Nitrogen Use Efficiency and Nitrogen Fertilizer Recovery of Durum Wheat Genotypes as Affected by Interspecific Competition

Abstract

A gronomy J our n al • Volume 102 , I s sue 2 • 2 010 707 O ver the last four decades, N fertilization has been an essential tool for increasing crop yield and quality, especially for cereals, and for ensuring maximum economic yield (Hirel et al., 2001). However, the energetic cost of synthesizing N fertilizers is very high (Smil, 2001), and N fertilization oft en represents the most expensive energy input in cereal-based cropping systems (Crews and Peoples, 2004). Moreover, because of its high mobility in the soil-plant-atmosphere system, N greatly contributes to agriculture-related pollution through leaching, volatilization, and denitrifi cation (Drinkwater et al., 1998;Limaux et al., 1999). Indeed, it has been estimated that oft en 50% or less of the N fertilizer applied to soil is recovered by cereals and that this percentage decreases as the N fertilizer rate increases (Foulkes et al., 1998;Raun and Johnson, 1999;Blankenau et al., 2002).Developing cropping systems and management practices that improve the ability of crops to absorb N could minimize the potential for N losses. Nitrogen use effi ciency is generally defi ned as the grain yield produced per unit of N available from the soil and fertilizer (Moll et al., 1982); it is the product of two physiological factors: (i) N uptake effi ciency (NUpE, defi ned as the amount of N uptake by the crop per unit of N available to the crop) and (ii) N utilization effi ciency (NUtE, defi ned as the grain yield per unit of N uptake by the crop). With regard to management practices, the choice of plant variety is particularly important; in fact, several studies have shown that many crop species have genetic variability for NUE (Fageria et al., 2008) and that the use of the best-adapted genotype can contribute to improved effi ciency in how cereal crops acquire and use soil N or fertilizer N. Foulkes et al. (1998) found that modern wheat varieties were less effi cient at recovering soil N than older varieties, which suggests that old varieties may be the best choice for low input and organic growing systems. In contrast, other researchers (Le Gouis et al., 2000;Brancourt-Hulmel et al., 2003;Guarda et al., 2004) have found that NUpE and NUE have increased with the introduction of improved varieties, and that modern varieties give the best results even under limited N availability. Sylvester-Bradley and Kindred (2009) state that wheat breeding has greatly increased grain yield and that this improvement has been associated with an increase in optimum N rate; the increase in N fertilizer use has counter-acted the improvement in grain yield, resulting in a static NUE at optimum N levels.Th e varieties suited for low input or organic systems should combine high N use effi ciency with superior competitive ability against weeds. To this end, it is also necessary to take into account the fact that N application can signifi cantly aff ect the competitive interactions between the crop and the weeds and that N application oft en increases the competitiveness of weeds more than tha...

Influences of Different Nitrogen Levels on Competition between Spring Wheat (Triticum aestivum L.) and Wild Mustard (Sinapis arvensis L.)

“…The density of 15 plants of wild mustard m -2 decreased the spike number by 18.2, 21.2 and 35.1 % under 90, 150 and 210 kg N ha -1 respectively. Our results are corroborating with Giambalvo et al (2010). They stated that the interspecific competition of weed, Hordeum vulgare L. decreased the spike number of wheat (Triticum durum Desf Var.…”

Optimising nitrogen in order to improve the efficiency, eco-physiology, yield and quality on one cultivar of durum wheat

“…However, the rainy conditions result in pathological problems in the plant, causing the lower yield in 2012. The use efficiency (NUtE) values were in the range measured in modern durum wheat varieties in other experiments (Giambalvo et al, 2010). The seasonal trend of the three years, with higher values of rain, was favourable for the use of nitrogen, as found from López-Bellido (2012).…”

Nitrogen Use Efficiency of Three Maize (Zea Mays L.) Cultivars

“…This could probably be attributed to the inability of plants to assimilate all of nitrogen taken up. Similar result was reported by a researcher who indicated that nitrogen use efficiency decreased with the increase of nitrogen rate because the plants were unable to assimilate all of nitrogen taken up [3]. Furthermore, nitrogen caused highly significant differences in crude protein and crude fiber content in both seasons.…”

“…Nitrogen use efficiency parameters are high under low nitrogen levels and decrease with increasing nitrogen level. Decreased nitrogen use efficiency at high nitrogen is attributed to higher losses because the plant is unable to absorb all of nitrogen applied [3]. Maize is nitro positive and needs ample quantity of nitrogen to attain high yield.…”