Relationships between Nitrogen Utilization and Grain Technological Quality in Durum Wheat: I. Nitrogen Translocation and Nitrogen Use Efficiency for Protein

Abstract

Durum wheat (Triticum durum Desf.) is widely cultivated in the Mediterranean area where plants generally suff er from water stress during grain-fi lling period. Th is study was conducted to evaluate the infl uence of N levels and water regimes on N translocation and nitrogen use effi ciency for protein (NUEP) in durum wheat grown under Mediterranean conditions. A 2-yr experiment was performed in southern Italy using four cultivars, two water regimes (irrigated and rainfed) and three N levels (0, 60, and 120 kg ha -1 ). Among the cultivars under study, Simeto showed the highest N translocation in both years and, together with Ofanto, also the highest NUEP values, especially in rainfed condition. Th is highlights their good adaptability to dry southern Italy environment. Nitrogen fertilization caused a general decrease of NUEP and its components in both growing seasons; this was more evident in the fi rst drier year, mainly due to a decrease in N uptake. Under water stress the higher N level caused a decrease in N translocation, N translocation effi ciency, and grain N content. Th e contribution of translocated N to grain N content was 75% in the wetter year and 57% in the drier year, showing that in drought condition preanthesis N assimilation was lower. In conclusion under water stress condition the higher N level (120 kg ha -1 ), despite determining an increase in plant N content, did not imply an increase in grain N content, due to a decrease in N translocation and effi ciency.

Relationships between Nitrogen Utilization and Grain Technological Quality in Durum Wheat: II. Grain Yield and Qualities

“…The lower rainfall recorded in the first growing season induced a shortening of the growing cycle by 20 d (Table 1); this caused a lower N uptake in the first year than in the second year, with a consequently lower N content in the plant both at anthesis and at maturity, as reported by Giuliani et al (2011). This may have caused a decrease in assimilation and grain yield, as already reported by other researchers (Blum, 1998; Ercoli et al, 2008).…”

“…Finally, to look for the relationships among plant N content, N utilization, and grain technological quality, a correlation matrix among quality parameters and plant and grain N content, N translocation, N use efficiency for protein, and its components, previously evaluated in Giuliani et al (2011), is shown in Table 9. Plant N content at anthesis and at maturity were highly positively correlated with all the quality parameters; straw N content at maturity showed high and positive correlations with protein and gluten content, much lower correlations with alveograph indices W and P/L, and no correlation with the gluten index.…”

“…The cultivars and detailed procedures for the field experiments conducted in the 2000–2001 and 2001–2002 crop seasons, and relative to the samples investigated in this study, have already been described (Giuliani et al, 2011). Briefly, four durum wheat cultivars (Appio, Creso, Ofanto, and Simeto) were grown in the field under two water regimes (irrigated and rainfed) and three N levels (0, 60, and 120 kg ha −1 ) in southern Italy (Foggia, 41°46´ N, 15°54´ E).…”

“…In both years, measurements of crop growth were done at both anthesis and physiological maturity, as already reported in Giuliani et al (2011). In particular, samples were taken from 0.5 m of two adjacent rows.…”

Cultivar and N Fertilizer Rate Affect Yield and N use Efficiency in Irrigated Durum Wheat

“…However, in this study, RE for the six durum wheat cultivars ranged from 60 to 81%. Finally, it must be emphasized that frequent, sizeable irrigations in our study resulted in rapid biomass production and much greater grain yields than the 2 to 3 Mg ha -1 in the wheat studies with RE <50% (Guarda et al, 2004;Giambalvo et al, 2010;Giuliani et al, 2011a). The high RE and AE was probably due to the fact that sudangrass cover crop removed most of the available soil N, and low soil organic matter (<10 g kg -1 ) means lower N mineralization in these soils.…”