Postharvest Deterioration Research Articles

Metabolite changes of apple Penicillium expansum infection based on a UPLC-Q-TOF metabonomics approach

The Penicillium expansum (P. expansum) infection causes apple postharvest deterioration and declines the quality of apple derived products. Investigation into the metabolic process of apple P. expansum infection will help to illustrate the mechanism of pathology and discover the biomarkers for quality control. Here, the changes of metabolite during the apple P. expansum infection were explored by ultra performance liquid chromatography and the quadrupole-time of flight mass spectrometry (UPLC-Q-TOF/MS) based metabonomics. Between four group of 32 samples, average 1720 positive and 1761 negative peaks were obtained, which aligned into comparable peaks of 5048 and 4945. Significantly metabonomic differences were observed between the control and P. expansum infected samples. A total of 485 differential metabolites were screened. In these different metabolites, the majority of sugars were decreased during P. expansum infection, whereas the majority of organic acids, amino acids and peptides were increased. Changes in the profile of phenolics and fatty acids were diverse, and major of them were increased for disease resistance. Disturbed metabolic pathways in early infection were mainly secondary metabolite biosynthesis, ATP-binding cassette transporters, amino acid and carbon metabolism. The intergroup comparison obtained 140 differential metabolites to represent the core metabolic changes during infection. And 27 metabolites were strongly increased along with the disease process, which could aid the biomarker discovery. This study highlights the differential metabolites during the apple P. expansum infection, and provide a basis for further investigation.

Effect of Scopoletin and Carotenoids on Postharvest Physiological Deterioration (PPD) of Transgenic High Beta Carotene Cassava

Cassava tubers suffer from postharvest physiological deterioration (PPD) which normally sets in within 72 hours of harvest. This study examines the role of scopoletin and carotenoids in the onset or delay in PPD in two transgenic varieties EC20-7 and EC20-8 compared to a wild variety TME-7. Scopoletin and carotenoids were quantified by liquid chromatography-mass spectrometry. The scopoletin content (0.10 – 0.20 nmol/g) in the fresh varieties was not significantly (P>0.05) different from the amount in stored cassava roots (12.58 – 14.90 nmol/g). The carotenoid content values in EC20-7 variety were 6.66 µg/g (α-carotene), 80.45 µg/g (β-carotene) and 5.98 µg/g (lutein). As for EC20-8, α-carotene, β-carotene and lutein values were 6.19 µg/g, 69.11 µg/g and 3.12 µg/g, respectively. There was no significant (P>0.05) difference between the varieties in α-carotene content but in their lutein content. The results indicate that carotenoids are more relevant in the delay of PPD and scopoletin content is not a major factor in PPD vascular streaking or discolouration. Hence scopoletin content of cassava varieties may not be considered as a chemical marker for determining the potential of PPD in cassava tubers.

Comparative transcriptome and proteome provide new insights into the regulatory mechanisms of the postharvest deterioration of Pleurotus tuoliensis fruitbodies during storage

The Pleurotus tuoliensis (Pt), a precious edible mushroom with high economic value, is widely popular for its rich nutrition and meaty texture. However, rapid postharvest deterioration depreciates the commercial value of Pt and severely restricts its marketing. By RNA-Seq transcriptomic and TMT-MS MS proteomic, we study the regulatory mechanisms of the postharvest storage of Pt fruitbodies at 25 ℃ for 0, 38, and 76 h (these three-time points recorded as groups A, B, and C, respectively). 2,008 DEGs (Differentially expressed genes) were identified, and all DEGs shared 265 factors with all DEPs (Differentially expressed proteins). Jointly, the DEGs and DEPs of two-omics showed that the category of the metabolic process contained the most DEGs and DEPs in the biological process by GO (Gene Ontology) classification. The top 17 KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways with the highest sum of DEG and DEP numbers in groups B/A (38 h vs. 0 h) and C/A (76 h vs. 0 h) and pathways closely related to energy metabolism were selected for analysis and discussion. Actively expression of CAZymes (Carbohydrate active enzymes), represented by laccase, chitinase, and β-glucanase, directly leads to the softening of fruitbodies. The transcription factor Rlm1 of 1,3-β-glucan synthase attracted attention with a significant down-regulation of gene levels in the C/A group. Laccase also contributes, together with phenylalanine ammonia-lyase (PAL), to the discoloration reaction in the first 76 h of the fruitbodies. Significant expression of several crucial enzymes for EMP (Glycolysis), Fatty acid degradation, and Valine, leucine and isoleucine degradation at the gene or protein level supply substantial amounts of acetyl-CoA to the TCA cycle. Citrate synthase (CS), isocitrate dehydrogenase (ICDH), and three mitochondrial respiratory complexes intensify respiration and produce high levels of ROS (Reactive oxygen species) by significant up-regulation. In the ROS scavenging system, only Mn-SOD was significantly up-regulated at the gene level and was probably interacted with Hsp60 (Heat shock protein 60), which was significantly up-regulated at the protein level, to play a dominant role in antioxidation. Three types of stresses - cell wall stress, starvation, and oxidative stress - were suffered by Pt fruitbodies postharvest, resulting in cell cycle arrest and gene expression disorder.

Fungi Diversity on Some Fruits and Biological Control using Two Plants Extracts

Fruits play an essential role in human nutrition by contributing the necessary growth factors like essential minerals and vitamins in human daily diet maintaining a good and normal health. But rot diseases caused by fungi cause severe losses of agricultural and horticultural crops every year. This work aimed to study fungi diversity on some fruits and carry out biological control using two plant extracts. A total of 17 infected fruit samples were collected from two local markets, small pieces of infected parts were inoculated on prepared plates of Potato Dextrose Agar. Incubation was done for 7 days and pure cultures were made, and pure isolated fungi were identified according to the recommended references. Ethanolic leaf extracts of Ocimum gratissimum and Moringa oleifera were evaluated for in vitro antifungal activities on Aspergillus and Fusarium species isolated from spoilt tomatoes and banana using the Agar Dilution Method. Eleven different fungi species comprising nine genera were isolated from the 17 fruits collected from the Nkwen and main markets of Bamenda. The fungi were identified as Saccharomyces cerevisiae, Aspergillus niger, Penicillium digitatum, Mucor sp, Fusarium sp, Mucor racemosus, Alternaria alternata, Colletotrichum sp, Nodulisporium sp, Fusarium oxysporum and Aspergillus flavus. There was some diversity in isolation frequency of the fungi from the fruits. Aspergillus, Penicillium, and Fusarium were the most common genera that colonized the fruits, with Aspergillus sp. found to be the most dominant fungi responsible for extensive damage of fruits. Ocimum gratissimum and Moringa oleifera leaf extracts had inhibitory activities on the test fungi. The diversity of the fungi identified in this study could be regarded as the most common causes of post-harvest deterioration of fruits. The findings of this study bring further evidence that Moringa oleifera and Ocimum gratissimum leaves extracts have the potential of becoming powerful and safe alternative means of fungi control on fruits instead of the harmful, expensive, environmentally unfriendly chemical fungicides.

Treatment with 1-MCP: an alternative to extend storage in plums harvested with advanced maturity

Maturity at harvest is a determining factor in fruit storage potential, especially in such perishable species as plums (Prunus salicina L.). However, harvest´s logistics is very complex, and a large percentage of fruits are harvested at a more advanced stage of maturity than the optimum recommended for long storage. Treatment with 1-MCP has shown to be effective in reducing the post-harvest deterioration rate of Japanese plums, but the effectiveness of this treatment may be reduced in late harvested fruit. The aim of this trial was to determine the efficiency of treatment with 0.4 µL L-1 of 1-MCP in Larry Ann plums harvested at 4 different maturity stages. The results showed that the treatment was effective in reducing the ripening rate of the fruit at all harvest timings. The duration of this effect and the number of parameters affected decreased as harvest was delayed. In maturity stage 1 (M1, ~62 N) and maturity stage 2 (M2, ~58 N), 1-MCP delayed ethylene production rate during shelf life after 30, 40, and 50 days of storage at 0 ºC and reduced loss of flesh firmness, and acidity. At the maturity stage 3 (M3, ~50N) 1-MCP delayed ethylene production rate during shelf life after 30 and 40 days of storage at 0 ºC and maintained higher flesh firmness values. In fruit harvested at the maturity 4 (M4, ~35 N), 1-MCP did not affect ethylene production rate, but reduced loss of flesh firmness during shelf life, supporting the hypothesis that the treatment has a direct inhibitory effect on softening enzymes, independent of ethylene.

Potential Aspects of Plant Growth Promoting Bacteria to Improve Horticultural Crop Production

Beneficial microorganisms which help plants to grow better especially under stress conditions are known as plant growth-promoting bacteria (PGPB). These biotic agents, especially Bacillus subtilis have well-known role in plant growth promotion and induction of tolerance to stress in plants. They are deemed to act as bio-active and eco-friendly agents to facilitate plant growth under stressful conditions and even to control postharvest decays. Microbial antagonists, including B. subtilis, effectively control postharvest diseases of different fruits, vegetables and flowers, which is manifested in prolonged storage period and shelf/vase life, while preserving qualities and reducing weight losses. In this review paper we highlight the potential benefit of PGPBs especially B. subtilis, as important biotic useful agents to help horticultural plant perform better under stressful conditions and to delay senescence and control the postharvest deterioration through activation of different defense mechanisms. We further elaborate the underlying mechanisms that PGPB used to help plants to cope with stressful conditions. Nevertheless, the mechanisms of PGPB especially B. subtilis action requires further detailed investigations to fully utilize their potentials in horticulture industry.

Antagonistic Activity of Lactic Acid Bacteria Against Phytopathogenic Fungi Isolated from Cherry Tomato (Solanum lycopersicum var. cerasiforme).

The postharvest deterioration of cherry tomatoes due to diseases caused by fungi is one of the main causes of the loss of this product. The objective of this study was to determine the antagonistic capacity by evaluating the antifungal power of nine strains of lactic acid bacteria (LAB) in vitro against the phytopathogenic fungi Aspergillus niger, Fusarium sp., and Rhizopus stolonifer isolated from cherry tomatoes (Solanum lycopersicum var. cerasiforme) and to measure the biosurfactant production capacity, its antagonism in vivo, and the production of organic acids. The results showed that seven of the nine strains were able to inhibit at least one of the three fungi isolated in the in vitro assay. In eight of nine strains, biosurfactant production was identified, and the strains Weissella confusa and Lactiplantibacillus plantarum A6 showed the highest antifungal activity in vitro and in vivo against the fungi evaluated, with the identification of organic acid production in both strains. LAB demonstrated the ability to inhibit cherry tomato fungi, thus emerging as an alternative to the use of chemical preservatives in the production of this fruit and being projected as a preservation technology for this type of product through the use of strains or their metabolites.

Autonomous solar thermal system design for indirect dehydration of Aguaymanto (Physalis Peruviana L.), Junín

This paper aimed to design an autonomous indirect solar dryer, which can dehydrate the aguaymanto in a costeffective manner, yielding a quality product suitable for export from the central part highland of Peru. To complete this task, it was proposed to design a prototype of autonomous solar dryer of 100 kg per batch of aguaymanto, equipped with flat reflectors and forced air feed, and powered with photovoltaic energy. This system allows to dry aguaymanto fruit at the requirements needed for its exportation. The fryer has the following dimensions: inner dimensions of the drying chamber: bottom 0.60 m, width 1.40 m, and height 1.10 m, with additional 0.05 m for insulation. Hence, the outer measures are bottom 0.70 m, width 1.50 m, and height 1.20 m. Two solar collectors are proposed with the dimensions of each: 1.50 m wide, 2.40 m long, and 0.15 m height; 2 flat mirror reflectors are required. A 80 Wp photovoltaic panel was selected for the forced air system and process control. This solar dryer is expected to cope with the problem of post-harvest deterioration. Also, it will facilitate the export by improving product quality and providing a cost-effective technology.

The application of 1-methylcyclopropene preserves the postharvest quality of cabbage by inhibiting ethylene production, delaying chlorophyll breakdown and increasing antioxidant capacity

Freshly harvested cabbages were treated with air (control group) or 1 μL L−1 1-methylcyclopropene (1-MCP) for 12 h, followed by storage for 8 d at 25 ± 1 °C. The effects of 1-MCP on postharvest deterioration characteristics, antioxidant capacity, health-promoting compounds and nitrite accumulation in cabbage leaves were investigated. Treatment with 1-MCP significantly extended the shelf life, reduced postharvest deterioration, retarded chlorophyll degradation and inhibited the accumulation of malondialdehyde and nitrite in cabbage. Ethylene production and respiration rate were also inhibited by 1-MCP. Furthermore, 1-MCP treatment delayed the decrease in total glucosinolates, sulforaphane and folic acid during storage. High levels of ascorbic acid, total phenolic content and antioxidant capacity were also maintained in 1-MCP-treated cabbage. This study demonstrates that 1-MCP is a potential postharvest treatment to delay the senescence process, maintain desirable quality properties and reduce the loss of certain health-promoting compounds in cabbage.

Development of an Edible Coating Based on Pectin, Glycerol and Oregano Essential Oil for the Control of Post-Harvest Deterioration of Mango

Development of an Edible Coating Based on Pectin, Glycerol and Oregano Essential Oil for the Control of Post-Harvest Deterioration of Mango

A study of commonly occurring fungal diseases on stored tomatoes of Kathmandu Valley

Fungal pathogens destruct the quality and quantity of tomato production and cause health hazards to the consumers as well as economic loss to the traders. This study was carried out to identify some fungal diseases associated with post-harvest deterioration of stored tomato fruits in three vegetable markets of Lagankhel, Balkhu and Kalimati of Kathmandu Valley. The samples were collected from selected sites in three separate trials and cultured in Potato Dextrose Agar. During investigation, 16 species belonging to 15 genera of fungi were identified. They were Alternaria alternata, A. solani, Aspergillus niger, Botrytis cinerea, Cladosporium fulvum, Colletotrichum truncatum, Curvularia tetramera, Fusarium oxysporum, Geotrichum candidum, Mucor mucedo, Penicillium notatum, Phytophthora infestans, Phoma exigua, Pullularia pullulans, Pythium aphanidermatum and Rhizopus stolonifer. These were responsible for 15 different diseases of Alternaria fruit rot, Anthracnose, Black mold rot, Botrytis Bunch Rot, Damping off/ fruit rot, Drechslera mold, Fusarium rot, Mucor rot, Penicillium rot, Phoma blight, Phytophthora rot, Rhizopus rot, Russet, Scab and Sour rot. The presence of these fungi and corresponding rot diseases on stored tomato indicate the need for management of fungi, farm sanitation and improved market in order to prevent field-to-storage transmission of pathogens.

Pathogenic Fungi Associated with Post-Harvest Deterioration of Cassava

Cassava (Manihot esculenta) is a valued root crop grown throughout the tropics for food, feed, biofuel, and other industrial products. Nigeria is the largest producer of Cassava, and post-harvest deterioration of Cassava is one of the major challenges of long-term storage of cassava tubers. This study aimed to isolate and characterize pathogenic fungi implicated in the deterioration of cassava tubers, using samples from Iwo, Osun State, and Ijebu-Ode, Ogun State, Nigeria. The fungi genera isolated at the end of this study and their frequency of occurrence were Aspergillus (45.5%), Botryodioplodia (9.1%), Penicillium (18.2%), Rhizopus (18.2%), and P.sorghina (9.1%). A total of eleven fungi species were isolated and characterized in this study, seven of which were from the Ijebu- Ode Cassava samples and 4 fungi species from the Iwo samples. The pathogenicity test showed that Aspergillus nigricans (60mm) and P.sorghina (50mm) caused extensive deterioration of Cassava tuber. However, mild deterioration was observed from samples inoculated with Botryodiplodia (10mm) and Penicillium (14mm). This study has shown that a consortium of fungi species is implicated in the Post harvested deterioration of Cassava tubers.

A Study of Fungal Diseases Occurring on Stored Tomatoes of Balkhu Agriculture and Vegetable Market, Nepal

Tomatoes are one of the most widely produced and consumed vegetable in Nepal. Fungal pathogens deteriorate the quality and quantity of tomato and cause health hazards to the consumers as well as economic loss to the traders. This study was carried out to identify some fungal diseases associated with post-harvest deterioration of stored tomato fruits in Balkhu Agriculture and vegetable Market of Kathmandu, Nepal. Collected samples were cultured in Potato Dextrose Agar (PDA) media in complete randomized design. Fifteen species of fungi namely Alternaria alternata, A. solani, Aspergillus niger, Botrytis cinerea, Fulvum fulva, Colletotrichum truncatum, Curvularia spicifera, Fusarium oxysporum, Dipodascus geotrichum, Mucor mucedo, Penicillium chrysogenum, Phytophthora infestans, Boeremia exigua, Pythium aphanidermatum and Rhizopus stolonifer were identified. These were responsible for 14 different diseases of Alternaria fruit rot, Anthracnose, Black mold rot, Botrytis Bunch Rot, Damping off/ fruit rot, Drechslera mold, Fusarium rot, Mucor rot, Penicillum rot, Boeremia blight, Phytophthora rot, Rhizopus rot, Russet, and, Sour rot. The presence of these fungi and corresponding rot diseases on stored tomato indicates the need for management of fungi, farm sanitation and improved market in order to prevent field-to-storage transmission of pathogen.

The Eruca sativa Genome and Transcriptome: A Targeted Analysis of Sulfur Metabolism and Glucosinolate Biosynthesis Pre and Postharvest.

Rocket (Eruca sativa) is a source of health-related metabolites called glucosinolates (GSLs) and isothiocyanates (ITCs) but little is known of the genetic and transcriptomic mechanisms responsible for regulating pre and postharvest accumulations. We present the first de novo reference genome assembly and annotation, with ontogenic and postharvest transcriptome data relating to sulfur assimilation, transport, and utilization. Diverse gene expression patterns related to sulfur metabolism, GSL biosynthesis, and glutathione biosynthesis are present between inbred lines of rocket. A clear pattern of differential expression determines GSL abundance and the formation of hydrolysis products. One breeding line sustained GSL accumulation and hydrolysis product formation throughout storage. Multiple copies of MYB28, SLIM1, SDI1, and ESM1 have increased and differential expression postharvest, and are associated with GSLs and hydrolysis product formation. Two glucosinolate transporter gene (GTR2) copies were found to be associated with increased GSL accumulations in leaves. Monosaccharides (which are essential for primary metabolism and GSL biosynthesis, and contribute to the taste of rocket) were also quantified in leaves, with glucose concentrations significantly correlated with the expression of numerous GSL-related genes. Significant negative correlations were observed between the expression of glutathione synthetase (GSH) genes and those involved in GSL metabolism. Breeding line “B” showed increased GSH gene expression and low GSL content compared to two other lines where the opposite was observed. Co-expression analysis revealed senescence (SEN1) and oxidative stress-related (OXS3) genes have higher expression in line B, suggesting that postharvest deterioration is associated with low GSL concentrations.

Cassava shrunken-2 homolog MeAPL3 determines storage root starch and dry matter content and modulates storage root postharvest physiological deterioration

Key messageAmong the five cassava isoforms (MeAPL1–MeAPL5), MeAPL3 is responsible for determining storage root starch content. Degree of storage root postharvest physiological deterioration (PPD) is directly correlated with starch content.AGPase is heterotetramer composed of two small and two large subunits each coded by small gene families in higher plants. Studies in cassava (Manihot esculenta) identified and characterized five isoforms of Manihot esculenta ADP-glucose pyrophosphorylase large subunit (MeAPL1–MeAPL5) and employed virus induced gene silencing (VIGS) to show that MeAPL3 is the key isoform responsible for starch and dry matter accumulation in cassava storage roots. Silencing of MeAPL3 in cassava through stable transgenic lines resulted in plants displaying significant reduction in storage root starch and dry matter content (DMC) and induced a distinct phenotype associated with increased petiole/stem angle, resulting in a droopy leaf phenotype. Plants with reduced starch and DMC also displayed significantly reduced or no postharvest physiological deterioration (PPD) compared to controls and lines with high DMC and starch content. This provides strong evidence for direct relationships between starch/dry matter content and its role in PPD and canopy architecture traits in cassava.

Effect of Some Citrus Essential Oils on Post-Harvest Shelf Life and Physicochemical Quality of Strawberries during Cold Storage

Utilization of essential oils alone or incorporation with edible films is an appropriate technique to conserve the quality attributes and reduce post-harvest deterioration in fresh vegetables and fruits. Strawberries, being perishable fruits have a short shelf life, and using essential oils is considered one of the most suitable methods to prolong their shelf life during storage. The current study assessed the impact of different essential oils, including lemon oil (L), orange oil (O) and mandarin oil (M) on the physicochemical and microbial load of strawberries (Fragaria × ananassa cv. Festival) stored at 2 ± 1 °C and 95% relative humidity (RH) for 18 days. The differences in the physicochemical and microbial properties of strawberries were assessed by determining the following parameter changes: weight loss, decay percentage, firmness, soluble solids content, titratable acidity, color, anthocyanins, vitamin C, total phenol, total antioxidant, catalase activity, polyphenol oxidase activity, sensory evaluation, microbial content, total coliforms, molds, and yeasts. The results of this study indicated that the fruits treated with all essential oils treatments (L, O and M) had higher total antioxidant content and physicochemical properties than untreated fruits, due to protection against the microbial growth of molds, and yeasts. At the end of the storage period, the treated fruits showed a greater acceptance and sensory attributes than the untreated fruits. Furthermore, the correlation study showed a significant and negative relationship between the total antioxidant of treated fruits and following quality attributes including, weight loss, decay percentage, respiration rate soluble solids content, polyphenol oxidase activity, molds, and yeasts. It is noteworthy that all the essential oil treatments extended the shelf-life of strawberries and delayed their deterioration up to 18 days.

Postharvest Loss and Mycofloral Association in Some Culinary Mushrooms in Kathmandu City, Nepal

Postharvest deterioration of perishable crop is one of the major constrains in food supply. Similar instances are also prevalent in mushrooms. Contamination by fungal pathogens, occurrence of mycotoxins in these goods pose serious health issue. As such, evaluation of mycofloral contamination on commonly grown mushroom namely; Pleurotus sp and Agaricus sp. were made with focus on reducing its postharvest loss. Questionnaire survey to the mushroom growers and mushroom seller of Kathmandu valley was carried out to evaluate the post-harvest losses, causes and management procedure followed by them. Postharvest loss in Agaricus bisporus was higher than in Pleurotus sp., caused by microbial contaminants where extensive use of synthetic fungicides was found. Samples (i.e., Agaricus bisporus, Pleurotus ostreatus and Pleurotus florida) were collected from three major vegetable market of Kathmandu city to detect the mycoflora associated with postharvest deterioration. A total of 21 fungal species belonging to 10 genera were isolated from the samples. The most frequent fungal contaminants were Aspergillus niger (57.77%), Rhizopus sp (42.22 %), Trichoderma viride (34.44%) and Aspergillus flavus (27.77%). As the mushrooms appeared prevailed with many fungal contaminants, more caution should be taken such as selection of strain from resistant varieties, proper sanitation during in-field and postharvest conditions.

Biocontrol of Fungi Associated with Onion (Allium cepa) Bulb Rot during Post Harvest

Post-harvest deterioration is a major problem of onions (Allium cepa) in Nigeria. The use of chemicals has been the main control measure. Chemicals are hazardous and environmentally unfriendly. There is therefore, a need for search for effective bio-pesticides as alternatives. A survey of fungal onions diseases was conducted in two markets in Mkpat Enin Local Government Area, Akwa Ibom State, Nigeria. Two hundred onions bulbs (100 from each market) were collected separately from the two markets. The collected bulbs were put into separate polythene bags before taken to the laboratory for macroscopic and microscopic examinations. Fungal isolates were obtained from naturally infected bulbs and their pathogenicity confirmed using Kochs’ postulate. In vivo and in vitro testing based on growth inhibition were also carried out to determine the efficacy of the aqueous plant extracts. Phytochemical analysis of alcohol extracts was conducted following standard procedures. Results of market surveys indicated disease incidences of 26% and 23% from Akpaden and Ukam markets, respectively. Three fungal species were isolated and identified as Botrytis allii, Fusarium oxysporum and Alternaria porri. Pathogenicity tests confirmed these isolates to be common agents of onion bulb rot. In vitro testing of Chromolaena odorata and Mangiferia indica leaf extracts at 10, 20 and 30% concentrations showed inhibitory effects of both extracts with increasing concentrations on the pathogens. C. odorata extracts indicated significantly higher inhibition, compared to M. indica. In vivo tests of the extracts also showed a significant growth inhibition of the pathogens on onion bulb rot, compared to the control. Phytochemical screening of the extracts indicated the presence of tannins, saponins, polyphenols and flavonoids. The antifungal activities of these extracts and their availability makes them potential control agents of fungal onion rot. C. odorata and M. indica plant extracts should therefore, be further explored as alternatives bio-control agents or onions fungal rot.

Effects of Some Ethno Medicinal Plant Extracts on Botryodiplodia theobromae the Causal Organism of Yam (Dioscorea rotundata Poir) Rot

Post-harvest deterioration and rot caused by diverse microorganisms is the single most important factor militating against yam production in Nigeria. In an approach towards the development of ecofriendly antifungal compound in controlling yam rot, ethanol and aqueous extracts of six commonly available plants: Vernonia amygdalina, Ocimum gratissimum, Azadirachta indica, Cymbopogon citratus, Carica papaya and Citrus sinensis were tested in combination for their synergistic effect against Botryodiplodia theobromae. Four different extract concentrations (2.5%, 5.0%, 7.5% and 10%) were obtained from each extract mixture. Cold solvent extraction method was used for the extraction of plant materials while food poisoning technique was used for in vitro screening of plant extracts against rot inducing fungal organism. Botryodiplodia theobromae was tested to be pathogenic on healthy yam tubers with rot incidence of 80 mm. The synergistic effects of the combined extract varied with the plants combined, solvent of extraction, concentration of extract and test fungi. Ethanol extract showed greater effect in the inhibition of the entire organism than aqueous. All the extract combinations that had Neem as a component did better than other combinations in aqueous extracts. Inhibition of fungal growth was best observed at 7.5% and 10% extract concentrations. The highest inhibitory effect on the test organism (Botryodiplodia theobromae) was by the combination of Neem/Bitter leaf and Orange/Scent leaf, with values of 98.40±0.095% and 94.24±0.583% respectively for aqueous while the highest inhibition for ethanol extract was observed from Scent leaf/Bitter leaf and Pawpaw/Lemon, with values of 99.80±0.000% and 98.83±0.619% respectively these were significantly (P<0.05) better than other combinations. With respect to the synergistic activity between the plants materials combined in this study, all the combinations showed great synergism against the test organisms. This is likely to be a means of achieving pragmatic, effective control and prevention of food spoilage, since the development of new classes of antifungal agents is of paramount importance. The crude aqueous and ethanolic extracts of all the six plant extracts showed potential synergy on organisms responsible for yam rot, hence they are recommended for the control of rot inducing microbial organisms.

KERUSAKAN PASCAPANEN PADA UBI KAYU HASIL PEMULIAAN SELAMA PENYIMPANAN

Postharvest deterioration is a major problem which is an obstacle for cassava handling both for conventional cassava variety and mutant variety. There are two types of postharvest deterioration on cassava, namely postharvest primary deterioration (PPD) or primer deterioration of physiological deterioration, and microbiological deterioration. Damage can be minimized by carrying out storage in optimal conditions. This study aimed to determine the level of postharvest deterioration on cassava variety R and U during 35 days of storage. The storage treatment was storage consist of 1) wooden boxes and moist sawdust storage (P1) and 2)control storage (P2). The results indicated that RP2 and UP2 produced physiological deterioration by 25% on the 7th day of storage and reached 100% on the 35th day of storage. Meanwhile, the percentage of microbiological deterioration reached more than 20% on the 14th day of storage. On the other hand, RP1 and RP2 indicated good results. Both varieties experienced only less than 25% physiological deterioration and did not experience microbiological deterioration during storage.