Evaluation of early generations for iron chlorosis in relation to productivity in groundnut (Arachis hypogaea L.)

Five popular but iron-inefficient cultivars were crossed with three efficient genotypes and both parents and F₁s were evaluated for iron-efficiency in potted calcareous and noncalcareous soil. The iron-efficient genotypes were dark green or green in both noncalcareous and calcareous soils whereas inefficient types were light green to yellow in calcareous soil. The chlorophyll and active iron (Fe²⁺) concentration of leaves was less in iron-efficient genotypes compared to efficient types in calcareous soil and reduction of both the parameters from noncalcareous to calcareous soil was considerably high in iron-inefficient lines. There was significant correlation between visual scores, chlorophyll and active iron content. There were no differences among F₁s for iron chlorosis and they were all iron-inefficient. The frequency of iron-inefficient plants was higher than the efficient plants in all F₂ populations. But most of the productive plants came from iron-efficient segregants indicating strong association between iron-efficiency and productivity. Based on the results selection for iron-efficiency in early generations and extensive evaluation for productivity in advanced generations is suggested for developing varieties for cultivation in calcareous soils.     

The lifetime of molecular (Davydov) solitons

The lifetime of Davydov solitons in a one-dimensional system is studied theoretically. The process of thermalization and the properties of solitons at finite temperature are investigated and the processes of soliton creation and disintegration are discussed.     

Successful disinfection of trumpet mouthpieces using domestic steam disinfection

There have been numerous reports in the literature describing the diversity of microbial flora isolated from woodwind and brass instruments, with potential infection risks for players, especially when such instruments are shared. Steam disinfection has become established as a trusted method of decontamination; however, there have been no reports on the employment of this technology to disinfect parts of musical instruments, hence it was the aim of this study to examine the fate of bacterial and yeast pathogens on artificially contaminated trumpet mouthpieces and to evaluate whether such disinfection is an effective method of disinfection for such instrument parts. Trumpet mouthpieces were artificially contaminated with 18 microbial strains (17 bacteria from four genera (Enterococcus, Escherichia, Staphylococcus and Streptococcus) and one yeast (Candida)), each at an inoculum density of approximately 1·5 × 10⁷ colony forming units and subjected to a disinfection cycle. The experiment was repeated including 50% (v/v) sterile sputum as soil. No bacteria or yeast organisms were recovered post disinfection, including following recovery and with nonselective cultural enrichment techniques.     

Empirical relationships to estimate asymptotic length, length at first maturity and length at maximum yield per recruit in fishes, with a simple method to evaluate length frequency data

Empirical relationships are presented to estimate in fishes, asymptotic length (L∞) from maximum observed length (L_max), length at first maturity (L_m) from L_∞, life span (t_max) from age at first maturity (t_m), and length at maximum possible yield per recruit (L_opt) from L_∞ and from L_m, respectively. The age at L_opt is found to be a good indicator of generation time in fishes. A spreadsheet containing the various equations can be downloaded from the Internet at http://www.fishbase.org/download as popdynJFB.zip. A simple method is presented for evaluation of length–frequency data in their relationship to L_∞, L_m and L_opt. This can be used to evaluate the quality of the length–frequency sample and the status of the population. Three examples demonstrate the usefulness of this method. 2000 The Fisheries Society of the British Isles     

The effect of diffusion and convection on the rate of transfer of solutes across an interface

The transfer of substances across the interface between water and a membrane or between water and a solvent occurs in series with transport up to and away from the interface. These processes have been difficult to resolve. Recently D. M. Miller (Biochim Biophys Acta 856: 27–35, 1986) has used a moving drop technique to measure the rates of transfer of short-chain alcohols and tritiated water between water andn-octanol. This technique produces equivalent unstirred layers which are less than about 10 m thick. Based on the trends in the observed rates of phase transfer, he proposes that the transfer is limited by the actual interfacial step. If so, water-oil interfacial transfer would be sufficiently slow to limit the rate of permeation of lipid membranes by these substances. It is shown here that the observed rates of phase transfer can be explained quantitatively if they are limited by convection or by diffusion across the combination of 5–10 m unstirred layers both inside and outside the moving drops. For water, comparison of the observed rates with the rate of evaporation from a clean surface, suggests that the interfacial step at the water-octanol interface is not rate-limiting.     

Maternal effects and generation mean analysis of seed-oil content in cotton (Gossypium hirsutum L.)

Summary The nature of gene action and of maternal influence governing cottonseed oil attributes were determined with four lines, two each with high and low seed-oil percentage. For this purpose, P1, P2, F0, F1, F2 and alternative sets of BC1 and BC2 generations were analysed in six cross-combinations and their reciprocals. Marginal extents of heterosis for seed-oil percentage were noticeable in F1, with inbreeding depression in F2. Data from reciprocal backcrosses provided evidence in favour of maternal rather than cytoplasmic effects of seed-oil development. Relatively higher extents of heterosis, sizeable inbreeding depression and reciprocally unequal F2 averages were characteristic of the seed index trait, which often showed a reversal of effects from F1 to F2. Reverse reciprocal backcrosses exhibited some differences, including greater resemblance between the types, (A/B)A and (B/A)A, in addition to variable dose effects in seed index. Thus, the differences between F1 seed index values were not due to cytoplasmic influence. Positive heterotic effects for seed-oil index, especially among the backcrosses, ranged between 16.08% and 47.29% over midparent averages. Genetic component estimates from analysis of similar sets of crosses differing only in reciprocal backcrosses, and also from sets of reciprocal crosses between any two parental combinations, were inconsistent. Scaling tests detected presence of epistasis within and between a majority of cross-combinations. Despite reciprocal differences, additive gene effects for seed-oil percentage were significant in 7 out of 24 crosses, representing high x low, low x high and low x low seed-oil parents. Those were, however, accompanied by significant dominance effects of higher order. In crosses involving low seed-oil percentage parents SA1060 and SA229, all six components were detected significant, with opposite effects of dominance and dominance x dominance epistatic components. Significant additive components were also detected for seed index and seed-oil index in 7 and 5 out of 24 crosses, respectively. In the inheritance of seed index and seed-oil index, dominance effects were more important. Epistatic components of additive x additive, and to a lesser extent, those of dominant x dominant were found significant.     

Effects of calcium input/output on the stability of a system for calcium-regulated viscoelastic strain fields

The Goodwin and Trainor model of pattern generation in calcium-regulated strain fields is studied in the case where calcium input and calcium output processes are involved. It is shown that the properties of the original model may still remain provided that the input-output processes are not unstable. In this last case, despite the eventual stabilizing effect of the calcium exchange term, perturbations of the generalized system can grow and lead to inhomogeneous solutions. Applications to cell differentiation and cell growth are discussed.     

Effects of selection criteria on yield stability in chickpea (Cicer arietinum L.)

Summary Selection in the F₃ generation for seed yield, fruiting branches/plant, effective pods/plant, and seed index (100-seed weight) was carried out in two chickpea crosses. Sixty F₅ lines (15 lines/selection criterion) along with check variety were evaluated for seed yield in three distinct environments. The effects of selection criteria on yield stability was examined using linear regression approach and genotype-grouping technique. There were no differences between selection criteria for linear yield responses of F₅ lines to different environments. Within all four selection criteria the lines showed similar linear responses. The non-linear component was relatively higher for lines selected for effective pods and seed index than lines selected for yield and fruiting branches. On the basis of mean yield and coefficient of variation across environments, the seed index was the least effective selection criterion for developing high yielding and stable lines. When the results of stability parameters and genotype-grouping technique were considered together, selection for yield and fruiting branches was highly effective for isolating stable and high yielding lines.     

The intrinsic rates of increase of insects of different sizes

ABSTRACT.

• 1 A negative relationship between intrinsic rate of increase, r, and body size has only clearly been shown using data for species drawn from a number of phyla and covering several orders of magnitude in size. Analyses for more closely related species are equivocal.
• 2 Data for ninety-one species of insects, from nine orders, were used to examine the correlation between intrinsic rate of increase and size.
• 3 Intrinsic rate of increase was negatively correlated with both length and weight across orders, but no relationship could be shown within orders.
• 4 Generation times were positively related to body size, but there was no relationship between net reproductive rate (R_Q) and size.
• 5 These results support the hypothesis that documented relationships between species size and colonization success in insects could be a consequence of the scaling of intrinsic rate of increase with size.