Hybrid wheat (Triticum aestivum L.) offers promises to break the yield stagnation in global wheat productivity as a result of heterosis. But, for this promise to be realized, the level of heterosis must be adequate. To test this, elite winter wheat lines from the breeding programs of the University of Nebraska-Lincoln (UNL) and Texas A&M University (TAMU) were crossed in a 25-by-25 full-diallel design using a chemical hybridizing agent (CHA) to produce experimental hybrids. These hybrids were planted in a modified augmented design with commercial checks and parents at McGregor, TX, in 2016 (n = 612) and Greenville and Bushland, TX, in 2017 (n = 470) to evaluate for yield heterosis and combining ability. A subset of hybrids (n = 333) were repeated between years. The effect of field heterogeneity in grain yield was corrected by spatial modelling in ASReml-R. Commercial heterosis ranged from −78.3 to 20.4% in 2016 and −32.9 to 6.2% in 2017. High-parent heterosis (HPH) ranged from −70.4 to 54.3% in 2016 and −26.9 to 29.2% in 2017. General combining ability (GCA) variance was significantly higher than zero, whereas specific combining ability (SCA) variance was not. Significant maternal effect was identified in some crosses tested by computing reciprocal effects between crosses and estimating variances. This indicates that most of the heterosis is due to additive rather than dominance effect. These results suggest exploitation of GCA for higher yield while underscoring the need for development of heterotic pools to maximize SCA and dominance effects.

Anther extrusion (AE) is the most important male floral trait for hybrid wheat seed production. AE is a complex quantitative trait that is difficult to phenotype reliably in field experiments not only due to high genotype-by-environment effects but also due to the short expression window in the field condition. In this study, we conducted a genome-wide association scan (GWAS) and explored the possibility of applying genomic prediction (GP) for AE in the CIMMYT hybrid wheat breeding program. An elite set of male lines (n = 603) were phenotype for anther count (AC) and anther visual score (VS) across three field experiments in 2017–2019 and genotyped with the 20K Infinitum is elect SNP array. GWAS produced five marker trait associations with small effects. For GP, the main effects of lines (L), environment (E), genomic (G) and pedigree relationships (A), and their interaction effects with environments were used to develop seven statistical models of incremental complexity. The base model used only L and E, whereas the most complex model included L, E, G, A, and G × E and A × E. These models were evaluated in three cross-validation scenarios (CV0, CV1, and CV2). In cross-validation CV0, data from two environments were used to predict an untested environment; in random cross-validation CV1, the test set was never evaluated in any environment; and in CV2, the genotypes in the test set were evaluated in only a subset of environments. The prediction accuracies ranged from −0.03 to 0.74 for AC and −0.01 to 0.54 for VS across different models and CV schemes. For both traits, the highest prediction accuracies with low variance were observed in CV2, and inclusion of the interaction effects increased prediction accuracy for AC only. In CV0, the prediction accuracy was 0.73 and 0.45 for AC and VS, respectively, indicating the high reliability of across environment prediction. Genomic prediction appears to be a very reliable tool for AE in hybrid wheat breeding. Moreover, high prediction accuracy in CV0 demonstrates the possibility of implementing genomic selection across breeding cycles in related germplasm, aiding the rapid breeding cycle.

The net form of net blotch, caused by Pyrenophora teres f. teres (Ptt), is an economically important disease of barley (Hordeum vulgare L.) that is best managed by breeding for resistance. Previous linkage mapping and genome‐wide association studies (GWAS) have identified many resistance quantitative trait loci (QTL) in barley. Here we report eight novel resistance QTL identified in a unique collection of barley landraces from Ethiopia and Eritrea (EEBC) using a GWAS approach. Lines from the EEBC were genotyped with the Illumina barley iSelect chip and phenotyped with four Ptt isolates. A GWAS was conducted using the efficient mixed model association (EMMA) method with principal components and kinship to control false positives. Using a significance threshold of false discovery rate (FDR) of 0.05, two marker–trait associations (MTAs) were found on chromosomes 6H and 5H, respectively. Since this is a stringent method, markers in the lower 0.1 percentile of the p value distribution were also considered significant, identifying 20 unique MTAs. The 20 MTAs corresponded to 15 unique genomic loci, based on analysis of local linkage disequilibrium. Of the 15 QTL identified, one was identified in chromosome 1H, six in 2H, three each in 3H and 5H, and two in 6H. Eight of these QTL appear to be novel and thus could be of value to barley breeding programs to introgress novel net blotch resistance.

A field experiment was conducted to evaluate the plant height, yield and yield attributes of wheat under different tillage practices and nitrogen level at Dang, Nepal during winter season 2018-19. The experiment was laid out in split plot design with two tillage practices viz. zero tillage and conventional tillage as main plot factor and four level of N viz. 50 kg ha-1, 75 kg ha-1, 100 kg ha-1and 125 kg ha-1 as sub plot factor and each replicated thrice.  The result revealed that there is no significant relation between tillage practice and plant height of wheat while N level significantly affect the plant height. 125 kg N ha-1 recorded the highest plant height (110.7 cm). Zero tillage recorded the highest effective tiller m-2 (254) and grain yield (3.3 t ha-1) whereas spike length, grain spike-1, biological yield and harvest index were not significant with tillage practices. Regarding the N level, 125 kg N ha-1 recorded the highest effective spike m-2 (279), spike length (10.6 cm), grain spike-1 (48), thousand grain weight (46.3 g), grain yield (3.6 t ha-1) and biological yield (9.4 t ha-1). 50 kg N ha-1 recorded the highest harvest index (42.9%). The interaction between the tillage practice and nitrogen level showed the significant effect on grain yield and harvest index where as other parameters showed non-significant relation. The zero tillage with 125 kg N ha-1 recorded the highest grain yield (3.9 t ha-1).