Nitrogen Metabolism at Tillering Stage Differently Affects the Grain Yield and Grain Protein Content in Two Durum Wheat Cultivars

Fortunato Fortunato,Gadaleta Gadaleta,Nigro Nigro,Agrimi Agrimi,Trani Trani,Blanco Blanco,Paradiso Paradiso,Cucci Cucci,Lacolla Lacolla,De Pinto De Pinto

doi:10.3390/d11100186

Fortunato Fortunato, Gadaleta Gadaleta + Show 8 more

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https://doi.org/10.3390/d11100186

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Abstract

Soil nitrogen abundance, as well as nitrogen use efficiency (NUE), significantly affect the crop yield and grain protein content (GPC). Depending on the genotype, a negative correlation between the yield and GPC can occur. The aim of the study was to assess the agronomic performance, and to explore physiological pathways for the efficient use of N fertilizer for two durum wheat cultivars, “Aureo” and “Vespucci”. After fertilization, the nitrogen content and values of some of the agronomic parameters and yield-related traits increased in both cultivars; nevertheless, a simultaneous rise in both the yield and GPC occurred only in Aureo. The biochemical parameters, analyzed at tillering, confirm the genotypic specificity of nitrogen use. In Vespucci’s roots, the nitrogen supply did not affect the nitrate reductase (NR), but greatly increased the amino acids and proteins, suggesting that ammonium is preferentially assimilated. In Aureo, nitrate is in part assimilated by the roots, as suggested by the ammonium increase and NR enhancement. In the leaves of both cultivars, organic nitrogen significantly increased after fertilization; however, the rise in amino acids, as well as in NR activity, was higher in Aureo than in Vespucci. These results indicate that the different nitrogen use, and in particular the diverse NR behavior, at tillering, are in part responsible of the cultivar differences in grain yield and GPC.

Highlights

Nitrogen is an essential element playing a crucial role in plant growth and development, as it is involved in the biosynthesis of several molecules, such as amino acids, proteins, nucleotides, nucleic acids, chlorophyll, vitamins, and hormones [1,2]
N fertilization can increase the N content of kernels, and grain protein content (GPC) [61], but this character shows a negative correlation with yield, whose extent is closely dependent on the genotype [62,63]
Our results indicate that the two genotypes use the inorganic N exogenously supplied differently

Summary

Introduction

Nitrogen is an essential element playing a crucial role in plant growth and development, as it is involved in the biosynthesis of several molecules, such as amino acids, proteins, nucleotides, nucleic acids, chlorophyll, vitamins, and hormones [1,2]. Durum Desf.) represents about 5% of the total global wheat production, with Italy being. The economic value of this crop depends on several agronomic traits, such as grain yield and grain protein content (GPC), the latter being directly related to both the nutritional and technological values of the final products [4,5]. As reported by several authors, both traits are strictly affected by nitrogen metabolism during plant growth [6,7]. A stable QTL (Quantitative Trait Locus) for GPC and grain protein deviation (GPD) were found to be co-migrating with nitrogen-related genes [8]

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