Significant Crossover Interactions Research Articles

B - 88 The Role of Cognitive Functioning on Trauma and Suicidality in Inpatient Cisgender and Gender-Minority Youth.

This study aimed to examine how executive functioning (EF) and processing speed (PS) moderate the relationship between adverse childhood experiences (ACE's) and suicidality in cisgender and gender-minority youth (GMY) in an inpatient setting. We hypothesized that neurocognitive domains will moderate the relationship between ACE's and suicidality in GMY. An inpatient psychiatric sample of 43 GMY and 43 cisgender adolescents ages 13-19 (M = 15.02, SD = 1.57) participated in this study. Participants completed the ACEs to measure cumulative trauma exposure, and the Millon Adolescent Clinical Inventory that assessed suicidality. EF and PS composite scores were used as moderators. Two regression models were conducted to examine how EF, PS, ACEs, and the ACEs*EF and ACEs*PS interactions predicted suicidality for cisgender and GMY respectively. For cisgender adolescents, no significance was found in the regression model (F(5,36) = 1.11, p = 0.370) or interactions between ACEs and EF (b = -2.24, p = 0.122) or PS (b = 2.14, p = 0.390). Although the regression model was not significant (F(5,37) = 1.52, p = 0.207) for GMY, there were significant crossover interactions between ACEs and EF (b = -3.50, p = 0.013; 95%CI = -6.20, -0.80), and PS (b = -3.67, p = 0.027; 95%CI = 0.44, 6.90) on suicidality. These results suggest that EF and PS meaningfully attenuate the relationship between ACEs and suicidality for GMY in an inpatient setting whereas this attenuation is not seen in their cisgender counterparts. Such findings can lead to better indicators and interventions for GMY in inpatient settings.

The Effects of a Brief Mindfulness Intervention on Mindfulness, Stress and Emotional Intelligence in Medical Students

This study aimed to evaluate the effects of a brief mindfulness-based intervention (b-MBI) on the levels of mindfulness, perceived stress and emotional intelligence (EI). Fifty-nine undergraduate students in medicine course were randomly allocated to either 4 weekly b-MBI sessions (n = 30) or waitlist control (n = 29). All participants completed Mindful Attention Awareness Scale (MAAS), Perceived Stress Scale (PSS-10) and USM Emotional Quotient Inventory (USMEQ-i) at pre- and post-intervention. Findings from mixed-factorial ANOVA revealed significant cross-over interactions, but no significant main effects of treatment conditions and time, on mindfulness and perceived stress. Post-hoc analyses indicated intervention group to experience significantly increased levels of mindfulness (p = 0.012) and decreased perceived stress (p = 0.003) at post-intervention, which were unobserved in the controls. Significant main effect of time was observed (p = 0.001) for EI; however, only intervention group reported significant increase in the scores (p = 0.004). The lack of between-group treatment effects could be justified due to relatively low stress and high EI for intervention and control groups at baseline. Nonetheless, within-group findings provided preliminary evidence that b-MBI may be beneficial in improving mindfulness, perceived stress and EI. This intervention may be adapted into the medical curriculum to improve the psychological well-being of medical students.

Fathers' oxytocin responses to first holding their newborns: Interactions with testosterone reactivity to predict later parenting behavior and father-infant bonds.

Little is known about human fathers' physiology near infants' births. This may represent a period during which paternal psychobiological axes are sensitive to fathers' new experiences of interacting with their newborns and that can provide insights on how individual differences in fathers' biology relate to post-partum parenting. Drawing on a sample of men in South Bend, IN (U.S.), we report results from a longitudinal study of fathers' oxytocin, cortisol, and testosterone (N=211) responses to their first holding of their infants on the day of birth and men's reported caregiving and father-infant bonding at 2-4months post-partum (N=114). First-time fathers' oxytocin was higher following first holding of their newborns, compared to their pre-holding levels. Contrasting with prior results, fathers' percentage change in oxytocin did not differ based on skin-to-skin or standard holding. Drawing on psychobiological frameworks, we modeled the interactions for oxytocin reactivity with testosterone and cortisol reactivity, respectively, in predicting father-infant outcomes months later. We found significant cross-over interactions for (oxytocin×testosterone) in predicting fathers' later post-partum involvement and bonding. Specifically, we found that fathers whose testosterone declined during holding reported greater post-partum play if their oxytocin increased, compared to fathers who experienced increases in both hormones. We also observed a similar non-significant interaction for (oxytocin×cortisol) in predicting fathers' post-partum play. Fathers whose testosterone declined during holding also reported less involvement in direct caregiving and lower father-infant bonding if their oxytocin decreased but greater direct care and bonding if their testosterone increased and oxytocin decreased. The results inform our understanding of the developmental time course of men's physiological responsiveness to father-infant interaction and its relevance to later fathering behavior and family relationships.

Parametric and Non-parametric Procedures for Identifying Stable and Adapted Tropical Maize Genotypes in NLB Disease Infested Environments

Multi-locational trials are critical for establishing stable and adaptable genotypes across different geographic areas prior to considering commercial release. The stability and adaptation of 20 tropical maize hybrids in environments infected with Northern leaf blight disease were assessed using 12 parametric and 14 nonparametric parameters across five environments. The purpose of this research is to estimate the genotype-environment interaction (GEI) for grain yield in selected maize genotypes and to identify associated stability factors to aid in the rationalization of stability analysis in Multi-Environment Trial (MET) data used in breeding programs. Except for De Kroon and Van der Laan (1981), both the combined ANOVA and nonparametric tests of GEI showed significant differences across hybrids, as well as significant crossover and non-crossover interactions. This suggests differential genotypes responses to the test environments. Spearman correlation analysis revealed significant differences between many nonparametric and parametric parameters, indicating that the two may be utilized interchangeably. Additionally, the correlation matrix and principal component analysis results from parametric and nonparametric parameters demonstrated their potential to assess the responses of maize genotypes to changing environments. G13 and G20 appeared most phenotypically stable with associated high mean yield based on the high values expressed by most parametric and nonparametric parameters.

Impact of Psychiatric Diagnosis and Treatment on Medication Adherence in Youth With Systemic Lupus Erythematosus.

Youth with systemic lupus erythematosus (SLE) experience high rates of psychiatric comorbidities, which may affect medication adherence. We undertook this study to examine the association between psychiatric disorders and hydroxychloroquine adherence and to determine whether psychiatric treatment modifies this association. We identified incident hydroxychloroquine users among youth with SLE (ages 10-24 years) using de-identified US commercial insurance claims in Optum Clinformatics Data Mart (2000-2016). Adherence was estimated using medication possession ratios (MPRs) over a 365-day time period. Multivariable linear regression models were used to estimate the effect of having any psychiatric disorder on MPRs, as well as the independent effects of depression, anxiety, adjustment, and other psychiatric disorders. We tested for interactions between psychiatric diagnoses and treatment with psychotropic medications or psychotherapy. Among 873 subjects, 20% had a psychiatric diagnosis, most commonly depression. Only adjustment disorders were independently associated with decreased MPRs (β -0.12, P = 0.05). We observed significant crossover interactions, in which psychiatric disorders had opposite effects on adherence depending on the receipt of psychiatric treatment. Among youth with any psychiatric diagnosis, psychotropic medication use was associated with a 0.15 increase in the MPR compared with no psychotropic medication use (P = 0.02 for interaction). Among youth with depression or anxiety, psychotherapy was also associated with a higher MPR compared with no psychotherapy (P = 0.05 and P < 0.01 for interaction, respectively). The impact of psychiatric disorders on medication adherence differed by whether youth had received psychiatric treatment. Improving recognition and treatment of psychiatric conditions may increase medication adherence in youth with SLE.

Victim Gender, Number of Perpetrators, and Interpersonal Interaction in Stranger Rape: An Analysis of Direct and Moderator Effects

AbstractThis study examined the direct and moderator effects of number of perpetrators and gender of victim on interpersonal behaviour in stranger rape. Crime scene behaviours representative of hostility, involvement, control, and offender penetration in rape were examined for 496 UK, police‐recorded cases of stranger rape. Cases were grouped according to victim gender (male or female) and number of perpetrators (lone or multiple). This resulted in four groups (lone female, lone male, multiple female, and multiple male) with 124 cases in each. Binary logistic regression and one‐way analysis of variance were used to investigate the relationships between the two predictor variables and 11 criterion variables.Significant direct effects of number of perpetrators were found whereby multiple perpetrator offences were more likely to involve violence and less likely to involve involvement interactions than lone perpetrator offences. Significant direct effects of victim gender were also found whereby male victims were more likely than female victims to experience hostile interactions and be threatened with a weapon and were less likely to experience offender penetration and involvement interactions. Significant crossover interactions were also found for four hostility variables. The utility of the findings are discussed in relation to crime prevention, victim support, and offender intervention. Copyright © 2013 John Wiley &amp; Sons, Ltd.

Evaluation of winter wheat breeding lines for traits related to nitrogen use under organic management

There is growing interest in breeding crop cultivars specifically for organic agriculture, based on recognized differences in environmental conditions and management in organic systems compared to conventional systems, and especially due to environmental heterogeneity among and within individual organic systems. There is a need to develop effective strategies for improving crop performance in organic systems through plant breeding. This study evaluated 12 diverse winter wheat breeding lines chosen from conventional and organic breeding nurseries, six historic varieties, and an experimental perennial wheat population under organic management in the Inland Pacific Northwest region of the USA. A randomized complete block design with three replications in two locations over 2 years was used. Based on an analysis of variance, significant genetic differences and crossover interactions across years were found for grain yield, grain percent nitrogen, grain total nitrogen, and aboveground biomass. There were no main effects of locations or location-by-genotype effects for these traits. Based on comparisons among these breeding lines, it appears that there is a possibility of selecting for performance across a limited ecological zone as top-yielding lines were the same in both locations. However, individual entries may have variable performance across years within a single location so selection for stability of performance over years is also necessary. Using an analysis of direct measures of grain yield and grain %N in each location–year combination and overall, we identified breeding lines with relatively high yield, acceptable grain protein, and stable performance over all four location–year combinations. The use of indirect measures or index selection to simultaneously select for grain yield and protein did not appear to be more effective than direct selection based on yield and grain %N measured under organic management.

Interpreting Genotype × Environment Interaction in Bread Wheat (Triticum aestivum L.) Genotypes Using Nonparametric Measures

The objectives of this study were to compare nonparametric stability measures, and to identify promising high-yield and stable bread wheat (Triticum aestivum L.) genotypes in 7 environments during 2003-2005 in the central Black Sea region of Turkey. The bread wheat genotypes (20 advanced lines and 5 cultivars) were grown in a randomized complete block design with 4 replications in 7 different environments. Three nonparametric statistical tests of significance for genotype × environment (GE) interaction and 10 nonparametric measures of stability were used to identify stable genotypes in 7 environments. Combined ANOVA and nonparametric tests (Kubinger, Hildebrand, and De Kroon/Van der Laan) of genotype × environment interaction indicated the presence of significant crossover and non-crossover interactions, as well as significant differences between genotypes. In this study high TOP values (proportion of environments in which a genotype ranked in the top third) and low rank-sum values (sum of ranks of mean yield and Shukla’s stability variance) were associated with high mean yield. Nonetheless, results of the other nonparametric tests were negatively correlated with mean yield. In the simultaneous selection for high yield and stability, only the rank-sum and TOP methods were useful in terms of the principal component analysis (PCA) results, and correlation analysis of nonparametric stability statistics and yield. According to these stability parameters (TOP and rank-sum) G7 (VONA//KS75210/TAM101), G9 (JUP/4/CLLF/3/II14.53/ODIN//CI13431/WA 00477), G20 (Sakin), and G21 (VORONA/KAUZ//1D13.1/MLT) were the most stable genotypes for grain yield. The results also revealed that based on nonparametric test results stability could be classified into 3 groups, according to agronomic and biological concepts of stability.

Comparison of parametric and non-parametric methods for selecting stable and adapted durum wheat genotypes in variable environments

Twenty parametric and non-parametric measures derived from grain yield of 15 advanced durum genotypes evaluated across 12 variable environments during the 2004–2006 growing seasons were used to assess performance stability and adaptability of the genotypes and to study interrelationship among these measures. The combined ANOVA and the non-parametric tests of Genotype × environment interaction indicated the presence of significant crossover and non-crossover interactions, and of significant differences among genotypes. Principal component analysis based on the rank correlation matrix indicated that most non-parametric measures were significantly inter-correlated with parametric measures and therefore can be used as alternatives. The results also revealed that stability measures can be classified into three groups based on static and dynamic concepts of stability. The group related to the dynamic concept and strongly correlated with mean grain yield of stability included the parameters of TOP (proportion of environments in which a genotype ranked in the top third), superiority index (P i) and geometric adaptability index. The second group reflecting the concept of static stability included, Wricke’s ecovalence, the variance in regression deviation (S 2 di), AMMI stability value, the Huehn’s parameters [S i (1) , S i (2) ], Tennarasua’s parameter [NP i (1) ], Kang’s parameter (RS) and yield reliability index (I i) which were not correlated with mean grain yield. The third group influenced simultaneously by grain yield and stability included the measures S i (3) , S i (6) , NP i (2) , NP i (3) , environmental variance (S 2 xi), coefficient of variability and coefficient of regression (b i). Based on the concept of dynamic stability, genotypes G6, G4, and G3 were found to be the most adapted to favorable environments, whereas genotypes G8, G9, and G12 were more stable and are related to the concept of static stability.

Effect of Environment on Resistance to the European Corn Borer (Lepidoptera: Crambidae) in Maize

The European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), is a major pest of maize, Zea mays L., in many temperate parts of the world. Genotype-by-environment interaction effects can make relative performance unpredictable and may hamper selection for resistance to European corn borer. The objective of this study was to determine the effect of environment on genotypic reaction to European corn borer resistance in maize. A set of 12 maize inbred lines was chosen to represent a range of European corn borer responses. Eleven testing environments ranged from Delaware, Ohio, Illinois, Iowa, Nebraska, Missouri, to Mississippi. For length of stalk tunneling, environmental and genotypic main effects (estimated by restricted maximum likelihood) were >20- and 10-fold larger than their interaction effect, respectively. Length of tunneling means for genotypes (across environments) ranged from 10.1 to 35.4 cm. Several putatively resistant genotypes grouped with the susceptible checks, B73 and Mol7. By breaking factors and the interaction into single degree of freedom components, we observed that GEMS-0001 had significant crossover interactions toward less susceptibility in both Mississippi and the Nebraska environments. Environments displaying several crossover interactions indicated that European corn borer screening at these sites would not necessarily apply to other locations, whether due to small differences in experimental conduct and/or environmental effects. The five most resistant genotypes were fairly consistent across environments. Because all environments except Illinois used larvae from the same insectary, and these environments differed in damage intensity and rankings, it is unlikely that insect biotype was a factor contributing to genotype-by-environment effects.

Clustering Environments to Minimize Change in Rank of Cultivars

Crossover interactions occur in evaluation trials when ranks of cultivars change across environments. Determining groups of environments within which crossover interactions are minimized may facilitate making cultivar recommendations. The goal of this research was to test a new approach for determining these environmental groups in which crossover interaction between a pair of cultivars was defined across all environments. The number of groups was based both on reduction in crossover interaction and repeatability of cultivar means within groups. The validity of this procedure was tested on three simulated data sets with known crossover interactions. For each data set, the approach divided the environments into the two groups that minimized crossover interactions. The approach also was applied to yield data from a maize (Zea mays L.) trial in which 59 environments previously had been clustered by a different measure of crossover interaction. Three groups of 12 environments and one group of 23 environments were defined. The previous clustering had identified six clusters. The amount of crossover interaction within the four environmental groups was reduced by 53% from the total crossover interaction in all 59 environments. The results of the clustering depended on whether all pairwise comparisons among cultivars or only the significant crossover interactions among the higher yielding cultivars were used. The latter method was deemed more appropriate when the goal is to recommend specific cultivars for specific groups of environments. Regardless of the approach used, clustering based on crossover interactions only has practical significance if these interactions are repeatable.

Clustering Environments to Minimize Change in Rank of Cultivars

Crossover interactions occur in evaluation trials when ranks of cultivars change across environments. Determining groups of environments within which crossover interactions are minimized may facilitate making cultivar recommendations. The goal of this research was to test a new approach for determining these environmental groups in which crossover interaction between a pair of cultivars was defined across all environments. The number of groups was based both on reduction in crossover interaction and repeatability of cultivar means within groups. The validity of this procedure was tested on three simulated data sets with known crossover interactions. For each data set, the approach divided the environments into the two groups that minimized crossover interactions. The approach also was applied to yield data from a maize (Zea mays L.) trial in which 59 environments previously had been clustered by a different measure of crossover interaction. Three groups of 12 environments and one group of 23 environments were defined. The previous clustering had identified six clusters. The amount of crossover interaction within the four environmental groups was reduced by 53% from the total crossover interaction in all 59 environments. The results of the clustering depended on whether all pairwise comparisons among cultivars or only the significant crossover interactions among the higher yielding cultivars were used. The latter method was deemed more appropriate when the goal is to recommend specific cultivars for specific groups of environments. Regardless of the approach used, clustering based on crossover interactions only has practical significance if these interactions are repeatable.

Effect of Environment and Genotype on Durum Wheat Gluten Strength and Pasta Viscoelasticity

ABSTRACTData on the quality of durum wheat genotypes grown under eight environments (site‐year combinations) were evaluated to determine the relative effects of genotype and environment on quality characteristics associated with gluten strength, protein content, and pasta texture. The 10 durum wheat genotypes assessed in this study represented a range of gluten strength types from the very strong U.S. desert durum genotype, Durex, to the medium strength Canadian genotype, Plenty. Considerable genetic variability was detected for all quality characteristics studied. Genotype‐environment interaction was significant for all quality parameters evaluated, with the exception of mixograph development time. Genotypeenvironment interaction was most important in determining protein content and least important in determining gluten index, gluten viscoelasticity, and SDS sedimentation volume. The nature of the genotype‐environment interaction was evaluated by determining the number of significant crossover (rank change) interactions. There was at least one significant crossover interaction between pairs of genotypes and environments for five of eight quality traits tested. Of 45 genotype pairs, eight and six showed significant crossover interactions for protein content and pasta disk viscoelasticity, respectively. Significant crossover interactions were at least partially due to the differential response of Canadian genotypes as compared with U.S. genotypes. With the exception of protein content and pasta disk viscoelasticity, our results suggest that among the selected sample of 10 genotypes, genotype‐environment interactions were minor and due primarily to changes in magnitude rather than changes in rank.

Sites Regression and Shifted Multiplicative Model Clustering of Cultivar Trial Sites under Heterogeneity of Error Variances

Previous papers have developed the shifted multiplicative model with one multiplieative term (SHMM1) as a model for clustering yield trial sites or cultivars into groups in which cultivar rank changes are statistically negligible. Properties of SHMM1 are proportionality of predicted cultivar differences within sites, and of site differences within cultivars. The latter constraint is relaxed if the sites regression model with one multiplicative term (SREG1) is used instead of SHMM1. Dendrograms for the two methods are identical, but SHMM and SREG analyses of clusters suggested by the dendrogram may lead to different conclusions concerning acceptability of a particular cluster. This study compared SREG clustering to SHMM clustering in two international maize (Zea mays L.) cultivar trials, when the data to which models were fitted were original unscaled cell means, and, as a way to cope with site to site heterogeneity of error variance, cell means scaled by dividing by the standard error of a cultivar mean within the particular site. Results of both trials confirmed our expectation that SREG clustering would occasionally allow clusters to merge which would not be statistically acceptable under SHMM analysis. This occurred at a cost of a modest increase in percentage and magnitude of significant crossover interactions within the clusters. Both trials exhibited significant site to site heterogeneity of error variances. Scaling of data resulted in more effective removal of significant rank‐change interactions from within clusters, provided that the test criterion was based on the assumption of heterogeneous variance. Besides occasionally allowing larger clusters, advantages for SREG clustering of sites are (i) all solutions (including constrained non‐crossover solutions) exist in closed form and (ii) the analysis of scaled data is equivalent to a weighted least squares analysis, neither of which holds for SHMM.

Yield Potential Progress in Short Bread Wheats in Northwest Mexico

Germplasm from the spring wheat (Triticum aestivum L.) breeding program at the International Center for Improvement of Maize and Wheat (CIMMYT) has had a major impact on the yield of irrigated spring wheats in most developing countries in the past 30 yr. The rate and nature of yield potential progress in this germplasm was measured comparing eight outstanding short cultivars released in northwest Mexico between 1962 and 1988. They were grown under irrigation and optimal management, including disease and lodging protection, in each of six winter growing seasons (1989–1990 to 1994–1995) at the CIANO (Centro de Investigaciones Agricolas del Noroeste) experiment station in Sonora, Mexico. There were highly significant effects of cultivar on grain yield, and, although cultivar × year interaction was significant, there were few significant crossover interactions between pairs of genotypes and years in the grain yield data set. Yield averaged across the 6 yr increased linearly from 6680 kg ha−1 for the earliest cultivar, Pitic 62, to 8475 kg ha−1 for Bacanora 88, the latest. The rate of progress against year of release was 67 kg ha−1 yr−1 (r = 0.99, P &lt; 0.001), or 0.88% per year. Grain yield progress was correlated with kernel number per square meter (r = 0.84, P &lt; 0.01) and harvest index (r = 0.81, P &lt; 0.02), but not with total biomass production, kernel weight, days to anthesis, spikes per square meter, or kernels per spike. Thus linear progress in yield within short germplasm has continued at least until the late 1980s, and the yield components studied did not indicate any clear direction for future progress, apart from that suggested by the strong relationships between grain yield and harvest index and grain yield and kernels per square meter, as has been seen in most studies of yield progress in cereals.

Heritability and Genotype × Environment Interactions for Straighthead in Rice

Straighthead is a physiological disorder of rice (Oryza sativa L.), which is manifested by floret sterility resulting in yield loss. The objectives of this study were to estimate the narrow‐sense beritability (h2) and the relative importance of genotype × environment interactions for straighthead and to suggest an optimum experimental design for straighthead screening. Ten commercial cultivars and 22 randomly chosen experimental lines representing southern USA rice germplasm were tested from 1991 to 1993 at three Arkansas locations: Stuttgart [Crowley silt loam (fine, montmorillonitic, thermic Typic Albaqualf)], Marianna (Loring silt loam [fine‐silty, mixed, thermic Typic Fragiudalf)], and Colt [Calloway silt loam (fine‐silty, mixed, thermic Glossaquic Fragiudalf)]. Straighthead was induced by monosodiumm ethane arsenate [4.48 kg a.i. ha−1] incorporated into the soil before planting combined with a permanentf lood established at the five‐leaf stage and maintained at each location. The genotype × year and the genotype × location interaction variance components were near zero. The three‐way interaction was significant, but its variance component was one‐fourth the magnitude of the genetic variance. The nature of the genotype × environment interaction was explored by determining the number of significant crossover (rank change) interactions. There were 798 significant crossover interactions or 4.5% of the possible 17 856 quadruples. Thus, genotype × environment interactions were minor and due primarily to changes in magnitude rather than to changes in rank. Heritability (single plot basis) was 61%, indicating that selection for resistance to straighthead should be relatively easy in southern U.S. rice germplasm. Two locations with four replications per location should be adequate for screening southern U.S. rice germplasm for reaction to straighthead.

Interference effects in white clover genotypes grown as pure stands and binary mixtures with different grass species and varieties

Six white clover genotypes and eight grass varieties belonging to four different species were grown both in monoculture and as grass-legume binary mixtures in dense swards for two years under a mowing regime and a management including N fertilization. Dry matter yield and yield-related traits were recorded to investigate some aspects of inter-specific interference in white clover-based mixtures and to define a methodology for selecting genotypes of this clover suited to conditions of association. Clover was at a competitive disadvantage in most mixtures. Differences among grasses for aggressiveness were related more to variety vigour than to species. Clover compatibility proved specific only in relation to grass vigour. Variation among clovers for tolerance to competitive stress involved significant cross-over interactions passing from monoculture to severe stress conditions for clover yield and other traits, and was related positively to stolon density and negatively to yield and leaf gigantism traits recorded in monoculture. Clover selection for high levels of competitive stress seems possible either by genotype assessment in stress conditions or by a combination of high yield and stolon density assessed in monoculture.

AGRONOMIC PERFORMANCE OF SEMI-DWARF AND NORMAL HEIGHT SPRING WHEATS SEEDED AT DIFFERENT DATES

Emergence, maturity, and yield of four semi-dwarf and five normal height spring wheat (Triticum aestivum L.) genotypes were evaluated in 10 replicated field experiments at Saskatoon in 1985–1987. Although significant crossover interactions were observed, semi-dwarf and normal height genotypes responded similarly to date of seeding.Key words: Triticum aestivum, seeding date, crossover interaction, wheat (spring)

TESTS FOR CROSSOVER GENOTYPE-ENVIRONMENTAL INTERACTIONS

Two statistical tests for crossover genotype-environmental interactions are illustrated. One test, suitable for investigating two-factor interactions in factorial experiments, was used to show that interactions between wheat cultivars and temperatures for median germination time did not involve significant changes in rank order. A second test was used to compare yields of three cultivars of spring wheat evaluated in nine environments and to demonstrate that the differences between HY320 and Fielder involved significant crossover interactions, whereas the differences between HY320 and Neepawa, and between Fielder and Neepawa, did not involve crossover interactions. Calculations required for the two tests are shown. The importance of the tests for investigating genotype-environmental interactions and related topics is discussed.Key words: Genotype-environmental interactions, qualitative interaction, statistical tests, Triticum aestivum L., wheat (spring)