Abstract

Old durum wheat cultivars are attracting renewed attention due to their suitability to low input agricultural systems. Fourteen old durum wheat cultivars were analyzed in two field trials to assess the effect of grain number and N absorbed and translocated by the crops on grain protein percentage. The mean grain yield was below 3 t ha−1 and strongly associated with the number of grains m−2 (GNO) (r = 0.97 ***). Grain yield displayed a low sensitivity to severe terminal stressful conditions due to the ability of the old durum wheat cultivars to maintain high grain weights despite the high temperatures and short time available for grain filling caused by their late anthesis. The N source for the growing grains was mainly dependent on pre-anthesis N uptake, which was positively associated with the total biomass produced by anthesis. The tall cultivars generally left a greater amount of N m−2 (8–15 g m−2) in their straw compared with shorter ones (5–6 g m−2). The low and variable GNO modulated the amount of N potentially available for each grain and probably limited the possibility of delivering the large N source to the grains. The large grains played a positive role in determining both grain yield (by compensating for the low GNO) and grain protein percentage, as their high grain filling rate was associated with a high N accumulation rate, and hence with a high grain N content and protein percentage.

Highlights

  • Old durum wheat cultivars have been proposed as a sustainable management option for low input cultural systems in the less fertile areas of the Mediterranean region where the combination of poor soils and the parsimonious use of fertilizer make old durum wheat cultivars sustainable [1]

  • Their high grain filling rate often results in high final grain weights [5] that can counterbalance the low grain number per m−2 associated with the low grain yield generally attainable in marginal areas and low input systems [1]

  • Rainfall was scarce in the springs of both seasons, and 2017 was even worse than 2016. 2017 was characterised by higher maximum temperatures compared with 2016 and the long-term mean (a 40-year mean for the period spanning 1970 to 2010), as well as a greater number of days in which the maximum temperature exceeded 25 ◦C in May–the period in which most of the grain filling occurs

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Summary

Introduction

Old durum wheat cultivars have been proposed as a sustainable management option for low input cultural systems in the less fertile areas of the Mediterranean region where the combination of poor soils and the parsimonious use of fertilizer make old durum wheat cultivars sustainable [1]. From a morpho-physiological point of view, old cultivars combine a late anthesis [3] and a high maximum grain filling rate [4,5] two interesting traits proposed by [6] to overcome the antagonism between grain yield and grain protein concentration under future climate scenarios Their high grain filling rate often results in high final grain weights [5] that can counterbalance the low grain number per m−2 associated with the low grain yield generally attainable in marginal areas and low input systems [1]. The amount of nitrogen absorbed by the crop is related to its biomass [8]; differences in biomass at anthesis could be responsible for differences in the quantity of nitrogen source available to the grains

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