Effects of CO2 Enrichment and Drought on Photosynthesis,Growth and Yield of an Old and a Modern Barley Cultivar

Susceptibility of crops to drought may change under atmospheric CO₂ enrichment. We tested the effects of CO₂ enrichment and drought on the older malting barley cultivar Golden Promise (GP) and the recent variety Bambina (BA). Hypothesizing that CO₂ enrichment mitigates the adverse effects of drought and that GP shows a stronger response to CO₂ enrichment than BA, plants of both cultivars were grown in climate chambers. Optimal and reduced watering levels and two CO₂ concentrations (380 and 550 ppm) were used to investigate photosynthetic parameters, growth and yield. In contrast to expectations, CO₂ increased total plant biomass by 34 % in the modern cultivar while the growth stimulation was not significant in GP. As a reaction to drought, BA showed reduced biomass under elevated CO₂, which was not seen in GP. Grain yield and harvest index (HI) were negatively influenced by drought and increased by CO₂ enrichment. BA formed higher grain yield and had higher water‐use efficiency of grain yield and HI compared to GP. CO₂ fertilization compensated for the negative effect of drought on grain yield and HI, especially in GP. Stomatal conductance proved to be the gas exchange parameter most sensitive to drought. Photosynthetic rate of BA showed more pronounced reaction to drought compared to GP. Overall, BA turned out to respond more intense to changes in water supply and CO₂ enrichment than the older GP.     

Differences in Ion Accumulation and Salt Tolerance among Glycine Accessions

Salinity reduces crop yield by limiting water uptake and causing ion‐specific stress. Soybean [Glycine max (L.) Merr.] is sensitive to soil salinity. However, there is variability among soybean genotypes and wild relatives for salt tolerance, suggesting that genetic improvement may be possible. The objective of this study was to identify differences in salt tolerance based on ion accumulation in leaves, stems and roots among accessions of four Glycine species. Four NaCl treatments, 0, 50, 75 and 100 mm , were imposed on G. max, G. soja, G. tomentella and G. argyrea accessions with different levels of salinity tolerance. Tolerant genotypes had less leaf scorch and a greater capacity to prevent Na⁺ and Cl^? transport from soil solution to stems and leaves than sensitive genotypes. Magnitude of leaf injury per unit increase in leaf Na⁺ or Cl^? concentrations was lower in tolerant than in susceptible accessions. Also, plant injury was associated more with Na⁺ rather than with Cl^? concentration in leaves. Salt‐tolerant accessions had greater leaf chlorophyll‐meter readings than sensitive genotypes at all NaCl concentrations. Glycine argyrea and G. tomentella accessions possessed higher salt tolerance than G. soja and G. max genotypes.     

Foliage‐applied sodium nitroprusside and hydrogen peroxide improves resistance against terminal drought in bread wheat

Terminal drought is threatening the wheat productivity worldwide, which is consumed as a staple food by millions across the globe. This study was conducted to examine the influence of foliage‐applied stress signalling molecules hydrogen peroxide (H₂O₂; 50, 100, 150 μm ) and nitric oxide donor sodium nitroprusside (SNP; 50, 100, 150 μm ) on resistance against terminal drought in two bread wheat cultivars Mairaj‐2008 and BARS‐2009. These stress signalling molecules were applied at anthesis stage (BBCH 61); drought was then imposed by maintaining pots at 35% water holding capacity. Terminal drought caused significant reduction in grain yield of both tested bread wheat cultivars; however, foliage application of both stress signalling molecules at either concentration improved the performance of both bread wheat cultivars. Maximum improvement in 100‐grain weight (12.2%), grains per spike (19.7%), water‐use efficiency (WUE; 19.8%), chlorophyll content index (10.7%), total soluble phenolics (21.6%) and free leaf proline (34.3%), and highest reduction in leaf malondialdehyde contents (20.4%) was recorded when H₂O₂ was foliage‐applied at 100 μm . Foliage application of SNP enhanced the grains per spike, 100‐grain weight and grain yield by 14.9%, 11.3% and 20.1%, respectively, than control. The foliage‐applied stress signalling molecules improved the accumulation of soluble phenolics, proline and glycine betaine with simultaneous reduction in malondialdehyde contents, which enabled wheat plants to sustain the biological membranes under stress resulting in better stay green (high chlorophyll contents) under drought. This helped improving the grain number, grain weight, grain yield, WUE and transpiration efficiency. In crux, foliage‐applied H₂O₂ and SNP, at pre‐optimized rate, may be opted to lessen the drought‐induced yield losses in bread wheat in climate change conditions.     

Incubation success and habitat selection of shore‐spawning kokanee Oncorhynchus nerka: effects of water‐level regulation and habitat characteristics

Changes to water‐level regimes have been known to restructure fish assemblages and interfere with the population dynamics of both littoral and pelagic species. The effect of altered water‐level regimes on shore‐spawning kokanee Oncorhynchus nerka incubation success was evaluated using a comprehensive in situ study in Lake Pend Oreille, ID, USA. Survival was not related to substrate size composition or depth, indicating that shore‐spawning kokanee do not currently receive a substrate‐mediated survival benefit from higher winter water levels. Substrate composition also did not differ among isobaths in the nearshore area. On average, the odds of an egg surviving to the preemergent stage were more than three times greater for sites in downwelling areas than those lacking downwelling. This study revealed that shoreline spawning habitat is not as limited as previously thought. Downwelling areas appear to contribute substantially to shore‐spawning kokanee recruitment. This research illustrates the value of rigorous in situ studies both for testing potential mechanisms underlying population trends and providing insight into spawning habitat selection.     

国家重点实验室专项经费绩效预算管理方式应用于其他财政专项管理的思考

绩效预算是我国部门预算管理改革的重要内容。国家重点实验室专项经费绩效预算安排机制，是财政科研经费绩效预算的典型示例。文章通过剖析国家重点实验室专项经费绩效考评管理机制，对国家重点实验室绩效预算机制推广应用于其他财政专项的范围、考评指标、考评工作方法、考评结果应用等方面提出了意见建议。     

Addition of structural complexity – contrasting effect on juvenile brown trout in a natural stream

In a field experiment, we examined the effects of structural complexity in the form of added artificial plastic plants and shredded plastic bags on growth and abundance of juvenile brown trout (Salmo trutta). Just after emergence, the added complexity had a positive effect on the density, biomass and condition factor of young‐of‐the‐year (0+) brown trout. This difference in density was not present six weeks later. In contrast, both young‐of‐the‐year and older brown trout generally tended to be larger in the simple habitat. Hence, our data suggest that increased complexity initially is beneficial for young‐of‐the‐year individuals probably due to lower risk of predation and increased densities of prey. However, as density increases in the complex environment, it may induce negative density‐dependent effects, here reflected in smaller sized fish in the complex environment. This might force fish to redistribute to habitats with lower densities of conspecifics as they grow larger. We propose that habitat complexity can increase survival of yearlings in early phases and thereby also affect the overall population structure of brown trout in natural streams.     

Comparison of dietary essential amino acid requirements determined from group‐housed versus individually‐housed juvenile bluegill,Lepomis macrochirus

Two 60‐day experiments were conducted sequentially to determine (i) lysine requirement of juvenile bluegill, Lepomis macrochirus based on the dose–response method, (ii) requirements for other essential amino acids (EAAs) using whole‐body amino acid profile and (iii) whether differences in growth rates of group‐housed versus individually‐housed bluegills lead to different lysine requirement levels because of the presence and absence, respectively, of social hierarchies. Seven, semi‐purified, experimental diets (isonitrogenous, isocaloric) were prepared to contain graded levels of digestible lysine (10–31 g kg⁻¹). Experiment‐1 involved group‐housed bluegills (approximately 27 g, n = 10 fish/chamber, 4 chambers/diet) whereas experiment‐2 involved individually‐housed bluegills (approximately 30 g, n = 1 fish/chamber, 14 chambers/diet). Fish were fed twice daily to apparent satiation. Bluegill growth responses in both experiments generally improved (P < 0.05, anova ) with increasing dietary lysine levels from 10 to 16 g kg⁻¹, and then levelled off with further increase in lysine level (P > 0.05). Optimal dietary lysine level (digestible basis) was estimated to be 15 g kg⁻¹ based on broken‐line regression analyses of relative growth rate and feed conversion ratio with no differences being observed between the two rearing methods. Determined dietary requirement levels for other EAAs ranged from 2.4 g kg⁻¹ (tryptophan) to 15.3 g kg⁻¹ (leucine).     

Effects of forage type and gibberellic acid on nitrate leaching losses

Nitrogen (N) leaching from soil into water is a significant concern for intensively grazed forage‐based systems because it can cause a decline in water quality and is a risk to human health. Urine patches from grazing animals are the main source of this N. The objective of this study was to quantify the effect that forage type and gibberellic acid (GA) application had on N leaching and herbage N uptake from urine patches on perennial ryegrass–white clover (RGWC), Italian ryegrass and lucerne. A lysimeter study was conducted over 17 months to measure herbage growth, N uptake and N loss to water beneath each of the three forage types with the following treatments: control, urine (700 kg N/ha) and urine with GA (8 g GA active ingredient/ha). Compared with RGWC (205 kg N/ha), N leaching losses were 35.3% lower from Italian ryegrass (133 kg N/ha) and 98.5% higher from lucerne (407 kg N/ha). These differences in leaching loss are likely to be due to winter plant growth and N uptake. During the winter months, Italian ryegrass had higher N uptake, whereas lucerne had lower N uptake, compared with RGWC. The application of GA had no effect on N leaching losses, DM yield or N uptake of forage treated with 700 kg N/ha urine.     

Soil organic and inorganic carbon sequestration by consecutive biochar application: Results from a decade field experiment

Biochar addition can expand soil organic carbon (SOC) stock and has potential ability in mitigating climate change. Also, some incubation experiments have shown that biochar can increase soil inorganic carbon (SIC) contents. However, there is no direct evidence for this from the field experiment. In order to make up the sparseness of available data resulting from the long‐term effect of biochar amendment on soil carbon fractions, here we detected the contents and stocks of the bulk SIC and SOC fractions based on a 10‐year field experiment of consecutive biochar application in Shandong Province, China. There are three biochar treatments as no‐biochar (control), and biochar application at 4.5 Mg ha^?1 year^?1 (B4.5) and 9.0 Mg ha^?1 year^?1 (B9.0), respectively. The results showed that biochar application significantly enhanced SIC content (3.2%–24.3%), >53 μm particulate organic carbon content (POC, 38.2%–166.2%) and total soil organic carbon content (15.8%–82.2%), compared with the no‐biochar control. However, <53 μm silt–clay‐associated organic carbon (SCOC) content was significantly decreased (14%–27%) under the B9.0 treatment. Our study provides the direct field evidence that SIC contributed to carbon sequestration after the biochar application, and indicates that the applied biochar was allocated mainly in POC fraction. Further, the decreased SCOC and increased microbial biomass carbon contents observed in field suggest that the biochar application might exert a positive priming effect on native soil organic carbon.     

Drought Stress in Grain Legumes during Reproduction and Grain Filling

Water scarcity is a major constraint limiting grain legume production particularly in the arid and semi‐arid tropics. Different climate models have predicted changes in rainfall distribution and frequent drought spells for the future. Although drought impedes the productivity of grain legumes at all growth stages, its occurrence during reproductive and grain development stages (terminal drought) is more critical and usually results in significant loss in grain yield. However, the extent of yield loss depends on the duration and intensity of the stress. A reduction in the rate of net photosynthesis, and poor grain set and grain development are the principal reasons for terminal drought‐induced loss in grain yield. Insight into the impact and resistance mechanism of terminal drought is required for effective crop improvement programmes aiming to improve resistance to terminal drought in grain legumes. In this article, the impact of terminal drought on leaf development and senescence, light harvesting and carbon fixation, and grain development and grain composition is discussed. The mechanisms of resistance, management options, and innovative breeding and functional genomics strategies to improve resistance to terminal drought in grain legumes are also discussed.