International audiencePlant diseases are responsible for major economic losses in the agricultural industry worldwide. Monitoring plant health and detecting pathogen early are essential to reduce disease spread and facilitate effective management practices. DNA-based and serological methods now provide essential tools for accurate plant disease diagnosis, in addition to the traditional visual scouting for symptoms. Although DNA-based and serological methods have revolutionized plant disease detection, they are not very reliable at asymptomatic stage, especially in case of pathogen with systemic diffusion. They need at least 1–2 days for sample harvest, processing, and analysis. Here, we describe modern methods based on nucleic acid and protein analysis. Then, we review innovative approaches currently under development. Our main findings are the following: (1) novel sensors based on the analysis of host responses, e.g., differential mobility spectrometer and lateral flow devices, deliver instantaneous results and can effectively detect early infections directly in the field; (2) biosensors based on phage display and biophotonics can also detect instantaneously infections although they can be integrated with other systems; and (3) remote sensing techniques coupled with spectroscopy-based methods allow high spatialization of results, these techniques may be very useful as a rapid preliminary identification of primary infections. We explain how these tools will help plant disease management and complement serological and DNA-based methods. While serological and PCR-based methods are the most available and effective to confirm disease diagnosis, volatile and biophotonic sensors provide instantaneous results and may be used to identify infections at asymptomatic stages. Remote sensing technologies will be extremely helpful to greatly spatialize diagnostic results. These innovative techniques represent unprecedented tools to render agriculture more sustainable and safe, avoiding expensive use of pesticides in crop protection

In a field experiment conducted in a Mediterranean area of inner Sicily, durum wheat was inoculated with plant growth-promoting rhizobacteria (PGPR), with arbuscular mycorrhizal fungi (AMF), or with both to evaluate their effects on nutrient uptake, plant growth, and the expression of key transporter genes involved in nitrogen (N) and phosphorus (P) uptake. These biotic associations were studied under either low N availability (unfertilized plots) and supplying the soil with an easily mineralizable organic fertilizer. Regardless of N fertilization, at the tillering stage, inoculation with AMF alone or in combination with PGPR increased the aboveground biomass yield compared to the uninoculated control. Inoculation with PGPR enhanced the aboveground biomass yield compared to the control, but only when N fertilizer was added. At the heading stage, inoculation with all microorganisms increased the aboveground biomass and N. Inoculation with PGPR and AMF+PGPR resulted in significantly higher aboveground P compared to the control and inoculation with AMF only when organic N was applied. The role of microbe inoculation in N uptake was elucidated by the expression of nitrate transporter genes. NRT1.1, NRT2, and NAR2.2 were significantly upregulated by inoculation with AMF and AMF+PGPR in the absence of organic N. A significant down-regulation of the same genes was observed when organic N was added. The ammonium (NH4+) transporter genes AMT1.2 showed an expression pattern similar to that of the NO3- transporters. Finally, in the absence of organic N, the transcript abundance of P transporters Pht1 and PT2-1 was increased by inoculation with AMF+PGPR, and inoculation with AMF upregulated Pht2 compared to the uninoculated control. These results indicate the soil inoculation with AMF and PGPR (alone or in combination) as a valuable option for farmers to improve yield, nutrient uptake, and the sustainability of the agro-ecosystem.

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...

Much research around the world has compared the performance of cereals grown under conventional and conservation tillage systems; however, relatively few long‐term experiments have been conducted in Mediterranean areas, and little attention has been given to interactions among tillage techniques and other system components across space and time. In this study, we investigated the effects of the long‐term (18‐yr) use of three tillage techniques (conventional tillage, CT; reduced tillage, RT; and no‐till, NT) on wheat (Triticum durum Desf.) grain yield and quality within three crop sequences: continuous wheat, faba bean (Vicia faba L.)–wheat, and berseem clover (Trifolium alexandrinum L.)–wheat. In addition, we investigated the effects of climatic variability on the treatments and evaluated whether cumulative effects occurred from continuous treatment. On average, NT resulted in a grain yield advantage over CT when water stress was high and, conversely, a disadvantage when water stress was low. The effect of the tillage system on grain yield varied by crop sequence. Grain yield differences between NT and CT when wheat was grown after faba bean or berseem clover were explained primarily by climatic variability without a cumulative effect over time. In contrast, in continuous wheat, NT resulted in a progressive decrease in grain yield compared with CT. On average, wheat grain protein content varied significantly by tillage system (CT > RT > NT). This suggests that fertilizer N requirements increase with NT compared with CT because of changes in N cycling that lead to a reduction in plant‐available soil N.

Knowledge of the effects of agricultural practices on weed seedbank dynamics is essential for predicting future problems in weed management. This article reports data relative to weed seedbank structure after 18 years of continuous application of conventional tillage (CT, based on mouldboard ploughing) or no tillage (NT) within three crop sequences (continuous wheat, WW; wheat-faba bean, WF; and wheat-berseem clover, WB). Tillage system did not affect the size of the total weed seedbank, but altered both its composition and the distribution of seeds within the soil profile. In particular, the adoption of CT favoured some species (mainly Polygonum aviculare), whereas the continuous use of NT favoured other species (Papaver rhoeas, Phalaris spp. and Lactuca serriola). The effects of tillage system on weed seedbank size and composition were less pronounced in the WB cropping system than in either the WW or WF. Compared with WF and WB, WW resulted in an increase in total weed seedbank density (about 16 000 seedlings m-2 in WW, compared with 10 000 and 6000 seedlings m-2 in WF and WB, respectively) and a reduction in weed diversity, with a strong increase in some species (e.g. Polygonum aviculare). Our results for the effect of NT application on weed seedbank size and composition suggest that farmers should only apply such a conservative technique within an appropriate crop sequence