Nitrogen uptake and nitrogen fertilizer recovery in old and modern wheat genotypes grown in the presence or absence of interspecific competition

Choosing genotypes with a high capacity for taking up nitrogen (N) from the soil and the ability to efficiently compete with weeds for this nutrient is essential to increasing the sustainability of cropping systems that are less dependent on auxiliary inputs. This research aimed to verify whether differences exist in N uptake and N fertilizer recovery capacity among wheat genotypes and, if so, whether these differences are related to a different competitive ability against weeds of wheat genotypes. To this end, 12 genotypes, varying widely in morphological traits and year of release, were grown in the presence or absence of interspecific competition (using Avena sativa L. as a surrogate weed). Isotopic tracer 15N was used to measure the fertilizer N uptake efficiencies of the wheat genotypes and weed. A field experiment, a split-plot design with four replications, was conducted during two consecutive growing seasons in a typical Mediterranean environment. In the absence of interspecific competition, few differences in either total N uptake (range: 98–112 kg N ha–1) or the 15N fertilizer recovery fraction (range: 30.0–36.7%) were observed among the wheat genotypes. The presence of competition, compared to competitor-free conditions, resulted in reductions in grain yield (49%), total N uptake (29%), and an 15N fertilizer recovery fraction (32%) that were on average markedly higher in modern varieties than in old ones. Both biomass and grain reductions were strongly related to the biomass of the competitor (correlation coefficients > 0.95), which ranged from 135 g m–2 to 573 g m–2. Variations in both grain and biomass yield due to interspecific competition were significantly correlated with percentage of soil cover and leaf area at tillering, plant height at heading, and total N uptake, thus highlighting that the ability to take up N from the soil played a certain role in determining the different competitive abilities against weed of the genotypes

Transcriptome changes induced by Arbuscular mycorrhizal symbiosis in leaves of durum wheat (Triticum durum Desf.) promote higher salt tolerance

The salinity of soil is a relevant environmental problem around the world, with climate change raising its relevance, particularly in arid and semiarid areas. Arbuscular Mycorrhizal Fungi (AMF) positively affect plant growth and health by mitigating biotic and abiotic stresses, including salt stress. The mechanisms through which these benefits manifest are, however, still unclear. This work aimed to identify key genes involved in the response to salt stress induced by AMF using RNA-Seq analysis on durum wheat (Triticum turgidum L. subsp. durum Desf. Husn.). Five hundred sixty-three differentially expressed genes (DEGs), many of which involved in pathways related to plant stress responses, were identified. The expression of genes involved in trehalose metabolism, RNA processing, vesicle trafficking, cell wall organization, and signal transduction was significantly enhanced by the AMF symbiosis. A downregulation of genes involved in both enzymatic and non-enzymatic oxidative stress responses as well as amino acids, lipids, and carbohydrates metabolisms was also detected, suggesting a lower oxidative stress condition in the AMF inoculated plants. Interestingly, many transcription factor families, including WRKY, NAC, and MYB, already known for their key role in plant abiotic stress response, were found differentially expressed between treatments. This study provides valuable insights on AMF-induced gene expression modulation and the beneficial effects of plant-AMF interaction in durum wheat under salt stress

Exploring the genetic landscape of nitrogen uptake in durum wheat: genome-wide characterization and expression profiling of NPF and NRT2 gene families

Nitrate uptake by plants primarily relies on two gene families: Nitrate transporter 1/peptide transporter (NPF) and Nitrate transporter 2 (NRT2). Here, we extensively characterized the NPF and NRT2 families in the durum wheat genome, revealing 211 NPF and 20 NRT2 genes. The two families share many Cis Regulatory Elements (CREs) and Transcription Factor binding sites, highlighting a partially overlapping regulatory system and suggesting a coordinated response for nitrate transport and utilization. Analyzing RNA-seq data from 9 tissues and 20 cultivars, we explored expression profiles and co-expression relationships of both gene families. We observed a strong correlation between nucleotide variation and gene expression within the NRT2 gene family, implicating a shared selection mechanism operating on both coding and regulatory regions. Furthermore, NPF genes showed highly tissue-specific expression profiles, while NRT2s were mainly divided in two co-expression modules, one expressed in roots (NAR2/NRT3 dependent) and the other induced in anthers and/ovaries during maturation. Our evidences confirmed that the majority of these genes were retained after small-scale duplication events, suggesting a neo- or sub-functionalization of many NPFs and NRT2s. Altogether, these findings indicate that the expansion of these gene families in durum wheat could provide valuable genetic variability useful to identify NUE-related and candidate genes for future breeding programs in the context of low-impact and sustainable agriculture

Early Sowing Allows To Reduce Weed Pressure In No-Till Organic Durum Wheat Production

In organic farming, the adoption of the conventional tillage (CT) technique is considered by many farmers to be necessary to control weeds. Such tillage system, in fact, permits to bury weed seeds deep in the soil by means of soil inversion with moldboard plowing and to eliminate the weed plants that gradually emerge by means of the secondary tillage operations. However, it is also true that intensive tillage progressively reduces the soil organic matter content and the stability of soil aggregates, thus increasing the risk of soil erosion (Six et al. 2000). This is in contrast with one of the basic principles of organic agriculture, which is the conservation of soil fertility. Alternatively to CT, the no tillage (NT) technique can maintain or even enhance soil fertility by increasing C storage, soil biological activity, and soil aggregate stability, but, as a matter of fact, its application relies on herbicide use as the primary weed control mechanism (Gattinger et al. 2011). In the light of these considerations, efforts must be made to revisit the NT technique to make it applicable in organic farming. Without prejudice to the fact that this challenge should be addressed through a systemic approach (Peigné et al. 2007), one possible option could be to take advantage of the possibility given by the NT technique to sow the crop in an earlier period than what usually the farmer does when adopts the CT technique. Anticipating the sowing time would allow operating when most of the weed plants are still poorly developed, so that the sowing operation itself can kill many of them. Moreover, sowing early, when temperatures are still relatively mild, could accelerate the initial growth, thus reducing the period during which the crop is particularly vulnerable to weed competition. Usually, early sowing in the CT systems is not possible since a proper seedbed preparation needs time so that clods formed as a result of plowing could be broken down by natural weathering processes and by one or more secondary tillage operations. Therefore, an experiment was performed under organic management to study the effects of NT compared to CT on durum wheat (Triticum durum Desf.) grain yield, and to verify whether early sowing under NT conditions, compared to sowing at the ordinary time for the study area, can provide an advantage to the crop by increasing its competitiveness against weeds. Furthermore, the above effects were investigated on two durum wheat genotypes highly different for pheno-morphological and agronomic characteristics, assuming for them different competitiveness against weeds

Polyester microplastic fibers in soil increase nitrogen loss via leaching and decrease plant biomass production and N uptake

Microplastic contamination, like other global change factors, can induce effects on ecosystem functions and processes, affecting various soil biophysical properties. However, effects of such contaminants on nutrient cycles in agroecosystems are still poorly understood. We here performed two pot experiments to investigate the effect of polyester microplastic fibers (PMFs) on soil physical properties, nitrogen cycle, and plant performance in a maize-based agroecosystem. Moreover, we followed the N loss via leaching in soil contaminated or not with PMFs by simulating heavy rainfall events that mimic a future scenario of climate change. Our results show that soil contaminated with PMFs (at a concentration of 0.5% w/w) can jeopardize agroecosystem sustainability by affecting soil physical properties and in particular soil macro- and microporosity, the nitrogen cycle, and plant performance. In particular, we found that soil PMF contamination limited crop growth and N uptake by circa 30%, and consequently increased N loss via leaching. Overall, our findings show that soil contamination with PMFs may pose problems to future agricultural challenges like food security and environmental protection

Yield And Competitive Ability Against Weeds Of Mixtures Between Old And Modern Wheat Varieties

Durum wheat is the keystone of the agro-ecosystems in the arable land of the Mediterranean environments and an important part of its area falls within organic farms. For this crop competition exerted by weeds for the use of resources (natural and auxiliary) can determine drastic yield and quality reductions (Ruisi et al., 2015). In organic farming such critical issue is often addressed through a remodelling of several techniques such as soil tillage management, sowing time, plant density and genotype choice. With regard to the latter, there is a growing interest by organic farmers towards the old varieties as they, compared to the modern varieties, have a definitely greater competitive weed abilities thanks to some morpho-physiological plant traits (establishment speed, tillering capacity, plant height) (Röös et al., 2018); moreover, the old varieties/landraces are often characterized by a greater protein and gluten content and for peculiar sensory properties (Newton et al., 2010; Vita et al., 2016). On the other hand, the new varieties have a much higher production potential and technological characteristics of the grain often more responsive to the needs of the processing industry (De Vita et al., 2007). This study, carried out in a organic farming system, aimed to answer the following questions: 1) can the mixture of old and modern durum wheat varieties offer advantages over the monovarietal crop, combining the qualities of the different genotypes? 2) Which mixing ratio should be used in order to maximize the potential advantages of the mixture

Nitrogen Transfer Is Enhanced By AMF Fungi In A Faba Bean/Wheat Intercropping

Intercropping is an agricultural practice that can offer several benefits allowing a better native resources use efficiency and, consequently, a restraint of the auxiliary inputs and often a greater production compared to the monocultures (Brooker et al. 2015). Several authors observed that, in a legume/non-legume mixture, one of the benefits could be the N transfer (up to 80 % of the non-legume N demand; Thilakarathna et al. 2016). The transfer may occur via different pathways: legume rhizodeposition, plant tissue decomposition and direct transfer through arbuscular mycorrhizal fungi (AMF) (Bedoussac et al. 2015). The latter, can simultaneously establish symbiotic relationship with different plant species creating a common mycorrhizal network, which serve as a preferential pathway for exchange among plants (He et al. 2003). However, contrasting results have been reported about the contribution of the AMF on N transfer; for instance, Li et al. (2009) showed that N transfer from mung bean to rice increased from 5.4% to 15.7% due to hyphal linkage, whereas Ikram et al. (1994) showed no significant differences with or without AMF inoculum. This experiment aimed to investigate the role of AMF on N transfer from faba bean to durum wheat grown in mixture, using the stem 15N injecting method

Le varietà di grano duro per le semine 2013: Sicilia.

Annata caratterizzata da rese elevate e ottimi pesi ettolitrici. Tra le varietà, le collaudate Tirex e Claudio e la nuova costituzione Marco Aurelio si sono distinte per le rese elevate e stabili, superiori alle medie in tutti gli areali

Early sowing can boost grain production by reducing weed infestation in organic no-till wheat

Conservative tillage techniques have several agro-ecological benefits for organic farming. The application of these techniques, however, can create quite a few challenges due to the increased weed competition. Here, we report the results of an organic field experiment in which the responses of wheat and weeds to no tillage (NT) were evaluated compared with conventional tillage (CT). We also tested the hypothesis that, under NT, moving up the sowing date, compared with using the ordinary sowing date for the study area, can result in increased competitiveness of the crop against weeds. Two wheat genotypes, a modern variety and an ancient landrace, were tested

Polyester microplastic fibers affect soil physical properties and erosion as a function of soil type

Microplastics are recognized as a factor of global change contaminating many environmental compartments. Agricultural soils are very likely to receive microplastic contamination and are of particular concern due to their role in food production. Microplastic fibers have already been shown to be able to affect soil properties, but their effect on different soil types is poorly understood. Moreover, limited information is available on how the presence of this pollutant can affect soil water erosion processes, which are extremely important issues in many environments. In the light of this, we performed two experiments (carried out on a microscale) to investigate how the presence of polyester microplastic fibers affects soil physical and hydrological parameters and processes such as aggregate formation and soil erosion in three different agricultural soil types (a Vertisol, an Entisol, and an Alfisol). Our data show that the effects of polyester microplastic fibers on soil physical parameters and erosion are strongly dependent on soil type. We found that microplastic fiber contamination can affect soil bulk density, capacitive indicators of soil physical quality, and decrease the formation of new aggregates (labile in the incubation period applied in our experiments) but did not affect their stability in water. However, we found that polyester microplastic fibers reduced soil loss and sediment concentration, especially in the most erodible soils. In this paper, we provide some hypotheses, but certainly future data are still needed to confirm or disprove our hypotheses. Overall, our results highlight the importance of broadly exploring soil properties, such as texture, mineralogy, organic carbon content, etc., to better understand how the various soil types respond to microplastic fiber contamination