Herbicide application strategies for wild radish management in Imidazolinone tolerant faba bean

The extensive and continual use of herbicides in cropping situations has inevitably led to the phenomenon of "herbicide-resistance" in weeds and this has become one of the most challenging issues in modern agriculture. Herbicide-tolerant crops (HTC) were introduced to diversify weed management practices, but the lack of integrated weed management strategies, along with the continuous use of the same herbicide mode of action (MOA) demanded by the HTC has continued to impose selection pressure on weeds to evolve with herbicide resistance. Consequently, this thesis has been focused on the introduction of herbicide MOA combinations into HTC systems in an attempt to reduce the rate of herbicide resistance evolution in weeds. Raphanus raphanistrum is the number one broadleaf weed in Australia, and for this case study, the newly released ALS-inhibiting imidazolinone tolerant faba bean cultivar PBA Bendoc with its conventional cultivar, PBA Samira, were selected as the study species. ALS-inhibiting (imazamox + imazapyr and imazethapyr) and PSII-inhibiting (metribuzin) herbicides were used as the two herbicide MOAs. The herbicide sensitivity of R. raphanistrum was initially evaluated at different growth stages, in glasshouse studies using herbicide-resistant and susceptible biotypes to ALS-inhibiting herbicides. The highest susceptibility was observed at the earliest growth stage regardless of the biotype and Imazamox + imazapyr proved to be more effective in controlling both biotypes compared to imazethapyr. The same two herbicides were tested on faba bean cultivars at different growth stages to assess crop tolerance and identify the herbicide application window. The field trials conducted in 2018 and 2019 showed increased ALS-inhibiting herbicide tolerance in PBA Bendoc compared to PBA Samira even at the most advanced growth stage. Both faba bean cultivars were then evaluated for their tolerance to metribuzin in-crop application at different herbicide rates. Both cultivars responded similarly, showing progressive herbicide damage with increasing application rates. However, the reduced pod number, even at the lowest rate used, flagged the possible yield penalties that may result in using in-crop metribuzin applications. It is thus suggested that metribuzin must be used post sowing pre-emergent (PSPE) respecting the label recommendations. The potential herbicide combinations were then tested on herbicide-resistant R. raphanistrum and PBA Bendoc to evaluate their efficacies. Metribuzin was initially used as PSPE in all combinations, and was to be followed by imazamox + imazapyr applications at the same growth stages of the weed and the crop as in previous experiments. However, 100% control of R. raphanistrum was achieved using metribuzin alone, and thus no second herbicide was required. All the assessed herbicide combinations were tolerated by PBA Bendoc, proving the suitability of these herbicide combinations for incorporation into the PBA Bendoc cropping system. These results led to two potential herbicide combination strategies: (i) herbicide rotations, with metribuzin as PSPE in one year along with another potential herbicide MOA in the following year, (ii) herbicide sequential application, with metribuzin applied at PSPE and imazamox + imazapyr applied at the 2-4 leaf stage if R. raphanistrum plants survived the metribuzin treatment. A seed germination study was conducted under different temperature/photoperiods, pH levels, osmotic potentials, salinity and burial depths to identify the optimal germination conditions for R. raphanistrum. The optimum germination conditions for both herbicide-resistant and susceptible biotypes of R. raphanistrum were found to be 25ºC/15ºC temperature range under 24 hours complete dark. However, the significant interaction between photoperiod and temperature indicated that the seed germination under higher temperatures is less favoured by 24 hours dark conditions regardless of the biotype. An increased moisture stress tolerance in herbicide-resistant seeds was observed, whilst both biotypes reacted similarly to different pH levels and burial depths. In summary, this thesis has elucidated the effectiveness of two herbicide MOAs in controlling R. raphanistrum while addressing the crop tolerance to these herbicide MOA combinations. These findings will help in setting up stewardship guidelines to be used with the PBA Bendoc faba bean cultivar to mitigate the misuse of herbicides, thus ensuring their sustainable application. In addition, the demonstration of differential seed germination requirements of resistant and susceptible R. raphanistrum seeds has provided further information to help with its systematic management. Overall, this study can be used as a case study to investigate herbicide options that can be used in different HT crop cultivars to control a range of weed species.Doctor of Philosoph

A global review of the woody invasive alien species mimosa pigra (giant sensitive plant): Its biology and management implications

Populations of invasive alien plants create disruptive plant communities that are extremely adaptable, imposing severe ecological impacts on agriculture, biodiversity and human activities. To minimise these impacts, prevention and effective weed management strategies are urgently required, including the identification of satellite populations before they invade new areas. This is a critical element that allows weed management practices to become both successful and cost-effective. Mimosa pigra L. (Giant sensitive plant) is an invasive weed that has spread across various environments around the world and is considered one of the world’s top 100 most invasive plant species. Being adaptable to a wide range of soil types, in addition to its woody protective prickles and low palatability, M. pigra has quickly spread and established itself in a range of habitats. Current control methods of this species include biological, chemical and physical methods, together with attempts of integrated application. Reports suggest that integrated management appears to be the most effective means of controlling M. pigra since the use of any single method has not yet proved suitable. In this regard, this review synthesises and explores the available global literature and current research gaps relating to the biology, distribution, impacts and management of M. pigra. The contribution of this work will help guide land managers to design appropriate and sustainable management programs to control M. pigra

Correlation Analysis of Grass and Broad Leaves in Relation to Moisture Using Quadrat and Interrupted Belt Transect Techniques

This paper presents a study on the correlation between grass and broad leaves, as well as their relationship with moisture. The data was collected using a quadrat and an interrupted belt transect method. The paper employs Spearman’s rank correlation, t-test test to analyze the data. The results reveal insights into the potential relationships and effects on grass and broad leaves in the given area.Spend two days to finish off this paper Special thanks to Methul, Isala, Yasitha & Siraj :) And all who supported to make this a reality Thank you all for +1000 views it means lot to us (31 AUG) :

Amaranthus retroflexus L (redroot pigweed) : effects of elevated CO2 and soil moisture on growth and biomass and the effect of radiant heat on seed germination

Amaranthus retroflexus L. (Amaranthaceae), Redroot pigweed, is native to North America, but has become a weed of agriculture worldwide. Previous research into competition with food crops found it significantly reduces yields. Additionally, taxonomy, biomass allocation, physiological responses to light intensity, water stress, elevated CO2, and herbicide resistance have been inves-tigated. To extend other research findings, we investigated growth and biomass yield in response to (i) soil moisture stress, and (ii) drought and elevated CO2. Additionally, we investigated seed germination rates following exposure to three elevated temperatures for two different time periods. Overall, moisture stress reduced plant height, stem diameter, and number of leaves. Elevated CO2 (700 ppm) appeared to reduce negative impacts of drought on biomass productivity. Heating seeds at 120◦C and above for either 180 or 300 s significantly reduced germination rate. These results inform an understanding of potential responses of A. retroflexus to future climate change and will be used to predict future occurrence of this weed. The finding that exposing seeds to high temperatures retards germination suggests fire could be used to prevent seed germination from soil seed banks, particularly in no-till situations, and therefore may be used to address infestations or prevent further spread of this weed. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. **Please note that there are multiple authors for this article therefore only the name of the first 5 including Federation University Australia affiliates “Sandra Weller, Singarayer Florentine, Amali Welgama, Aakansha Chadha, Chrisopher Turville" are provided in this record*

A retrospective analysis of cannabis use in a cohort of mentally ill patients in Sri Lanka and its implications on policy development

<p>Abstract</p> <p>Background</p> <p>Several epidemiological studies have shown that cannabis; the most widely used illegal drug in the world, is associated with schizophrenia spectrum disorders (SSD).</p> <p>Aims</p> <p>To assess the characteristics of cannabis use and its association with SSD in a cohort of psychiatrically ill patients and discuss the implications for policy development</p> <p>Methods</p> <p>This is a retrospective analytical study of a cohort of psychiatric patients who received treatment in the psychiatry unit of the Provincial General Hospital, Ratnapura, Sri Lanka over five years (2000 - 2004). The schizophrenia spectrum disorders defined in this article include schizophrenia and the schizoaffective disorders.</p> <p>Results</p> <p>A total of 3644 patient records were analyzed. The percentage of self reported life time cannabis (LTC) use was 2.83% (103, all males). Sixteen percent (576) of the total cohort was diagnosed with SSD by 2009. Male sex and LTC use were significantly associated with SSD (p < 0.01 and 0.001 respectively). In the majority (91.5%), cannabis use preceded the diagnosis. There were 17(16.5%) patients diagnosed as cannabis induced psychosis and 7 (41.2%) of them were subsequently diagnosed as SSD. This group was significantly more likely to have had a past psychiatric consultation, but other demographic and clinical correlates did not differ from the rest of the LTC users.</p> <p>Conclusions</p> <p>Self reported LTC use was strongly associated with being diagnosed with SSD. However we could not identify a particular subgroup of users that are at increased risk to recommend targeted primary prophylaxis. The policy implications of this observation are discussed.</p

Symptoms of anxiety and depression in adolescent students; a perspective from Sri Lanka

Background: Sri Lanka recorded an extraordinary high suicide rate for adolescents aged 15 - 19 in the early 1990s (46.5/100,000). With this in perspective, the Ministry of Health in Sri Lanka recommends school programmes for adolescents by mental health units of local hospitals.Methods: We conducted cross sectional surveys to screen for symptoms of anxiety and depression among students aged 14 - 18 during school mental health programmes. Two schools were randomly selected within the Ratnapura municipality (urban population of approx. 50,000), Sri Lanka and all students aged 14-18 were assessed with self administered (pre tested, Sinhalese translations) questionnaires [Center for epidemiologic studies depression scale, Anxiety screening test of suicide and mental health association international].Results: A total of 445 students were assessed (male-54.4%, female 45.6%). Thirty six percent screened positive for depression (mild depression-17%, severe depression-19%) and 28% screened positive for severe anxiety. Females screened positive for depression and anxiety significantly more than the males (p = 0.0001, 0.005 respectively). Students in classes facing barrier examinations at the end of the year had the highest positivity rates. Examination related issues (36%) were the most commonly cited problem.Recommendations: It is recommended that:. 1. School mental health development programmes in Sri Lanka concentrate more on reducing examination related stress, and in particular focus on the female students. 2. Policy decisions are made to reduce competition for higher education. 3. A nationally coordinated survey on mental health of adolescent students is carried out utilizing the island-wide network of medical officers of mental health. © 2010 Rodrigo et al; licensee BioMed Central Ltd

Incidence and effects of Varicella Zoster Virus infection on academic activities of medical undergraduates - a five-year follow-up study from Sri Lanka

<p>Abstract</p> <p>Background</p> <p>The adult population in Sri Lanka is having high level of susceptibility for Varicella Zoster Virus (VZV) infection. Among medical undergraduates, 47% are VZV seronegative. The purpose of the present study was to determine the incidence of VZV infection in medical undergraduates in Sri Lanka, and to describe the effects of VZV infection on their academic activities.</p> <p>Methods</p> <p>A retrospective cohort of medical undergraduates' susceptible for VZV infection was selected from the University of Peradeniya, Sri Lanka. Data on the incidence of VZV infection (Chickenpox) during their undergraduate period was collected using a self-administered structured questionnaire. A second questionnaire was administered to collect data on the details of VZV infection and the impact of it on their academic activities. VZV incidence rate was calculated as the number of infections per 1,000 person years of exposure. Descriptive statistics were used to describe the impact of VZV infection on academic activities.</p> <p>Results</p> <p>Out of the 172 susceptible cohort, 153 medical undergraduates were followed up. 47 students reported VZV infection during the follow up period and 43 of them participated in the study. The cumulative incidence of VZV infection during the period of five and half years of medical training was 30.7%. Incidence density of VZV infection among medical undergraduates in this cohort was 65.1 per 1,000 person years of follow-up. A total of 377 working days were lost by 43 students due to the VZV infection, averaging 8.8 days per undergraduate. Total academic losses for the study cohort were; 205 lectures, 17 practicals, 13 dissection sessions, 11 tutorials, 124 days of clinical training and 107 days of professorial clinical appointments. According to their perception they lost 1,927 study hours due to the illness (Median 50 hours per undergraduate).</p> <p>Conclusions</p> <p>The incidence of VZV infection among Sri Lankan medical undergraduates is very high and the impact of this infection on academic activities causes severe disruption of their undergraduate life. VZV immunization for susceptible new entrant medical undergraduates is recommended.</p

Viral Load, Clinical Disease Severity and Cellular Immune Responses in Primary Varicella Zoster Virus Infection in Sri Lanka

BACKGROUND: In Sri Lanka, varicella zoster virus (VZV) is typically acquired during adulthood with significant associated disease morbidity and mortality. T cells are believed to be important in the control of VZV replication and in the prevention of reactivation. The relationship between viral load, disease severity and cellular immune responses in primary VZV infection has not been well studied. METHODOLOGY: We used IFNgamma ELISpot assays and MHC class II tetramers based on VZV gE and IE63 epitopes, together with quantitative real time PCR assays to compare the frequency and phenotype of specific T cells with virological and clinical outcomes in 34 adult Sri Lankan individuals with primary VZV infection. PRINCIPAL FINDINGS: Viral loads were found to be significantly higher in patients with moderate to severe infection compared to those with mild infection (p&lt;0.001) and were significantly higher in those over 25 years of age (P&lt;0.01). A significant inverse correlation was seen between the viral loads and the ex vivo IFNgamma ELISpot responses of patients (P&lt;0.001, r = -0.85). VZV-specific CD4+ T cells expressed markers of intermediate differentiation and activation. CONCLUSIONS: Overall, these data show that increased clinical severity in Sri Lankan adults with primary VZV infection associates with higher viral load and reduced viral specific T cell responses