Carbon Accumulation and Fossil Fuel Substitution During Different Rotation Scenarios

Accumulation of carbon (C) in biomass and soil, and using forest residues for bioenergy are examples of forestry’s contribution to reducing the enhanced concentration of greenhouse gases in the atmosphere. The aim of this report was to study the effect of rotation length on carbon accumulation in biomass and soil, and on the amount of forest residues that could substitute fossil fuel during 2000–2100. Two models, based on inventory data from the Swedish National Forest Inventory, were used to simulate the effects of a changed rotation length in the region of Dalarna (1.8 × 10⁶ ha), in central Sweden. During the studied period, the accumulation of carbon in biomass was 32 kg C ha^?1 yr^?1 larger for the prolonged rotation period and 105 kg C ha^?1 yr^?1 smaller for the shortened rotation period compared with the base scenario. The build-up of carbon in forest soil was 23 kg C ha^?1 yr^?1 larger for the prolonged rotation than for the base scenario, whereas the shortened rotation was 24 kg C ha^?1 yr^?1 smaller than the base scenario. The potential to substitute fossil fuel was 37 kg C ha^?1 yr^?1 larger for the shortened rotation and 17 kg C ha^?1 yr^?1 smaller for the prolonged rotation compared with the base scenario. The annual accumulation of carbon in biomass decreased in all scenarios, which resulted in a prolonged rotation scenario possibly being a poor long-term solution (> 100 yrs). The amount of forest residues that could substitute fossil fuel increased in all scenarios during the studied period.     

Ability of chromosome 4H to compensate for 4D in response to drought stress in a newly developed and identified wheat–barley 4H(4D) disomic substitution line

A spontaneously developed wheat–barley 4H(4D) disomic substitution line was identified cytogenetically using genomic in situ hybridization (GISH), multicolour fluorescent in situ hybridization (FISH) and microsatellite markers. The ability of the barley 4H chromosome to compensate for wheat 4D in response to mild drought stress was also investigated. In the barley cv. 'Betzes' and the 4H(4D) substitution line, mild osmotic stress induced intensive stomatal closure, resulting in reduced water loss through transpiration and unchanged relative water content in the leaves. As the CO₂ assimilation rate remained relatively high, the water use efficiency, which is an important factor associated with drought tolerance, increased extensively under mild osmotic stress in these lines. In the case of the parental wheat genotypes, however, mild drought stress induced less intense stomatal closure and a greater decrease in the CO₂ assimilation rate than in barley or in the substitution line, resulting in unaugmented or reduced water use efficiency. The results demonstrate that genes localised on the 4H chromosome of barley were able to increase the water use efficiency of the wheat substitution line, which is suitable for improving wheat drought tolerance through intergeneric crossing.     

北京市高保护价值森林价值评估理论与方法初探

结合现行经济学理论界对森林价值的评估，针对高保护价值森林的特征，从生物多样性和生态服务功能两方面对北京市高保护价值森林的价值评估方法进行探讨。结合效用论、边际效益论等理论，根据实地情况，运用支付意愿法、补偿法、替代法等，从森林的实用价值和精神文化价值等方面作了评估方法概述。     

Roles of Root Aerenchyma Development and Its Associated QTL in Dry Matter Production under Transient Moisture Stress in Rice

Abstract

Enhanced aerenchyma development in rice under transient drought-to-waterlogged (TD-W) stress promotes root system development by promoting lateral root production. This study analyzed the quantitative trait loci (QTLs) associated with the plasticity in aerenchyma development under TD-W stress. A mapping population of 60 F₂ genotypes of chromosome segment substituted lines (CSSL) derived from CSSL47 and Nipponbare crosses were grown in rootboxes and evaluated for shoot and root growth, and aerenchyma development (expressed as root porosity). The TD-W stress was imposed starting with water saturated soil condition at sowing and then to progressive drought from 0 to 21 days after sowing (DAS) prior to exposure to sudden waterlogging for another 17 days (21 to 38 DAS). We performed simple and composite interval mapping to identify QTLs for aerenchyma development. QTL associated with aerenchyma development was mapped on the short-arm of chromosome 12 and designated as qAER-12. The effect of qAER-12 on the plasticity in aerenchyma development under TD-W was significantly associated with the increase in lateral root elongation and branching. This resulted in greater root system development as expressed in total root length and consequently contributed to higher dry matter production. This qAER-12 is probably the first reported QTL associated with aerenchyma development in rice under TD-W and is a useful trait for the improvement of the adaptive capability under fluctuating soil moisture conditions.     

Quality Effects of Rye (Secale cerealeL.) Chromosome Arm 1RL Transferred to Wheat (Triticum aestivumL.)

Quality effects of rye (Secale cerealeL.) chromosome arm 1RL transferred to wheat (Triticum aestivumL.) were characterised by comparison of a group 1R(1B) substitution lines and 1BL.1RS translocation lines. The experimental materials were sister lines derived from the mating Mironovskaya10/NE7060//NE80413. 1R(1B) substitution lines were identified by the presence of ryeomega- andgamma-secalins among 70% ethanol soluble proteins, combined with the presence of high molecular weight (HMW) secalin proteins in total grain protein extracts. Genes on 1RL reduced grain weight, grain hardness, Mixograph time, Mixograph tolerance and SDS sedimentation volumes. 1RL had no effect on flour yield or grain and flour protein concentrations. The HMW secalin proteins encoded by genes on 1RL most probably caused the decline in dough strength seen in 1R(1B) lines relative to that of 1BL.1RS sister lines. Reduced grain hardness might also be related to the presence of HMW secalins, although a role for additional, unidentified genes on 1RL could not be discounted.     

Characterization of a wheat–Thinopyron intermedium substitution line with resistance to powdery mildew

Among the progenies of a hybrid between common wheat Triticum aestivum L. cv. Yannong 15 and Thinopyron intermedium, plant E99018 was identified with the chromosome number 2n = 42 and stable agronomic traits. An analysis of the metaphase chromosome pairing indicated that it formed 21 bivalents but that 2 univalents were present in the F₁ hybrid of this plant with common wheat. Resistance verification by race 15 and with mixed races of Blumeria graminis f. sp. tritici at the seedling and adult stages showed that at both stages, the plant was immune to powdery mildew. In situ hybridization with the genomic Th. intermedium and the St genome DNAs as probes and wheat DNA as a block has shown that it contained a pair of Th. intermedium chromosomes. On the basis of the hybridization pattern of the St genome probe to the critical chromosome, a conclusion was reached that this pair of chromosomes belonged to the E genome. Therefore, plant E99018 was a spontaneously formed substitution line. An analysis by 116 SSR markers indicated that the substituted wheat chromosome was 2D and the most likely substitution in E99018 is 2E(2D).     

Genetic studies on the interspecific cytoplasm substitution lines of an Asian perennial strain of Oryza rufipogon Griff. and O. glaberrima Steud.

Summary It is shown that the restorer gene Rf _j extracted from the Japanese rice variety Akebono is effective on pollen restoration in the cytoplasm substitution line having the nucleus of Oryza glaberrima and japonica or indica cytoplasm of O. sativa, and is of the sporophytic type.The Asian perennial type of the wild rice species O. rufipogon is considered to be the progenitor of O. sativa. Two substitution lines having the cytoplasm of a perennial strain of O. rufipogon from Sri Lanka and the nucleus of O. glaberrima with or without the gene Rf _j in homozygous condition have been bred by means of successive backcrosses. These lines have now reached the BC₅ generation. Plants of the lines resemble morphologically the recurrent parent, but do not show pollen restoration, indicating that the cytoplasm of the rufipogon strain induced male sterility and that the gene Rf _j does not act as the restorer.     

Effects of homoeologous group 1 and 6 chromosomes of the Cappelle-Desprez (Bezostaya 1) substitution lines on aspects of bread-making quality of wheat

Summary The group 1 and 6 inter-varietal chromosome substitution lines of Cappelle-Desprez (Bezostaya 1) were intercrossed along with the donor and recipient varieties, Cappelle-Desprez and Bezostaya 1, to give 36 genetically different families. The analysis of the means of these families showed that variation in SDS-sedimentation volume fitted a predominantly additive model. There were no significant within or between chromosome interactions among the group 1 and 6 chromosomes. Nor was there any evidence for interactions between these chromosomes and those of the background. Significant dominance/within chromosome interactions amongst the background chromosomes were however detected. Some of the positive effects on SDS-sedimentation were associated with increased grain hardness. Chromosome effects on % grain protein were not correlated with SDS-sedimentation.     

Further manipulation by centric misdivision of the 1RS.1BL translocation in wheat

Complete chromosomes 1R and 1B were reconstructed in wheat from the centric wheat-rye translocation 1RS.1BL. Three substitutions: 1R(1A), 1R(1B), 1R(1D), and three new centric translocations: 1RS.1AL, 1RS.1BL, 1RS.1DL were produced from the reconstructed chromosome 1R. Each one of these has the same rye chromosome arm 1RS which was present in the original translocation 1RS.1BL of ‘Kavkaz’ wheat. Reconstructed chromosome 1B and a normal chromosome 1R were used to produce a new 1RS.1BL translocation. This translocation has the long arm from the original 1RS.1BL translocation of ‘Kavkaz’, but a different 1RS arm. The third generation centric translocations were mitotically stable and were normally transmitted to progeny. Misdivision frequency of the reconstructed chromosomes 1R did not change relative to normal 1R, whereas the misdivision frequency of the two reconstructed chromosomes 1B tested was significantly higher relative to normal 1B. These experiments demonstrate that repeated cycles of centric breakage and fusion do not impair the function of centromeres in wheat and rye but may change chromosome's susceptibility to misdivision. This revised version was published online in July 2006 with corrections to the Cover Date.