Character association and path analysis for yield and its related traits in finger millet (Eleusine coracana (L.) Gaertn) genotypes

The present investigation was conducted during Kharif, 2014 at Research Block, Department of Crop Improvement, College of Forestry, Ranichauri Campus, V.C.S.G. Uttarakhand University of Horticulture and Forestry. The thirty-five diverse genotypes of finger millet, Eleusine coracana (L.) including three checks viz., PRM-1, PRM-2 and VL-149 laid out in Randomized Complete Block Design with replication. The data on 14 quantitative traits viz., days to 50 per cent flowering, days to maturity, plant height (cm), flag leaf area (cm2), peduncle length (cm), number of leaves on main culm, number of productive tillers per plant, number of fingers per ear, finger length (cm), ear length (cm), biological yield per plant (g), harvest index (%), 1000 seed weight, grain yield per plant (g) were collect-ed randomly from 5 plants form each genotypes. Analysis of variance revealed highly significant differences among all thirty five genotypes with a wide range of mean values for different characters. Grain yield per plant exhibited very strong positive association with biological yield per plant (0.6196, 0.6805), harvest index (0.4370, 0.3624), number of productive tillers per plant (0.3950, 0.4477), 1000 seed weight (0.3697, 0.3972) and peduncle length (0.2473, 0.2694) at phenotypic and genotypic level. Path-coefficient analysis indentified biological yield per plant (0.8983, 1.1590) and harvest index (0.7390, 0.9162) as major direct contributors towards grain yield per plant at phenotypic and genotypic level. The characters identified above merit due consideration in formulating effective selection strategy in finger millet for developing high yielding varieties

Qualitative and quantitative assessment of diatom deformities and protoplasmic condition under metal and metalloid stress

Metals and metalloids are toxic, persistent, and non-biodegradable and can be biomagnified (e.g., Hg), and therefore pose a serious threat to the algal flora of aquatic ecosystems. This laboratory study tested the effects of metals (Zn, Fe, and Hg) and a metalloid (As) on the cell wall morphology and protoplasmic content of living cells of six widespread diatom genera over 28 days. Diatoms exposed to Zn and Fe had a higher frequency of deformed diatom frustules (> 1%) compared to the As, Hg, and control treatments ( Fe > Hg≈As. Deformities were more frequent in Achnanthes and Diploneis (adnate forms) than in the motile genera of Nitzschia and Navicula. The correlation between the % healthy diatoms and % deformities in all six genera showed a negative relationship with the integrity of protoplasmic content (i.e., greater alteration in protoplasmic content was associated with greater frustule deformation). We conclude that diatom deformities can be a good indicator of metal and metalloid stress in waterbodies and are very useful in the rapid biomonitoring of aquatic ecosystems

Climate change and diatoms

Climate change has triple-pronged effects – warming, deoxygenation, and acidification – in freshwater and marine environments, effects which have a full spectrum of impacts on primary producers. Diatoms are an appropriate model for indicating climate change effects because they are ubiquitous in aquatic ecosystems and are the most important primary producers in marine ecosystems (i.e., 40% of productivity) and contribute 20% of atmospheric oxygen, but have not been adequately studied in relation to climate change. Diatoms have numerous characteristics that can be used to measure the effects of climate change. For example, climate change may increase the relative abundance of dinoflagellates compared to diatoms, leading to more frequent occurrences of harmful algal blooms in marine ecosystems, where diatoms and dinoflagellates dominate blooms. Such blooms can have far-reaching impacts on ecosystems and can impact on humans by affecting fisheries, tourism, and other economic losses. These changing climatic scenarios may be accompanied by a change in the various life-forms of diatoms, such as a shift from mixed life-forms (undisturbed) to the dominance of pioneer and adnate diatoms (disturbed by an increase in carbon dioxide concentration) in the community. Diatoms store excess energy as lipids, and the number and biovolume of lipid bodies can be a valuable diagnostic tool for stress, including climate change. At the molecular level, organic lipid biomarkers can provide information to help decipher past and present climatic conditions, such as glaciation and deglaciation processes in polar regions. Reductions in diatom size and silica availability for frustule formation have been linked to increasing temperatures, such as those from global warming, in both freshwater and oceanic ecosystems – although not all studies are supportive. Finally, diatoms are excellent experimental organisms for indicating potential impacts of climate change on living organisms