QTLs for earliness and yield-forming traits in the Lubuski × CamB barley RIL population under various water regimes

Drought has become more frequent in Central Europe causing large losses in cereal yields, especially of spring crops. The development of new varieties with increased tolerance to drought is a key tool for improvement of agricultural productivity. Material for the study consisted of 100 barley recombinant inbred lines (RILs) (LCam) derived from the cross between Syrian and European parents. The RILs and parental genotypes were examined in greenhouse experiments under well-watered and water-deficit conditions. During vegetation the date of heading, yield and yield-related traits were measured. RIL population was genotyped with microsatellite and single nucleotide polymorphism markers. This population, together with two other populations, was the basis for the consensus map construction, which was used for identification of quantitative trait loci (QTLs) affecting the traits. The studied lines showed a large variability in heading date. It was noted that drought-treatment negatively affected the yield and its components, especially when applied at the flag leaf stage. In total, 60 QTLs were detected on all the barley chromosomes. The largest number of QTLs was found on chromosome 2H. The main QTL associated with heading, located on chromosome 2H (Q.HD.LC-2H), was identified at SNP marker 5880–2547, in the vicinity of Ppd-H1 gene. SNP 5880–2547 was also the closest marker to QTLs associated with plant architecture, spike morphology and grain yield. The present study showed that the earliness allele from the Syrian parent, as introduced into the genome of an European variety could result in an improvement of barley yield performance under drought conditions.     

The energy relations of Carassius auratus l.—III. Growth and the overall balance of energy

• 1.1. No simple relationship was observed between either gross or net efficiencies of growth and food input.
• 2.2. Net efficiencies of growth were highest when food intake just exceeded the maintenance requirements.
• 3.3. A tentative energy balance-sheet was drawn up for goldfish at 21.5°C.

     

Where do nutrients in an inlet-less lake come from? The water and nutrient balance of a small mesotrophic lake

In this article we verified the hypothesis that precipitation is the main nutrient source in an inlet-less lake. We tested this hypothesis by calculating the water and nutrient (phosphorus and nitrogen) balances of a lake located in a hypsographically diverse moraine landscape (northern Poland). All components of the water and nutrient budgets were measured independently, including precipitation and ground water fluxes. The investigations showed that although precipitation constituted about a half or more of the annual water balance in this inlet-less lake, the ground water inflow and outflow play the most important role in the balance of nutrients. Therefore, critical nutrient loads calculated according to the methodology developed within the OECD Eutrophication Programme, which was focused mostly on drainage-type lakes, appeared inadequate in the case of this small seepage lake. Moreover, studies showed that throughout the investigations, a continuous ground water flow-through occurred in the lake. It questions the possibility of calculating the ground water flow simply as a difference between surface inflows and outflows.     

The influence of arbuscular mycorrhizal colonization on soil–root hydraulic conductance in Agrostis stolonifera L. under two water regimes

The hypothesis that mycorrhizal colonization improves the soil–root conductance in plants was experimentally tested in a growth chamber using pot cultures of Agrostis stolonifera L. colonized by Glomus intraradices. Plants were grown in 50-l pots filled with autoclaved sand/silt soil (1:1), with and without the mycorrhizal fungus. Within the mycorrhizal treatment, half of the pots remained well watered, while the other half was subjected to a progressive water deficit. Soil water potential (estimated as plant water potential measured at the end of the dark period), xylem water potential measured at the tiller base, transpiration rate, and soil water content were monitored throughout the experiment. Soil–root hydraulic conductance was estimated as the ratio between the instantaneous transpiration rate and the soil and xylem water potential difference. To obtain cultures with similar nutritional status, the P in the modified Hoagland’s nutrient solution was withheld from the inoculated pots and applied only once a month. Even though there were no differences on growth or nutrient status for the mycorrhizal treatments, water transport was enhanced by the inoculum presence. Transpiration rate was maintained at lower xylem water potential values in the presence of mycorrhizae. The analysis of the relationship between soil–root hydraulic resistance and soil water content showed that mycorrhizal colonization increased soil–root hydraulic conductance as the soil dried. For these growing conditions, this effect was ascribed to the range of 6–10%.     

Constitutive toxin production under various nitrogen and phosphorus regimes of three ecotypes of Cylindrospermopsis raciborskii ((Wołoszyńska) Seenayya et Subba Raju)

Cylindrospermopsis raciborskii is a global invasive cyanobacterium, with some ecotypes (i.e. strains) producing the toxin cylindrospermopsin, CYN. Multiple ecotypes can co-exist, complicating prediction of toxin concentrations based on cell concentrations. This study examined the growth response and toxin production of three Australian ecotypes of C. raciborskii, two toxic (CS-505, CS-506) and one non-toxic (CS-510), to a range of nitrogen (N) and phosphorus (P) concentrations. CYN cell quota was constant under all N:P ratios and concentration conditions, indicative of a constitutive response, yet the CYN cell quota was 6-fold higher in CS-506 compared to CS-505. The ecotypes differed in response to dissolved N depletion: there was a 4-fold difference in the number of cells heterocyst mL⁻¹ between CS-505 and CS-510, while CS-506 did not produce any heterocysts and was unable to grow in N deplete conditions. Growth rates were lower for all ecotypes as [P] increased, indicative of a species with a strategy of P storage rather than increased growth. Presumably this is an adaptation to low and fluctuating P conditions. However, the negative effect of increasing [P] on growth is surprising. In contrast, increasing [N] resulted in higher growth rates across ecotypes. This study highlights the importance of understanding differences in growth and toxin production between ecotypes in response to environmental conditions in order to more effectively predict blooms and toxin yields.     

Biochemistry of sphingolipids—X. Comparative study of sulfatides and cerebrosides in brain tissues of various animals

• 1.1. The isolation of sulfatides and cerebrosides from brain tissues of fourteen animal species (vertebrates and invertebrates) was performed using column chromatography.
• 2.2. On comparing the character of glycolipids by paper chromatography no differences were found in vertebrates except frog and fish cerebroside fractions, where a further unknown component was observed. In brain tissue of invertebrates, both the above-mentioned lipids were also detected.
• 3.3. The quantity of glycolipids decreased towards the lower vertebrates.
• 4.4. In contrast to other animals, the fatty acids in frog and fish brains were characterized by CP₁₈ and C₁₆ acids. Some differences related to long-chain base composition of sphingolipids in invertebrates were also observed.

     

Influence of nutrient and water stress on Norway spruce production in south Sweden — the role of air pollutants

A field experiment primarily designed for simulating the indirect effects of air pollutants for a 25-year-old Norway spruce stand in SW Sweden is presented (The Skogaby project). Treatment include irrigation; artificial drought; ammonium sulphate addition; nitrogen-free-fertilization and irrigation with liquid fertilizers including a complete set of nutrients. The experiment has a randomized block design with four replicates per treatment. Growth response on an areal basis of basal area, height and dry mass of stems, branches and needles after up to four years of treatment are presented. Dry mass is estimated using allometric equations based on destructive samplings of trees.The stand suffered from temporary water stress during all four years investigated despite 970– 1160 mm of annual precipitation. Irrigation resulted in improved above-ground dry mass production (stem, bark, branches, needles, litter fall) by 20% during the first 3 years of treatment, whereas 2 years of drought treatment followed by 1 year of recovery led to 10% reduced dry mass growth. During year 2 of recovery, however, basal area growth was only about half of that of the control.Nitrogen, markedly, was a growth limiting nutrient, although the stand got approx. 20 kg N ha^-1 y^-1 from deposition. Ammonium sulphate addition (100 kg N ha^-1 y^-1) resulted in 31% improved dry mass production whereas irrigation with liquid fertilization (100 kg N ha^-1 y^-1) including all important nutrient elements led to 57% increased dry mass growth after 3 years of treatment. Basal area growth of the latter treatment gradually increased and during year 4 of treatment was 123% larger than the control. Nitrogen-free-fertilization resulted in a small improvement of dry mass production (+10%).After 3 years of treatment, the amount of needles had increased markedly for both treatments including irrigation, whereas drought treated trees instead had decreased their needle amount vs control. The increase in needle amount occurred as a result of both larger formation of needles and higher preservence of old needles, the opposite relations being found for the drought treated trees. At the same point larger needle formation in combination with a higher shedding of older needles was found for trees treated with ammonium sulphate and nitrogen-free-fertilizer.It is concluded that there is no stage of N saturation in the Skogaby site as there is no leaching of N from the control plots and N fertilization results in both increased tree growth and N uptake.     

Experiments on the water balance of individual attached twigs of Picea abies (L .) Karst. in pure and ozone-enriched air

 Rates of transpiration and xylem sap flow were continuously measured in individual twigs in the upper crown of an 18-year-old spruce. Two gas exchange chambers were run simultaneously under identical conditions. One of two equivalent twigs was exposed to pure air whereas the other received the ozone-enriched air of the site. A third gas exchange chamber in mid-crown ran independently with normal outside air and was used for basic experiments. At certain times needles were sampled for water potential measurements. Chamber humidity was reduced step by step and the transpiration and xylem sap flow rates were permanently compared. It turned out that sap flow keeps up with transpiration without lagging as long as chamber humidity is high and the twigs outside the chamber are not subject to substantial evaporative demand. However, in warm summer weather and with high flow rates sap flow is no longer sufficient. As the balance quotient (uptake/release) of 0.8 was reached the stomata began to close and water balance improved. The flux quotient increased far above 1.0 without water potential of the needles, which had decreased before, increasing significantly. The balance quotient of the twig in ozone-enriched air fell to relatively low values and only increased again correspondingly slowly due to lagging stomatal closure. Despite increased water uptake after the light phase, the ozone-treated twig ran into a water deficit in the daily balance during the course of an uninterrupted drought period. Water deficit increased from day to day and only disappeared with the next rainfall. For providing insight into the ozone effect shown in this study it was thought necessary to discuss comprehensively the controversial views of the stomatal control mechanism. The results show that the stomata react to small scale changes in water status as expected for an effective negative feedback system. The less sensitive reaction of the stomata under the influence of ozone confirms earlier results. Increased severity and duration of the daily drought stress loads were attributed to a lag in adjustment due to poor stomatal control. The demonstrated function mechanism shows that the detrimental effect of ozone is dependent on weather conditions. Received: 12 April 1996 / Accepted: 24 June 1996     

The significance of denitrification of applied nitrogen in fallow and cropped rice soils under different flooding regimes I. Greenhouse experimènts

The role of nitrification-denitrification in the loss of nitrogen from urea applied to puddled soils planted to rice and subjected to continuous and intermittent flooding was evaluated in three greenhouse pot studies. The loss of N via denitrification was estimated indirectly using the¹⁵N balance, after either first accounting for NH₃ volatilization or by analyzing the¹⁵N balance immediately before and after the soil was dried and reflooded. When urea was broadcast and incorporated the loss of¹⁵N from the soil-plant systems depended on the soil, being about 20%–25% for the silt loams and only 10%–12% for the clay. Ammonia volatilization accounted for an average 20% of the N applied in the silt loam. Denitrification losses could not account for more than 10% of the applied N in any of the continuously flooded soil-plant systems under study and were most likely less than 5%. Intermittent flooding of soil planted to rice did not increase the loss of N. Denitrification appeared to be an important loss mechanism in continuously flooded fallow soils, accounting for the loss of approximately 40% of the applied¹⁵N. Loss of¹⁵N was not appreciably enhanced in fallow soils undergoing intermittent flooding. Apparently, nitrate formed in oxidized zones in the soil was readily denitrified in the absence of plant roots. Extensive loss (66%) of¹⁵N-labeled nitrate was obtained when 100 mg/pot of nitrate-N was applied to the surface of nonflooded soil prior to reflooding. This result suggests that rice plants may not compete effectively with denitrifiers if large quantities of nitrate were to accumulate during intermittent dry periods.     

Studies onBacillus thuringiensis H-14 strains isolated in Egypt—III. Selection of media for δ-endotoxin production

Several medium ingredients locally available in Egypt were investigated for their ability to support -endotoxin production by two mosquito-toxic strains ofBacillus thuringiensis H-14 usingCulex pipiens for the bioassay of -endotoxin. Soya beans, black-eyed beans, common peas and lentils supported good production of toxin whereas peanuts, fodder yeast, cheese whey and corn steep liquor gave only low amounts of toxin. Molasses as the sole carbon source at 2 and 3% (w/v) with soya (or Proflo) as the sole nitrogen source at 3% gave the best yields of toxin for strain M1 and S128 respectively.

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Résumé On a étudié plusieurs ingrédients de milieu de culture, disponibles en Egypte pour leur capacité de favoriser la production d'endotoxine par deux souches deBacillus thurigiensis H-14, toxiques pour les moustiques, en utilisantCulex pipiens pour l'essaiin vivo d'endotoxine . Les fèves de soja, les haricots à taches noires, les pois communs et les lentilles favorisent la production de toxine, tandis que les arachides, la levure fourragère, le petit lait et la liqueur de trempage de maïs ne produisent que de faibles quantités de toxines. La mélasse comme seule source de carbone à 2% (p/v) avec la soja (ou le Proflo) comme seule source d'azote de 2 à 3% donnent les meilleurs rendements en toxine.

     

The postnatal growth of the skull in the house mouse Mus musculus Linné, 1758, and in 2 different large subspecies of the field mouse Microtus arvalis Pallas, 1779. I. Introduction, materials and methods]

In order to describe postnatal skull growth in Mus musculus, Microtus arvalis arvalis and M. a. asturianus, a total of 408 animals were raised and measured. The growth rate of single bones was followed by means of a maximum-likelihood estimator for the parameters A, B and C of the growth function Y(t) = A-B exp(-Ct). Supplementary techniques used to estimate the morphological divergence of the different taxa included methods of allometry research and multivariate statistical methods such as discriminate analysis and MANOVA. Drawings of selected stages of skull-bone ossification are provided to assist researchers in determining the age of undated specimens.     

Changes in micropore system of roots of wheat and triticale seedlings under aluminum stress as determined using water vapor adsorption—desorption

Plant root structure including the pore system is severely injured in Al-toxic environments. Experimental water vapor desorption isotherms estimated using vacuum chamber method were used to characterize micropore build-up of roots of wheat (Lanca) and triticale (Debo) 4-day seedlings and its changes after 24 h (8 mg dm⁻³) aluminum stress. The micropore volumes and average pore radii increased after the stress whereas pore fractal dimensions decreased. The above changes were more pronounced for these roots which were not able to grow further after the stress when compared to the control roots, the total micropore volume was almost twice higher and the fractal dimension reached a value of 2 which is characteristic for flat, two-dimensional surface. The observed alterations of pore system indicate damage of root tissue and possible strong binding of aluminum on cell wall surfaces.     

Post-natal growth of the skull in the house mouse Mus musculus Linné, 1758, and in 2 different large subspecies of the field mouse Microtus arvalis Pallas, 1779. II. Results (I)

Postnatal skull ontogeny of Mus musculus, Microtus arvalis arvalis and M. a. asturianus was studied qualitatively and quantitatively. To facilitate age determination for undated specimens, the most important stages in ossification of the skull bones are described, with drawings of selected ontogenetic stages (Part I). Using Parameter C of the growth function Y(t) = A - B exp (- Ct), it is possible to establish skull growth gradients. The growth functions are subdivided into 3 classes, based on Parameter C, associated with different growth regions of the skull. Changes in individual skull proportions are demonstrated by means of ontogenetic and intraspecific allometries.     

Hormonal control of tanning in the American cockroach—III. Hormone stability and post-ecdysial changes in hormone titre

The concentration of bursicon in the blood of the cockroach reached a detectable level within 10–20 min after ecdysis. It reaches a maximum at 90 min and declines slowly until 8 hr after ecdysis when it is no longer detectable.Crude homogenates are most active at 16 mg protein/ml of hormone extract and blood is active at one-fourth dilution (12 mg/ml). The cockroach bursicon is relatively stable to freezing but temperatures exceeding 60°C inactivate the hormone.     

Seed production and seed predation in a patchy and time-varying environment. Dynamics of a milkweed — tephritid fly system

Summary Vincetoxicum hirundinaria is a longlived perennial herb. Its pod production was measured during seven years in about 40 small isolated patches in two study areas in southeastern Sweden. Total pod production in the two areas varied synchronously and up to about 200 times between years. This variation was mainly due to drought conditions as determined by the interplay of weather (sunshine h) and site characteristics.Populations of a univoltine tephritid fly, euphranta connexa, whose larva feeds on V. hirundinaria seeds in the maturing pods, were monitored for five and seven years in the two study areas respectively. Larval fly populations in the two areas varied 30 and 50-fold between years, with highs in years when pods were abundant and lows when pods were scarce. The percentage of pods attacked by E. connexa, however, varied in the opposite direction, with very high attack rates (about 100%) when pods were scarce and low rates (down to 10–20%) when pods were common. Thus the temporal tracking of food resources by E. connexa was poor, resulting in yearly variations in the amount of unattacked pods (and seeds) being about 2,00-fold.Many host plant patches were small and totally without pods in some years, causing frequent local extinctions of E. connexa. Patches were, however, readily colonized in later years when pods appeared again. Low overall attack rates in certain years were thus only to a minor extent explainable by host plant patches being uncolonized by the fly. The efficient spatial tracking of resources by the fly population allows this population system to be analyzed largely in terms of its temporal dynamics.Although E. connexa populations often exploit only a minor part of their potential larval resources, the rate of population change was closely correlated with these resources expressed on a per capita basis. Natural enemies only have negligible effects on E. connexa population trends. In this population system the herbivore (seed predator) population is thus controlled by its food resources, but weather-imposed temporal variations in resource set are too large for the herbivore population to closely track its resource base. This temporal tracking inertia has important implications for the long-term production of healthy seeds.