Abstract
Nitrogen fertilization is a key factor in wheat crop management, but it has environmental impacts [through nitrate leaching, use of fossil fuels for manufacture and application, as well as important greenhouse gas (N2O) emissions] and represents a significant cost for the growers. Therefore, there is presently an increasing concern to reduce the excessive use of N fertilizers. We analyzed results of seven yield trials with winter wheat cultivars grown on two levels of Nitrogen fertilization, performed during the years 2021-2023 at five sites, where the average yield difference between the two levels of N fertilization was higher than 5%. The analyzed trials included a large variation for grain yield and protein concentration, as well as for the index of tolerance to Nitrogen deficiency. ANOVA for grain yield and protein concentration showed significant effects of cultivars and environments for both yield and protein concentration, but for tolerance index only environments had a significant effect. The effect of lower N availability was stronger and more variable on protein content than on yield. Correlation between grain yield and protein concentration was not significant, but manifested the known negative trend, similar both under recommended and reduced N fertilization. Deviations from regression of protein concentration on grain yield were similar in most cultivars under recommended and reduced N fertilization, but in cultivar FDL Consecvent were higher under lower N availability, suggesting a better adaptation to this stress. Deviations from the regression of performance under Nitrogen deficiency stress on the performance with better N availability, for yield and protein percentage were not significantly correlated, and only three cultivars (FDL Consecvent, Voinic and FDL Miranda) showed positive deviations for both traits. Performance under N deficiency stress is influenced by the potential manifested under no stress and by the response to stress, described by the tolerance index. Analyzing the effect of these two components, we found that, for the analyzed germplasm and environments, performance under no N stress showed higher correlation with performance under reduced N fertilization than the tolerance index. The implications for breeding programs are that (1) genetic progress in grain yield and protein concentration under normal N fertilization, which should be easier to achieve, will be reflected in the performance under reduced fertilization, and (2) a wider diversity of germplasm should be explored, to identify possible differences in the tolerance index, which could further improve performance under reduced fertilization. Deviations from the regressions that describe the general relationship between the levels of N fertilization highlighted a few cultivars with better efficiency in using less available nitrogen, and are worth exploiting in breeding for improved performance under reduced fertilization.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 13
Claim · model-written summary
Cultivars and environments significantly affected yield and protein concentration.
Not reportedTaxonDirection
Verbatim
e0“ANOVA for grain yield and protein concentration showed significant effects of cultivars and environments for both yield and protein concentration”
Claim · model-written summary
Only environments significantly affected tolerance index.
Not reportedTaxonDirection
Verbatim
e0“but for tolerance index only environments had a significant effect.”
Claim · model-written summary
Lower nitrogen availability had a stronger and more variable effect on protein than yield.
- Treatment
- lower N availabilitye0
- Outcome
- protein contente0
- Direction
- stronger and more variablee0
- Comparator
- yielde0
Not reportedTaxon
Verbatim
e0“The effect of lower N availability was stronger and more variable on protein content than on yield.”
Claim · model-written summary
Yield and protein correlation was nonsignificant with a negative trend.
- Treatment
- recommended and reduced N fertilizatione0
- Outcome
- Correlation between grain yield and protein concentratione0
- Direction
- negative trende0
Not reportedTaxon
Verbatim
e0“Correlation between grain yield and protein concentration was not significant, but manifested the known negative trend, similar both under recommended and reduced N fertilization.”
Claim · model-written summary
FDL Consecvent had higher protein regression deviations under lower nitrogen availability.
- Material
- FDL Consecvente0
- Treatment
- lower N availabilitye0
- Outcome
- Deviations from regression of protein concentration on grain yielde0
- Direction
- highere0
Not reportedTaxon
Verbatim
e0“Deviations from regression of protein concentration on grain yield were similar in most cultivars under recommended and reduced N fertilization, but in cultivar FDL Consecvent were higher under lower N availability, suggesting a better adaptation to this stress.”
Claim · model-written summary
Yield and protein deviations under nitrogen deficiency were not significantly correlated.
Not reportedTaxonDirection
Verbatim
e0“Deviations from the regression of performance under Nitrogen deficiency stress on the performance with better N availability, for yield and protein percentage were not significantly correlated”
Claim · model-written summary
FDL Consecvent showed positive deviations for yield and protein.
Not reportedTaxon
Verbatim
e0“only three cultivars (FDL Consecvent, Voinic and FDL Miranda) showed positive deviations for both traits.”
Claim · model-written summary
Voinic showed positive deviations for yield and protein.
Not reportedTaxon
Verbatim
e0“only three cultivars (FDL Consecvent, Voinic and FDL Miranda) showed positive deviations for both traits.”
Claim · model-written summary
FDL Miranda showed positive deviations for yield and protein.
Not reportedTaxon
Verbatim
e0“only three cultivars (FDL Consecvent, Voinic and FDL Miranda) showed positive deviations for both traits.”
Claim · model-written summary
Unstressed performance correlated more strongly with reduced-N performance than tolerance index did.
- Outcome
- correlation with performance under reduced N fertilizatione0
- Direction
- highere0
- Comparator
- tolerance indexe0
Not reportedTaxon
Verbatim
e0“performance under no N stress showed higher correlation with performance under reduced N fertilization than the tolerance index.”
Claim · model-written summary
Authors suggest normal-N breeding gains will carry over under reduced fertilization.
- Outcome
- genetic progress in grain yield and protein concentration under normal N fertilizatione0
Not reportedTaxon
Verbatim
e0“genetic progress in grain yield and protein concentration under normal N fertilization, which should be easier to achieve, will be reflected in the performance under reduced fertilization”
Claim · model-written summary
Authors recommend exploring broader germplasm for tolerance index diversity.
- Outcome
- a wider diversity of germplasm should be explorede0
Not reportedTaxon
Verbatim
e0“a wider diversity of germplasm should be explored, to identify possible differences in the tolerance index”
Claim · model-written summary
Regression deviations identified cultivars with better efficiency under less available nitrogen.
- Treatment
- levels of N fertilizatione0
- Outcome
- a few cultivars with better efficiency in using less available nitrogene0
Not reportedTaxon
Verbatim
e0“Deviations from the regressions that describe the general relationship between the levels of N fertilization highlighted a few cultivars with better efficiency in using less available nitrogen”