Indices of Drought Tolerance in Wheat Genotypes at Early Stages of Plant Growth

Thirty diverse genotypes of bread wheat were evaluated for seed vigour index, germination percentage, root length, shoot length, root‐to‐shoot length ratio, coleoptile length and osmotic membrane stability under laboratory conditions. Considerable variation was observed for all the characters. Discrimination among the genotypes on the basis of mean values was better under normal than under moisture stress conditions, indicating suppression of variability under moisture stress conditions. Comparison of mean performance under normal and osmotic stress conditions indicated that the seed vigour index was the most sensitive trait, followed by shoot length, germination percentage and root length. The root‐to‐shoot length ratio, however, increased under osmotic stress. The magnitude of genetic components of variance and heritability were, in general, lower under osmotic stress than under normal conditions. All the characters except germination percentage, shoot length and coleoptile length showed considerable genetic variability. Heritability in the broad sense was also moderate to high for all the characters under both environments. Due to high heritability and genetic advance great benefit from selection can be expected for the osmotic membrane stability of leaf segments and root‐to‐shoot length ratio. Moderate progress can be expected from root length and seed vigour index. Correlation studies indicated that the osmotic membrane stability of the leaf segment was the most important trait, followed by root‐to‐shoot ratio and root length on the basis of their relationships with other traits.     

High value of ecological information for river connectivity restoration

Context

Efficient restoration of longitudinal river connectivity relies on barrier mitigation prioritization tools that incorporate stream network spatial structure to maximize ecological benefits given limited resources. Typically, ecological benefits of barrier mitigation are measured using proxies such as the amount of accessible riverine habitat.

Objectives

We developed an optimization approach for barrier mitigation planning which directly incorporates the ecology of managed taxa, and applied it to an urbanizing salmon-bearing watershed in Alaska.

Methods

A novel river connectivity metric that exploits information on the distribution and movement of managed taxon was embedded into a barrier prioritization framework to identify optimal mitigation actions given limited restoration budgets. The value of ecological information on managed taxa was estimated by comparing costs to achieve restoration targets across alternative barrier prioritization approaches.

Results

Barrier mitigation solutions informed by life history information outperformed those using only river connectivity proxies, demonstrating high value of ecological information for watershed restoration. In our study area, information on salmon ecology was typically valued at 0.8–1.2 M USD in costs savings to achieve a given benefit level relative to solutions derived only from stream network information, equating to 16–28% of the restoration budget.

Conclusions

Investing in ecological studies may achieve win–win outcomes of improved understanding of aquatic ecology and greater watershed restoration efficiency.

     

Relative efficiency of different Gramineae genera for haploid induction in triticale and triticale x wheat hybrids through the chromosome elimination technique

The study was undertaken to evaluate the relative efficiency of different Gramineae genera for haploid induction in triticale (x Triticosecale) and triticale × wheat (Triticum aestivum) hybrids through the chromosome elimination (wheat × maize, Zea mays) system. Eight intergenotypic triticale and 15 triticale x wheat crosses were subjected to hybridization with nine different Gramineae genera viz., Z. mays, Sorghum bicolor, Pennisetum americanum, Setaria italica, Festuca arundinacea, Imperata cylindrica, Cynodon dactylon, Lolium temulentum and Phalaris minor in two separate experiments. This was followed by in vivo auxin treatment of the crossed spikes and subsequent rescue of the haploid embryos to regenerate green haploid plantlets. All the triticale and triticale x wheat crosses resulted in seed set in variable frequencies when hybridized with maize, I. cylindrica, pearl millet and sorghum. Seed set was also obtained with S. italica, F. arundinacea and P. minor in a few crosses in both groups. In general, all the triticale x wheat crosses, except for one in each case, resulted in embryo formation and green haploid plantlet regeneration when hybridizations were carried out with maize and I. cylindrica. However, the latter outperformed the former in embryo formation (25.48% vs. 20.0%) and regeneration (34.17% vs. 15.10%) frequencies, the differences being significant for regeneration frequencies. In the case of triticale hybrids, no significant differences between maize and I. cylindrica were observed for the three parameters of haploid induction. Embryo formation and regeneration were also observed in some of the triticale as well as triticale × wheat F₁ hybrids when hybridized with sorghum and pearl millet.     

Interactions between poaching and management policy affect marine reserves as conservation tools

To explore the effects of poaching within marine reserve boundaries under three different management policies this analysis uses a simple age-structured reserve model based on yield maximization or reproductive thresholds of Black rockfish (Sebastes melanops). Departures from the traditional assumptions of full compliance to reserve boundaries alter the conclusions of prior modeling work that demonstrate yield equivalence to no-reserve effort control management and augmented reproductive benefits when small reserves are implemented. By degrading the recruitment subsidization effect to nonreserve areas from protected reserve populations, poaching resulted in negative externalities for compliant fishermen in open areas in terms of yield and degraded the reproductive output and age-structure of the system. All three policies required effort reduction in open areas as a response to poaching in reserves. The strength of the impacts from poaching varied with policy choice and harvest intensity in the reserve, where at the highest level of poaching modeled here (15% annual exploitation rate of the vulnerable reserve population) biological and fishery benefits of implementing reserves were totally negated. Under the assumptions of this model, a policy managing for a reproductive threshold that excludes the reserve population is the precautionary choice if poaching is likely. The results of this exercise emphasize the importance of garnering compliance to reserve boundaries from resource-users for spatial closures to be successful ocean management tools.     

Inheritance of excised-leaf water loss and relative water content in bread wheat (Triticum aestivum)

Little information is available on the genetics of excised leaf water loss and relative water content in wheat. An experiment conducted on the F₁ generation from a half-diallel set of crosses involving two drought tolerant, two moderately tolerant and two sensitive varieties was initiated to investigate the inheritance of excised-leaf water loss and relative water content. This experiment was conducted under glass-house and field conditions at tillering and anthesis stages of plant development. Additive gene action, in general, played a major role in determining the inheritance of these traits. General combining ability (GCA) was the main source of genetic variation among crosses, while specific combining ability (SCA) was negligible. Strong phenotypic correlations existed between per se performance and GCA effects in the majority of cases. Heterosis was unimportant. Genotype-environmental interactions and/or differential gene expression appeared to account for different results found between environments and growth stages, respectively. Selection for relative water content appeared to be more effective at anthesis, while for excised-leaf water loss at both stages of plant growth. In addition to drought resistance, wide differences for morphological characters and relative positions of parental arrays revealed the possibility of obtaining desirable segregants for drought stress conditions from the cross Kharchia 65 × WH 147. This revised version was published online in August 2006 with corrections to the Cover Date.     

Resource use efficiency of broiler production in tunnel-ventilated environmental control vis-à-vis open-sided conventional shed during summer

Present study was conducted to assess the resource use efficiency of broilers production, in tunnel-ventilated environment control (ECBH) and open-sided conventional (OSCBH) house under different stocking densities. Different treatments comprised of T ₀ (birds with floor space, 1.0/ft²/bird in open-sided conventional broiler house (OSCBH) as control, while different treatments in tunnel-ventilated environment control broiler house (ECBH) were T ₁, T ₂, T ₃, T ₄ and T ₅ with floor space of 1.0, 0.9, 0.8, 0.7and 0.6 ft² per bird, respectively. The results of shed microclimate indicated that shed temperature and temperature humidity index (THI) at 12:00 and 15:00 IST and maximum and minimum temperature in OSCBH were significantly (p ≤ 0.05) higher than ECBH. Litter moisture and pH did not differ significantly and were within permissible limits in both OSCBH and ECBH. Final body weight, body weight gain, feed intake were significantly higher and FCR, PER and EER were significantly better in ECBH than OSCBH (T ₀) even at 10% increase in stocking density (T ₂). Margin of receipt in T ₂ in ECBH from sale of live bird/unit area and kilogram live weight per unit area was maximum which was Rs. 5.08/- and 3.56/- higher than T ₀ for OSCBH.     

Influence of winter and spring wheat genetic backgrounds on haploid induction parameters and trait correlations in the wheat × maize system

The interactive influence of winter and/or spring wheat genetic background on haploid induction parameters and trait correlation was studied by hybridizing five elite and diverse genotypes each of winter and spring wheat and their F₁s (winter × winter, spring × spring, and winter × spring, generated in a diallel design excluding reciprocals) with a single genotype of maize. Data were recorded with respect to per cent seed formation, embryo formation, and regeneration. High genetic variability was present among the wheat genotypes (parents + F₁s) for the three haploid induction parameters. Significant differences were obtained within and between different groups viz., spring wheats, winter wheats, spring × spring wheats, winter × winter wheats, and winter × spring wheats with respect to the three haploid induction parameters based on ANOVA. The winter genotypes (winter parents and winter × winter wheat hybrids) responded better than the spring groups (spring wheat parents, spring × spring and winter × spring wheat hybrids) with respect to embryo formation and winter × spring wheat hybrids yielded significantly the highest numbers of regenerants. Correlation studies amongst the haploid induction parameters indicated that the genes controlling seed formation and haploid plantlet regeneration are negatively correlated when the genetic backgrounds of both ecotypes are combined in winter × spring hybrids. Haploid embryo formation had no association with seed formation and regeneration in all genetic backgrounds, suggesting independent inheritance.     

Capture versus tagging impacts on chum salmon freshwater spawning migration travel times

The spawning migration travel times of chum salmon, Oncorhynchus keta (Walbaum), fitted with gastrically implanted radio tags vs external spaghetti tags were tested for a short [≈60 river km (rkm)] and long migration route (≈730 rkm) on the Koyukuk River, Alaska, USA. Using a novel application of statistical arrival curve models to infer travel times for uncaptured fish, migrations by chum salmon not directly handled during the study were also assessed. Results demonstrated negligible differences in travel times within migration routes between fish fitted only with spaghetti tags and fish fitted with radio tags, indicating low impacts on migration travel behaviour associated with gastric tags once deployed. Conversely, travel times for unhandled fish as inferred by statistical arrival models may have been 12%–24% shorter than those for fish captured with gillnets for tagging. These results suggest that, if present, chum salmon migration behaviour impacts may be more strongly associated with fish capture than tag deployment.     

Activation of bovine monocytes and neutrophils by the Bb fragment of complement factor B: demonstration by the uptake of 3H-deoxyglucose.

The Bb fragment is the enzymatically active split product of bovine complement factor B. The Bb fragment was obtained after zymosan treatment of fresh bovine serum and fractionation of the treated serum, first over diethylaminoethyl-Sephacel and then over an affinity column made up of monoclonal antibody to bovine Bb, coupled to cyanogen-bromide-activated Sepharose. Purified Bb has a molecular weight of 64,000, as determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The ability of purified Bb to activate phagocytes was assessed. The activation assay was based on the principle that the primary source of energy for the phagocytes is obtained from glucose. 3H-deoxyglucose, a nonmetabolizable analogue of glucose, was used to obtain the quantitative measurement of the activation process. The activation by Bb was shown by the uptake of the labelled deoxyglucose in the phagocytic cells and was comparable to the activation caused by phorbol myristate acetate and N-formyl-L-methionyl-L-leucyl-L-phenylalanine, run in parallel. These data showed that fragment Bb activates bovine monocytes and neutrophils and also suggested that, when generated after complement activation, Bb may stimulate monocytes and neutrophils for enhanced phagocytosis.