For relative grain yield, analysis of variance across locations and N levels revealed highly significant genotypic and G x L interaction variance in all 18 multisite experiments (data not shown).
For relative grain yield, genotypic variability was larger at LN, while the same analysis with the original data pointed out a greater genotypic variance at HN (data not shown).
Following the prediction given by the regression equation of efficiency of direct selection on N-deficiency stress (data not shown), indirect selection at HN will be less efficient than direct selection when relative grain yield reduction at LN is >21%.
Variance components estimates and their standard errors ([+ or -] SE) for genotypes ([[sigma].sup.2.sub.G]), genotype (G) x location (L) interaction ([[sigma].sup.2.sub.GL], and error ([[sigma].sup.2.sub.E]) for relative grain yield in 21 maize experiments at high and low N levels conducted between 1989 and 1999.
Shoot N concentration at the PI stage was correlated with absolute grain yield ([r.sup.2] = 0.44, P < 0.05, data not presented), whereas N concentration at the EB stage had a better fit with relative grain yield (Fig.
As with relative grain yield, relative protein yield did not have a high correlation with N concentration of shoot tissue at the PI stage (Fig.
A shoot tissue N concentration [greater than or equal to] 31 g [kg.sup.-1] dm at early boot was highly correlated to optimum relative grain yield ([r.sup.2] = 0.65*) and was considered the critical N concentration at that growth stage.
2) and relative grain yields
(Table 8): Othello = Carneval < Radley < Kyle < Cyclone.
Despite the 1:1 Noble-Wapiti mixture having the best total relative grain yield of all treatments in the Wapiti triticale-based Test at 1.30, in the Noble barley-based tests this treatment had a total relative yield of only 0.98 (Table 5).
At maturity, samples were collected, sorted, and threshed to determine relative grain yields. In a 1:1 mixture, if the yields in the mixture of the components were the same as in the monocrop, each would be 0.50; in a 3:1 mixture, the relative yields would be 0.75 and 0.25; in a 1:1:1 mixture, the relative yields would each be 0.33; and in a 3:1:1 mixture, they would be 0.60, 0.20, and 0.20, respectively.
Monocrop yields and relative grain yields (RY) of mixture components, by cultivar, of barley grown at Lacombe, AB in 1994 and 1995.
Effects of seeding rate on relative grain yields (RY) of barley cultivars grown as mixtures in the Seebe barley-based test averaged across treatments.