Dragon fruit (Hylocereus polyrhizus) is an herbaceous perennial climbing cactus species belonging to the family Cactaceae and commonly known as Pithaya, Strawberry Pear, Night Blooming Cereus, Belle of the night, Jesus in the Cradle and recently named ‘Kamalam’ in India. In July 2022, severe stem rot symptoms were observed on dragon fruit plants grown at the Horticulture (25⁰40’59’’N, 91⁰54’47’’E) and Plant Pathology (25⁰39’45’’N, 91⁰53’37’’E) Experimental Farms of ICAR-Research Complex for North Eastern Hill Region, Umiam, Meghalaya, India. Infected stems showed circular rot, brown sunken lesions, sporodochia with orange masses of conidia, and white mycelium developed in the lesion. The associated fungus (DFSR-1) was isolated on potato dextrose agar (PDA), producing fluffy colony, whitish mycelial growth with irregular margins and a radial growth rate of 0.45 cm/day was observed, with development of a white cream pigmentation on the back side of plate. Pathogenicity test produced an identical symptom with natural infection, henceforth fulfilling Koch’s postulates. Based on morphological characteristics, DNA sequences and phylogenetic analysis of genomic regions for ITS (PX599360), TEF-1(PX990095) and RPB2 (PX990096), the fungal isolate (DFSR-1) was identified as Fusarium longifundum. To the best of our knowledge, this study represents the first documented report of F. longifundum causing stem rot on red flesh dragon fruit in India, thereby broadening the pathogen’s known host spectrum and emphasizing the urgency for effective disease management strategies.

Soil-plant-microbe interaction underpins terrestrial ecosystem functioning and are fundamental to plant nutrition and productivity. Since the origin of life, microorganisms have shaped soil formation, nutrient cycling and plant evolution. Plants require seventeen essentials for growth, although these nutrients exist in soil, their availability and uptake are largely governed by rhizospheric microorganisms. Through the exchange of metabolites and signaling molecules, plants and microbes establish complex interactions. This chapter presents an overview of plant nutrition with a focus on microbial metabolites and signaling pathways that enhance nutrient availability. Primary and secondary metabolites produced by plants and microorganisms’ function not only as metabolic intermediates but also as chemical signal regulating rhizospheric communication. Microbial secondary metabolites are central to plant-microbe recognition and symbiosis. Plant growth-promoting rhizobacteria (PGPR), arbuscular mycorrhizal fungi and rhizobia represent key microbial partners that facilitate N-fixation, P-solubilization, K-mobilization and improved plant resilience. The chapter also highlights the coexistence of multiple microbial species within a single plant system, emphasizing their complementary roles in meeting nutritional demands. Overall, metabolites-driven plant-microbe interactions are vital for sustainable nutrient management, ecosystem stability and ecofriendly agriculture.

Background: The advancement of pulse crops, especially lentil (Lens culinaris Medik.) in acid soils is very challenging due to poor nodulation efficiency and nitrogen fixation. The build-up of Rhizobium population near the germinating seeds (spermosphere) in acid soils with seed inoculation alone is not sufficient, thus limiting its survivability, multiplication and poor Rhizobium-legume interactions. The present investigation aimed at effectiveness of native Rhizobium strain tolerant to acid soil through seed inoculation and through enriched compost fortified with Rhizobium. Methods: For this a field experiment on lentil crop (variety PL-8) was conducted in acid soil with 9 treatments combination: T1: 100% RDF (@20:60:20 kg N-P-K ha-1 ), T2: 50% RDF, T3: seed inoculation (SI) with NR2+EC 1+50% RDF, T4: SI with ER (CK1)+EC 1+50% RDF, T5: SI with NR2+EC 2+50% RDF, T6: SI with ER (CK1)+EC 2+50% RDF, T7: SI with NR2+EC 4+ 50% RDF, T8: SI with ER (CK1)+EC 5+50% RDF, T9: SI with NR2+ EC 3+50% RDF. Result: The nodulation efficiency, pod and seed yield and the soil parameters after the harvest of crop were significantly higher in treatments receiving enriched compost amended with Rhizobium, PSB and RP. Thus, seed inoculation along with enriched compost amended with native Rhizobium, PSB and RP had showed great potential in supporting higher nodulation efficiency and yield of lentil crop grown under acid soil.

Approximately 500 million people around the globe is affected by arsenic (As) contamination of ground water. The regions of India, Bangladesh, Nepal, Vietnam, and China that make up the South and Southeast Asian Belt are the most arsenic-polluted areas. Although the amounts are often lower in contrast to Asian countries, developed countries such as the USA, Mexico, and Canada also face extensive levels of groundwater contamination from As. A worldwide concern is the toxic concentration of As in soil and water and its short- and long-term impacts on human and animal health. In addition to being a health risk to humans and animals when consumed in tainted water, food produced on soil contaminated with As also poses a serious threat to human health. Plants may utilise As in soil in a variety of ways, mostly as arsenate [As(V)] and arsenite [As(III)]. The availability of As in soil depends on a number of soil physiochemical parameters, including pH and water content. Plants use the uptake pathways for phosphate (P) and silicon (Si) since they lack a unique mechanism for the uptake and transport of As. To lessen the harmful effects on plants and human health, it is essential to comprehend the chemistry of As in soil, how it is absorbed, and the physiological and metabolic changes it causes in plants. Effective management of As can be done by various agronomical interventions such as water management, application of inorganic fertilizers containing P, Si and molybdenum (Mo) and soil incorporation of biochar, identification and/or development of varieties which accumulate less As in the consumable part and where ratio of inorganic to organic forms of As is low, growing of As tolerant cultivars, adoption of phytoremediation technique and increased use of different organic manures and green manure crops. Among the various management strategies, application of Si fertilizer proves promising, as it reduces soil available As and further, being a structural analogue of As, limiting the As uptake by the plants thereby improves plant health. In addition to reducing As toxicity through competitive absorption, Si aids in the growth and development of plants under a variety of harsh environmental circumstances. Numerous studies have shown that Si may help plants cope with a variety of biotic and abiotic stressors. Besides sharing similar transporters with As, Si also have positive role on uptake of different macro and micronutrients and improve the physiological parameters of the crop thereby alleviate the negative impacts of As toxicity. According to studies, exogenous application of Si reduces As toxicity by improving secondary root development, imparting mechanical strength, and limiting As uptake through cell wall lignification. This review has emphasized that application of Si stimulated the activity of the enzyme arsenate reductase, improved pigment synthesis, scavenged reactive oxygen species (ROS) through both enzymatic and non-enzymatic routes, and promoted the synthesis of phytochelatins in plants exposed to arsenic toxicity. Moreover, the continuous application of biomass rich in Si has no negative effects on the Si status of soil as well as soil health. Therefore, Si fertilization may be considered as an effective and environmentally responsible way to reduce As toxicity at the field level for improving food safety and human health around the globe.

In recent years, synthetic microbial communities (SMC) have garnered significant attention as a promising approach to harness the collective capabilities of multiple microbial species across diverse applications, including plant disease management. Advances in omics technologies have provided deeper insights into the complex interactions between plant microbiomes and their surrounding environments. Notably, significant progress has been made in the design and engineering of SMC that exhibit synergistic interactions, demonstrating great potential in managing phytopathogens. Novel tools, such as automated design and artificial intelligence, are increasingly being integrated to enhance the precision and efficiency of SMC engineering. Given the complexity of natural and agricultural plant-associated systems, along with the multitude of variables that influence SMC performance, developing a universal rationale for engineering SMC for biocontrol application remains challenging. This review discusses the design perspective of SMC for biocontrol application, their underlying design principles, critical considerations, and current research endeavors. Additionally, it briefly contemplates the challenges and prospects of SMC application in plant disease management.

A field experiment was conducted at the research farm of the College of Agriculture (CAU), Kyrdemkulai, Ri-Bhoi, Meghalaya, during the Kharif season of 2023 to study the “Comparison of Application Methods of Phosphorus and Silicon in Finger Millet (Eleusine coracana).” The experiment was designed in a factorial randomized block design with three replications. Factor-A (phosphorus) consisted of three application methods: broadcasting (BC), band placement (BP), and seedling root dip (SRD). Similarly, Factor-B (silicon) also included three application methods: broadcasting, band placement, and seedling root dip. The results revealed that the different application methods of phosphorus and silicon significantly influenced most of the parameters studied. Yield parameters and soil parameters were all affected. Yield parameters, including biological yield, grain yield, and stover yield, were significantly highest in the A2B2 treatment (phosphorus-band placement and silicon-band placement) at 7632, 2967, and 4665 kg ha-1, respectively, and lowest in A3B1 (phosphorus-seedling root dip and silicon-broadcasting) at 4797, 1789, and 3008 kg ha-1, respectively. Soil parameters such as available nitrogen (N), available phosphorus (P), exchangeable acidity, and exchangeable Al were significantly highest in A3B3 (P-SRD and Si-SRD) at 344 kg ha-1, 25.7 kg ha-1, 1.9 meq 100g-1 soil, and 1.117 meq 100g-1 soil, respectively. Soil available silicon (Si) was significantly highest in A1B2 (P-BC and Si-BP) at 25.63 mg/kg soil. Total phosphorus and silicon nutrient uptake were significantly highest in A2B2 (phosphorus-band placement and silicon-band placement) at 8.14 kg ha-1 and 108.92 kg ha-1, respectively. The results of the experiment indicated that the band placement method for both phosphorus and silicon (P-BP and Si-BP) was superior in terms of yield, while the seedling root dip method (P-SRD and Si-SRD) was more effective for soil fertility in the mid-hills of Meghalaya. This is first time reporting comparison of application methods of phosphorus and silicon in finger millet.

Silicon (Si) affects soil formation, carbon (C) cycling, nutrient dynamics, vegetation growth and plant stress resilience, all of which are critical to the general health and sustainability of forest ecosystems. Despite its abundance and diverse functions, the pivotal role of Si in forest ecology is frequently overlooked. This review aims to clarify the intricate role of Si in forest ecosystems by focusing on soil genesis and properties, vegetation requirements, and biogeochemical cycles. Podzolization and laterization, two distinct pedogenic processes with differing Si chemistries, are strongly influenced by forest vegetation type. Si is the basic building block of sand, silt, and clay, and influences soil properties such as soil erodibility, long-term nutrient availability, and water retention, which are fundamental for sustainable forest management. In addition to providing mechanical support, Si protects several plant species from both biotic and abiotic stresses, thereby enhancing forest longevity and health. Soil-plant Si dynamics influence C sinks by stabilizing phytoliths, accelerating silicate weathering, and prolonging biomass lifespan. The stability of phytoliths and silicate minerals in the soil is governed by interactions among Si pools, fluxes and biogeochemical cycles. Forest vegetation composition, stand maturity, and Si absorption capacity also play significant roles. Therefore, research on Si in forest ecosystems is crucial for ecological science and sustainable forest resource management. This is particularly important in addressing current global environmental challenges, where Si’s influence on soil stability, nutrient cycling, and C sequestration has far-reaching implications.

. KEYWORDS :Arnica montana, Belladonna, compatibility, Thuja occidentalis, Trichoderma reesei

The present study focuses on deciphering the mechanism of action of nano zinc loaded bioactive formulation (En-ZnO-NP-PGPR-BF) against the sheath blight inciting pathogen of rice, Rhizoctonia solani Kuhn. Zinc oxide nanoparticles are promising antimicrobial agents and are safer to use in field conditions as they are GRAS (Generally recognized as safe) materials. In an in vitro study, En-ZnO-NP-PGPR-BF was tested at eight concentrations (1, 5, 10, 20, 50, 100, 150, and 200 ppm) and control was kept for sterile water. The application of En-ZnO-NP-PGPR-BF demonstrated a prominent effect on the pathogen by inducing oxidative stress through the generation of reactive oxygen species (ROS) molecules, as measured by antioxidant enzymatic tests. En-ZnO-NP-PGPR-BF exhibited the best enzymatic activity at 200 ppm on superoxide dismutase (1.61 U/ml), catalase (2.97 U/ml) and malondialdehyde content (55.26 nmol/mg) compared to the control (− 0.12 U/ml, 0.04 U/ml and − 1.65 nmol/mg) respectively. When studying the effect of the optimal concentration of En-ZnO-NP-PGPR-BF on the inoculum of the pathogen, it was found that mycelial growth inhibition at 200 ppm was 98.81

Rice (Oryza sativa L.) is a key food grain crop in acid soil regions of the world. An economical and efficient nutrient application method should be developed for crops in acidic soil region. Use of Si as a source of beneficial nutrient is well known. Therefore, a pot experiment was planned with rice variety CAU-R1 to find out the effective combination of application method and source of Si. Three sources of Si viz. silicic acid (C1), calcium silicate (C2), and sodium meta silicate (C3), and five different application methods: (1) M1, seedling root-dipping (SRD) in soil: water slurry (applied @ 225 mg kg−1 soil as silicic acid, calcium silicate and sodium meta silicate), (2) M2, foliar spray (1

The study aims to evaluate the impact of different inoculum levels of root-knot nematodes (Meloidogyne spp.) on tomato plants under polyhouse conditions in Northeast India. The research provides early predictions of nematode infestation severity and guides farmers on sustainable management practices, including biological control, to keep nematode populations below the economic threshold. Soil samples from key tomato-growing areas in Nongpoh, East Khasi Hills, and West Jaintia Hills districts of Meghalaya were collected, and inoculum levels ranging from 500 to 8000 J2 were tested using completely randomized design. The study found a significant increase in root gall index, egg mass production, and nematode population with higher inoculum levels. Even low inoculum levels (500 J2) caused notable damage to the plants. These findings underscore the importance of managing nematode populations early to reduce crop losses and highlight the need for efficient, low-inoculum control strategies. This study contributes to the sustainable management of nematodes in agricultural practices.

Phosphorus (P) limitation in acidic soils is well known and P-use and -recovery efficiency (PUE and PRE) is quite low. Rhizosphere-based P management has been considered as a means of enhancing PUE in acidic rice soils, but no clear dynamic study on this context. Rice was grown in pots using different P-sources [rock-phosphate (RP), single-super-phosphate (SSP), compost, P solubilizing bacteria (PSB), PSB + RP, PSB + compost, and compost + PSB + RP] in acidic Inceptisols (pH 4.31). Additionally, a micro-plot field experiment validated the results, using control, SSP, RP, PSB, and PSB + RP. Available-P (AvlP) and pH were analyzed every 10-days, while acid-phosphomonoesterases activity (PHA) and P-uptake in every 30-days until harvest. AvlP was peaked at 20 days after transplanting (DAT) and decreased until harvest. Compost + PSB + RP maintained significantly higher AvlP, soil pH and PHA, while root volume was highest in SSP throughout the growing period, and Soil pH showed an asymptotic trend. The P-content and uptake in biomass showed the highest peak at 60DAT and gradually declined until harvest. The effects of SSP and compost + PSB + RP on grain yield, chlorophyll concentration index (CCI), grain P content and uptake were comparable, but PUE and PRE were higher in compost + PSB + RP. Similar result was also observed in micro-plot field experiment, wherein grain yield and P uptake were comparable in SSP broadcast and PSB + RP. The study clearly shows that the combined application of PSB with RP, compost, or both in a 50% reduced amount can maintain higher AvlP in rice in acidic soil compared to full dose SSP while achieving a comparable yield.

Accurate and timely mapping of rice areas is crucial for effective agricultural planning and food security management in the North Eastern Hill Region of India, especially amid changing climate conditions. This study developed a method to estimate rice transplanting dates by utilizing VH polarized backscattering-coefficients rom Sentinel-1A SAR data and also assessed thermal requirements for rice productivity in Ri-Bhoi district, Meghalaya during kharif 2021. The methodology involved 3 steps- (i) preprocessing data to construct time-series SAR images (ii) rule-based classification of SAR data integrating phenological and topographical information to identify transplanting windows (iii) assessing mapping accuracy. The results when compared with field data, revealed five distinct transplanting windows from early June to early August across 9031 ha of rice area. Overall accuracy was 85%, with a kappa coefficient of 0.74. User and producer accuracies ranged from 0.74 to 0.93 and 0.75 to 0.92, respectively for various transplanting windows. GDD varied between 1432.8 degrees C day and 3290.4 degrees C day, with higher values corresponding to earlier planting dates. This study formulates a robust methodology for rice mapping in hilly, small-field landscapes with multiple transplanting dates by integrating Sentinel-1A SAR data with ancillary and crop phenology information, contributing to improved crop management and climate change adaptations.

Yield potential of maize having distinct genetic diversity in Eastern Himalayan Region (EHR) hill ecologies is often limited by Al toxicity caused due to soil acidity. Stress physiological analysis of local check exposed to 0-300 mu M Al under sand culture revealed that 150 mu M Al as critical and 200 mu M Al as tolerable limit. Increase in Al from 0 to 300 mu M reduced total chlorophyll, carotenoids by 74.8 % and 44.7 % respectively and enhanced anthocyanin by 35.3 % whereas LA, SLW and SL have reduced by 81.3%, 21.3 % and 47.8 % respectively. R/S ratio was 51.0 and 13.7 % higher at lower Al levels (50 mu M and 100 mu M) and photosynthetic, transpiration rate and TDM were 62.5 %, 42.9 % and 78.6 % lower at higher Al (300 mu M) as compared to control. TRL, RSA, RDW and RV at higher Al (300 mu M) were 92.6 %, 98.7 %, 78.7 and 97.5 % lower over control respectively. Root and shoot Al and PUpE at higher Al (300 mu M) was 194.0, 69.2 and 830 % higher whereas PUE decreased to 88.5 % over control. Evaluation of 31 indigenous maize cultivars at 0, 150, and 250 mu M Al in sand culture, alongside tolerance scoring and assessment, revealed that Megha-9, Megha-10, and MZM-19 exhibits high Al tolerance, Megha-1, MZM-22, and MZM-42 demonstrated moderate tolerance, whereas Uruapara, Sublgarh, and BRL Para were identified as Al-sensitive. Stress physiological parameters like SDW, TDM, TRL, SL and LA contributed 46.02 % of variability to PC1, whereas A, RV, RSA, anthocyanin and Chlorophyll_b, contributed 13.56 % of variability to PC2. Highest values of CMS, SL, LP, LA, TRL and anthocyanin were recorded in cluster I having sensitive cultivars while highest CMS, SL, LA, LP, TRL and RSA were found in cluster II having moderately tolerant cultivars and highest mean values for TRL, RSA, LP, LA, CMS and SL were recorded in cluster III having highly Al stress tolerant cultivars. The traits viz., A, RV, RSA, anthocyanin and Chlorophyll_b, total chlorophyll and TDM were emanated as physio-morphological for assessing Al toxicity stress tolerance in Maize with high divergence values. Tolerant cultivars showing 63.4 % and 22.4 % higher anthocyanin at 150 mu M Al and 250 mu M Al than moderately tolerant one in acid soil experiment with increased root Al, shoot Al, root P and shoot P by 42.6 %, 11 %, 95.1 % and 34 % respectively were emerged as promising for novel maize improvement under acid soils of EHR.

Rhizospheric based phosphorus (P) fertilizer management is necessary for crop production due to environmental concerns caused by the overuse of the broadcasting method and limited P reserves. This study proposes a comparison of P management that enhances P nutrition in Chilli (variety: Arka Khyati) through seedling root-dipping (SRD) in P-enriched slurry (SSP-amended; pH of 8.1), micro-dose placement (MDP; drill and place closer to plant root), and full dose (187.6 mg kg-1) placement by broadcasting (FD). In SRD, seedlings were dipped in five different P concentrations (50, 100, 200, 300, and 400 mg P2O5 kg-1) for varying durations (0, ½, 1, 2, 3, and 4 hours) and transplanted into pots (dipping in 0 mg P2O5 kg-1 consider as control), along with the MDP and FD treatments (total 33 treatments with 5 replications). [Seedlings dipped in 200, 300, and 400 mg P2O5 kg-1 died within a week after transplanting, thus were excluded from further analysis]. The amount of P received in MDP and FD were 21-90 times higher than P adhesion to seedling roots in SRD treatments. Root volume was in order SRD>MDP>FD. Seedlings dipped in 100 mg P2O5 kg-1 for 2 hours in SRD exhibited the highest biomass production, P-use and -recovery efficiency; and showed an increase of 52%, 178%, and 293% in FD, MDP, and SRD compared to the control respectively. It is recommended to use the SRD method with other P sources in reduced amount to maintain the native P pool in soil, and further multilocational trials are needed to validate.

Khasi mandarin (Citrus reticulata Blanco) is the most economically important crop among the citrus growing region in the north-eastern India (Singh et al. 2016). An extensive survey was conducted to identify the causal agent of citrus root rot and gummosis in north eastern states (Meghalaya, Tripura, Manipur, Arunachal Pradesh, Sikkim, Nagaland and Assam) of India during October 2021-23. The gummosis disease incidence ranged from 5 to 95 % in 10 to 25 years old Khasi mandarin plants showing relatively more chronic symptoms on mature trees. Yellowing and dropping of leaves, twigs die back, gum oozing from infected bark and loss of feeder roots were the typical symptoms of the disease. Infected bark tissue and young lemon leaf baits in rhizosphere soil were plated on corn meal agar medium supplemented with pimaricin (10 µg/ml), ampicillin (250 µg/ml), rifamycin (10 µg/ml) and 300µg/ml carbendazim and incubated at 26℃. Fifty isolates were purified and maintained on Carrot agar medium. These isolates showed similar cultural and morphological characteristics. Two representative isolates from Arunachal Pradesh (AP21 and AP26) were selected for further experiments and deposited to Indian Type culture collection (ITCC), New Delhi with accession no. 9156 and 9157 respectively. The colonies were fast growing, showing rosette pattern along with whitish blooming mycelium appearance with no visual sporulation at the surface. The hyphae were coenocytic with initially right-angled branching. Sporangia were globose or sub globose and papillated. Oogonia were smooth and globose (16.29-21.09 µm) in diameter. Antheridia were irregular, cylindrical and broadly attached to oogonia. Empty sporangia were also observed. Multilocus phylogenetic analysis using internal transcribed spacer region (Das et al. 2011), β tubulin (Blair et al. 2008) and Cytochrome oxidase II gene (Noireung et al. 2020) showed that these isolates formed a stable clade with Phytopythium vexans (CBS119.80) sequence retrieved from NCBI database. BLAST analysis showed that ITS sequence of AP21 (OQ372986) and AP26 (OQ381083) had >99 % identity with P. vexans isolate NS-3 (ON533631). Further, BLAST analysis of β tubulin (AP21 OQ446053, AP26 OR405377) and Cox II gene (AP21 OQ473414, AP26 OR552422) sequences showed that our Indian isolates showed >99 % similarity with P. vexans voucher strain CBS119.80. To fulfil Koch's postulates, Khasi mandarin (Citrus reticulata) seedlings were inoculated by adding 100 ml zoospore suspension of P. vexans (1x105 spores/ml) in sterilized soil (Thao et al. 2020). The experiment was carried out in triplicate. Yellowing of leaves and leaf drop were observed 7 days post inoculation while 30 days post inoculation, treated plants started showing symptoms of root rot, including mild root decay. No symptoms were observed in control treatment. The pathogen was reisolated from symptomatic roots and confirmed through colony and sporangium morphology. Recently, it was reported that P. vexans is associated with apple and pear decline in the Saiss plain of Morocco (Jabiri et al. 2021), root rot on mandarin in Thailand (Noireung et al. 2020) and on Durian in Vietnam (Thao et al. 2020). As per our knowledge, this is the first report of P. vexans causing root rot and gummosis in Khasi mandarin from north eastern states of India. This finding is significantly important for the development of a successful disease management strategy in India.

Despite Northeastern India being “Treasure House of Citrus Genetic Wealth,” genetic erosion of citrus diversity poses severe concern with a corresponding loss in seed microbial diversity. The seed microbiome of citrus species unique to the Purvanchal Himalaya is seldom explored for their use in sustainable orchard management. Isolation and characterization of culturable seed microbiomes of eight citrus species, namely, Citrus reticulata Blanco, C. grandis (L.) Osbeck, C. latipes Tanaka, C. megaloxycarpa Lushaigton, C. jambhiri Lush, C. sinensis (L.) Osbeck, C. macroptera Montr, and C. indica Tanaka collected from NE India were carried out. The isolates were then screened for an array of plant growth–promoting (PGP) traits [indole acetic acid (IAA) production, N2 fixation, phosphate and zinc complex dissolution, siderophores, and Hydrogen Cyanide (HCN) production]. The pure culture isolates of seed microbiomes were capable of dissolving insoluble Ca3(PO4)2 (1.31–4.84 µg Pi ml-1 h-1), Zn3(PO4)2 (2.44–3.16 µg Pi ml-1 h-1), AlPO4 (1.74–3.61 µg Pi ml-1 h-1), and FePO4 (1.54–4.61µg Pi ml-1 h-1), mineralized phytate (12.17–18.00 µg Pi ml-1 h-1) and produced IAA-like substances (4.8–187.29 µg ml-1 h-1). A few isolates of the seed microbiome were also able to fix nitrogen, secrete siderophore-like compounds and HCN, and dissolve ZnSO4 and ZnO. The 16S ribosomal Ribonucleic Acid (rRNA)–based taxonomic findings revealed that Bacillus was the most dominant genus among the isolates across citrus species. Isolates CG2-1, CME6-1, CME6-4, CME6-5, CME6-9, CJ7-1, CMA10-1, CI11-3, and CI11-4 were identified as promising bioinoculants for development of microbial consortium having multifaceted PGP traits for nutritional benefits of nitrogen, phosphorus and zinc, and IAA hormonal benefits to citrus crops for better fitness in acid soils.

“Huanglongbing” (HLB) or citrus greening is the most devastating diseases of citrus that affects all cultivars causing systematic death of trees worldwide. The disease is associated with the presence of the phloem-limited α-proteobacteria ‘Candidatus Liberibacter asiaticus’, ‘africanus’, and ‘americanus’. The Asian Citrus Psyllid (ACP), is the main vector that transmits the pathogen while feeding the leaves of citrus trees, affecting fruit traits including fruit shape and size, ripening, and quality of fruits and compromising plant health, eventually leading to economic loss to the citrus industry. In this review, the history of HLB, its pathosystem, and geographical distribution with a primary focus on the various diagnostic measures that are in practice are described. The HLB identification in the field is the most challenging task for the growers as the symptoms of asymmetrical, blotchy mottling patterns on leaves are often confused with nutritional deficiency. The unavailability of precise methods for identification of HLB at the initial infection is of major concern. Hence, the development of field-based detection methods could help citrus growers to take protective measures to minimize disease spread in citrus plantations. The review also highlights the existing detection and management options of HLB as well as the perspectives in this research field.

The combined effect of land use change, long‐term soil management, and orchard age (18–40 years) on soil quality of guava ( Psidium guajava L. cv. Allahabad Safeda) and sapota ( Manilkara achras Mill. cv. Cricket Ball) orchards was investigated. Besides, the soil quality of the orchards was compared against an adjacent forest soil (AFS, considered a baseline ecosystem). Values of pH, SOC, porosity, PHA, DHA, GSA, ExCa, ExMg, and DTPA‐Cu were significantly lower in drip circle soils relative to inter‐row space soils. The extent of reduction was prominent in older orchards. There was a significant building up of BD, AvP, AvK, DTPA‐Fe, and DTPA‐Zn in drip circle soils relative to inter‐row space soils. The soil variability between drip circles and inter‐row spaces across the soil depths was significant ( p < 0.01). Principal component analysis (PCA) plots were generated to determine the variability of soil quality among orchards and AFS. Long‐term soil management (18–40 years) induced soil spatial variability within the orchards. Analysis of similarity showed a significant difference in variability of soil quality within an orchard, among the orchard types, and between the orchards and the AFS. Except for soil AvK, all soil quality attributes maintained a significant correlation with the PC‐axis‐1 ( p < 0.05 and 0.01) that explained maximum variability (40.2%–49.4%). The DHA and SOC contributed the maximum variability ( r = 0.95 and 0.92, respectively with PC axis‐1). In conclusion, the stronger factor of the variability of soil quality was in the order of land use change > soil management > orchard age.