Petiole explants were obtained from in vitro grown diploid (2x = 22) Echinacea purpurea plantlets. Shoots were regenerated by culturing the explants on MS basal medium containing 0.3 mg/L benzyladenine (BA), 0.01 mg/L naphthaleneacetic acid (NAA) and four concentrations (30, 60, 120, and 240 mg/L) of colchicine for 30 days, or 120 mg/L of colchicine for various durations (7, 14, 21, and 28 days). The regenerated shoots were induced to root on MS basal medium with 0.01 mg/L NAA, and then the root-tips of the regenerated shoots were sampled for count of chromosome number. It was found that a treatment duration of >7 days was necessary for induction of tetraploid (4x = 44) shoots, and treatment with 120 mg/L colchicine for 28 days was the most efficient for induction of tetraploids, yielding 23.5% of tetraploids among all the regenerated shoots. Chimeras were observed in almost all the treatments. However, the ratio of tetraploid to diploid cells in a chimeric plant was usually low. In comparison with diploid plants, tetraploid plants in vitro had larger stomata and thicker roots with more root branches, and had prominently shorter inflorescence stalk when mature.
Anthers containing microspores at the uninucleate stage were excised from capitula of field grown plants of purple coneflower, Echinacea purpurea, and cultured on medium conducive to callus growth. In callus induction cultures, N6 basal medium was more effective than Murashige and Skoog (MS), and a combination of benzyladenine (BA) at 2.22 lM with naphthaleneacetic acid (NAA) at 0.054 lM was more effective than 2,4-dichlorophenoxyacetic acid (2,4-D) alone at 4.52, 9.05 and 13.57 lM. Callus induction rate as high as 85.8% was achieved, and no statistically significant differences were found among cultures with various densities of 20, 40, 60, 80 and 100 anthers per bottle each filled with 40-ml medium. Shoots were regenerated from calluses on MS medium containing 2.22 lM BA and various concentrations of NAA, with the highest regeneration rate of 95.24% obtained when 0.27 lM NAA was applied. Although a large portion of the regenerated shoots had prominent symptom of vitrification, some normal shoots could be easily rooted on MS medium containing 0.054 lM NAA. Thirty regenerated plants were randomly selected and 19 of them were confirmed to be haploid by observation of chromosome number of root-tip cells.
Background Continuous positive airway pressure (CPAP) therapy is commonly used for respiratory failure due to severe COVID-19 pneumonitis, including in patients deemed not likely to benefit from invasive mechanical ventilation (nIMV). Little evidence exists demonstrating superiority over conventional oxygen therapy, whilst ward-level delivery of CPAP presents practical challenges. We sought to compare clinical outcomes of oxygen therapy versus CPAP therapy in patients with COVID-19 who were nIMV. Methods This retrospective multi-centre cohort evaluation included patients diagnosed with COVID-19 who were nIMV, had a treatment escalation plan of ward-level care and clinical frailty scale ≤ 6. Recruitment occurred during the first two waves of the UK COVID-19 pandemic in 2020; from 1 st March to May 31 st , and from 1 st September to 31 st December. Patients given CPAP were compared to patients receiving oxygen therapy that required FiO 2 ≥0 . 4 for more than 12 hours at hospitals not providing ward-level CPAP. Logistic regression modelling was performed to compare 30-day mortality between treatment groups, accounting for important confounders and within-hospital clustering. Findings Seven hospitals provided data for 479 patients during the UK COVID-19 pandemic in 2020. Overall 30-day mortality was 75.6% in the oxygen group (186/246 patients) and 77.7% in the CPAP group (181/233 patients). A lack of evidence for a treatment effect persisted in the adjusted model (adjusted odds ratio 0.84 95% CI 0.57-1.23, p=0.37). 49.8% of patients receiving CPAP-therapy (118/237) chose to discontinue it. Interpretation No survival difference was found between using oxygen alone or CPAP to treat patients with severe COVID-19 who were nIMV. A high patient-initiated discontinuation rate for CPAP suggests a significant treatment burden. Further reflection is warranted on the current treatment guidance and widespread application of CPAP in this setting.
Grain yield in rice is a complex trait and highly dependent on the other agronomic characters. Agronomic characters and grain yield of twenty traditional rice cultivars were evaluated at Faculty of Agriculture, University of Ruhuna in Maha-2010/2011 and in Yala/2011. The experiment was conducted according to the randomized complete block design with three replicates. Twenty plants from each cultivar were evaluated for the selected characters, Plant height, Leaf blade length, Leaf blade width, Number of tillers, Number of reproductive tillers, Panicle length, Number of spikelets per panicle, Number of fertile spikelets per panicle, Number of infertile spikelets per panicle, Seed length, Seed width, 100 seed weight and Yield per plant. Recommended modern rice cultivar Bg 379/2 was used as the reference. Deviations of each character in different traditional rice cultivars from those of recommended rice cultivar Bg 379/2 were recorded. The average plant height of the tallest rice cultivar, Podihatatha was 198 cm and that of the shortest rice cultivar, Rathranwee was 68 cm. The longest leaf blade and longest culm length were also belonged to Podihatatha. The highest number of tillers (9.6 tillers per plant) and the highest average number of reproductive tillers (9 per plant), were recorded by rice cultivar Mahasudu wee. The highest value of 100 seed weight was recorded by rice cultivar Galpa wee. However, the most important economical character, the highest yield per plant (28.52g/plant) was recorded by Thanthiribalan which was significantly higher than that of in the recommended rice cultivar Bg 379/2 (26.5 g/plant). Significant correlations were found between the yield per plant and the characters such as number of reproductive tillers (r = 0.692), panicle length (r = 0.565) and number of spikelets per panicle (r = 0.761). Agronomic data collected in the present study would be important to understand the suitability of an individual rice cultivar for the farmer field.
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