Pyrethrins and flower yield of pyrethrum (Chrysanthemum cinerariaefolium Viz.) plants were determined after application of ethrel, chlormequat chloride and paclobutrazol. Ethrel at 50, 100, 250 and 500 mg l -l produced a significant positive effect on pyrethrins level, decreased plant height, while 50 and 100 mg l -l significantly increased fresh and dry flower yield. Chlormequat chloride at 1000 and 2000 mg l -l and paclobutrazol (80 and 160 mg l -l ) increased pyrethrins level, single flower weight and decreased plant height and flower yield. 14 C-acetate incorporation studies further substantiated positive effect of growth retardants on pyrethrins biosynthesis. The effect of growth retardants on pyrethrins seems to be mediated through its effect on biosynthesis.
The present study evaluated the effects of glyphosate on Pisum sativum germination as well as its effect on the physiology and biochemistry of germinated seedlings. Different physico-chemical biomarkers, viz., chlorophyll, root and shoot length, total protein and soluble sugar, along with sodium and potassium concentration, were investigated in germinated seedlings at different glyphosate concentrations. This study reports the influence of different concentrations of glyphosate on pea seeds and seedlings. Physicochemical biomarkers were significantly changed by glyphosate exposure after 15 days. The germination of seedlings under control conditions (0 mg/L) was 100% after 3 days of treatment but at 3 and 4 mg/L glyphosate, germination was reduced to 55 and 40%, respectively. Physiological parameters like root and shoot length decreased monotonically with increasing glyphosate concentration, at 14 days of observation. Average root and shoot length (n=30 in three replicates) were reduced to 14.7 and 17.6%, respectively, at 4 mg/L glyphosate. Leaf chlorophyll content also decreased, with a similar trend to root and shoot length, but the protein content initially decreased and then increased with an increase in glyphosate concentration to 3 mg/L. The study suggests that glyphosate reduces the soluble sugar content significantly, by 21.6% (v/v). But internal sodium and potassium tissue concentrations were significantly altered by glyphosate exposure with increasing concentrations of glyphosate. Biochemical and physiological analysis also supports the inhibitory effect of glyphosate on seed germination and biochemical effects on seedlings.
This study focused on isolation and identification of possible phosphate‐solubilizing bacteria (PSB) from the sewage‐fed East Kolkata Wetland (EKWL), a prospective water resource for pisciculture. In addition, different limnological parameters have been correlated with orthophosphate and seasonal variations. PSB have been isolated in Pikovskaya medium and identified morphologically and biochemically and finally analysed by 16S rDNA gene sequence. Limnological studies involving temperature (potentiometric), pH (potentiometric), dissolved oxygen (iodometric), ammonia‐nitrogen (spectrophotometric) and orthophosphate (spectrophotometric) concentrations were conducted. The results of this study established the presence of Bacillus megaterium, a potential PSB in EKWL. The activity of B. megaterium is also supported by the seasonal orthophosphate variations. The changes in concentration of other limnological parameters were also prominent. The water quality parameters of temperature (r = 0.886), dissolved oxygen (r = 0.729) and ammonia‐nitrogen (r = 0.396) concentrations exhibited a positive correlation with orthophosphate and a negative correlation with pH (r = −0.699). The B. megaterium obtained in this study, exhibited a significant alteration in regard to orthophosphate content and relationships with other factors. Further experiment on the soluble phosphorus solubilization potential of B. megaterium revealed the biological availability of phosphorus was increased by threefold after 120 hr of incubation, with the decreasing pH value, although the phytase activity was 0.419 U/ml. PSB have a vital function in plant nutrition in supplying phosphate, essential nutrients and its uptake results in appropriate functioning and metabolism of different aquatic plants and organisms. PSB are competent biofertilizer to amplify aquaculture production for sustainable development.
Stratification and assessment of the limnological conditions of an abandoned opencast coal pit (OCP), locally called Khadan, which is a potential water reserve located at the Raniganj-Asansol Coalfield Areas of Burdwan, are the main objectives of this study. Water quality changes occurred with increasing depths in the OCP water and suggest a gradual and significant ecological restoration over time, which can create a condition of sustainable pisciculture. The physical and chemical variables of the OCP water changed with changing depths and seasons. The temperature and alkalinity decreased with depth throughout the year. The dissolved oxygen concentration exhibited a mixing characteristic in the summer and winter, but decreased with depth in the monsoon and postmonsoon seasons. The total hardness increased with depth in the monsoon season, being maximum in the winter (196.0 mg L À1 ). The biochemical oxygen demand (BOD) and chemical oxygen demand (COD) increased with depth in the winter. The silicon concentration increased with depths, exhibiting a maximum value of 14.2 mg L À1 in the winter and a minimum value of 1.24 mg L À1 in the postmonsoon season. The ammonia-nitrogen, nitrate-nitrogen, potassium, chloride and sulphate concentrations only exhibited seasonal variations. The concentration of heavy metals (arsenic, chromium, cadmium, manganese) decreased with increasing depth. The fluoride concentration exhibited high concentrations in each OCP water layer. The results of this study indicated that limnological variables in thermally stratified lakes may be an important measure for better understanding the gradual process of developing an improved ecological conditions in the OCP and which can facilitate the possibility of pisciculture in the near future.
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