Agronomic Strategies to Improve N Efficiency Indices in Organic Durum Wheat Grown in Mediterranean Area.

Federica Carucci,Anna Gagliardi,Pasquale De Vita,Giuseppe Gatta,Simone Bregaglio,Marcella Michela Giuliani

doi:10.3390/plants10112444

Federica Carucci, Anna Gagliardi + Show 4 more

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https://doi.org/10.3390/plants10112444

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Abstract

Organic farming systems are often constrained by limited soil nitrogen (N) availability. Here we evaluated the effect of foliar organic N and sulphur (S), and selenium (Se) application on durum wheat, considering N uptake, utilization efficiency (NUtE), grain yield, and protein concentration as target variables. Field trials were conducted in 2018 and 2019 on two old (Cappelli and old Saragolla) and two modern (Marco Aurelio and Nadif) Italian durum wheat varieties. Four organic fertilization strategies were evaluated, i.e., the control (CTR, dry blood meal at sowing), the application of foliar N (CTR + N) and S (CTR + S), and their joint use (CTR + NS). Furthermore, a foliar application of sodium selenate was evaluated. Three factors—variety, fertilization strategies and selenium application—were arranged in a split-split-plot design and tested in two growing seasons. The modern variety Marco Aurelio led to the highest NUtE and grain yield in both seasons. S and N applications had a positive synergic effect, especially under drought conditions, on pre-anthesis N uptake, N translocation, NUtE, and grain yield. Se treatment improved post-anthesis N uptake and NUtE, leading to 17% yield increase in the old variety Cappelli, and to 13% and 14% yield increase in Marco Aurelio and Nadif, mainly attributed to NUtE increase. This study demonstrated that the synergistic effect of foliar applications could improve organic durum wheat yields in Mediterranean environments, especially on modern varieties.

Highlights

Durum wheat organic systems are often characterized by limited nitrogen (N) availability, due to low soil fertility and the use of organic N fertilizers [1]
We demonstrated that modern varieties grown under organic system can lead to better N utilization efficiency with respect to old varieties
Marco Aurelio had a higher efficiency in using plant nitrogen to increase yield even under stress conditions

Summary

Introduction

Durum wheat organic systems are often characterized by limited nitrogen (N) availability, due to low soil fertility and the use of organic N fertilizers [1]. Unravelling the real factors causing low soil N availability in organic systems requires additional experimental evidence, given the complex and dynamic transformations of soil organic N As a consequence, this subject is highly debated in literature, especially in Mediterranean regions: Fagnano et al [2] reported that low soil organic matter content, low temperatures, and high autumn–spring rainfall can cause deficient levels of available soil N during most wheat crop cycles; on the contrary, Rossini et al [3] highlighted that soil temperature and water availability during winter can sustain the mineralization activity of the soil microbial community. All scientists agree that NUtE improvement is largely associated with the choice of the wheat variety, which results as an essential management practice in organic systems

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