16 research outputs found
Deterioration of Soybean [Glycine Max (L.) Merr.] Seed by Colletotrichum Truncatum and its Control Through Bio-priming
No full textA study was conducted to evaluate the effect of Colletotrichum truncatum infection on soybean seed quality and its control through bio-priming. A total of 11 genera comprising of 17 species of seed-borne fungi were found to be associated with soybean var. Palmetto. The prominent fungus isolated externally and internally was C. truncatum with the frequency values of 12.75 and 9.75%, respectively, followed by Fusarium oxysporum f. sp. glycines and Diaporthe phaseolorum var. sojae based on moist blotter and agar plate methods. The typical symptoms of C. truncatum on the infected seeds appeared as brown to black speckled lesions, producing numerous acervuli with black setae and conidia over the seed surface. Seed infection by C. truncatum in soybean seed caused pre and post-emergence damping-off, resulting in reduced seed germination and seedling survivability by 62.35 and 88.24%, respectively. Histopathological studies of naturally infected soybean seeds confirmed the presence of C. truncatum predominantly both intra- and inter-cellularly in the seed coat, cotyledon and embryonic axes of seed. The fungi were also detected on and in the seed coat, cotyledon and embryonic axes of artificially infected seeds. Seed viability and vigour were also reduced in C. truncatum infected seeds as determined by tetrazolium (TZ) and electrical conductivity (EC) tests. Seed volume of infected seeds was reduced, with an increase in soluble protein and oleic acid and a decrease in linoleic acid content as compared with healthy seeds. Two fungal biocontrol agents (BCAs), Trichoderma virens (UPM23) and T. harzianum (UPM40) were found to inhibit strongly the growth of C. truncatum through mycoparasitism, competition and antibiosis based on PIRG (Percent Inhibition of Radial Growth) values. However, one bacterial BCA, Pseudomonas aeruginosa (UPM13B8) gave the highest PIRG values of 100% in the culture filtrate test, suggesting that antibiosis could be the main mechanism of antagonism. No phytotoxic effect was observed on soybean seeds and seedlings, when treated with suspensions of UPM23, UPM40 and UPM13B8. Therefore, the efficacy of bio-priming was conducted for controlling C. truncatum infection in soybean seeds using UPM23, UPM40 and UPM13B8. Artificially infected seeds by C. truncatum were bio-primed for 12 hours as this was determined as the safe time limit for soybean. Treatments included were chemo-primed, Benlate® (T1); bio-primed, UPM13B8 (T2); bio-primed, UPM40 (T3); bio-primed, UPM23 (T4); bio-primed, UPM23+40 (T5) and the controls as hydro- primed (T6) and non- primed seeds (T7). Trichoderma isolates used either singly (UPM 23 and UPM40) or as a mixture (UPM23+40) colonized the seed surface with germinating hyphae after 12 hours of bio-priming. Bacterial isolate, P. aeruginosa was also detected to colonize the seed surface with increase in the colony forming unit (CFU) from 1.2 × 109 to 5.1 × 109 seed-1 after the bio-priming period. Bio-priming was effective to control pre and post-emergence damping-off and promote seed germination, seedling establishment and growth in the presence of C. truncatum in soybean seeds. Under the glass house conditions, Trichoderma isolates however, gave better control of pre and post-emergence damping-off and enhancement of growth followed by bio-priming with UPM13B8 and chemo-priming with Benlate®. Under the field conditions, UPM13B8 was better in controlling pre and post-emergence damping-off ranging from 48.64 to 51.85% and 65.0 to 97.20%, respectively and also enhanced seed germination, final seedling stand and increase in shoot length and dry weight of seedling. However, the biocontrol efficacy and subsequent growth enhancement of UPM13B8 were not significantly (P≤0.05) different from UPM40 or UPM23+40 or the fungicide ‘Benlate®’.
Bio-priming with Malaysian isolates of P. aeruginosa and T. harzianum offered an effective biological seed treatment system and an alternative to chemo-priming with Benlate® to control seed-borne infection by C. truncatum in seeds and seedlings of soybean. Besides, they also improve seed germination, seedling establishment and vegetative growth. This study has explored up new dimension of biological control for preventive as well as remedial of seed-borne infection by C. truncatum. Thus, bio-priming can be exploited by seed companies and organic farmers in the sustainable agriculture, which would be more economical and environmental friendly
Coping with floods : the experience of rural women in Bangladesh : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University
No full textThis study focuses on how rural women in Bangladesh, who live in the poorest sector of one of the poorest countries in the world, cope with floods. It seeks to explain the principal factors structuring their responses. It addresses several related questions: how do women perceive and experience floods? What problems do they face and how do they respond to them? Arc they merely the passive victims of floods or do they play an active role in protecting their households? Do all women use the same coping strategies? Are the major parameters of rural society changed as a consequence of the way in which women cope with floods? In responding to these questions a sociological perspective is adopted but not to the exclusion of other approaches. However, it is the social and sociological aspects of the phenomena being explored which are of most concern to the author. The occurrence of floods in Bangladesh is as old as its history but over the last 40 years (1954-1995) the problem has become greatly aggravated and is now one of the main concerns of most rural households, life in which is precarious even in non-flood conditions. These problems affect women more severely than men because of the wider range of responsibilities that they have for their households and the fact that those responsibilities keep them tied to their households more strictly and more effectively than those of male members. Those responsibilities include food processing and cooking, cleaning, collecting water and fuel, bearing and rearing children, looking after livestock and income generation, all of which become much more difficult to perform under flood conditions. Despite this heavy burden, which women bear in extremely difficult circumstances, they demonstrate considerable fortitude and ingenuity in their attempts to maintain the livelihoods of their households. Explanation of these phenomena is sought in the economic, cultural and political structure of the country. Factors stressed in this study are the male-dominated structures of a predominantly conservative and Muslim society; the dominance of parda in the sub-culture of women and the position of women within the socio-economic context of their households
Ralstonia solanacearum: A Threat to Potato Production in Bangladesh
No full textPotato is one of the most important vegetable crop in Bangladesh which made it 7th producer in the world. This vegetable crop is affected by one of the most notorious soil borne pathogen, Ralstonia solanacearum and caused wilt symptoms in plant and brown rot in potato tuber throughout the world. The pathogen entered into the plants through different natural opening and wounds and is easily disseminated via infected biological material (seeds, vegetatively propagative materials, plants etc.), soil, contaminated irrigation water, surface water, farm equipment etc. and could survive for many years in association with alternate hosts. The bacteria is a quarantine organism being economically a serious problem for potatoes and other major crops in many tropical, subtropical and warmer areas of the world. It has an unusually wide host range including economically important crops (potato, tomato, tobacco, banana, ginger, geranium etc.) and weeds. The disease appeared as rapid and fatal wilting symptoms in the potato plants and vascular browning and/or rotting on tubers. The pathogen can be detected through the isolation of the bacteria on semi-selective TZC and/or selective SMSA (modified) media and through different biochemical tests and/or molecular test. It is a Gram-negative type bacterium, subdivided into five races based on host range and race I biovar 3 is reported in Bangladesh. Direct yield losses caused by R. solanacearum may vary 33 to 90% depending on the different factors such as cultivar, climate, soil type, cropping pattern, strain of the bacteria etc. Due to the latent infection of tuber by this organism, Bangladesh had been facing a temporary embargo on potato export which was imposed by Russia during 2014-15. But, latency and some other survival strategy of the pathogen created much more problems with disease detection, control and dispersal. The biological features of this pathogen makes it unusually successful against the traditional management practices. Therefore, the review focused on the biological abilities of R. solanacearum in relation to dispersal, survival and influences which might be important in designing effective management against the pathogen. [Fundam Appl Agric 2018; 3(1.000): 407-421
Ultrastructural studies of soybean seed-borne infection by Diaporthe phaseolorum var. sojae and screening of antagonistic potentiality by selected biocontrol agents in vitro
No full textThe association of Diaporthe phaseolorum var. sojae with soybean seed decay was examined by ultrastructural studies using light microscopy and scanning electron microscopy. The fungus was detected over the seed surface as whitish-grey mycelial growth and scattered black pycnidia. Hyphae and pycnidia were also observed in palisade, hourglass and parenchyma cell layers of the seed coat. Mycelial growth of D. phaseolorum var. sojae was abundant in the hourglass cell layer compared with other layers of the seed coat. Neither mycelium nor pycnidium was found in any tissues of the cotyledon and embryo of the infected seed. Asymptomatic seeds were free from infections. Artificial seed inoculation with D. phaseolorum var. sojae significantly reduced seed germination over control by 21.2% and increased seed rot by 120% in sterilized soil under glass house conditions. Six isolates of Trichoderma and three isolates of bacteria were tested in vitroagainst D. phaseolorum var. sojae in dual culture test. Among these organisms, T. harzianum isolate UPM40 exhibited the most antagonistic potential based on Percent Inhibition Radial Growth (PIRG) of 92.9% and shortest time needed (7 days) to overgrow the D. phaseolorum var. sojae colony as compared to other tested isolates
Major postharvest fungal diseases of papaya cv. 'Sekaki' in Selangor, Malaysia
No full textA total of seven fungi were identified from the surface of fully matured papaya fruits cv. 'Sekaki' collected form two different fields namely University Agriculture Park, UPM and MARDI, Selangor and a fruit exporter [Seng Chew Hup Kee (M) Sdn Bhd, Kajang, Selangor, Malaysia]. They were identified as Botryodiplodia theobromae, Colletotrichum capsici, C. gloeosporioides, Fusarium sp., Phomopsis sp., Rhizopus stolonifer and Stemphylium sp.. Among the diseases, the highest incidence ranged from 90 to 98% and severity of 25 to 38% were recorded for anthracnose caused by C. gloeosporioides for all three sources, followed by stem-end-rot caused by Botryodiplodia theobromae. Pathogenicity test showed that both wounded and unwounded fruits inoculated with conidial suspension of C. gloeosponoides developed distinct symptoms of anthracnose after three and five days of inoculation, respectively
Potential co-application of Burkholderia cepacia, calcium and chitosan on enhancement of storage life and quality of papaya fruits
No full textThe fruit of harvested papayas (cv. Sekaki), at colour stage two (mature-green with trace yellow), were treated with fungicide benocide® (0.33 gL-1) or with a combination of Burkholderia cepacia B23 (109 CFU mL-1) and 0.75% chitosan solution, amended with 3% calcium chloride and stored at 14 ± 0.5ºC and 90-95% RH for 28 d. The effectiveness of the treatments was assessed by evaluating their impacts on storability and changes in the quality attributes of fruits. Results indicated that fruit treated with the combination of B. cepacia B23-chitosan-CaCl2 showed delayed climacteric ethylene evolution and reduced respiration rate. The combined treatment reduced weight loss by more than 25% to the control. It also markedly slowed down the ripening of fruits, as shown by their retention of firmness 4.17 N after storage. Moreover, a delayed change in external colour and pH without compromising fruit quality was observed in the fruit receiving the combined treatment. The storage life was thus extended up to 15 d compared to the control. In addition, the incorporation of 3% CaCl2 into the combined treatment significantly increased the calcium content (81%) in the fruit compared to the control, resulting in the improved nutritional value of the papaya. This study provided an alternative method for fungicides treatment of papaya at post-harvest
Antagonistic potential of selected fungal and bacterial biocontrol agents against Colletotrichum truncatum of soybean seeds
No full textTen fungal and bacterial biocontrol agents (BCAs) were evaluated in vitro for their antagonistic potential against Colletotrichum truncatum isolated from soybean seeds. Two fungal BCAs namely Trichoderma virens isolate UPM23 and Trichoderma harzianum isolate UPM40 and a bacterial BCA namely Pseudomonas aeruginosa isolate UPM13B8 strongly inhibited the growth of C. truncatum based on high PIRG values in dual culture and culture filtrate tests. Studies on the mechanism of action using mycoparasitism technique and antibiosis observed under light microscope revealed that T. virens and T. harzianum inhibited the growth of C. truncatum by coiling and penetration into the hyphae. Consequently, the hyphae of C. truncatum became malformed and swollen. Pseudomonas aeruginosa also caused mycelial malformation; the mycelia turned vacuoled and swollen in or at tips of hyphae. Pseudomonas aeruginosa gave the highest PIRG value in the culture filtrate test, suggesting that antibiosis could be the main mechanism of antagonism. No inhibitory effect was observed on soybean seeds and seedlings when the seeds were artificially inoculated with T. virens, T. harzianum and P. aeruginosa. On the contrary, T. virens and T. harzianum were found to enhance seed germination and seedling establishment, while P. aeruginosa enhanced fresh and dry weights of seedlings
Antimicrobial activities of chitosan and calcium chloride on in vitro growth of Colletotrichum gloeosporioides from papaya
No full textThe antimicrobial activities of chitosan and calcium chloride (CaCl2) on the growth, spore germination, and hyphal morphology of Colletotrichum gloeosporioides, isolated from naturally infected papaya fruits, was investigated in in vitro studies. Chitosan was found to inhibit the radial growth and spore germination of the fungus significantly at higher concentrations. Radial growth was inhibited by 52 and 82% with 0.75 and 1% chitosan, respectively. Spore germination was completely inhibited in Potato Dextrose Agar (PDA) medium containing 0.5% and above chitosan concentrations. Light microscope observations showed that chitosan induced morphological changes, including abnormal branching, swelling hyphal tips, vacuolation and distortion. Calcium chloride at 1 to 4% had no pronounced effects on mycelial growth inhibition. However, PDA amended with 3 and 4% CaCl2 significantly (P≤0.05) inhibited about 26% of spore germination relative to the control. Findings from these experiments demonstrated that chitosan has suppressive activity against C. gloeosporioides of papaya and could be used as part of a disease management program. Nevertheless, to a lesser extent, CaCl2 can also be included as part of the program
Rate of Wound Infection of Non-traumatic Emergency Laparotomy at a Teaching Hospital in Bangladesh: Experience of 100 cases
No full textBackground: Wound infection is an important issue for surgical operations. Objective: The purpose of the present study was to measure the rate of wound infection of non-traumatic emergency laparotomy cases.Methodology: This descriptive cohort study was carried out in the Department of Surgery at Dhaka Medical College, Dhaka from July 1997 to June 1998 for a period of 1(one) year. Pre-operative patients were carefully assessed for any host factors related to wound infection. Different per-operative factors that influence the rate of postoperative wound infection were also analyzed. Swabs were taken from the suspected postoperative wound and sent for bacteriological examination. Result: In this series, 100 cases of emergency laparotomies (non-traumatic) were analyzed. Bacteriological examination showed positive culture in most of the cases but three were found to be negative result. Wound infection rate of specific type of operation were 12.5%, 20.0%, 6.6%, 40.0%, 40.0%, 33.3%, 50.0%, 50.0%, and 100.0% in duodenal ulcer perforation, pre-pyloric and gastric ulcer perforation, acute appendicitis, burst appendix, ileal perforation, small intestinal obstruction due to bands and adhesions, volvulus of sigmoid colon, obstructed inguinal hernia, generalized peritonitis due to puerperal sepsis respectively. The overall surgical wound infection rate was 19.0%. Conclusion: The rate of wound infection of non-traumatic emergency laparotomy cases are frequently found in a well-established tertiary care teaching hospital. Bangladesh J Infect Dis 2015;2(1):9-12</jats:p
Association of serum ferritin with insulin resistance in women with polycystic ovarian syndrome
No full textBackground: Emerging scientific evidence has disclosed unsuspected influences between iron metabolism, insulin resistance and type 2 diabetes. Even mildly elevated body iron stores are associated with statistically significant increases in glucose homeostasis indices. But till now high serum ferritin associated with type 2 diabetes is not recognized as an entity in the current clinical guidelines for the management of type 2 diabetes.Methods: This was a Cross sectional study carried out from September 2016 to March, 2017 at PCO clinic of infertility outpatient department (OPD), department of obstetrics and gynecology, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh. The study population consisted of all the diagnosed PCOS patients. Purposive sampling Main outcome variable: serum ferritin level and insulin resistance index (Homeostatic model assessment of insulin resistance: HOMA-IR).Results: Most of the (90.9%) patients were aged 20-30 years having BMI >25 kg/m2, mostly overweight (52.53%) or obese (25.25%). Significant increase of serum ferritin level (72.89±34.97; p=0.001) was noted in PCOS patients with insulin resistance. Marked increase in serum ferritin (82.81±31.57, p<0.001), fasting serum insulin (16.39±7.1; p<0.001), HOMA-IR (3.51±1.55; p<0.001) and more cases with insulin resistance (78.3%; p<0.001) were found in women with high ferritin level (when ≥45.5 ng/ml). Statistically significant strong positive correlation between serum ferritin level and fasting insulin level (r=0.528; p<0.001) as well as HOMA-IR (r=0.492; p<0.001) were observed.Conclusions: These results demonstrated that elevated level of serum ferritin was associated with insulin resistance in PCOS women
