Okra Seedlings Research Articles

Influence of irrigation intervals on essential nutrient content in okra (Abelmoschus esculentus) seeds

The influence of irrigation intervals on the accumulation of essential nutrients in okra seeds, especially those intended for coffee production, has not been thoroughly documented. This study aimed to investigate the effects of irrigation intervals on essential nutrient levels in okra seeds. By exploring how different irrigation schedules impact nutrient content, this research aims to optimize water use and enhance seed quality to meet the growing demand for nutrient-dense food products. The present study was conducted during late summer (December-January) 2022 and validated in 2023 at the Green Biotechnologies Research Centre of Excellence (GBRCE), University of Limpopo, Limpopo Province, South Africa (23°53'10"S, 29°44'15"E). Okra seedlings were subjected to irrigation intervals of 2, 4, 6, 8, 10, 12, and 14 days, with each interval replicated 10 times. Each seedling received 2,000 mL of tap water per irrigation. At 59 days after transplanting, pods were harvested and shelled, with seed samples prepared for the determination of malnutrition essential element tests. Calcium, K, Mg, and P versus irrigation interval exhibited quadratic relations with the model explained by 80, 78, 79, and 77% associations, respectively. Similarly, Cu, Fe, Na, Mn, and Zn versus irrigation interval exhibited quadratic relations, with the model explained by 71, 86, 79, 81, and 68% associations, respectively. Using x = −b1/2b2 relation, the average optimal irrigation intervals for macro and micronutrient elements were 9 and 8 days, respectively, with the average suggesting that the Day-8 irrigation interval was suitable for improving malnutrition essential elements of okra seeds under field conditions.

Effects of nano oxide particles on the growth and photosynthetic characteristics of okra plant under water deficiency

ABSTRACT Drought, as abiotic stress, has significant detrimental effects on the growth, physiology, yield and nutritional quality of plants. The distinctive characteristics of nanoparticles (NPs) significantly contribute to essential physiological processes, indicating their considerable potential in promoting plant growth. This study investigated the effects of different NPs, including aluminium oxide nanoparticles (ANPs), silica nanoparticles (SNPs) and titanium dioxide nanoparticles (TNPs), on the growth and photosynthesis of okra (Abelmoschus esculentus L.) seedlings under drought stress conditions. The growth characteristics of okra plants were assessed after 48 days of watering. Photosynthetic parameters like photosynthetic rate, transpiration rate, intercellular CO2 concentration (Ci), stomatal conductance and water use efficiency (WUE) were measured with a portable photosynthesis system. The results demonstrated that both ANPs and SNPs can promote the growth and photosynthesis activity of okra plants, with SNPs exhibiting a stronger effect compared to ANPs. The administration of 50 mg · kg−1 SNPs for a defined period demonstrated the most pronounced enhancement in growth and photosynthetic properties. In contrast, TNPs were found to have a significantly harmful influence on the growth and photosynthetic properties of the okra plant. These findings lay an important foundation for assessing the effects of nano oxide particles on okra plants.

Physiological and biochemical responses of okra (Abelmoschus esculentus) under salinity stress in Iran

Saline soil and water present significant agricultural challenges, particularly in arid and semi-arid regions like Iran. Around 15 % of Iran's land is categorized as saline. Salt stress disrupts various physiological processes in plants, leading to reduced crop yields. Considering the demand for food and the limitation of cultivated areas is rising, the cultivation of salt-resistant crops is gaining attention. This study was conducted to examine the morpho-physiological responses tolerance of a native cultivar of okra (Abelmoschus esculentus L. cv. White Ahvazi) under conditions of salinity stress. Understanding how this native cultivar responds to salinity stress is crucial for increasing its productivity. The okra seedlings were subjected to seven different levels of electrical conductivity (EC) (1.7 as control, 4.4, 6.2, 8.5, 10.6, 12.5, 14.4, and 15.8 mS/cm) after the appearance of their first true leaves by dissolving NaCl salt in Hoagland's nutrient solution. The results showed that morphological traits in the treated samples were not significantly different from the non-treated samples until EC reached a value of 10.6 mS/cm. The increases in EC from 1.7 to 10.6 mS/cm resulted in a significant rise in the antioxidant capacity and content of biochemical constituents. While salinity stress from EC 12.5 mS/cm onwards caused significant induction of hydrogen peroxide free radicals and peroxidation of membrane lipids. The yield was also significantly reduced at ECs of 12.5, 14.4, and 15.8 mS/cm, which were 31.1, 40.6, and 59.6 % less than control plants, respectively. Increasing salinity stress resulted in a remarkable reduction of photosynthetic pigments in plants as compared to the non-treated plants. Generally, it can be concluded that the White Ahvazi cultivar of okra commonly cultivated in Iran had a moderate tolerance to EC with a threshold of 10.6 mS/cm. Thus, this study can contribute towards enhancing food production in regions facing challenges related to salinity.

An Exploration into “Do-It-Yourself” (DIY) CO2 Enrichment Chambers: Utilising Grey Oyster Mushroom (Pleurotus pulmonarius (Fr.) Quél) Respiration to Improve Okra (Abelmoschus esculentus L.) Seedlings Growth

The endeavour to employ CO2 from natural sources to improve plant growth is often challenging, especiallyin tropical climates. While mycelium bags from the mushroom industry can generate CO2, they need indoorconditions with controlled temperature, high humidity, and low light. These conditions are not present inopen fields, leading to low CO2 production. Inspired by the ancient clay evaporative cooling device calledthe zeer pot, a new solution was developed to address this problem. The eventual design was a confinementchamber that housed the mycelium bags and the okra seedlings. The chamber conditions were sufficientlyconducive for the mycelium bags to produce an ambient CO2 level of around 800 ppm during the day. Theresulting okra seedlings under this high CO2 concentration of natural origin had a notable increase in overallbiomass accumulation (+ 277%), carbon assimilation rate (+103%) as well as improved water use efficiency(+95%) compared to seedlings grown under ambient CO2 level. These promising findings not only provedthe capability of mycelium as a natural CO2 generator but also as an additional economic potential for thefarmers to gain income from the CO2-enriched crops as well as the harvested mushroom bodies at the timeof mycelium bags maturity. Furthermore, this simple innovation opens the avenue for furtherinterdisciplinary research in other agricultural efforts to improve crop yield and quality.

Use of by-Products from Bentonite Extraction in the Composition of Substrates for the Production of Okra Seedlings (Abelmoschus esculentus L.)

O quiabeiro é uma hortaliça comum entre os brasileiros e a utilização de fertilizantes alternativos nessa cultura é de extrema importância. Desse modo, objetivou-se avaliar o uso de subprodutos da extração de bentonita na composição de substratos para produção de mudas de quiabo (Abelmoschus esculentus L.). O experimento foi realizado na Universidade Federal da Paraíba, campus II, em Areia-PB. O delineamento experimental foi realizado em blocos casualizados com cinco tratamentos, a testemunha e quatro proporções de subproduto da extração de bentonita, resultando em 100 plantas. Foi realizada a caracterização física e química do substrato, e avaliado o índice de velocidade de emergência e as medidas biométricas. Os dados foram submetidos à análise estatística. Logo, observou-se que a área foliar apresentou maior diferença de médias entre os substratos, sendo o S-2 o que obteve a maior delas, enquanto o S-1 e S-5 apresentaram médias idênticas. A massa fresca de parte aérea apresentou médias mais divergentes entre si, destacando o S-2 com maior valor e o S-5 com o menor. O substrato que obteve as melhores médias na produção das mudas de quiabeiro foi o S-2, com 4% do subproduto da extração de bentonita.

Effects of Different Priming Treatments on The Germination and Growth of Okra (Abelmoschus esculentus L.)

The study was designed to overcome the low germination of okra seed and to assess the effects of different seed priming treatments on okra (Abelmoschus esculentus) seedlings, which were encompassed nine treatments: control, hydro priming, SMP-sand metrix priming, H2SO4 - 40%, H2O2 - 2%, NaCl - 3%, KCl - 3%, CaCl2 - 3%, and KI - 1%. A randomized complete block design was used with three replications. Germination percentages, germination speed index (GSI), seedling vigor index (SVI), and relative growth rate (RGR) were measured. The highest germination percentage (89.77%) and GSI (9.6) were observed with (H2O2 - 2%). T3 (H2SO4 - 40%) exhibited the highest SVI (0.7), indicating robust seedling health. Additionally, H2O2 - 2%. demonstrated the longest root and shoot length (11.7 cm and 14.2 cm, respectively) and highest seedling fresh weight (0.87 g). Treatment with H2SO4 - 40% displayed the highest dry weight (0.18 g). Notably, H2O2 - 2% treatment significantly enhanced germination and growth compared to the control. These findings underscore the potential of seed priming, particularly H2O2 - 2%, in enhancing okra seedling growth and development, offering valuable implications for crop productivity and establishment.

Effect of Drought Acclimation on Drought Stress Resistance in Okra Seedlings

Öz
 Bu çalışmada bamyada (Abelmoschus esculentus L.) fide döneminde kuraklık aklimasyonunun etkileri araştırılmıştır. Bu amaçla, aklimasyon yapılmamış ve stressiz (NA), aklimasyon yapılmış ve stressiz (DA), aklimasyon yapılmamış ve kuraklık stresli (NAS), aklimasyon yapılmış ve kuraklık stresli (DAS) olmak üzere dört farklı sulama uygulaması yapılmıştır. Uygulamaların bamya fidelerinin bitki boyu, gövde çapı, bitki taze ağırlığı, bitki kuru ağırlığı, kök taze ağırlığı, kök kuru ağırlığı, yaprak alanı, yaprak bağıl su içeriği (LRWC), klorofil değeri (SPAD), klorofil içeriği (a, b ve toplam klorofil), hidrojen peroksit (H2O2) içeriği, malondialdehit (MDA) içeriği ve antioksidan enzim aktivitesi (CAT, POD ve SOD) gibi parametreler üzerine etkisi incelenmiştir. Kuraklık stresi (NAS), bitki büyüme parametreleri üzerinde olumsuz bir etkiye sahipken, DAS'ın neden olduğu hasar daha düşük olmuştur. Ayrıca bitki boyu, gövde çapı, bitki taze ağırlığı, bitki kuru ağırlığı, kök taze ağırlığı, kök kuru ağırlığı, yaprak alanı, LRWC, SPAD ve klorofil içeriği DA ile en yüksek düzeyde olmuştur. Kuraklık stresi (NAS) ile H2O2, MDA ve antioksidan enzim aktivitesinde artış olmuş, DAS ile bu parametrelerdeki artış NAS uygulamasına göre daha düşük olmuştur. Çalışmada bamyada fide döneminde uygulanan kuraklık aklimasyonunun, normal koşullarda bitki büyümesine olumlu etkisinin yanı sıra kuraklık stresine karşı toleransı artırabileceği belirlenmiştir.

Laboratory Study of Fortin Pro25 WP Efficacy Against Seed Rot and Seedlings Death Causes Rhizoctonia solani and Pythium spp.

The objective of this study was to ascertain the fungal species responsible for inducing seed rot illnesses and seedling mortality in okra plants, a prevalent issue throughout many parts in Al-Muthanna governorate. The objective of this study was to assess the efficacy of the fungicide Fortin Pro25WP in inhibiting the growth and biomass of the pathogenic fungus R. solani and Pythium spp in vitro, using various mediums. The findings from the process of isolation, phenotypic characterization, and molecular identification indicate that the samples of deceased and diseased okra seedlings were linked to the presence of R. solani and Pythium spp. The results also showed the high pathogenic ability of the two fungi in reducing percentage of okra seeds germintion, especially R. solani, which did not allow any seed to germinate on the culture media, while Pythium spp. reduced germination rate from 100% in the control treatment to 68.33%. The study also showed that the fungicide showed high efficiency in inhibiting the growth of pathogenic fungi by 77.78% and 89.78% for R. solani and Pythium spp. respectively. The fungal biomass was reduced by estimating the fresh weight FW and dry weight DW, with percentages ranging from 75-92% of the FW and 74-86% of the DW value of both fungi, respectively, on the PDB liquid medium.

The effects of different pineapple wastes on soil chemical properties and growth and yield of Okra (Abelmoschus esculentus L.)

The high demand for pineapple fruit generates several waste products that can be recycled through composting. This study examined the impact of pineapple waste compost on the chemical properties of soil and its effect on growth and yield of okra (Abelmoschus esculentus L.). T0 (control), T1 (pineapple peel compost), and T2 (pineapple core compost) of pineapple compost were added to the okra growth medium, and these treatments were arranged in a Randomised Complete Block Design (RCBD) along with five replications. The pineapple peel and core compost were applied at a homogeneous rate (10% of the volume of the polybag). The treatments were applied one week before the transplants of the okra seedlings. Base fertiliser NPK Green (15:15:15) was applied one week after transplanting, with the same amount for all treatments. Analysis of variance (ANOVA) was used to compare all of the data in this study, and the Tukey Test to separate the statistically different means at p<0.05. There was no significant (p≥0.05) variation in plant growth characteristics such as plant height, leaf number, fruit number, root length, and plant biomass in this study. Pineapple peel compost (T1) showed better growth performance than other treatments except for the parameter of root length. The application of pineapple waste compost enhanced soil pH, macronutrients (K, Ca, and Mg), and micronutrients (Zn, Cu, and Mn). However, no significant (p≥0.05) differences were identified except for soil pH, exchangeable calcium (Ca), and total zinc (Zn). Using both composts revealed that they could improve the chemical properties of the soil, which led to better plant growth compared to the control treatment (T0).

Genome-wide assessment of genetic diversity and association mapping for salt tolerance traits in okra (Abelmoschus esculentus L. Moench) using genotyping-by-sequencing

Okra is a vegetable that is widely grown worldwide. However, there are few reports on genetic diversity analysis and genome-wide association studies (GWASs) based on large-scale molecular markers in okra. In this study, 353,001 SNP markers were developed based on a genotyping by sequencing (GBS) strategy to analyze the population structure, genetic diversity and GWAS of 180 okra germplasms from all over the world. Both phylogenetic tree and population structure analyses classified all accessions into three categories, and the classification of most accessions in the two methods were the same. Some okra accessions from warm and cool areas were classified into one category, and some from hot areas were classified into one category. The Shannon‒Wiener index (I), Nei's genetic diversity index (Hei), minor allele frequency (MAF) and polymorphic information content (PIC) of the 180 okra accessions were 0.5071, 0.3366, 0.2580 and 0.2691, respectively. The B subgroup had the highest level of genetic diversity. A total of 180 okra seedlings were treated with 120 mM (T1) and 200 mM (T2) NaCl solutions, and salt tolerance-related traits were analyzed by GWAS. Seventy-seven SNP loci were identified to be associated with four salt tolerance traits. c3341.graph_c0 was aligned in multiple SNP loci, which may be an important unigene regulating the salt tolerance of okra seedlings. To our knowledge, this was the first study to use large-scale SNP markers to carry out population genetic analysis and GWAS in okra.

Influence of SiO2, Al2O3 and TiO2 nanoparticles on okra seed germination under PEG-6000 simulated water deficit stress

Abstract: A comparative study for evaluating the influence of metal oxide nanoparticles (MONPs) (Al2O3, TiO2, and SiO2) on seed germination and seedling growth in okra was implemented under water deficit stress stimulated by PEG-6000. The results revealed that additive of SiO2 nanoparticles (SNPs) and Al2O3 (ANPs) have significant positive effect on seeds germination, while a reduction of that were observed by using TiO2 nanoparticles (TNPs) at 50 mg.L-1 concentration under 5% PEG-6000 stimulated drought stress as compared to that without MONPs. Further, relative to non-MONPs treatment, all the tested MONPs dramatically enhanced the drought stress tolerance in okra seedlings due to the improvement of morphological growth despite a few traits were inhibited under certain water deficiency to some degree. Improvement of drought resistance induced by TNPs and ANPs were found to be higher than that by SNPs. Our finding provides a promising approach to cope with water scarcity, as application of metal oxide nanoparticles to be a potential option to protect okra plants against drought stress.

Interacting effects of botanicals, biocontrol agents, and potting media on Rhizoctonia solani led damping-off of okra seedlings

The interacting effects of botanicals, biocontrol agents, and potting media against the Rhizoctonia solani led damping-off in okra ( Abelmoschus esculentus L.) were investigated. The treatments comprised of different combinations of extracts of five botanicals:wood apple/Indian bael – Aegle marmelos L., Neem – Azadirachta indica A. Juss, Turmeric – Curcuma longa L., Ginger – Zingiber officinale Roscoe, and Onion – Allium cepa L.,and two biocontrol agents, Pseudomonas fluorescens and Trichoderma viride as first factors and two potting media; vermicompost with soil and farm yard manure with soil as the second factor in a completely randomized design with 42 treatments and 4 replications. The seeds were sown after pathogen inoculation. Okra seedling health was recorded daily for the first 16 days after sowing. Pseudomonas soil treatment and Pseudomonas+onion seed treatment showed the least pre-emergence damping off (35%). Almost all the combinations of wood apple extracts showed inhibitory effects on seed germination and growth of seedlings. The greatest number of days for the onset of post-emergence damping-off was recorded with Pseudomonas + Onion seed treatment (14.88 days) followed by Pseudomonas seed treatment (14.13 days). Germination Index (GI) was better for farm yard manure(0.32) than Vermicompost substrates (0.23). The GI was greatest in Pseudomonas soil treatment (0.53) followed by Pseudomonas + Onion seed treatment (0.51). Similarly, Dickson Quality Index (DQI) was greatest for Pseudomonas + Neem seed treatment (0.0015), with a greater value of DQI indicating better seedling quality. No significant interaction was observed between the substrates and biocontrol agents for any studied parameters. Pseudomonas + Onion seed treatment and Pseudomonas soil treatment were most effective for controlling R. solani -led damping-off in okra. • We studied the control of damping-off disease in okra seedlings. • Seed treatment with Pseudomonas fluorescens and onion blub extract were effective. • Trichoderma treatment in combination with other botanicals decreased the efficacy. • Hard wood apple extract had inhibitory effects on the germination of okra.

Ectopic Expression of AeNAC83, a NAC Transcription Factor from Abelmoschus esculentus, Inhibits Growth and Confers Tolerance to Salt Stress in Arabidopsis.

NAC transcription factors play crucial roles in plant growth, development and stress responses. Previously, we preliminarily identified that the transcription factor AeNAC83 gene was significantly up-regulated under salt stress in okra (Abelmoschus esculentus). Herein, we cloned the nuclear-localized AeNAC83 from okra and identified its possible role in salt stress response and plant growth. The down-regulation of AeNAC83 caused by virus-induced gene silencing enhanced plant sensitivity to salt stress and increased the biomass accumulation of okra seedlings. Meanwhile, AeNAC83-overexpression Arabidopsis lines improved salt tolerance and exhibited many altered phenotypes, including small rosette, short primary roots, and promoted crown roots and root hairs. RNA-seq showed numerous genes at the transcriptional level that changed significantly in the AeNAC83-overexpression transgenic and the wild Arabidopsis with or without NaCl treatment, respectively. The expression of most phenylpropanoid and flavonoid biosynthesis-related genes was largely induced by salt stress. While genes encoding key proteins involved in photosynthesis were almost declined dramatically in AeNAC83-overexpression transgenic plants, and NaCl treatment further resulted in the down-regulation of these genes. Furthermore, DEGs encoding various plant hormone signal pathways were also identified. These results indicate that AeNAC83 is involved in resistance to salt stress and plant growth.

Enhancement in Okra (Abelmoschus esculentus) Growth Performance Under Salt Stress Using Exogeneous Application of L- tryptophan

Salinity is one of the major stress factors that has a substantial impact on agricultural resilience and concerns global food safety. L-tryptophan being an essential regulator with specialized activities in plant functioning, as well as an increase in tolerance to various abiotic stressors. A hydroponic experiment was carried out to determine the effective role of L-tryptophan in okra seedlings in saline environment in terms of growth, physiological, ionic, and antioxidant properties. Salinity was imposed in growth medium with two levels of NaCl (Control and 80 mM NaCl) whereas one level of L-tryptophan (50 µM L-1) administered externally in both combined and single forms. MDA and H2O2 contents increase while plant dry matter, chlorophyll content, relative water contents, membrane stability index, K+/Na+ ratio decreases due to salt stress. Salt toxicity was reduced when L-tryptophan was added as illustrated by increased relative water contents, membrane stability index, K+/Na+ ratio, as well as suppression of MDA and H2O2 generation. Our findings suggested that L-tryptophan increased salinity tolerance in okra, which could be a cause of viable sustainable production from salt-affected soils.

Morphological variability in okra germplasm due to the infection of root-knot nematode (Meloidogyne incognita)

Root-knot nematode (Meloidogyne incognita) is a notorious pathogen of okra (Abelmoschus esculentus L.) from the family Malvaceae. This investigation was planned to corroborate the damaging impact of M. incognita on growth parameters of different varieties of okra. Seeds of ten different varieties of okra were taken and sown in earthen pots containing sterilized soil. There were five replications for each variety along with control. Approximately 1000 freshly hatched juveniles of M. incognita were applied on okra seedlings after three weeks of seed germination. Harvesting was done after 60 days of inoculation and different plant growth and nematode reproduction parameters were recorded. Significant differences of growth parameters were observed among all the varieties of okra. The variety Kiran showed maximum number of galls, egg masses and females with lowest number of fruits and other growth parameters except root weight while Anarkali showed minimum number of galls with better growth parameters.

A sustainable approach for processing organic waste in India

There are about 3430 million poultry populations in India, with a waste generation of 3.30 million tons per year. India is the world's third-largest egg producer and the fourth-largest broiler chicken producer, and Tamil Nadu plays a significant role in poultry egg and meat production. As the poultry hub of Tamil Nadu, Namakkal has been struggling to manage these wastes dumped in open areas by the poultry farms and small industrial units in recent years. The dumping of Bio-organic waste like chicken feathers and chicken intestines in the municipal solid waste landfill creates an unpleasant odor, environmental contamination, and various health issues. These organic wastes can be recycled through composting as a sustainable approach to waste management. In this study, discarded chicken waste from the poultry units and slaughterhouses in and around the Namakkal was collected and mixed with other organic manure like cow dung, rice husk, and tea powder in various proportions to generate organic compost. The composting process has been carried out in-vessel composters for 40 days by both aerobic and anaerobic methods at the lab scale. The parameters such as C: N ratio, pH, Organic matter, Dry matter, Moisture content, and NPKvalues are analyzed for aerobic and anaerobic processes. It is found that the C: N ratio is optimum in aerobic compost compared to anaerobic compost. Also, it is observed that the aerobic compost had a positive influence on the plant growth, i.e., okra (ladies finger) seedlings, then the anaerobic compost. The study indicates that the addition of external agents is required for the complete and rapid degradation of chicken feathers due to fiber-rich keratin. Thus, the present study will effectively reduce the potential hazards of chicken waste disposal through the proposed sustainable approach.

Interacting Effects of Botanicals, Biocontrol Agents, and Potting Media on Rhizoctonia Solani Led Damping-Off of Okra Seedlings

Interacting Effects of Botanicals, Biocontrol Agents, and Potting Media on Rhizoctonia Solani Led Damping-Off of Okra Seedlings

SEED PRIMING AND EXOGENOUS APPLICATION OF SALICYLIC ACID ENHANCE GROWTH AND PRODUCTIVITY OF OKRA (Abelmoschus esculentus L.) BY REGULATING PHOTOSYNTHETIC ATTRIBUTES

Low and uneven germination is a serious problem for the successful production of okra seedlings. Priming of seeds as well as supplementation of different plant growth regulators exhibited better response in successful seedling production which eventually results in higher yield. Therefore, the present study was conducted to evaluate the effects of seed priming and exogenous application of salicylic acid (SA) on okra seed germination and plant development. The okra seeds were primed by 1 mM and 2 mM of SA for 60 minutes whereas the seeds were washed several times with distilled water for the control treatment. Similar doses of SA have been exogenously sprayed to the 12 days okra seedlings for 4 days. The results of the study revealed that seed priming with SA enhanced germination percentage (GP), increased coleoptile length and weight, shoot and root length, and seed vigor index (SVI). Similarly, exogenous application of 1 mM SA increased relative water content (RWC), contents of chlorophyll a, chlorophyll b, total chlorophyll while a higher dose of SA (2 mM) degraded the leaf pigments. Supplementation of SA altered photosynthetic attributes, net photosynthetic (Pn) and transpiration rate (Tr), stomatal conductance (Gs), and water use efficiency (WUE). Moreover, SA treatment reduced the time duration of flower bud initiation and days to first flowering and enhanced the yield per plant. The results of this study indicated that seed priming and exogenous application of SA enhanced germination and okra productivity by regulating RWC and photosynthetic attributes where 1 mM SA is more effective compared to 2 mM SA.

Impact of controlled microwave radiation in enhancing the productivity of Abelmoschus esculentus seedlings (L.) Moench

ABSTRACT The study describes the impact of microwave radiation on the germination rate and growth of Abelmoschus esculentus (L.) Moench (okra). The two okra varieties, viz. Meenaxi-371 and Soniya-1402, were used for the experiment. Their seeds were exposed to 0–14 h (h) of microwave radiation (9.3 GHz). Non-irradiated seeds (0 h exposure) served as control. We found that microwave radiation on seeds resulted in an increase in their germination indices and also stimulated the concentration of β-1,3-glucanase enzyme. The results also indicate a remarkable increase in bioactive compounds such as flavonoids, polyphenols, carotenoids, chlorophyll, lutein, protein, and β-carotene in okra seedlings exposed to 8–10 h of radiation. A further dose escalation in the microwave radiation caused a decline in the germination and growth of the okra plant. The expression level of ACS4, ETR2, and ACS6 showed up-regulation under the influence of microwave irradiated conditions. Therefore, it is evident that a well-controlled and defined irradiation has the potential to enhance the overall growth and yield of selected okra varieties. Abbreviations: RNA: ribonucleic acid; qRT-PCR: quantitative real-time polymerase chain reaction; EMF: electromagnetic field; ACS: amino cyclo synthase; ETR: ethylene transport receptor

Agricultural residues as substrates in the production of formosa papaya, okra and zucchini seedlings

Using residues generated in agriculture to produce seedlingsis an economically interesting alternative, besides being a way to reduce the environmental impacts caused by their inadequate disposal. This study aimed to evaluate the potential of using coffee chaff (CC) and organic compost (OC) as substrate components for the production of Formosa papaya seedlings and the potential of grape pomace (GP), a vitiviniculture residue, in the composition of substrates for the production of okra and zucchini seedlings. We carried out two trials in a completely randomized design (CRD): the first had seven treatments and six replicates: T0: 100% commercial substrate Bioplant® (CS); from T1 to T6: increasing proportions of CC and decreasing of CC: 10/90; 20/80; 30/70; 40/60; 50/50 e 60/40%. The second had six treatments and six replicates, with increasing proportions of GP and decreasing proportions of CS: 0/100; 10/90; 20/80; 30/70; 40/60 and 50/50%.In the first trial we evaluated the number of leaves, root length, seedling height, stem diameter, shoot dry mass, root dry mass, total dry mass and Dickson Quality Index (DQI) at 59 days after sowing.The second trialwas performed at 12 and 18 DAS and we analyzed the number of leaves, plant height, root length, collar diameter, shoot dry mass, root dry mass, total dry mass and Dickson Quality Index (DQI). Variables that met the assumptions of normality and homoscedasticity were subjected to Dunnett’s test. The substrate composed of coffee chaff and organic compost has a high potential to be used as an alternative substrate due to promote better quality of papaya seedlings compared to the commercial substrate. Alternative substrate containing 60% coffee chaff and 40% organic compost is recommended for the production of Formosa papaya seedlings in tubes. The grape pomace (GP) has a high potential to be used as component in substrate for the production of okra and zucchini seedlings compared to the commercial substrate (CS) only. Alternative substrate composed of 50% GP and 50% CS is recommended for the production of zucchini seedlings, while substrate composed of 10% GP and 90% CS is recommended for the production of okra seedlings.