Kamila Nowosad

Mixed linear model approaches in mapping QTLs with epistatic effects by a simulation study

Epistasis refers to the phenotypic effects of interactions between alleles of different loci. Statistical detection of such interactions remains to be the subject of presented studies. A method based on mixed linear model was developed for mapping QTLs with digenic epistasis. Reliable estimates of QTL additive and epistasis effects can be obtained by the maximum-likelihood estimate methods. Likelihood ratio and t statistics were combined for testing hypotheses about QTL effects (additive and epistasis effects). Monte Carlo simulations were conducted for evaluating the unbiasedness, accuracy and power for parameter estimation in QTL mapping. The results indicated that the mixed-model approaches could provide unbiased estimates for effects of QTLs. Additionally, the mixed-model approaches also showed high accuracy in mapping QTLs with epistasis effects. The information obtained in this study will be useful for manipulating the QTLs for plant breeding by marker assisted selection.

Parallel coordinate plots of maize traits under different magnesium applications

Abstract The parallel coordinate plot is proposed as an efficient tool for visualization of 13 traits of “stay-green” maize ( Zea mays L.) cultivar exposed to different methods of magnesium application. The field experiment was conducted in the Department of Agronomy, Poznan University of Life Sciences, on the fields of the Department of Teaching and Experimental Station in Swadzim in 2006–2008. Experiment was conducted as a single-factor experiment with seven applications of magnesium in a randomized complete block design with four replicates. The highest mean values of grain yield and 1 000-grain weight were obtained after application of variant T3 of magnesium (10 kg MgO ha −1 soil) in the all three years of study.

Genotype by environment interaction for oil content in winter oilseed rape (Brassica napus L.) using additive main effects and multiplicative interaction model

The objective of this study was to assess genotype by environment interaction for oil content in winter rapeseed cultivars grown in West Poland by the additive main effects and multiplicative interaction model. The study comprised of 25 winter rapeseed genotypes (15 F1 CMS ogura hybrids, parental lines and two European cultivars: open pollinated Californium and F1 hybrid Hercules), evaluated at five locations in a randomized complete block design, with four replicates. Oil content of the tested genotypes ranged from 35.2 to 48.8%, with an average of 44.55%. AMMI analyses revealed significant genotype by environmental interaction with respect to oil content. The hybrid PN66×PN18 is recommended for further inclusion in the breeding program due to its high oil content, CMS ogura line PN66 and hybrid PN68×PN18 are recommended because of its stability and high oil content.

Path analysis and estimation of additive and epistatic gene effects of barley SSD lines

Abstract In the paper presented, 99 single seed descent barley lines as well as their parental forms Roland and Apex were studied. The grain weight components and their interrelations were analyzed using simple coefficients of correlation. The direct and indirect effects of such components on grain weight per plant and 1000-grain weight were estimated using path analysis. In the 2006 and 2007, the spike length and number of spikelets per spike were the determinants of grain weight. Genetic parameters as additive and epistasis effects were estimated for all studied traits. The results indicate the importance of both additive and epistasis gene effects of number of spikes per plant, grain weight per spike, grain number per plant and grain weight per plant in this study.

The influence of potassium to mineral fertilizers on the maize health

Abstract Field experiments (2009–2011) were conducted at the Department of Agronomy at Poznan University of Life Sciences on the fields of the Research Institute in Swadzim. We evaluated the health of maize plants of two types, depending on the variations in mineral fertilization. The conducted research recorded the occurrence of pests such as oscinella frit ( Oscinella frit L.) and the European corn borer ( Pyrausta nubilalis Hbn.). Diseases recorded during the research included two pathogenes: Fusarium ( Fusarium ssp.) and corn smut ( Ustilago maydis Corda). It was shown that the meteorological conditions during the maize vegetation had a significant influence on the occurrence of pests. Adding potassium to mineral fertilizers increased the maize resistance to Fusarium. Cultivation of “stay-green” cultivar shall be considered as an element of integrated maize protection. The occurrence of oscinella frit was correlated with the occurrence of Fusarium as well as the occurrence of the European corn borer for both examined cultivars.

Evaluation of the breeding value of the spring oilseed rape (Brassica napus L.) inbred lines based on a multi-trait analysis

Oilseed rape (Brassica napus L.) is the most important oilseed crop after soybean worldwide, especially in the countries with moderate climate. The aim of the present study was to assess the genetic crossing potential of eight inbred lines of the spring oilseed rape (B. napus L.) based on the indices of associative combinatory value. The main trait for calculation of multidimensional indices of genetic potential was the seed yield per plant. Obtained results showed that the selection index can enable the choice of the most valuable lines to be practically used in heterotic breeding of the oilseed rape.

Soil tillage methods by years interaction for harvest index of maize (Zea mays L.) using additive main effects and multiplicative interaction model

ABSTRACT The objective of this study was to assess soil tillage methods by years interaction for harvest index (HI) of maize (Zea mays L.) grown in West Poland by the additive main effects and multiplicative interaction model. The study comprised four soil tillage methods, analysed in 12 years through field trials arranged in a randomised complete block design, with four replicates. HI of the tested soil tillage methods varied from 0.354 to 0.692 throughout the 12 years, with an average of 0.530. In the variance analysis, 57.06% of the total harvest index variation was explained by years, 2.39% by differences between soil tillage methods, and 8.71% by soil tillage methods by years interaction. HI is highly influenced by year factors. The method of reduced conventional tillage [autumn shallow ploughing (15 cm), cultivator with string roller in spring] was the most stable (additive main effects and multiplicative interaction stability value, ASV=0.410) for the HI values among studied soil tillage methods. This result confirms the opinion on the possibility of shallowing autumn ploughing in the cultivation of maize for grain.

Genotype-by-environment interaction for seed glucosinolate content in winter oilseed rape (Brassica napus L.) using an additive main effects and multiplicative interaction model

Summary The objective of this study was to assess genotype-by-environment interaction for seed glucosinolate content in winter rapeseed cultivars grown in western Poland using the additive main effects and multiplicative interaction model. The study concerned 25 winter rapeseed genotypes (15 F1 CMS ogura hybrids, parental lines and two European cultivars: open pollinated Californium and F1 hybrid Hercules), evaluated at five locations in a randomized complete block design with four replicates. The seed glucosinolate content of the tested genotypes ranged from 5.53 to 16.80 μmol∙g-1 of seeds, with an average of 10.26 μmol∙g-1. In the AMMI analyses, 48.67% of the seed glucosinolate content variation was explained by environment, 13.07% by differences between genotypes, and 17.56% by genotype-by-environment interaction. The hybrid PN66×PN07 is recommended for further inclusion in the breeding program due to its low average seed glucosinolate content; the restorer line PN18, CMS ogura line PN66 and hybrids PN66×PN18 and PN66×PN21 are recommended because of their stability and low seed glucosinolate content.

Estimation of additive and epistatic gene effects of doubled haploid lines of winter oilseed rape (Brassica napus L.)

In this paper 60 doubled haploid lines of oilseed rape (Brassica napus L.) were studied. Genetic parameters as additive and epistasis effects were estimated for nine quantitative traits. The results indicate the importance of both additive and epistasis gene effects of number of branches per plant, number of siliques per plant, number of seeds per silique and silique length in this study.

Testing of uniformity of seven Lathyrus species using Bennett’s and Miller’s methods

In this paper we focused on uniformity of seven Lathyrus species: Lathyrus aphaca, L. cicero, L. clymenum, L. hirsutus, L. ochrus, L. sativus and L. tingitanus. Two statistical methods, the Bennett’s and the Miller’s were compared. In both methods, coefficient of variation for evaluation of the uniformity of crop varieties was used. Four quantitative traits were analyzed: length of the pod, width of the pod, weight of seeds from the pod and 100 seed weight. The results of the study demonstrated that, the Bennett’s method is less restrictive (lesser species were found to be uniform in analyzed traits) compared to the Miller’s one.