Selection for yield in small plots of spring wheat

Abstract

SUMMARYFour selection experiments were sown: single-row plots with single row-spacing (:::: 20 em), single-row plots with double row spacing (:::: 40 em), three-row plots and six-row plots both with single row-spacing (:::: 20 em). Selection entries were mimiced by 16 different varieties or advanced breeding lines, which were also sown in a yield trial. Each experiment was laid out as a 4-times replicated randomized block design. Row length was 2 m. Alley borders and border-rows of multiple-row plots were harvested separately to evaluate the effects of different harvesting procedures on the selection efficiency. Removal of alley borders was found to be disadvantageous, since the gain in precision was more than offset by the loss in sampled area. Wide spacing of single-row plots improved the selection efficiency in comparison with normal spaced single-row plots. In multiple-row plots the selection efficiency was not improved by harvesting only the central rows.For gross plot yield ( = yield of net plot + yield of alley borders) the differences in selection efficiency between the various selection plot-types were explained on the basis of the genetic variance, the environmental variance and the coefficient of genetic correlation with 'farm' yield as determined in the yield trial.

Correction models for intergenotypic competition in winter wheat

“…the ratio of the expected genetic gain in 6RP when selection is based on the SRP performance to the expected response when selection is applied directly to the 6RP trial. The relative selection efficiency was estimated by , where r is the correlation coefficient between the genotypic means of the two trials and the broad sense heritability in the 6RP trial [15]. Correlation coefficients between 6RP genetic means and SRP genetic values obtained with the different models described above (the two-factor analysis of variance model, neighbouring covariate models or the producer-competitor model) were statistically compared using the bootstrap resampling technique [8].…”

“…In these trials, interplot competition may lead to biased estimations of yield performances [9] and particularly to the overestimation of the value of aggressive genotypes. Several authors have noted very low or even no correlations between yields of genotypes in singlerow plots and their yield in larger plots due to competition [6,10,15].…”

Efficiency of 3 single-harvest tests for evaluation of yield in pickling cucumber

“…The correlated gain formula is appropriate where one test is the standard for comparison for the other tests. The correlated gain expected in performance of selections in the multiple-harvest trial (M) when using the rapid tests (R) for evaluation was calculated using a formula modified from KRAMER et al (1982) as shown in equation (1) …”

Competition between cultivars of fodder kale (Brassica oleracea L.) in yield trials with single-row plots

“…KRAMER et al (1982) found that with spring wheat, . The relation between DOM yield (t/ ha) and height (cm) for sixteen cultivars averaged ha) and height (cm) for sixteen cultivars in control over Kes.…”