Host Plant Nutrition Research Articles

Interactions between host plant quality and non‐consumptive predator effects on oviposition and larval behaviour of Plutella xylostella (Lepidoptera: Plutellidae)

Abstract The presence of predators can induce non‐consumptive effects on prey that result in subsequent changes to prey behaviour and defence. We investigate the interaction between top‐down non‐consumptive effects of various stages of the predator Coccinella septempunctata L.(Coleoptera: Coccinellidae) (larvae and adult) and bottom‐up effects of host nutrition on Plutella xylostella (L.) (Lepidoptera: Plutellidae) oviposition and larval host choice. We also compare the effect of presence of intact predators, predators without mandibles, confined predators and a no predator control treatment on P. xylostella larval growth, survival and herbivory. Host plant nutrition influenced the host choice of adult female P. xylostella; no interaction was observed between bottom‐up host plant nutrition and the presence of C. septempunctata adults or larvae on oviposition or larval host choice by P. xylostella. Predator presence impacted larval feeding and weight gain. The presence of free‐moving C. septempunctata adults without mandibles that could not predate P. xylostella reduced mean leaf consumption by P. xylostella larvae to 1.88 ± 0.21 cm2 and reduced weight gain to 2.12 ± 0.16 mg. Despite differences in leaf damage and larval weight gain, survival remained consistent across the non‐consumptive treatments. Intact C. septempunctata larvae reduced leaf damage and subsequent P. xylostella larval weight gain. The presence of larval predators across the non‐consumptive treatments, however, had no effect on feeding damage or weight gain. Results of our investigation indicate that C. septempunctata causes some non‐consumptive effects on P. xylostella that depend on predator life stage, level of confinement and prey life stage. It is likely that P. xylostella responds to multi‐modal cues in predator detection.

Suillus: an emerging model for the study of ectomycorrhizal ecology and evolution.

Research on mycorrhizal symbiosis has been slowed by a lack of established study systems. To address this challenge, we have been developing Suillus, a widespread ecologically and economically relevant fungal genus primarily associated with the plant family Pinaceae, into a model system for studying ectomycorrhizal (ECM) associations. Over the last decade, we have compiled extensive genomic resources, culture libraries, a phenotype database, and protocols for manipulating Suillus fungi with and without their tree partners. Our efforts have already resulted in a large number of publicly available genomes, transcriptomes, and respective annotations, as well as advances in our understanding of mycorrhizal partner specificity and host communication, fungal and plant nutrition, environmental adaptation, soil nutrient cycling, interspecific competition, and biological invasions. Here, we highlight the most significant recent findings enabled by Suillus, present a suite of protocols for working with the genus, and discuss how Suillus is emerging as an important model to elucidate the ecology and evolution of ECM interactions.

Nutrition of host plants influence the infectivity of nucleopolyhedrovirus to polyphagous caterpillar, Hyphantria cunea

Plants play an important role in interactions between insect herbivores and their pathogens. The ability of host plants to modify the infectivity of entomopathogens in herbivorous insects has been widely documented. However, the plants’ nutrients have always been neglected as a factor contributing to variation in the susceptibility of insect herbivores to entomopathogens. The fall-webworm (FWW), Hyphantria cunea Drury, is a typical polyphagous caterpillar, and the Hyphantria cunea nucleopolyhedrovirus (HycuNPV) is a distinctly specialized baculovirus for the FWW, which is safe for other organisms and has been effectively used as a biological insecticide against H. cunea in China. In this study, we investigated the nutrient components of four host plant species, i.e., Prunus serrulate, Cerasus serrulate, Camptotheca acuminata, and Populus deltoides, and their effects on the susceptibility of H. cunea larvae to HycuNPV. The HycuNPV-infected larvae fed on P. deltoides leaves exhibited higher survival rates, longer survival times, more food intake, and gained larger body size. These biological parameters were positively correlated with the nitrogen components of host plant leaves. Moreover, the larval antioxidant enzymes exhibited different responses to HycuNPV. HycuNPV infection significantly triggered the catalase (CAT) and prophenoloxidase (PPO) enzyme activity levels of H. cunea larvae. The uninfected larvae fed on poplar leaves induced a robust increase in the POD activity, which could scavenge extra reactive oxygen species and provide a protective effect against the HycuNPV. In conclusion, the plant-mediated effects of HycuNPV on the FWW have been investigated in this study. The nitrogen content in dietary was an essential factor in determining the insect herbivore susceptibility to entomopathogenic viruses, and it helped explain variations in the susceptibility of pests to the entomopathogenic viruses and aid in developing more robust tolerance monitoring assays in the lab that reflect the performance of pests in the field.Graphical

IMPACT OF PGPR ON THE SUSTAINABLE DEVELOPMENT OF AGRICULTURE: CURRENT AND FUTURE PROSPECTS

The quest for boosting agricultural yields due to increased stress on food production has inevitably brought about the indiscriminate use of chemical fertilizers and different agrochemicals. Biofertilizers facilitate the overall growth and yield of crops in an eco-friendly manner. They comprise residing or dormant microbes implemented in the soil or used for treating crop seeds. One of the most applicants in this respect is rhizobacteria. Plant growth-promoting rhizobacteria (PGPR) are an important group of beneficial, root-colonizing bacteria. They exhibit harmonious and divergent interactions with the soil microbiota and interact in an array of activities of ecological meaning. They encourage plant growth by facilitating biotic and abiotic stress tolerance and aid the nutrition of host plants. Due to their lively growth endorsing activities, PGPRs are considered an eco-friendly alternative to dangerous chemical fertilizers. Chemical fertilizers used in agriculture to improve yields and eradicate pathogens, however, negatively influence the ecosystem. The doubts over pesticide side effects, there is a growing interest in better thoughtfulhelpful interactions between plants and rhizosphere microbial populations. As a result, biological agents are in high demand around the world. The use of plant growth-promoting Rhizobacteria (PGPR). They have a crucial function in increasing soil fertility, promoting plant growth, and suppressing phytopathogens for the development of environmentally friendly sustainable agriculture.In this section, we try to devise a strategy for increasing crop output and health, developing sustainable agriculture, and commercialization through the use of plant growth-promoting rhizobacteria.

A systematic review on endophytic fungi and its role in the commercial applications.

EF have been explored for its beneficial impact on environment and for its commercial applications. It has proved its worth in these sectors and showed an impact on biological properties of plants by producing various bioactive molecules and enzymes. Endophytes are plant mutualists that live asymptomatically within plant tissues and exist in almost every plant species. Endophytic fungi benefit from the host plant nutrition, and the host plant gains improved competitive abilities and tolerance against pathogens, herbivores, and various abiotic stresses. Endophytic fungi are one of the most inventive classes which produce secondary metabolites and play a crucial role in human health and other biotic aspects. This review is focused on systematic study on the biodiversity of endophytic fungi in plants, and their role in enhancing various properties of plants such as antimicrobial, antimycobacterial, antioxidant, cytotoxic, anticancer, and biological activity of secondary metabolites produced by various fungal endophytes in host plants reported from 1994 to 2021. This review emphasizes the endophytic fungal population shaped by host genotype, environment, and endophytic fungi genotype affecting host plant. The impact of endophytic fungi has been discussed in detail which influences the commercial properties of plants. Endophytes also have an influence on plant productivity by increasing parameters such as nutrient recycling and phytostimulation. Studies focusing on mechanisms that regulate attenuation of secondary metabolite production in EF would provide much needed impetus on ensuring continued production of bioactive molecules from a indubitable source. If this knowledge is further extensively explored regarding fungal endophytes in plants for production of potential phytochemicals, then it will help in exploring a keen area of interest for pharmacognosy.

The function of the Medicagotruncatula ZIP transporter MtZIP14 is linked to arbuscular mycorrhizal fungal colonization.

Soil micronutrient availability, including zinc (Zn), is a limiting factor for crop yield. Arbuscular mycorrhizal (AM) fungi can improve host plant growth and nutrition through the mycorrhizal pathway of nutrient uptake. Although the physiology of Zn uptake through the mycorrhizal pathway is well established, the identity of the related molecular components are unknown. Here, RNA-seq analysis was used to identify genes differentially-regulated by AM colonization and soil Zn concentration in roots of Medicago truncatula. The putative Zn transporter gene MtZIP14 was markedly up-regulated in M.truncatula roots when colonized by Rhizophagus irregularis. MtZIP14 restored yeast growth under low Zn availability. Loss-of-function mutant plants (mtzip14) had reduced shoot biomass compared to the wild-type when colonized by AM fungi and grown under low and sufficient soil Zn concentration; at high soil Zn concentration, there were no genotypic differences in shoot biomass. The vesicular and arbuscular colonization of roots was lower in the mtzip14 plants regardless of soil Zn concentration. We propose that MtZIP14 is linked to AM colonization in M. truncatula plants, with the possibility that MtZIP14 function with AM colonization is linked to plant Zn nutrition.

Alhagi sparsifolia Harbors a Different Root-Associated Mycobiome during Different Development Stages.

The mycobiome in the rhizosphere and within the roots benefits the nutrition and function of host plants. However, compared with the bacterial community, root-associated mycobiomes of desert plants and the forces that drive their assemblage are limited. Here, we investigated the mycobiomes in bulk soil, rhizosphere, and root compartments of Alhagi sparsifolia Shap., a phreatophyte species dominating in Central Asia. The internal transcribed spacer (ITS) gene phylogenetic profiles displayed significantly diverse mycobiomes across three compartments and host growth times, together explaining 31.45% of the variation in the community composition. The community structure of the perennial stage was markedly different from that of other stages (30 days to 2 years old). Along the soil-plant continuum, the α-diversity (estimated by Chao1) decreased gradually, while concomitantly increasing the community dissimilarity and the influence of edaphic factors. Specific leaf area, soil water content, and soil organic matter levels were common factors driving the composition of the three mycobiome communities. A more complex and connected network was observed in the root community compared with the other compartments. Overall, our work suggests that an age-sensitive host effect restructured the desert-plant-root-associated mycobiome, and that edaphic factors and host growth strategy may play potential roles in this process.

Growth and metabolism of dark septate endophytes and their stimulatory effects on plant growth

Dark septate endophytes (DSE) colonize plant roots extensively and increase host plant growth and nutrition. However, the development of DSE-produced metabolites as plant biostimulants has been largely ignored. DSE growth curves and extracellular metabolite components were analyzed and the growth-promoting effects of DSE extracellular metabolites on alfalfa (Medicago sativa L.) grown for 4, 8 12, 16 and 20 days were evaluated. The growth curve of the DSE strain Alternaria sp. shows days 0-8 in the growth phase, days 8-16 in the stable phase, and days 16-20 in the senescent phase. The extracellular metabolite components of DSE were significantly different at different growth stages. The biomass of alfalfa was increased significantly by DSE extracellular metabolites (P < 0.05). Biomass of alfalfa inoculated with DSE extracellular metabolites more than doubled after growth for 8 days and nutrient availability also increased significantly compared with the uninoculated control. Six DSE extracellular metabolites, calycosin 7-galactoside, 1-[(5-amino-5-carboxypentyl)amino]-1-deoxyfructose, N2-fructopyranosylarginine, 2-(4-methyl-5-thiazolyl)ethyl hexanoate, kenposide B, and medinoside E, were significantly positively correlated with alfalfa biomass (P < 0.01). This study combines the DSE extracellular metabolites with plant and soil traits to provide a theoretical basis for the use of DSE metabolites in the product development of plant biostimulants.

Inoculations of soil by antagonistic strains modify tuberosphere bacterial communities and suppress common scab of potatoes

Common scab of potatoes is a soil-borne disease causing considerable economic losses worldwide. Although many management practices to control this disease have been introduced, the lack of efficiency increases an interest in effective and environmentally friendly alternatives. One of the attractive approaches to manage the disease is an application of antagonistic strains into soil. The aim of this study was to develop a selection approach for suitable biocontrol agents based on their in vitro properties and demonstrate their effect on soil microbial communities and host plant nutrition. Out of 56 isolates of Actinobacteria, three isolates and a mixture of six isolates with strong inhibitory activities against common scab pathogens and high growth rates were selected for the pot experiment to assess their biocontrol activity. The microbial community composition of the tuberosphere and the nutrient content in potato leaves was determined. One isolate significantly reduced the severity of the common scab. This isolate showed strong inhibitory activity against pathogens and reached the highest number of CFU/g of vermiculite. In the pot experiment, all the isolates affected the microbial community composition, yet the most substantial changes occurred in the treatment of the most efficient isolate. Moreover, it was determined that inoculation with isolates led to alterations in host plant nutrition suggesting plant-microbe interactions. We provided insights into relationships between antagonistic isolates, common scab pathogens, host plant and microbial communities, and their role in the disease control.

Carbon for nutrient exchange between Lycopodiella inundata and Mucoromycotina fine root endophytes is unresponsive to high atmospheric CO2

Non-vascular plants associating with arbuscular mycorrhizal (AMF) and Mucoromycotina ‘fine root endophyte’ (MFRE) fungi derive greater benefits from their fungal associates under higher atmospheric [CO2] (a[CO2]) than ambient; however, nothing is known about how changes in a[CO2] affect MFRE function in vascular plants. We measured movement of phosphorus (P), nitrogen (N) and carbon (C) between the lycophyte Lycopodiella inundata and Mucoromycotina fine root endophyte fungi using 33P-orthophosphate, 15 N-ammonium chloride and 14CO2 isotope tracers under ambient and elevated a[CO2] concentrations of 440 and 800 ppm, respectively. Transfers of 33P and 15 N from MFRE to plants were unaffected by changes in a[CO2]. There was a slight increase in C transfer from plants to MFRE under elevated a[CO2]. Our results demonstrate that the exchange of C-for-nutrients between a vascular plant and Mucoromycotina FRE is largely unaffected by changes in a[CO2]. Unravelling the role of MFRE in host plant nutrition and potential C-for-N trade changes between symbionts under different abiotic conditions is imperative to further our understanding of the past, present and future roles of plant-fungal symbioses in ecosystems.

Combining host plant defence with targeted nutrition: key to durable control of hemiparasitic Striga in cereals in sub-Saharan Africa?

Host plant defence mechanisms (resistance and tolerance) and plant nutrition are two of the most widely proposed components for the control of hemiparasitic weeds of the genus Striga in tropical cereal production systems. Neither of the two components alone is effective enough to prevent parasitism and concomitant crop losses. This review explores the potential of improved plant nutrition, being the chemical constituent of soil fertility, to fortify the expression of plant inherent resistance and tolerance against Striga. Beyond reviewing advances in parasitic plant research, we assess relevant insights from phytopathology and plant physiology in the broader sense to identify opportunities and knowledge gaps and to develop the way forward regarding research and development of combining genetics and plant nutrition for the durable control of Striga.

Plant Growth Promoting Rhizobacteria (PGPR) as Green Bioinoculants: Recent Developments, Constraints, and Prospects

The quest for enhancing agricultural yields due to increased pressure on food production has inevitably led to the indiscriminate use of chemical fertilizers and other agrochemicals. Biofertilizers are emerging as a suitable alternative to counteract the adverse environmental impacts exerted by synthetic agrochemicals. Biofertilizers facilitate the overall growth and yield of crops in an eco-friendly manner. They contain living or dormant microbes, which are applied to the soil or used for treating crop seeds. One of the foremost candidates in this respect is rhizobacteria. Plant growth promoting rhizobacteria (PGPR) are an important cluster of beneficial, root-colonizing bacteria thriving in the plant rhizosphere and bulk soil. They exhibit synergistic and antagonistic interactions with the soil microbiota and engage in an array of activities of ecological significance. They promote plant growth by facilitating biotic and abiotic stress tolerance and support the nutrition of host plants. Due to their active growth endorsing activities, PGPRs are considered an eco-friendly alternative to hazardous chemical fertilizers. The use of PGPRs as biofertilizers is a biological approach toward the sustainable intensification of agriculture. However, their application for increasing agricultural yields has several pros and cons. Application of potential biofertilizers that perform well in the laboratory and greenhouse conditions often fails to deliver the expected effects on plant development in field settings. Here we review the different types of PGPR-based biofertilizers, discuss the challenges faced in the widespread adoption of biofertilizers, and deliberate the prospects of using biofertilizers to promote sustainable agriculture.

Mycorrhizae Aided Nitrogen Nutrition and Drought Tolerance in Plants

Mycorrhizas are known to improve host plant nutritional status as a consequence of water transport from the soil to the host plant through the external mycelium as a direct effect or improved host plant nutrition primarily, phosphorus as an indirect effect. The direct hyphal water transport is quantified to be meager and a major part of the benefits of mycorrhizal symbiosis is indirect and nutritionally related. In arid and semi-arid regions where drought occurrence is very frequent and soil moisture content is highly restricted, mycorrhizas can assist in exploiting the soil beyond the rhizosphere that helps the host plant to withstand drought stress conditions. The drought tolerance in mycorrhiza-inoculated plants is quite complex and such response is due to a series of processes such as improved nitrogen (N) availability in soils, extensive root surface area and cationic exchange capacity, collective N assimilatory pathways in plant-mycorrhizal system, luxuriant uptake of nutrients besides remobilization of nutrients to support grain growth. These physiological, biochemical, nutritional and morphological changes in the mycorrhizas associated host plants have contributed to the ability of the host plants to survive under limited water environments. Despite mycorrhiza-assisted and N nutritionally enabled host plant drought tolerance is evident, more research is required to gain insights into the mechanisms involved. This review highlights the role of mycorrhizas on N dynamics in the rhizosphere and enhanced host plant N nutrition that collectively contributes to the sustained crop productivity under drought stress conditions.

High‐throughput phenotyping reveals growth of Medicago truncatula is positively affected by arbuscular mycorrhizal fungi even at high soil phosphorus availability

Societal Impact StatementArbuscular mycorrhizal fungi (AMF) may contribute to enhanced yield and nutrition of host plants for the purpose of sustainable agriculture. However, the growth response of the host plant to mycorrhizal colonization is generally only measured at harvest, and thus management decisions regarding AMF are made using only a single time point. This study highlights that AMF can provide growth benefits to the host plant over its life. Greater knowledge of how plants respond to AMF over time will improve understanding of how the association functions and ultimately lead to improved management decisions regarding AMF in an agricultural context.Summary Colonization by arbuscular mycorrhizal fungi (AMF) can result in variable responses in the growth and mineral nutrition of host plants, and is highly dependent on soil nutrient condition; limited studies have addressed the effects of AMF on plant growth over time. The aim of this study was to investigate the AMF effects on plant growth over the life of the plant, and interactions with soil phosphorus (P) and zinc (Zn) availability. We used a high‐throughput shoot phenotyping system to examine the temporal growth responses to AMF and soil P and Zn availabilities in the pasture legume Medicago truncatula. Plants were either inoculated with Rhizophagus irregularis or mock‐inoculated, and were examined under two soil P and five soil Zn availability treatments. Plants were then destructively harvested to obtain final biomass and shoot nutrition data. The growth of M. truncatula plants over time responded very differently to AMF depending on the soil P availability. At low P, projected shoot area and absolute growth rate (AGR) became increasingly greater in the mycorrhizal plants over the course of the experiment. At high P, there was a positive growth response to AMF until approximately 40 days after planting, after which the AGR of the non‐mycorrhizal plants increased and the response to AMF became neutral. Zinc availability was highly interactive with P availability, but not with AMF inoculation. This research demonstrates that growth responses to mycorrhizal fungi change over the plant's life, and are highly dependent on soil P availability.

Two herbicides, two fungicides and spore-associated bacteria affect Funneliformis mosseae extraradical mycelium structural traits and viability.

The extraradical mycelium (ERM) produced by arbuscular mycorrhizal fungi is fundamental for the maintenance of biological fertility in agricultural soils, representing an important inoculum source, together with spores and mycorrhizal root fragments. Its viability and structural traits, such as density, extent and interconnectedness, which are positively correlated with the growth and nutrition of host plants, may be affected by different agronomic practices, including the use of pesticides and by different mycorrhizospheric communities. This work, carried out using a whole-plant experimental model system, showed that structural traits of ERM, such as length and density, were strongly decreased by the herbicides dicamba and glufosinolate and the fungicides benomyl and fenhexamid, while anastomosis frequency and hyphal branching were differentially modulated by singly inoculated mycorrhizospheric bacteria, depending on their identity.

The Potassium Transporter SlHAK10 Is Involved in Mycorrhizal Potassium Uptake.

Most terrestrial plants form a root symbiosis with arbuscular mycorrhizal (AM) fungi, which receive fixed carbon from the plant and enhance the plant's uptake of mineral nutrients. AM symbiosis improves the phosphorous and nitrogen nutrition of host plants; however, little is known about the role of AM symbiosis in potassium (K+) nutrition. Here, we report that inoculation with the AM fungus Rhizophagus irregularis improved tomato (Solanum lycopersicum) plant growth and K+ acquisition and that K+ deficiency has a negative effect on root growth and AM colonization. Based on its homology to a Lotus japonicus AM-induced K+ transporter, we identified a mycorrhiza-specific tomato K+ transporter, SlHAK10 (Solanum lycopersicum High-affinity Potassium Transporter10), that was exclusively expressed in arbuscule-containing cells. SlHAK10 could restore a yeast K+ uptake-defective mutant in the low-affinity concentration range. Loss of function of SlHAK10 led to a significant decrease in mycorrhizal K+ uptake and AM colonization rate under low-K+ conditions but did not affect arbuscule development. Overexpressing SlHAK10 from the constitutive cauliflower mosaic virus 35S promoter or the AM-specific Solanum melongena Phosphate Transporter4 not only improved plant growth and K+ uptake but also increased AM colonization efficiency and soluble sugar content in roots supplied with low K+ Our results indicate that tomato plants have a SlHAK10-mediated mycorrhizal K+ uptake pathway and that improved plant K+ nutrition could increase carbohydrate accumulation in roots, which facilitates AM fungal colonization.

Impact of an arbuscular mycorrhizal fungus on the growth and nutrition of fifteen crop and pasture plant species.

The formation of arbuscular mycorrhizas (AM) can result in positive, neutral or negative responses in the growth and mineral nutrition of host plants, particularly that of P, Zn and other micronutrients. This study examined the growth and nutritional responses of 15 agriculturally important plant species, including cereals, legumes and vegetables, with and without inoculation with the AM fungus (AMF) Rhizophagus irregularis. Furthermore, we explored whether the responses differed between different functional groups of plants such as monocots and dicots, C3 and C4 plants, and N-fixing and non-N-fixing plants. We found that that mycorrhizal colonisation of roots, plant growth and plant nutrient responses differed between plant species. Among the species analysed, leek (Allium ampeloprasum L. var. porrum) was the most mycorrhiza-responsive, displaying the highest mycorrhizal colonisation and biomass response, and the greatest increases in most mineral nutrients. In other plant species, the concentration of P, Cu, Zn and S were generally enhanced by inoculation with AMF. Furthermore, ionomes differed more greatly between plant species than in response to inoculation with AMF. This research further improves our understanding of the responses of different and diverse plant species to the formation of AM in terms of growth and ionomics under standardised growth conditions. The results of this study may be used in further studies and to inform agricultural practices.

Unity in diversity: structural and functional insights into the ancient partnerships between plants and fungi.

Contents Summary 996 I. Introduction 996 II. An ancient, and diverse, symbiosis 998 III. Structural diversity in ancient plant-fungal partnerships 1000 IV. Mycorrhizal unity in host plant nutrition 1002 V. Plant-to-fungus carbon transfer 1003 VI. From individuals to networks 1003 VII. Diverse responses of mycorrhizal functioning to dynamic environments 1006 VIII. Summary of future research direction 1007 Acknowledgements 1006 References 1006 SUMMARY: Mycorrhizal symbiosis is an ancient and widespread mutualism between plants and fungi that facilitated plant terrestrialisation >500million years ago, with key roles in ecosystem functioning at multiple scales. Central to the symbiosis is the bidirectional exchange of plant-fixed carbon for fungal-acquired nutrients. Within this unifying role of mycorrhizas, considerable diversity in structure and function reflects the diversity of the partners involved. Early diverging plants form mutualisms not only with arbuscular mycorrhizal Glomeromycotina fungi, but also with poorly characterised Mucoromycotina, which may also colonise the roots of 'higher' plants as fine root endophytes. Functional diversity in these symbioses depends on both fungal and plant life histories and is influenced by the environment. Recent studies have highlighted the roles of lipids/fatty acids in plant-to-fungus carbon transport and potential contributions of Glomeromycotina fungi to plant nitrogen nutrition. Together with emerging appreciation of mycorrhizal networks as multi-species resource-sharing systems, these insights are broadening our views on mycorrhizas and their roles in nutrient cycling. It is crucial that the diverse array of biotic and abiotic factors that together shape the dynamics of carbon-for-nutrient exchange between plants and fungi are integrated, in addition to embracing the unfolding and potentially key role of Mucoromycotina fungi in these processes.

Plant Nutrition: A tool for the management of hemipteran insect-pests-A review

Nutrition of plants has a substantial impact on the predisposition of plants to insect-pests. Regulated and balanced crop fertilization can be helpful in altering host plant susceptibility to sucking insect-pests. Hemipteran herbivores are sensitive to alteration in host plant nutrition. Primary pest defence of plants like biochemical, physical and mechanical properties can be enhanced by balanced fertilization with plant nutrients. All plant nutrients may affect plant health but two of them namely, nitrogen and potassium play a major role. The effect of other nutrients is less frequently mentioned. Most studies revealed that generally excessive use of nitrogen decreases crop resistance to pests whereas potassium increases the same. So, the agricultural practices like excessive, injudicious and unscientific use of fertilizers can result in nutrient imbalance and finally into increased attack of insect-pests. Careful consideration of present and future information on this topic can lead to better predictive capabilities in hemipteran insect-pest management.

Influence of mycorrhizal fungi on growth, chlorophyll content, and potassium and magnesium uptake in maize

ABSTRACTMycorrhizal fungi affect growth and nutrition of host plants positively. In this research, influence of vesicular-arbuscular mycorrhiza (VAM) ongrowth, chlorophyll content, and potassium (K) and magnesium (Mg) uptake in maize seedlings in pot culture was studied. This experiment was performed using natural soil containing a mixture of spores of Glomus spp. Mycorrhizal spores were exposed to four concentrations of K solution, i.e. 0.61 (soil K content), 0.92, and 1.23 meq/L and three concentrations of Mg, i.e. 4.8 (soil Mg content), 7.2, and 9.6 meq/L concurrently. Plants were watered every 4 days for 16 days with 50 mL distilled water. A pot with sterilized soil was used as negative control. For study of mycorrhizal colonization, very thin manually prepared longitudinal sections of plant roots (>1 mm in diameter) were stained with lactophenol-cottonblue and examined microscopically. Percentage of mycorrhizal colonization was determined using the grid-line intersect method. Samples from root and shoot of maize were collected for further analysis. Results showed mycorrhizal plants had significantly higher dry and fresh weight and chlorophyll content than plants grown in sterilized soil (p ≤ 0.05). Treatments with concentrations of 7.2 meq/L of magnesium alone and in combination with 0.92 meq/L of potassium with7.2 meq/L of Mg had better effect on morphological characters (dry and fresh weight of root and shoot). Mycorrhizal colonization increased Mg uptake but decreased K uptake.