Genetic Variation for Nitrogen Assimilation and Translocation in Wheat. II. Nitrogen Assimilation in Relation to Grain Yield and Protein¹

Abstract

An understanding of the relationship between N assimilation and grain yield and protein, and the measurement of genetic variation in preanthesis and postanthesis N assimilation in wheat (Triticum aestivum L.) are necessary to achieve additional gains in selecting for both high grain yield and high grain protein. Thus, total N assimilation in the spring wheat cultivars ‘Anza’ and ‘Cajeme 71’ and 96 F5‐lines from the cross of these cultivars was studied in field experiments. Freanthesis N assimilation was similar for the two cultivars, but by maturity Anza had assimilated 9% (P < 0.01) more N than Cajeme 71 in both high and low N fertility levels. This difference was mainly due to greater postanthesis assimilation by Anza (22% of total) than Cajeme 71 (10%). Significant genetic variation among F5 lines in N assimilation prior to anthesis occurred in two of three experiments, but no relationships were found between this trait and grain yield, grain protein concentration, or grain protein yield. Significant genetic variability in N assimilation after anthesis was detected, although estimates of heritabilities were low. Nitrogen assimilation after anthesis strongly influenced grain and grain protein yields, explaining 27 to 39% of the variation, but no relationship was found with grain protein concentration. The residuals from the regression of N assimilation after anthesis on biomass at anthesis were also strongly related to grain and grain N yield in a stagewise regression analysis, indicating variation other than random error was involved. Grain protein concentration was also positively associated with these residuals in one experiment. Possible sources of this variation, particularly with relation to roots are discussed. Total N assimilation showed broad‐sense heritabilities of 21 to 27% and was correlated (r = 0.68 to 0.86; P < 0.01) with grain and grain protein yields. Thus genetic variation in N assimilation has a role in determining grain yield and protein concentration in wheat. Further work to determine the genetic and physiological basis of factors influencing N assimilation is needed, especially with regard to roots.

Effect of sowing date and nitrogen on dry matter and nitrogen partitioning in malting barley

“…also reported in a previous study (de Ruiter & Brooking 1994). Other work with wheat (Cox et al 1986) showed no association between post-anthesis N uptake and grain N concentration, but they did find a strong relationship with grain N on a unit area basis. In that study, most of the N was taken up late, in contrast to our study in which the N was predominantly taken up before anthesis.…”

Night-time warming affects N and P dynamics and productivity of winter wheat plants

“…This means more N retained in vegetative parts during grain filling, which was also reported in the rice plants (Cheng et al 2010). On the other hand, previous studies have shown that postanthesis N uptake that goes directly to the grain, was significantly correlated to grain yield for both low and high N conditions (Cox et al 1985). In our study, reduced post-anthesis N uptake might contribute to decrease of grain yield under night-time covered treatment.…”

Nitrogen translocation in wheat inoculated with Azospirillum and fertilized with nitrogen

“…This is in agreement with 1 Treatment means with and without inoculation; means followed by different letters are statistically different at P<0.05. the results obtained by Moll et al (1982) and Spiertz & Vos (1983). In general, there is a consensus that, in wheat, the amount of N remobilized from vegetative parts after anthesis is considerably higher than the amount of N assimilated after anthesis (Cox et al, 1985). Usually, the higher availability of late cycle absorbed N is initially associated with a greater root activity (absorption) and, secondly, with an increase in protein content of the grain (Eilrich & Hageman, 1973;Blacklow, 1982;Spiertz & Vos, 1983;Ugalde & Jenner, 1990).…”