of pods/plant (R2 = 97.7), number of pods/plant and number of days to maturity (R2 =78.4) and number of days to maturity and number of grains/pod (R2 = 45.5) accounted for total variations of grain yield in Karaj, Isfahan and Hamadan, respectively. The results showed that the number of days to maturity, number of pods/plant, number of grain/pods, stem diameter and plant height had the greatest positive effect on grain yield and oil content. Therefore, these traits can be used as suitable selection tools for increasing grain and oil yield in winter rapeseed breeding programs
S.n. Emrani, A.m. Rezai, A. Arzani,
Volume 11, Issue 42 (1-2008)
Abstract
The most desirable approach to improve characteristics such as yield with polygenic inheritance and genotype × environment interaction, is simultaneous selection using selection index based on related traits. This study was conducted Research Farm of Isfahan University of Technology, to compare selection indices for barley yield improvement under nitrogen stress and non stress conditions, using 49 F13 recombinant inbred lines derived from a cross between Azumamugi and Kanto Nakate Gold. A split plot design with randomized complete block layout in three replications was used. In non-stress condition 100 kg nitrogen per hectare as urea was used at early reproductive growth, stem elongation and grain filling stages. In stress condition, 50 kg nitrogen per hectare was only used at early vegetative growth stage. Smith-Hazel and Pesek-Baker indices based on 4 traits (days to heading, harvest index, growth rate and nitrogen harvest index) and also direct and correlated response of these traits were calculated. The result of response to selection and correlated response indicated that the selection based on higher harvest index and nitrogen harvest index under both conditions screens high yielding lines. Harvest index had high weight in both indices under stress and non stress conditions. Under both conditions and for Smith-Hazel and Pesek-Baker indices, growth rate had negative correlation coefficients. Therefore, the selection based on these indices, separates lines with lower growth rate. In this study, Smith-Hazel index had higher efficiency.
A. M. Rezai, M. Yousofi Azar,
Volume 12, Issue 45 (10-2008)
Abstract
To improve a complex character such as yield with low heritability, the use of indirect selection through other characters and a selection index based on different effective traits is recommended. This study was conducted to evaluate different selection methods by using 23 F2:4 wheat lines derived from the cross of Virmarin (susceptible cultivar) and Sardari (tolerant cultivar) at Research Farm of Isfahan University of Technology. A randomized complete block design with three replications was used in two irrigation treatments (i.e. irrigation after 70±3 and 120±3 mm evaporation from class A pan). For each irrigation treatment, different selection indices were constructed based on the number of spike per m2, days to heading, number of grain per spike and 1000 – kernel weight. Also direct and correlated responses were calculated for these traits. The results of the response to selection and correlated response indicated that in the same conditions of this study, early heading cultivars with high number of spikes and low number of grain per spike with high 1000-kernel weight will have more yield potential. Number of spike per m2 and 1000-kernel weight exhibited positive response in most of the indices and both irrigation treatments, while days to heading and number of grain per spike revealed negative responses. Thus selection based on these indices would result in early heading cultivars with high spike per m2, low number of grain per spike and high 1000–kernel weight. It was also found that Smith-Hazel and Brim-Williams indices had the highest efficiencies.
