Variations in soil microbial biomass and N availability due to residue and tillage management in a dryland rice agroecosystem   总被引：10，自引：0，他引：10  

C. P. Kushwaha  S. K. Tripathi  K. P. Singh   《Soil & Tillage Research》2000,56(3-4):153-166

Seasonal changes in the levels of soil microbial biomass C (MBC) and N (MBN), N-mineralization rate and available-N concentration were studied in rice–barley supporting tropical dryland (rainfed) agroecosystem under six combinations of tillage (conventional, minimum and zero tillage) and crop residue manipulation (retained or removed) conditions. Highest levels of soil MBC and MBN (368–503 and 38.2–59.7 μg g⁻¹, respectively) were obtained in minimum tillage residue retained (MT+R) treatment and lowest levels (214–264 and 20.3–27.1 μg g⁻¹, respectively) in conventional tillage residue removed (CT−R, control) treatment. Along with residue retention tillage reduction from conventional to zero increased the levels of MBC and MBN (36–82 and 29–104% over control, respectively). The proportion of MBC and MBN in soil organic C and total N contents increased significantly in all treatments compared to control. This increase (28% in case of C and 33% N) was maximum in MT+R and minimum (10% for C and N both) in minimum tillage residue removed (MT−R) treatment. In all treatments concentrations of N in microbial biomass were greater at seedling stage, thereafter these concentrations decreased drastically (21–38%) at grain-forming stage of both crops. In residue removed treatments, N-mineralization rates were maximum during the seedling stage of crops and then decreased through the crop maturity. In residue retained treatments, however, N-mineralization rates were lower than in residue removed treatments at seedling stage of both crops. At grain-forming stage in all instances the N-mineralization rates in residue retained treatments considerably exceeded the rates in corresponding residue removed treatments. Tillage reduction and residue retention both increased the proportion of organic C and total N present in soil organic matter as microbial biomass. Microbial immobilization of available-N during the early phase of crops and its pulsed release later during the period of greater N demand of crops enhanced the degree of synchronization between crop demand and N supply. The maximum enhancement effects were recorded in the minimum tillage along with residue retained treatment. In the dryland agroecosystem studied, two management practices in combination proved more advantageous than either practice alone in maintaining soil fertility levels. For soil fertility amelioration in dryland agroecosystems with least dependence upon chemical fertilizer input, post-harvest retention of about 20 cm shoot biomass (accounting for 25–40% aboveground biomass) of previous crop and its incorporation in soil through minimum tillage in the succeeding crop is suggested, especially in the case of cereal.  相似文献   

Effect of fungicides on the physiology of plants. Part IV: Protection of cellular organelles of senescent wheat leaves by carbendazim     

Ram K. Tripathi  Komal Tandon  Eckart Schlsser  Wilford M. Hess 《Pest management science》1982,13(4):395-400

Wheat leaves (cv. Kormoran) floated on water and kept in darkness turned yellow. This induced senescence was accompanied by a loss of electrolytes and amino acids, and by disorganisation of all cellular organelles except cell walls. Treatment with a solution of carbendazim (20 μg ml^?1) prevented the leakage of electrolytes and disorganisation of cell organelles. At 100 μg ml^?1, the fungicide did not prevent the damage caused by senescence but stimulated the loss of electrolytes from the leaves. It is proposed that one of the major mechanisms of the antisenescent activity of carbendazim is its protective effect on membranes.  相似文献   

Insensitivity of acetylcholinesterase as a factor in resistance of houseflies to the organophosphate Rabon     

Ram K. Tripathi  Richard D. O&#x;Brien 《Pesticide biochemistry and physiology》1973,3(4):495-498

Acetylcholinesterase from an organophosphate-resistant strain of housefly exhibited a decrease in sensitivity to Rabon in vitro, to the extent of 206-fold for the soluble enzyme and 38-fold for the particulate. These effects upon the bimolecular reaction constant, k_i, were due to a 573-fold decrease in affinity of the inhibitor for the soluble and 103-fold for the particulate enzyme, coupled with a small increase in reactivity.  相似文献   

Efficacy of thiabendazole against some gastro-intestinal nematodes of calves     

J C Tripathi  S C Dutt 《The Indian veterinary journal》1968,45(4):322-326

  相似文献   

Effect of submergence in water on the infective larvae of some common nematodes of goats     

J C Tripathi 《The Indian veterinary journal》1969,46(12):1038-1043

  相似文献   

Effects of endotoxin-induced fever and probenecid on disposition of enrofloxacin and its metabolite ciprofloxacin after intravascular administration of enrofloxacin in goats     

Rao GS  Ramesh S  Ahmad AH  Tripathi HC  Sharma LD  Malik JK 《Journal of veterinary pharmacology and therapeutics》2000,23(6):365-372

Pharmacokinetics of enrofloxacin and its active metabolite ciprofloxacin were investigated in normal, febrile and probenecid‐treated adult goats after single intravenous (i.v.) administration of enrofloxacin (5 mg/kg). Pharmacokinetic evaluation of the plasma concentration–time data of enrofloxacin and ciprofloxacin was performed using two‐ and one‐compartment open models, respectively. Plasma enrofloxacin concentrations were significantly higher in febrile (0.75–7 h) and probenecid‐treated (5–7 h) goats than in normal goats. The sum of enrofloxacin and ciprofloxacin concentrations in plasma ≥0.1 μg/mL was maintained up to 7 and 8 h in normal and febrile or probenecid‐treated goats, respectively. The t1/2β, AUC, MRT and ClB of enrofloxacin in normal animals were determined to be 1.14 h, 6.71 μg.h/mL, 1.5 h and 807 mL/h/kg, respectively. The fraction of enrofloxacin metabolized to ciprofloxacin was 28.8%. The Cmax., t1/2β, AUC and MRT of ciprofloxacin in normal goats were 0.45 μg/mL, 1.79 h, 1.84 μg.h/mL and 3.34 h, respectively. As compared with normal goats, the values of t1/2β (1.83 h), AUC (11.68 μg ? h/mL) and MRT (2.13 h) of enrofloxacin were significantly higher, whereas its ClB (430 mL/h/kg) and metabolite conversion to ciprofloxacin (8.5%) were lower in febrile goats. The Cmax. (0.18 μg/mL) and AUC (0.99 μg.h/mL) of ciprofloxacin were significantly decreased, whereas its t1/2β (2.75 h) and MRT (4.58 h) were prolonged in febrile than in normal goats. Concomitant administration of probenecid (40 mg/kg, i.v.) with enrofloxacin did not significantly alter any of the pharmacokinetic variables of either enrofloxacin or ciprofloxacin in goats.  相似文献   

Enzyme activities and microbial biomass in coastal soils of India   总被引：1，自引：0，他引：1  

Sudipta Tripathi  Ashis Chakraborty  Bimal Kumar Bandyopadhyay 《Soil biology & biochemistry》2007,39(11):2840-2848

Soil salinity is a serious problem for agriculture in coastal regions, wherein salinity is temporal in nature. We studied the effect of salinity, in summer, monsoon and winter seasons, on microbial biomass carbon (MBC) and enzyme activities (EAs) of the salt-affected soils of the coastal region of the Bay of Bengal, Sundarbans, India. The average pH of soils collected from different sites, during different seasons varied from 4.8 to 7.8. The average organic C (OC) and total N (TN) content of the soils ranged between 5.2-14.1 and 0.6-1.4 g kg⁻¹, respectively. The electrical conductivity of the saturation extract (ECe) of soils, averaged over season, varied from 2.2 to 16.3 dSm⁻¹. The ECe of the soils increased five fold during the summer season (13.8 dSm⁻¹) than the monsoon season (2.7 dSm⁻¹). The major cation and anion detected were Na⁺ and Cl⁻, respectively. Seasonality exerted considerable effects on MBC and soil EAs, with the lowest values recorded during the summer season. The activities of β-glucosidase, urease, acid phosphatase and alkaline phosphatase were similar during the winter and monsoon season. The dehydrogenase activity of soils was higher in monsoon than in winter. Average MBC, dehydrogenase, β-glucosidase, urease, acid phosphatase and alkaline phosphatase activities of the saline soils ranged from 125 to 346 mg kg⁻¹ oven dry soil, 6-9.9 mg triphenyl formazan (TPF) kg⁻¹ oven dry soil h⁻¹, 18-53 mg p-nitro phenol (PNP) kg⁻¹ oven dry soil h⁻¹, 38-86 mg urea hydrolyzed kg⁻¹ oven dry soil h⁻¹, 213-584 mg PNP kg⁻¹ oven dry soil h⁻¹ and 176-362 mg PNP g⁻¹ oven dry soil h⁻¹, respectively. The same for the non-saline soils were 274-446 mg kg⁻¹ oven dry soil, 8.8-14.4 mg TPF kg⁻¹ oven dry soil h⁻¹, 41-80 mg PNP kg⁻¹ oven dry soil h⁻¹, 89-134 mg urea hydrolyzed kg⁻¹ oven dry soil h⁻¹, 219-287 mg PNP kg⁻¹ oven dry soil h⁻¹ and 407-417 mg PNP kg⁻¹ oven dry soil h⁻¹, respectively. About 48%, 82%, 48%, 63%, 40% and 48% variation in MBC, dehydrogenase activity, β-glucosidase activity, urease activity, acid phosphatase activity and alkaline phosphatase activity, respectively, could be explained by the variation in ECe of saline soils. Suppression of EAs of the coastal soils during summer due to salinity rise is of immense agronomic significance and needs suitable interventions for sustainable crop production.  相似文献   

Fungal air-spora inside the central library of Gorakhpur University     

R. N. Tripathi 《Water, air, and soil pollution》1987,34(2):125-134

The study of the air-spora in the Central Library of Gorakhpur University indicated the presence of 19 different types of fungal spores. Amongst these Aspergillus niger, A. favus, Cladosporium spp., Curvularia spp., Paecilomyces sp., Penicillium spp., and periconia sp. were more than 80.5% followed by species of Absidia, Alternaria, Chaetomium, Mucor, Rhizopus, Trichophyton, and Cercospora. Fungal spores showed time trends during the study period. The fungal spore concentrations gradually increased from July to September and attained their maximum in September to October and thereafter decreased. Besides fungal spores, small pieces of paper, dust particles and insect derivatives loaded with fungal mycelium and bacterium were also observed throughout the investigation period.  相似文献   

Nutrient immobilization and release patterns during plant decomposition in a dry tropical bamboo savanna,India   总被引：3，自引：0，他引：3  

S. K. Tripathi  K. P. Singh 《Biology and Fertility of Soils》1992,14(3):191-199

Summary Decomposition and changes in nutrient content of six litter types (leaves, sheaths, roots, twigs, and wood of bamboo, and grass shoots) were studied in nylon net bags for 2 years. The annual weight loss was (% of initial) bamboo leaves 56.5, bamboo sheaths 79.5, bamboo roots 65.8, bamboo twigs 49.6, bamboo wood 31.2, and grass shoots 74.9. Elemental mobility followed the order K>Na>C>P>Ca>N in all components except wood. Generally, an initial increase was followed by a consistent decrease in the contents of N (leaves), P (leaves, roots, wood) and Ca (leaves, roots, grass), and Na (wood). Most of the nutrients were immobilized in the rainy season. C and K contents showed a constant decrease throughout the decomposition period. Materials with a greater C:N ratio (>50) tended to accumulate more nutrients and retain them for longer, except for the bamboo twigs. The critical C:N ratio (at which a net release of N occured) for the leaf material was 25. Litter components with more initial N (sheaths) showed greater weight loss than those with less N (leaves, twigs, and wood). Overall, N and P were lost at the slowest rates while C and K were lost at faster rates. Initial lignin, lignin: N, C:N and C concentrations had a better predictive value for annual weight loss and nutrient release in bivariate relationships. A combination of the initial lignin value and the C: N ratio explained 93% of the variation in annual weight loss. A significant relationship was also observed between the annual weight loss rate and the nutrient mineralization/release rate.  相似文献   

Inheritance and linkage relationship of scent in rice   总被引：6，自引：0，他引：6  

R. S. Tripathi  M. J. B. K. Rao 《Euphytica》1979,28(2):319-323

Summary The inheritance of scent in rice and linkage relationship of genes governing scent with those controlling leaf sheath colour, ripening hull colour and apiculus pigmentation were studied in a cross between Pankaj (nonscented) and Kalabhat (scented) rice cultivars. The scent was identified by leaf analysis.Two dominant complementary genes Sk ₁ and Sk ₂ were found to be responsible for controlling scent. Either of the genes produce mild scent, the presence of both Sk ₁ and Sk ₂ is necessary for production of parental type scent. The genes were independent of other genes controlling leaf sheath colour, ripening hull colour and apiculus pigmentation.  相似文献