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Late wilt disease, caused by Cephalosporium maydis in maize plant, is one of the main economical diseases in Egypt . Therefore, to cope with this problem, we investigated the potentiality of plant growth promoting rhizobacteria in controlling this disease. Six strains ( Bacillus subtilis , B. circulance , B. coagulanse, B. licheniformis , Pseudomonas fluroscence and P. koreensis ) were screened for siderophore production, and using dual plate culture method and greenhouse experiment, antagonistic activity against C. maydis was studied. Using two superior strains, single and dual inoculation treatments in maize were applied in field experiment during the 2018 and 2019 seasons. Results indicated that B. subtilis and P. koreensis strains had shown the most qualitative and quantitative assays for siderophore production and antagonistic activities. In greenhouse, the most effective treatments on the pre- and post-emergence damping off as well as growth promotion of maize were T3 treatment (inoculated with B. subtilis ), and T8 treatment (inoculated with P. koreensis ). In field experiment, T5 treatment (inoculated with a mixture of B. subtilis and P. koreensis ) showed significant increases in catalase (CAT), peroxidase (POX) and polyphenol oxidase (PPO) activities, as well as total chlorophyll and carotenoids than control treatments during the two growing seasons. In the same way, the highest effect in reducing infection and increasing the thickness of the sclerenchymatous sheath layer surrounding the vascular bundles in maize stem was observed and these results were a reflection of the increase in yield and yield parameters.

• Understanding how plant species influence soil nutrient cycling is a major theme in terrestrial ecosystem ecology. However, the prevailing paradigm has mostly focused on litter decomposition, while rhizosphere effects on soil organic matter (SOM) decomposition have attracted little attention. • Using a dual 13C/15N labeling approach in a ‘common garden’ glasshouse experiment, we investigated how the economic strategies of 12 grassland plant species (graminoids, forbs and legumes) drive soil nitrogen (N) cycling via rhizosphere processes, and how this in turn affects plant N acquisition and growth. • Acquisitive species with higher photosynthesis, carbon rhizodeposition and N uptake than conservative species induced a stronger acceleration of soil N cycling through rhizosphere priming of SOM decomposition. This allowed them to take up larger amounts of N and allocate it above ground to promote photosynthesis, thereby sustaining their faster growth. The N₂-fixation ability of legumes enhanced rhizosphere priming by promoting photosynthesis and rhizodeposition. • Our study demonstrates that the economic strategies of plant species regulate a plant–soil carbon–nitrogen feedback operating through the rhizosphere. These findings provide novel mechanistic insights into how plant species with contrasting economic strategies sustain their nutrition and growth through regulating the cycling of nutrients by soil microbes in their rhizosphere.

Aim Iodine (I) deficiency is distinct from other micronutrient deficiencies in human populations in having a high endemic prevalence both in well-developed and in developing countries. The very low concentration of iodine in agricultural soils and cereal-based foods is widely believed to be the main reason of iodine deficiency in humans, especially in developing countries. In the present study, the possibility of using iodine containing fertilizers for agronomic biofortification of cereal grains with iodine was studied. The aim was to establish the best application method (to the soil or as foliar spray), the best form of iodine (potassium iodate or potassium iodide) and the optimal dose of iodine. Additionally, experiments were conducted to study transport of iodine in plants and localization of iodine within the grains. Materials and methods Experiments were conducted both under greenhouse conditions and in the field on wheat ( Triticum aestivum ) grown in Turkey and Pakistan, on rice ( Oryza sativa ) grown in Brazil, Thailand and Turkey and on maize ( Zea mays ) grown in Turkey. The iodine concentration in the grain, localization of iodine in different grain fractions of wheat (i.e., endosperm, bran and embryo) and iodine concentration of both brown rice and polished rice was analyzed. In short-term experiments, the translocation of iodine from older into younger leaves was also studied. Inductively coupled plasma mass spectrometry (ICP-MS) was used for analysis of iodine in plant and soil samples. Results In greenhouse experiments on wheat, soil-applied potassium iodide (KI) and potassium iodate (KIO 3 ) at increasing rates (i.e., 0, 0.1, 0.25, 1, 2.5, 5, 10 and 20 mg I kg −1 soil) both iodine forms substantially increased iodine concentration in the shoot, with the highest shoot iodine resulting from the KI treatments. However, these soil treatments did not affect iodine concentrations in the wheat grain, with the exception of the highest iodine rates (i. e., 10 and 20 mg I kg −1 soil) which also depressed the grain yield. In contrast to the soil applications, foliar spray of KI and KIO 3 at increasing rates during heading and early milk stages did enhance grain iodine concentrations up to 5- to 10-fold without affecting grain yield. Including KNO 3 or a surfactant to the iodine containing foliar spray further increased the grain iodine concentration. In a short-term experiment using young wheat plants, it was found that iodine is translocated from older into younger leaves after immersion of the older leaves in solutions containing KI or KIO 3 . Adding KNO 3 or a surfactant in the immersion solution also promoted leaf absorption and translocation of iodine into younger leaves. Field experiments conducted in different countries confirmed that foliar application with increasing rates of iodine significantly increased grain iodine concentrations in wheat, brown rice and maize. This increase was also found in the iodine concentration of the endosperm part of wheat grains and in polished rice. Conclusions The results of the present study clearly show that foliar application of iodine containing fertilizers is highly effective in increasing grain iodine concentrations in wheat, rice and maize. Presented results suggest that iodine is translocated from shoot to grain by transport in the phloem. Spraying KIO 3 up to the rate of 0.05% w / v is suggested as the optimal form and rate to be used in agronomic biofortification with iodine. The substantial increase in grain iodine concentrations could contribute to the prevention of iodine deficiency in human populations with low dietary iodine intake. The reasons behind the higher effectiveness of foliar-applications compared to the soil applications of iodine fertilizers in improving grain iodine concentration are discussed.

1. Human settlements and transport networks are growing rapidly worldwide. Since the early 20th century their expansion has been accompanied by increasing illumination of the environment at night, a trend that is likely to continue over the decades to come. Consequently, a growing proportion of the world's ecosystems are exposed to artificial light at night, profoundly altering natural cycles of light and darkness. While in recent years there have been advances in our understanding of the effects of artificial light at night on the behaviour and physiology of animals in the wild, much less is known about the impacts on wild plants and natural or seminatural vegetation composition. This is surprising, as effects of low-intensity light at night on flowering, phenology and growth form are well known in laboratory and greenhouse studies. 2. In a long-term experimental field study we exposed a semi-natural grassland to artificial light at intensities and wavelengths typical of those experienced by roadside vegetation under street lighting. 3. We found that lighting affected the trajectory of vegetation change, leading to significant differences in biomass and plant cover in the dominant species. 4. Changes in flowering phenology were variable between years, with grass species flowering between 4 days earlier and 12 days later under artificial light. 5. Policy implications. Our results demonstrate that artificial light, at levels equivalent to those in street-lit environments, can affect species composition in semi-natural vegetation. This highlights the importance of considering artificial light as a driver of vegetation change in urban, suburban and semi-natural ecosystems, and where possible, of minimising or excluding artificial light from habitats of conservation importance.

Desert plants are able to survive under harsh environmental stresses inherent to arid and semiarid regions due to their association with bacterial endophytes. However, the identity, functions, and the factors that influence the association of bacterial endophytes with desert plants are poorly known. These bacterial endophytes can be used as an untapped resource to favor plant growth and development in agro-ecosystems of arid regions. The present study is therefore focused on the isolation and identification of bacterial endophytes from two native medicinal plants (Fagonia mollis Delile and Achillea fragrantissima (Forssk) Sch. Bip.) growing spontaneously in the arid region of the South Sinai (Egypt), and characterization of their plant growth promoting (PGP) traits. Thirteen putative bacterial endophytes were isolated from the leaves of both plant species and characterized for their plant growth promoting abilities using molecular and biochemical approaches, as well as greenhouse trials. Selected endophytic bacterial strains were applied to maize plants (Zea mays L. var. Single cross Pioneer 30K08) to further evaluate their PGP abilities under greenhouse conditions. Isolated bacterial strains have variable plant growth promoting activities. Among these activities, isolated bacterial endophytes have the efficacy of phosphate solubilizing with clear zones ranging from 7.6 ± 0.3 to 9.6 ± 0.3 mm. Additionally, the obtained bacterial endophytes increased the productivity of indole acetic acid (IAA) in broth media from 10 to 60 µg·mL−1 with increasing tryptophan concentration from 1 to 5 mg·mL−1. Bacillus and Brevibacillus strains were frequently isolated from the leaves of both plant species, and had significant positive effects on plant growth and shoot phosphorus (P) and nitrogen (N) contents. Results suggest that these endophytes are good candidates as plant growth promoting inoculants to help reduce chemical input in conventional agricultural practices and increase nutrient uptake and stress resilience in plant species.

Agricultural fertilization significantly affects arbuscular mycorrhizal fungal (AMF) community composition. However, the functional implications of community shifts are unknown, limiting understanding of the role of AMF in agriculture. We assessed AMF community composition at four sites managed under the same nitrogen (N) and phosphorus (P) fertilizer regimes for 55 yr. We also established a glasshouse experiment with the same soils to investigate AMF–barley (Hordeum vulgare) nutrient exchange, using carbon (13C) and 33P isotopic labelling. N fertilization affected AMF community composition, reducing diversity; P had no effect. In the glasshouse, AMF contribution to plant P declined with P fertilization, but was unaffected by N. Barley C allocation to AMF also declined with P fertilization. As N fertilization increased, C allocation to AMF per unit of P exchanged increased. This occurred with and without P fertilization, and was concomitant with reduced barley biomass. AMF community composition showed no relationship with glasshouse experiment results. The results indicate that plants can reduce C allocation to AMF in response to P fertilization. Under N fertilization, plants allocate an increasing amount of C to AMF and receive relatively less P. This suggests an alteration in the terms of P–C exchange under N fertilization regardless of soil P status.

Some plant species are able to distinguish between neighbours of different genetic identity and attempt to pre‐empt resources through root proliferation in the presence of unrelated competitors, but avoid competition with kin. However, studies on neighbour recognition have met with some scepticism because the mechanisms by which plants identify their neighbours have remained unclear. In order to test whether root exudates could mediate neighbour recognition in plants, we performed a glasshouse experiment in which plants of Deschampsia caespitosa were subjected to root exudates collected from potential neighbours of different genetic identities, including siblings and individuals belonging to the same or a different population or species. Our results show that root exudates can carry specific information about the genetic relatedness, population origin and species identity of neighbours, and trigger different responses at the whole root system level and at the level of individual roots in direct contact with locally applied exudates. Increased root density was mainly achieved through changes in morphology rather than biomass allocation, suggesting that plants are able to limit the energetic cost of selfish behaviour. This study reveals a new level of complexity in the ability of plants to interpret and react to their surroundings.

Sorgoleone is a secondary sorghum metabolite released from roots. It has allelopathic properties and is considered to inhibit ammonia-oxidizing archaea (AOA) and bacteria (AOB) responsible for the rate-limiting step (ammonia oxidation) in nitrification. Low activity of these microorganisms in soil may contribute to slow down nitrification and reduce nitrogen loss via denitrification and NO3− leaching. The potential nitrification rate (PNR) and the composition of microbial communities were monitored in rhizosphere soil to investigate the growth effect sorghum on biological nitrification inhibition (BNI). A greenhouse pipe experiment was conducted using sorghum lines IS20205 (high-sorgoleone release ability), IS32234 (medium-sorgoleone release ability), 296B (low-sorgoleone release ability), and a control (no plants) combined with fertilization application of 0 or 120 kg N ha−1. We applied nitrogen as ammonium sulfate at 16 days (20 N), 37 days (40 N), and 54 days (60 N). We collected soil solutions at 7.5 cm depths every 3 days and measured the pH and nitrate levels. At 1 and 2.3 months, we sampled the bulk and rhizosphere soils and roots in the 0–10 cm, 10–30 cm, and 30–80 cm depths to determine NO2, mineral N, total N, total C, sorgoleone, the composition of AOA, AOB, and total bacteria and archaea. Sorgoleone was continuously released throughout the 2.3 months’ growth and was significantly higher in IS20205, followed by IS32234 then 296B, which showed shallow levels. The IS2020 5rhizosphere showed lower NO2 and nitrate levels and significant inhibition of AOA populations. However, we did not find significant differences in the abundance of AOB between plant treatments. Multivariate analysis and Spearman’s correlations revealed that sorgoleone as well as environmental factors such as soil pH, soil moisture, NO3−-N, and NH4+-N shape the composition of microbial communities. This study demonstrated that the release of higher amounts of sorgoleone has great potential to inhibit the abundance of AOA and soil nitrification. The breeding of sorghum lines with the ability to release higher amounts of sorgoleone could be a strategic way to improve the biological nitrification inhibition during cultivation.

A greenhouse hydroponic experiment was performed using salt-tolerant (cv. Suntop) and -sensitive (Sunmate) wheat cultivars and a salt-tolerant barley cv. CM72 to evaluate how cultivar and species differ in response to salinity stress. Results showed that wheat cv. Suntop performed high tolerance to salinity, being similar tolerance to salinity with CM72, compared with cv. Sunmate. Similar to CM72, Suntop recorded less salinity induced increase in malondialdehyde (MDA) accumulation and less reduction in plant height, net photosynthetic rate (Pn), chlorophyll content, and biomass than in sensitive wheat cv. Sunmate. Significant time-course and cultivar-dependent changes were observed in the activities of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) in roots and leaves after salinity treatment. Higher activities were found in CM72 and Suntop compared to Sunmate. Furthermore, a clear modification was observed in leaf and root ultrastructure after NaCl treatment with more obvious changes in the sensitive wheat cv. Sunmate, rather than in CM72 and Suntop. Although differences were observed between CM72 and Suntop in the growth and biochemical traits assessed and modified by salt stress, the differences were negligible in comparison with the general response to the salt stress of sensitive wheat cv. Sunmate. In addition, salinity stress induced an increase in the Na+ and Na+/K+ ratio but a reduction in K+ concentrations, most prominently in Sunmate and followed by Suntop and CM72.

The roles of biochar, melatonin (Me), and P application have been well researched; however, biochar with Me application in helping plants be more drought tolerant are little understood. The aim of this greenhouse study is to evaluate the effects of Me and P in combination with biochar made from date (Phoenix dactylifera L.) and wheat (Triticum aestivum L.) residues on vegetative growth and biochemical impact of maize (Zea mays L.) varieties Azam and Mallika under drought stress. Date residue and wheat straw biochars combined with melatonin (D+W+Me) reduced oxidative stress caused by excessive reactive oxygen species (ROS) the most. Generations of ROS species (malondialdehyde [MDA], H2O2, thiobarbituric acid reactive substances [TBARS], O2−, lipoxygenase [LOX], and electolyte leakage [EL]) was 118 and 700% higher in Azam variety compared to Mallika. The application of D+W+Me maintained osmolyte accumulation, α‐amylase activity, and antioxidant enzyme activities at higher levels in Mallika (2−7, 29, 9−55%, respectively) than in Azam and the rest of the treatments. The D+W+Me treatment also enhanced leaf gas exchange traits in Mallika (3−20%) under drought stress, helping to main better photosynthesis machinery. The D+W+P and D+Me treatments application alleviated a portion of the drought stress. Overall, Me application with date residue and wheat straw biochars enhanced the efficiency of biochar, by better assuaging the adverse drought stress influences.