Okra Roots Research Articles

Reação de genótipos de batata ao nematoide das galhas Meloidogyne spp. em um campo naturalmente infestado

ABSTRACT The objective of this work was to verify the reaction of potato clones and cultivars to root-knot nematodes in a field area naturally infested by the root-knot nematodes Meloidogyne incognita and M. ethiopica. Fifteen clones and five potato cultivars were evaluated, in addition to plots with okra and tomato susceptible species, in a field naturally infested with a Meloidogyne incognita and M. ethiopica population mixture, in an experimental field of Embrapa Hortaliças located in the Federal District, Brazil. The experiment was carried out from April to August 2022, in a randomized complete block design with four replications of five plants per plot. At the planting time, as well as when harvesting the genotypes, soil was collected to determine the initial and final nematode populations. When the plants were harvested, the total number of juveniles extracted from plant tissues (potato tubers and okra roots and tomato) was determined, as well as the calculation of the reproduction factor (RF), and the evaluation of tuber yield of the potato genotypes. Data were submitted to analysis of variance and grouping of means by the Scott-Knott test. The clones C2743-09-09, CH41, F119-12-01, F129-12-08, F63-10-13A, F65-13-06, F88-11-01 and OD38-06, and the cultivars Markies, Agata and Asterix were the least susceptible genotypes to field mix of the root-knot nematodes M. incognita and M. ethiopica. But combining a lower degree of susceptibility and good tuber productivity, clones MB54-02, F53-11-05, F63-10-13A, F65-13-06, OD38-06 stood out. The commercial cultivars Atlantic and Epagri Catucha presented greater multiplication of nematodes in the field than the other evaluated cultivars.

DNA content, ploidy level determination and genetic variations of okra (Abelmoschus esculentus L.) genotypes

Okra (Abelmoschus esculentus L.) is a minor small crop in Jordan; it has attracted a lot of attention as a substitute for conventionalvegetables throughout the world. There are conflicting reports about chromosome numbers in this species. To determine the ploidylevel of different okra genotypes, okra root tips were treated with HCl maceration, enzymatic maceration, and Carmine acid squashing.Treating cells with HCl didn’t macerate the cell in a way that enables chromosome count. The enzymatic treatment combinationshowed no significant effect on cell maceration. Carmine’s acetic acid squashing method was able to digest the cells but in a way thatall chromosomes from neighboring cells gathered, making it difficult to count them from each cell. Flow cytometry as an alternativeway to assess okra ploidy, was considered as an option. The genome size of okra ranged from 4.11 pg 2C in genotype 43 to 6.27 pg 2Cin genotype 30.

The Efficiency of some Control Agents in Resisting the Okra Root Rot Disease Caused by the Fungus Pythium aphanidermatum

This study was conducted in the laboratory and plastic house belonging to the Department of plant protection – faculty of Agriculture - Anbar University to evaluate the efficiency of the biological control agent Trichoderma harzianum and the chemical inducing agents sodium bicarbonate NaHCO3 and melatonin C13H16N2O2 in inducing resistance in seeds and seedlings of okra to infection with the disease of seed rot and the fall of seedlings caused by the semi-pathogenic fungus Pythium aphanidermatum double transplantation of some isolates of the-biotic fungus T. harzianum that isolation T2 (centre of Organic Agriculture-Ministry of Agriculture-Iraq) achieved the highest ability in inhibiting the growth of pathogenic semi-fungus, reaching a degree of contrast of 1, while the result of measuring the effectiveness of volatile substances on the PDA medium of the same isolates showed that isolation T2 (center of Organic Agriculture-Ministry of Agriculture-Iraq) gave the highest percentage of inhibition against pathogenic semi-fungus P. aphanidermatum reached 36.4% and the test of the effectiveness of the inducing agents in protecting the seeds of okra, Petra on the medium of PDA showed the effectiveness of the inducing agents sodium bicarbonate and melatonin in protecting the seeds, as the germination rate reached 100% for both, while the bio-fungi isolates achieved isolation T2 (Organic Agriculture Center-Ministry of Agriculture-Iraq) the best germination rate reached 100% and the results of the plastic house experiment showed that the treatment with bio-fungi by soaking for 20 minutes gave high efficiency in the percentage of germination reached 83.33% and reduced the percentage and severity of infection to 23.67% and 18.33% respectively, as for the soaking treatment with melatonin 200 micromuller, the percentage of germination decreased to 63.67% or the percentage and severity The infection rate reached 43.33% and 37% sequentially, as for the spraying treatment with biological agent isolation T2 (Organic Agriculture Centre-Ministry of Agriculture-Iraq) after 15 days of germination reduced the percentage and severity of infection to 32.67% and 25% sequentially and the spraying treatment with melatonin after 15 days of germination achieved the percentage and severity of infection reached 49% and 39.33% sequentially, as for the spraying treatment with biological agent isolation T2 (Organic Agriculture Center-Ministry of Agriculture-Iraq) after 25 days of germination, it gave the highest efficiency in reducing the percentage and severity of infection 35.67% and 29.67% sequentially, while the percentage and severity of infection in the melatonin spraying treatment after 25 days of germination reached 51.33% and 43.67% sequentially compared to the comparison treatment Contaminated with semi-pathogenic fungus Pythium aphanidermatum .

Identification of Some Fungi Causing Okra Root Rot Disease from Different Regions of Anbar and Waist and Testing Pathogenicity

The study was conducted in the Department of Plant Protection - College of Agriculture - University of Anbar for the year 2022, as the results of collecting samples from the regions of Anbar and Waist governorates showed the spread of okra root rot disease in most of the study areas, and the results of phenotypic and molecular diagnosis showed the presence of the fungal species Pythium Aphanidermatum, Fusarium proliferatum, Epicoccum nigrum, Itersonilia perplexans, Fusarium chlamydosporum, Rhizoctonia solani, which were deposited in the International Genbank OQ572440, OQ540926, OQ566939, OQ540927, OQ540928, OQ540929 (NCBI) seeds, respectively. Okra, as the tested isolates achieved a significant decrease in the germination of okra seeds on the culture medium (W.A. Water agar) compared with the control treatment that was not contaminated with any of the tested isolates, in which the infection rate was 0.0%.

Effect of Metarhizium anisopliae (MetA1) on growth enhancement and antioxidative defense mechanism against Rhizoctonia root rot in okra

Rhizoctonia solani is an important necrotrophic pathogenic fungus that causes okra root disease and results in severe yield reduction. Many biocontrol agents are being studied with the intent of improving plant growth and defense systems and reducing crop loss by preventing fungal infections. Recently, a member of the Hypocrealean family, Metarhizium anisopliae, has been reported for insect pathogenicity, endophytism, plant growth promotion, and antifungal potentialities. This research investigated the role of M. anisopliae (MetA1) in growth promotion and root disease suppression in okra. The antagonism against R. solani and the plant growth promotion traits of MetA1 were tested in vitro. The effects of endophytic MetA1 on promoting plant growth and disease suppression were assessed in planta. Dual culture and cell-free culture filtrate assays showed antagonistic activity against R. solani by MetA1. Some plant growth promotion traits, such as phosphate solubilization and catalase activity were also exhibited by MetA1. Seed primed with MetA1 increased the shoot, root, leaves, chlorophyll content, and biomass content compared to control okra plants. The plants challenged with R. solani showed the highest hydrogen peroxide (H2O2) and lipid peroxidation (MDA) contents in the leaves of okra. Whereas MetA1 applied plants showed a reduction of H2O2 and MDA by 5.21 and 14.96%, respectively, under pathogen-inoculated conditions by increasing antioxidant enzyme activities, including catalase (CAT), peroxidase (POD), glutathione S-transferase (GST), and ascorbate peroxidase (APX), by 30.11, 10.19, 5.62, and 5.06%, respectively. Moreover, MetA1 increased soluble sugars, carbohydrates, proline, and secondary metabolites, viz., phenol and flavonoid contents in okra resulting in a better osmotic adjustment of diseases infecting plants. MetA1 reduced disease incidence by 58.33% at 15 DAI compared to the R. solani inoculated plant. The results revealed that MetA1 improved plant growth, elevated the plant defense system, and suppressed root diseases caused by R. solani. Thus, MetA1 was found to be an effective candidate for the biological control program.

Biocontrol agent of root-knot nematode Meloidogynejavanica and root-rot fungi, Fusariumsolani in okra morphological, anatomical characteristics and productivity under greenhouse conditions

This study was conducted to evaluate the ability of some fungal culture filtrate, as biocontrol agents against okra wilt caused by Fusariumsolani. and Meloidogynejavanica. In the present study, fungal culture filtrates (FCFs) of Aspergillusterreus (1), Aspergillusterreus (2), Penicilliumchrysogenum, and Trichoderma spp. were tested against M.javanica in vitro. The effects of P.chrysogenum and Trichoderma spp. (FCFs) in controlling root-rot fungi and root-knot nematode disease complex on okra plants were studied under greenhouse conditions (In vivo). In vitro experiment, the results revealed cumulative rate of J2s mortality of M.javanica reached to 97.67 and 95% by P.chrysogenum and Trichoderma spp., respectively, after 72 h. incubation. Additionally, Trichoderma spp exhibited the most effective inhibitory activity against the pathogen's radial growth, with a percentage of 68%. P.chrysogenum ranked second with 53.88%, while A.terreus (2) demonstrated the weakest inhibitory effect of 24.11%. T6 [Nematode infection (M.javanica) + Fungus infection (F.solani) + Overflowed with fungal culture filtrate (P.chrysogenum)] and T8 [Nematode infection (M.javanica) + Fungus infection (F.solani) + spray with fungal culture filtrate (P.chrysogenum)] had the greatest effects on nematode galling indices on okra roots and substantially reduced the reproductive factors in the greenhouse (In vivo experiment). T6 was the best treatment to decrease disease severity, as reached (28%) relatively. On the other hand, T12 [(Fungus infection (F.solani) + (Dovex 50% fungicide with irrigation water)] recorded the lowest disease severity reaching (8%) relatively. The results showed that nematode infection or fungus infection or both decreased all studied anatomical characteristics of okra root, stem, and leaves. We concluded from this study that root-knot nematode and root-rot fungi were reduced by using fungal culture filtrates and could improve plant growth.

Exploring the Plant Nematode Interaction of Meloidogyne Incognita under Okra Ecosystem

Southern root knot nematode, Meloidogyne incognita is an important nematode genus infesting okra growing tracts of Tamil Nadu. The present study was carried out to understand the cytological changes that occur during Meloidogyne incognita interaction with okra roots by employing Scanning Electron Microscope (SEM). The results exhibited the explicit changes in cellular structures of healthy and nematode-infested roots. The healthy roots possessed normal cell size for metaxylem, protoxylem, pith and cortex region nevertheless nematode infested roots revealed coalesced cellular structures. Root cell wall thickening, cell wall ingrowth, and starch granule accumulates of varying diameter were also observed in M. incognita infested okra roots, which were found to be the factors responsible for producing above ground symptoms during host-nematode interaction. Longitudinal imaging of nematode infested roots showed the nematode entry points of varying diameter along with adhered juveniles Juveniles on root topography and this was in contrast in M. incognita infested okra roots. Comparatively, these structures were absent in healthy roots.

“Pseudomonas fluorescens” as an Antagonist to Control Okra Root Rotting Fungi Disease in Plants

The common bacteria found in fruit and vegetables are Pseudomonas fluorescens which is Germ-negative and is rod-shaped. Pseudomonas fluorescens has been originated from the rhizosphere of Roorkee-grown okra. The presented work involves recognizing and controlling the isolates of Pseudomonas fluorescens. The scope of the proposed work is that the technique used here is a unique strategy to plant protection and control of rotting fungus diseases based on the recognition and management of Pseudomonas fluorescens isolates. Antagonist effect occurs commonly in vegetable and fruit plants. The main goal of this study is to isolate, identify, and evaluate the development of these bacteria which effects on plant growth. In this research work, five isolates have been chosen for further research based on their morphological, biochemical, and physiological characteristics. All five isolates have been identified as Pseudomonas fluorescens from Bergey’s Manual for the determination of bacteriology. Catalase, urease, amylase, and citrate utilization test were all positive in all of the isolates. PFTT4 was identified to be a likely strain for all plant growth promoting exercises such as age of IAA, HCN, ammonia, and phosphate solubilization subsequent to being assessed for their plant development advancing properties. Further, in vitro exploring uncovered that PFTT4 diminished the development of phytopathogens such as Fusarium solani and extraordinarily further developed seed germination just as all development boundaries like shoot and root length. Furthermore, Pseudomonas sp. PFTT4’s plant growth promoting and antifungal activities put forward to it could be there used because of bioinoculant agents for Abelmoschus esculentus.

A Root Density Tradeoff in an Okra-Assisted Subsurface Pipe Drainage System for Amelioration of Saline Soil

Subsurface pipe drainage technology can effectively improve coastal saline land in Northern China. We explored an okra (Abelmoschus esculentus L.)-assisted subsurface pipe drainage system to improve the water and salt discharge performance and benefits. In this study, the simulation box experiment was conducted to research the response of water and salt discharge performance in subsurface pipe drainage to okra root weight density (RWD). The drain outflow, soil salinity, and sodium adsorption ratio were determined. The results showed that okra RWD affected the vertical distribution of okra roots. Okra with an appropriate RWD (about 116 μg·cm−3) could significantly increase the cumulative drain outflow. Okra with an appropriate RWD (about 136 μg·cm−3) could significantly increase the desalting effect. Moreover, the RWD of okra also influenced the ability of subsurface pipe drainage to inhibit soil alkalization. The above results show that planting okra and installing subsurface pipe drainage to control drainage at the coastal saline land in Northern China can effectively improve the water and salt drainage effect when okra RWD is about 116–136 μg·cm−3. When using subsurface pipe drainage to improve coastal saline soils, planting okra with proper density may be an appropriate choice to improve the effect and benefit.

Plant Growth Promoting Activities of Spore-Forming and Vegetative Cells of Salt-Tolerant Rhizobacteria under Salinity Condition

Plant growth promoting rhizobacteria are able to enhance plant growth. This study isolated spore-forming rhizobacteria from vegetable rhizosphere soil samples. These isolates were tested for their abilities to promote plant growth and to be used in bio-fertilizers. Thirty-nine isolates with different characteristics were obtained. Three isolates, TYS1.1, TYS3.3, and TYS3.5, showed multifunctional activities on nitrogen fixation and potassium solubilization. They were tested for IAA production in liquid medium supplemented with tryptophan and NaCl, with the vegetative cells of isolate TYS3.5 showing the highest IAA production. The colonization of the three isolates on okra roots was checked by spread plate technique and scanning electron microscope. It was found that rhizobacteria could colonize plant roots with a concentration of 8.19 log CFU/g in the presence of 50 mM NaCl solution. Bio-fertilizer was produced by immobilizing the mixture of three isolates on carriers. The viable cells were enumerated during the storage at room temperature for 60 days. The results showed that the highest number of survival cells in the form of vegetative and spore-forming cells were obtained when using rice husk ash and vermiculite as a carrier. The concentration of viable cells was in a range of 8.14-8.44 log CFU/g. These isolates were Bacillus sp. according to the 16S rDNA sequencing analysis.

Economic okra plant act as a preventive-COVID-19 vaccine advanced horticulture agriculture environment biodiversity conservation science technology communication applications issues

The most ‘Economically-Important Number-One Consumption-Vegetable-Crops,’ is lost by different pathogens like nematodes, causing the root-knot disease which is definitely controlled by different chemical-pesticides, and on the opposite hand, the pandemic coronavirus 2 (SARS-CoV-2) outbreaks of Coronavirus disease 2019 (COVID-19) have emphasized the vulnerability of human populations to novel viral pressures, causing an emergent global pandemic and badly impacts on horticulture-agriculture-environment health socio-economy medical-pharmaceutical science-technology communication issues. So it's an urgent have to develop potential epidemiological and biomedical preventing COVID-19 vaccines. And India emphasis on okra, the ‘Nature's-Gift to Human-Disease-Free-Healthy-Life’, and therefore the ultra-high-diluted biomedicines prepared from okra root, applied and confirmed by foliar spray@ 20 ml/plant each group respectively, are highly effective against the root-knot disease of okra, with increasing fresh-plant growth and fruit production. The high-diluted-biomedicines of okra, are simpler than the untreated ones and show the foremost potential confirmed end in all respects. The genetic-effects of ultra-high-diluted-biomedicines thought to induce systemic acquired resistance response of the treated plants through the expression of pathogenesis-related -proteins-genes (22 to 4 numbers), which are more or less similar molecular range (295kD to 11kD) of the many coronaviruses, and it'll to blame for preventing root-knot and COVID-19 like variant-virus diseases by inducing defense-resistance or increasing innate-immunity, with the toxic-free world, and it should help to develop best potential new preventive treatments methods or drug or vaccines, within the field of ‘21st Century COVID-19 sort of a pandemic within the new normal situation in future, and confirms the “Economic okra Act as a Preventive-COVID-19 Vaccine Advanced Horticulture Agriculture Environment Biodiversity Conservation Science Technology-Communication Applications”, and whole plant act as ‘Nature's-Gift Preventive-COVID-19 Vaccine for All’.

Anatomical and morphological traits of the okra root system and the growing practice in plastic-covered greenhouses

The article presents studies of the anatomical and morphological traits of the okra root system and elements of the okra growing practice in plastic-covered greenhouses. The studies were carried out in 2018–2020 on the territory of the Educational and Scientific Production Center “Vegetable Experimental Station named after V. I. Edelstein”, Federal State Budgetary Educational Institution of Higher Education Russian State Agrarian University – Moscow Timiryazev Agricultural Academy. The two ways of formation were studied (1 and 2 stems). As a result of the research, the anatomical and morphological traits of the okra root system were clarified, the highest yield of okra fruits of the Lady’s Finger variety was established when plants were formed in two shoots. To obtain the highest yield of fruits, we recommend growing the Lady’s Finger variety, forming plants in 2 shoots, while the yield is 1.6 kg/m2, which is 0.2 kg/m2 higher than the yield of this variety obtained when plants were formed in 1 shoot.

The effectiveness of the Fungus Beauveria bassiana in reducing the infection of okra plant Abelmosechus eseulentus with fungal root diseases.

This study was conducted in the laboratories of the College of Agriculture - University of Basra in the years 2020 and 2021, in which the fungus B.bassiana was used. To combat the root fungus that infects okra, the results showed the isolation of many pathogenic fungi, and these fungi showed a significant difference in the effect on seed germination and seedling fall. The entomopathogenic fungus B.bassiana has a high ability to colonize roots and promote plant growth, such as plant height, fresh weight, and plant dry weight. The results of field surveys of four areas in Basra governorate showed, namely Shatt Al-Arab, Abu Al-Khasib, Al-Qurnah and Al-Madina. The highest incidence and severity of okra root rot disease was in Al-Madinah region, where the infection rate was 37% and the infection intensity was 67.33%, followed by Abu Al-Khasib district, where the infection rate was 24% and the infection severity was 52.89%. This disease is caused by the fungi Rhizoctonia solani, Fusarium solani and Macrophomina phaseolina. Pathogenicity test results showed that F. solani gave the highest mortality rate for seedlings, followed by R. solani and M.phaseolina efficiently inhibiting the growth of pathogenic fungi. In the greenhouse experiment test, the experiment showed that the highest length of the vegetative group was in the biological treatment of fungi,Corresponding author: E-mail (abdu1988875@yahoo.com) Al-Muthanna University All rights reserved

​Okra Plant: A Multi-purpose Underutilized Vegetable Crop: A Review

The plant kingdom has various species that are underutilised. Proper scientific approached help them to utilised for multiple end applications. Okra is one of such underutilized multi-purpose vegetable crop. Green immature okra fruits are consumed as a vegetable worldwide. Okra seed is a good source of oil and protein. Okra seeds are also used as a substitute for coffee. Okra roots are used for clarification of sugarcane juice. It has medicinal value as well as useful in wastewater treatment. Okra is also a potential source of natural fibers suitable for textile, paper and other engineering applications. The present paper reviewed the okra plant, its cultivation and applications in various form such as food, medicine, textile fiber, paper pulp, biomass, etc. for its introduction as a multi-purpose vegetable crop.

Quantitative Characteristics of the Okra [Abelmoschus esculentus (L.) Moench] Root System Under Water Constraints

The depth and density of roots play a determining role in the maintenance of the water supply of the plant in a condition of water deficit in the soil. Under water deficit conditions, a root system developing deep in the soil is the most desired character. This study aims to determine adaptive performance of the okra root system under water stress. Thus, the effects of water deficit induced by restriction of soil field capacity (SFC) to 60%, 40% and 20% were studied in two varieties of okra (V1 and V2) and compared to a control water regime ( 100% SFC irrigation). Results showed that the number of primary roots, the root volume, the root dry matter, the length of the main root and the root fineness varied according to varieties, water regimes and their interaction. However, varietal differences were observed for the characters length of the main root and root fineness. In addition, a significant difference and very highly significant were respectively observed for the interaction * variety hydric regime on the number of primary roots(p = 0.016) and the length of the main root (p ≤ 0.001). Under water regimes at 60% SFC, 40% SFC or 20% SFC, there is an increase in length of the main root of the varietyV2; but for the variety V1, the increase was noted in the plants irrigated at 40% SFC. On the other hand, in both varieties, root fineness increased under all restrictive water regimes.

Effect of root density of wheat and okra on hydraulic properties of an unsaturated compacted loam

Root‐induced changes of soil hydraulic properties, that is soil water retention curve (SWRC) and unsaturated hydraulic conductivity (K(ψ)), depend on plant species and root density. This study aimed to investigate the effects of wheat roots and okra roots on both SWRC andK(ψ) of soil within an extended range of matric potential (−300 ~ 0 kPa) and to investigate the effects of root density of wheat (i.e. grass species) and okra (i.e. shrub species) on SWRC andK(ψ) of a loamy soil. The SWRC andK(ψ) of soil planted with wheat and okra were measured by the simplified evaporation method. Soil matric potential was measured directly by high‐capacity tensiometers. Different root densities were obtained by establishing different seeding densities in the soil. Meanwhile, root characteristics in planted soil were obtained using image analysis. The results showed that wheat‐ and okra‐planted soil had significantly larger volumetric water content (VWC) within the range of matric potential from −90 to 0 kPa than that of unplanted soil. Within the range of matric potential from around −300 to −90 kPa, the effects of wheat and okra roots on SWRC were not significant. The effects of wheat and okra roots onK(ψ) were not significant within the range of matric potential from around −300 to −10 kPa. Wheat‐planted soil with a root length density (RLD) of 10.04 cm cm−3had larger values of VWC (ψ = 0, −33, −50 kPa) than those of wheat‐planted soil with RLD of 2.69 cm cm−3. The difference in hydraulic properties between okra‐planted soil and the two RLDs, 0.89 and 2.96 cm cm−3, was not significant. Okra roots were more effective in increasing saturated water content (θs) and field capacity (θfc) than wheat roots. This might be because okra roots are relatively coarser than wheat roots.HighlightsEffect of root density of wheat and okra on SWRC andK(ψ) was investigated.TheK(ψ) of soil planted with wheat and okra was measured at matric potentials less than −100 kPa.Okra roots were more effective in increasingθsandθfcthan wheat roots.Effect of wheat and okra roots onK(ψ) was not significant at matric potentials from −300 to −10 kPa.

Microscopic, elemental and molecular spectroscopic investigations of root-knot nematode infested okra plant roots

Okra (Abelmoschus esculentus (L.) Moenche) is one of the warm season crops that is grown in the tropical and subtropical regions of the world. Root-knot nematodes, Meloidogyne spp. is major constraints in growing okra crops and reduce the crop yield. The present study was aimed to perform microscopic, elemental and molecular spectroscopic investigations of root-knot nematode infested okra plant roots. The healthy, root-knot infested and root-knot infested with fungus okra roots have been studied to study the changes in chemical composition caused by infection with root-knot nematodes. We have utilized binocular spectroscopy for microscopic observations of nematode species in infected okra plant roots. Wavelength dispersive X-ray fluorescence spectrometry has been used to detect and quantify the minerals and heavy metals in healthy, nematode infested and nematode infested with fungus okra roots. Numerous major, minor and heavy elements were quantified which have shown their toxic effects in for developing root-knot nematodes in okra plant roots. We have observed the changes in the concentrations of major and heavy elements in nematode infected okra root samples as compared to healthy root samples and in particular higher contents of Ca, K, S, Ti, Sr, and Ni is detected in nematode infected okra roots than that from healthy root samples. Changes in contents of heavy metals Al and Cr were also observed in infected roots. No significant changes have been observed in the concentrations of heavy elements Br, Ni, Rb, and Zr in healthy as well as nematode infested roots. Ag and Pd have only been detected in nematode infested okra roots. Fourier transforms infrared and ultraviolet–visible spectroscopy is employed to investigate the molecular changes in the nematode infested roots as compared to healthy roots. Fourier transform infra-red spectral studies revealed the decreasing content of starch and increased level of protein contents in root-knot infested roots as compared with healthy roots. Intensity of absorption peaks appeared in diffused reflectance spectra was observed lower for infected roots and higher in healthy roots. The present study is important for further treatment strategies of okra crop to prevent the crop loss in effective manner. The authors have utilized different techniques like wavelength dispersive X-ray fluorescence; fourier transforms infrared and ultraviolet–visible spectroscopy along with optical microscopy in plant science to study healthy and infected plant samples.

Comparative Physiological, Biochemical, and Genetic Responses to Prolonged Waterlogging Stress in Okra and Maize Given Exogenous Ethylene Priming.

Waterlogging is an environmental challenge affecting crops worldwide. Ethylene induces the expression of genes linked to important agronomic traits under waterlogged conditions. The ability of okra (Abelmoschus esculentus L. Moench.) and maize (Zea mays L.) given exogenous ethylene priming to tolerate prolonged waterlogged conditions was investigated in this study. The investigation was carried out as field experiments using 3 week-old plants grouped into four treatments; control, waterlogged plants, ethylene priming of plants before waterlogging, and ethylene priming of plants after waterlogging. Different growth parameters were recorded. Soil chemical and bacterial analyses were performed. The activity and gene expression of antioxidant enzymes were studied. The ethylene biosynthetic genes expression analysis and root anatomy of surviving okra plants were also carried out. Results revealed that okra and maize plants showed increase in their height under waterlogged conditions. Ethylene priming and waterlogged conditions induced early production of adventitious roots in okra and maize. Maize survival lasted between 5 and 9 weeks under waterlogging without reaching the flowering stage. However, okra survived up to 15 weeks under waterlogging producing flower buds and fruits in all treatments. Variable changes were also recorded for total soluble phenolics of soil. Cross sections of waterlogged okra roots showed the formation of a dark peripheral layer and numerous large aerenchyma cells which may have assisted in trapping oxygen required for survival. The activity and gene expression levels of antioxidant enzymes were studied and showed higher increases in the root and leaf tissues of okra and maize subjected to both waterlogging and ethylene priming, as compared to control or waterlogged condition. Quantitative RT-PCR analysis also showed that the ethylene biosynthetic gene expression levels in all okra and maize tissues were up-regulated and showed much higher levels under ethylene-treated waterlogged conditions than those expressed under control or waterlogged conditions at all time points. These results indicate that okra and maize tissues respond to the conditions of waterlogging and exogenous ethylene priming by inducing their ethylene biosynthetic genes expression in order to enhance ethylene production and tolerate the prolonged waterlogging stress. In conclusion, this study revealed that exogenously generated ethylene gas as a priming treatment before or after waterlogging could enhance waterlogging tolerance in maize and okra crops.

Endophytic Alcaligenes Isolated from Horticultural and Medicinal Crops Promotes Growth in Okra (Abelmoschus esculentus)

The potential of endophytic bacteria to act as biofertilizers and bioprotectants has been demonstrated, and considerable progress has been made in explaining their role in plant protection. In the present study, three endophytic bacterial strains (BHU 12, BHU 16 isolated from the leaves of Abelmoschus esculentus, and BHU M7 isolated from the leaves of Andrographis paniculata) were used which displayed high sequence similarity to Alcaligenes faecalis. The biofilm formation ability of these endophytic strains in the presence of okra root exudates confirms their chemotactic ability, an initial step for successful endophytic colonization. Further, reinoculation of spontaneous rifampicin-tagged mutants into okra seedlings revealed a CFU count above 105 cells g−1 of all three endophytic strains in root samples during the first 15 days of plant growth. The CFU count increased up to 1013 by 30 days of plant growth, followed by a gradual decline to approximately 1010 cells g−1 at 45 days of plant growth. Systemic endophytic colonization was further supported by 2, 3, 5-triphenyl tetrazolium chloride staining and fluorescence imaging of ds-RED expressing conjugants of the endophytic strains. The strains were further assessed for their plausible in vivo and in vitro plant growth-promoting and antagonistic abilities. Our results demonstrated that the endophytic strains BHU 12, BHU 16, and BHU M7 augmented plant biomass by greater than 40 %. Root and shoot lengths of okra plants when primed by BHU 12, BHU 16, and BHU M7 increased up to 34 and 14.5 %, respectively. The endophytic isolates also exhibited significant in vitro antagonistic potential against the collar rot pathogen Sclerotium rolfsii. In summary, our results demonstrate excellent potential of the three endophytic bacterial strains as biofertilizers and biocontrol agents, indicating the possibility for use in sustainable agriculture.

Interactions between a plant growth‐promoting rhizobacterium and smoke‐derived compounds and their effect on okra growth

AbstractPlant growth‐promoting rhizobacteria (PGPR) are used in agriculture to improve crop yield. Crude smoke–water (made by bubbling plant‐derived smoke through water) stimulates germination and improves seedling growth. Some active compounds have been isolated from smoke with karrikinolide (KAR1) stimulating plant growth and trimethylbutenolide (TMB) being inhibitory. These smoke compounds have great potential in agriculture but their interaction with PGPR is unknown. In the present study, a two‐factorial pot trial with three replicates per treatment was designed to investigate the interactions between Bacillus licheniformis and two concentrations each of smoke–water, KAR1, and TMB on okra (Abelmoschus esculentus). Growth and physiological parameters (chlorophyll, carotenoid, protein, sugar and α‐amylase) of okra as well as bacterial abundance in the rhizosphere were measured after 5 weeks. Application of B. licheniformis and 10−7 M KAR1 significantly improved the shoot biomass and 10−7 M KAR1 also significantly improved leaf area of okra. However, when 10−7 M KAR1 was applied in combination with B. licheniformis, there was an antagonistic effect on plant growth. While TMB had a negative effect on plant growth, a combination treatment of TMB and B. licheniformis overcame the inhibitory effect of TMB resulting in plant growth similar to the control plants. All treatments had no effect on chlorophyll, carotenoid, protein and sugar concentrations, while α‐amylase activity was significantly elevated in okra root treated with 1:500 (v/v) smoke–water. Determining the rhizobacteria populations at harvest showed that all treatments had no significant effect on the rhizosphere microbial abundance. The modes of interaction between PGPR and smoke‐derived compounds need to be further elucidated.