不同年代大豆品种(系)根系生长动态的比较研究

不同年代大豆品种根干重积累动态可以用Logistic曲线方程进行模拟。在不同施肥水平下,根干重最大增长速率及出现的时间和平均增长速率有所不同。根干重最大增长速率出现的时间,中国当代品种、美国当代品种及中国20世纪20年代的品种间差异不显著,各品种间差异及施肥处理间差异也不显著。根干重最大增长速率,中国当代、美国当代及中国20世纪20年代的品种间差异不显著,各品种间差异也不显著,施肥处理间差异显著。平均增长速率,中国当代、美国当代及中国20年代的品种间差异显著,各品种间及施肥处理间差异也显著。不同施肥水平、不同生育时期,中国当代品种与美国当代品种根干重都比中国20年代品种大。     

Sex pheromone of the winter moth, a geometrid with unusually low temperature precopulatory responses

The sex pheromone for the winter moth, Operophtera brumata (L.), has been identified as the novel compound (Z,Z,Z)-1,3,6,9-nonadecatetraene. The male moths respond to the pheromone at low temperatures (4 degrees to 15 degrees C) and exhibit an upper response limit that coincides with the lower response limit for other reported moth sex pheromone systems. The pheromone attracted two other geometrid species, O. bruceata (Bruce spanworm) and O. occidentalis.     

Curcumin nanoparticles: preparation, characterization, and antimicrobial study

Curcumin is a highly potent, nontoxic, bioactive agent found in turmeric and has been known for centuries as a household remedy to many ailments. The only disadvantage that it suffers is of low aqueous solubility and poor bioavailability. The aim of the present study was to develop a method for the preparation of nanoparticles of curcumin with a view to improve its aqueous-phase solubility and examine the effect on its antimicrobial properties. Nanoparticles of curcumin (nanocurcumin) were prepared by a process based on a wet-milling technique and were found to have a narrow particle size distribution in the range of 2-40 nm. Unlike curcumin, nanocurcumin was found to be freely dispersible in water in the absence of any surfactants. The chemical structure of nanocurcumin was the same as that of curcumin, and there was no modification during nanoparticle preparation. A minimum inhibitory concentration of nanocurcumin was determined for a variety of bacterial and fungal strains and was compared to that of curcumin. It was found that the aqueous dispersion of nanocurcumin was much more effective than curcumin against Staphylococcus aureus , Bacillus subtilis , Escherichia coli , Pseudomonas aeruginosa , Penicillium notatum , and Aspergillus niger . The results demonstrated that the water solubility and antimicrobial activity of curcumin markedly improved by particle size reduction up to the nano range. For the selected microorganisms, the activity of nanocurcumin was more pronounced against Gram-positive bacteria than Gram-negative bacteria. Furthermore, its antibacterial activity was much better than antifungal activity. The mechanism of antibacterial action of curcumin nanoparticles was investigated by transmission electron micrograph (TEM) analysis, which revealed that these particles entered inside the bacterial cell by completely breaking the cell wall, leading to cell death.     

Methane emission from two Indian soils planted with different rice cultivars

In a greenhouse study, methane emissions were measured from two diverse Indian rice-growing soils planted to five rice cultivars under similar water regimes, fertilizer applications and environmental conditions. Significant variations were observed in methane emitted from soils growing different cultivars. Total methane emission varied between 8.04 and 20.92gm^–2 from IARI soil (Inceptisol) and between 1.47 and 10.91gm^–2 from Raipur soil (Vertisol) planted to rice. In all the cultivars, emissions from IARI soil were higher than from Raipur soil. The first methane flux peak was noticed during the reproductive phase and the second peak coincided with the grain-ripening stage of the rice cultivars. Received: July 7, 1996     

Isozyme Banding Pattern and Estimation of Genetic Diversity among Guinea Grass Germplasm

Isozyme banding pattern was studied in Guinea grass (Panicum maximum Jacq.), a widely cultivated grass having good fodder value. Similarity among 63 accessions collected from diverse sources was worked out using five enzyme systems (SOD, GOT, ACP, Esterase and Peroxidase) following horizontal starch gel electrophoresis. Biochemical markers such as isozymes are useful supplements in identifying the genetic variation present in any crop. A total of 35 clear and unambiguous bands were used for analysis of which 8 bands were monomorphic. Polymorphism exhibited by 27 bands from all five enzyme systems indicate presence of considerable diversity in this species. The dendrogram generated after UPGMA and SAHN cluster analysis using Jaccard genetic distance showed that 63 accessions from diverse geographical locations could be grouped in three main clusters, of which two could further be divided into sub-clusters. Although the clusters comprised members from different locations, most of the accessions from similar geographical locations tended to cluster in same group.     

Elevated CO2 Improves Growth and Phosphorus Utilization Efficiency in Cereal Species Under Sub-Optimal Phosphorus Supply

Cultivars of Triticum aestivum, T. durum, and Secale cereale were grown at low (2 μM) and sufficient (500 μM) phosphorus (P) under ambient carbon dioxide (380 μmol mol^?1; aCO₂) and elevated CO₂ (700 μmol mol^?1, eCO₂) to study responses of cereal species in terms of growth and P utilization efficiency (PUE) under P x CO₂ interaction. Dry matter accumulation increased under eCO₂ with sufficient P. Nevertheless, dry matter accumulated at eCO₂ with low-P was similar to that obtained at aCO₂ with sufficient P. Leaf area was 43% higher under eCO₂ with sufficient P. Significant increase in lateral root density, length and surface area were noted at low-P under eCO₂. Phosphorus use efficience (PUE) increased by 59% in response to eCO_2­ in low-P plants. Thus, eCO₂ can partly compensate effect of low-P supply because of improved utilization efficiency. Among cereals, durum wheat was more suitable in terms of PUE under high CO₂ and limiting P supply.     

Biochemical studies into variation and repeatability of glutathione concentrations in bovine and bubaline semens

Repeatability (r) value of glutathione (GSH) content was estimated in semen of Tharparkar, Red Dane, their crosses, and Murrah buffalo bulls. Mean GSH values were higher in bovine bull semen as compared to mean GSH values in bubaline bull semen. The r of GSH concentration for the pooled data was 0.1278. This trait is 12.78% repeatable. GSH value in semen of bovine and bubaline bull differed insignificantly. R estimates are expressed for selection of bulls of higher fertility and semen quality.