R. A. Martin

Genetic analysis of a two-row x six-row cross of barley using doubled-haploid lines

Abstract A study was conducted on a two-row/six-row cross of barley to (1) determine the yield potential, (2) detect epistasis and genetic correlations, (3) estimate the heritabilities of six agronomic traits, and (4) study the effect of the V locus on the agronomic traits in the barley cross. The effects of five other marker loci (Re2, s, R, Est1, and Est5) on the six agronomic traits were also studied. One hundred and ninety doubled-haploid (DH) lines were derived from a ‘Leger’/CI9831 cross using the bulbosum method. The DH lines and the two parents were tested for grain yield, test weight, seed weight, plant height, lodging, and heading/maturity at two locations in Eastern Canada in 1993. Additive×additive epistasis and genetic correlations were detected for some of the agronomic traits. Many of the heritability estimates were high; however, significant progress in yield improvement would be difficult to achieve because of a low mean yield of the DH lines. Under the growing conditions in Eastern Canada, six-row lines outyielded two-row by 20–27%. Six-row lines, however, were associated with low test weight, low seed weight, and severe lodging. Some two-row lines yielded higher than the two-row parent CI9831, but none of the six-row lines yielded higher than the six-row parent ‘Leger’. The R, s, and Est5 loci were associated with the six agronomic traits, but the Est1 locus was apparently not associated with the agronomic traits. The effect of the Re2 locus was probably due to its close linkage with the V locus. Further studies are needed to determine if superior six-row lines can be developed from two-row/six-row crosses.

Barley Traits Associated with Resistance to Fusarium Head Blight and Deoxynivalenol Accumulation

ABSTRACT Fusarium head blight (FHB) or scab is a destructive disease of barley in many countries. A better understanding of the interrelationships between plant traits and FHB resistance should help in the development of effective and efficient breeding strategies for FHB-resistant cultivars. Recent mapping studies indicate that many of the quantitative trait loci (QTL) for FHB resistance coincide with the QTL for plant height, heading date, and spike characteristics. Therefore, a study was conducted to investigate the relationship of morphological and physiological traits to FHB infection and deoxynivalenol (DON) accumulation in a barley doubled-haploid (DH) population derived from a Léger x CI9831 cross. Approximately 190 DH lines were grown at Ottawa (Ontario) for 2 years, Charlottetown (Prince Edward Island) for 1 year, and Hangzhou (Zhejiang) for 2 years. The field plots were inoculated with Fusarium graminearum at each location. FHB incidence was positively correlated with DON content. Resistance to FHB was associated with two-row spike, purple lemma, long glume awn, tall stature, and resistance to lodging, but it was not associated with long rachilla hairs, rough lemma awn, or heading date. Two-row spike was associated with tall stature and resistance to lodging. These associations as well as its spike characteristics helped reduce FHB infection and DON accumulation in two-row lines compared with six-row lines. The association between long glume awn and FHB resistance could be due to genetic linkages. Therefore, trait associations should be taken into consideration when breeding for FHB resistance and interpreting data from FHB experiments.

How many test locations and replications are needed in crop variety trials for a target region

How many test locations and replications are needed in crop variety trials is a question every plant breeder has to ask. Simple formulas were developed to estimate the optimum number of replicates and test locations. The optimum number of replicates in a trial was estimated by the formula

AC Legend barley

{\text{N}}_{{\text{r}}} {\text{ = 3}}\left( {\sigma _{\epsilon }^{{\text{2}}} /\sigma _{{\text{g}}}^{{\text{2}}} } \right)

AC Klinck barley

Nr= 3σϵ2/σg2, where

AC Parkhill barley.

\sigma_{\text{g}}^{2}