温室效应对红桦泡囊丛枝菌根侵染率和侵染强度的影响

本试验以红桦（Betulaalbo-sinensis）为材料,研究不同处理条件下,AMF侵染率和侵染强度的变化规律。结果表明：（1）在自然状态下,AMF的侵染率和侵染强度高;（2）光照强度可提高AMF的侵染率和侵染强度;（3）温度升高和二氧化碳浓度倍增加强AMF的侵染强度;（4）温度差值在4℃～7℃时对AMF侵染率有促进作用;（5）温度差值在2℃～4℃和二氧化碳浓度倍增对AMF侵染率夏季起抑制作用,秋季起促进作用;（6）从夏季到秋季,AMF侵染率下降,而二氧化碳浓度倍数却使AMF侵染率上升。     

Reliable data on fine-root turnover from sequential soil coring in an old carbon budget for a 14-year-old Scots pine from the late 1970s: Comments on Majdi et al., Scandinavian Journal of Forest Research 22: 299–303

Abstract

Comprehensive data from different research workers were included in the compilation of a carbon budget for a 14-year-old Scots pine (Pinus sylvestris) in the late 1970s, within the SWECON project (the Swedish Coniferous Forest Project). In a recent paper in the Scandinavian Journal of Forest Research, the authors published a surprisingly high turnover rate of fine roots (7.4 year^?1), maintaining that they had used our old SWECON data from our sequential soil coring. However, a close examination of our original data suggests a turnover of fine-root biomass of 2.3 and for fine-root standing crop (biomass+necromass) of 2.0 year^?1. Supporting evidence is available from other forest sites suggesting that our turnover rates were correctly estimated. Certain errors may exist in different parts of our old carbon budget, e.g. some measurements were carried out for different parts of the tree, while others were attributed to the whole stand. The sequential soil coring technique still remains the best technique available for fine-root growth and turnover estimates in forest stands.     

Carbon storage capacity of high altitude Quercus semecarpifolia,forests of Central Himalayan region

Abstract

Quercus semecarpifolia, Smith. (brown oak) forests dominate the high altitudes of central Himalaya between 2400 and 2750 m and the timber line areas. The species is viviparous with short seed viability and coincides its germination with monsoon rains in July–August. These forests have large reserves of carbon in their biomass (above and below ground parts) and soil. We monitored the carbon stock and carbon sequestration rates of this oak on two sites subjected to varying level of disturbance between 2004 and 2009. These forests had carbon ranging between 210.26 and 258.02 t ha^?1 in their biomass in 2009 and mean carbon sequestration rates between 3.7 and 4.8 t ha^?1 yr^?1. The litter production in both the sites ranged from 5.63 to 7.25 t ha^?1 yr^?1. The leaf litter decomposition of species took more than 720 days for approximately 90% decomposition. Even at 1 m soil depth soil organic carbon was close to 1.0%.     

Can carbon isotope discrimination and ash content predict grain yield and water use efficiency in wheat?

Drought is the main factor affecting crop grain yield. Increasing grain yield under drought and crop water use efficiency (WUE) is essential for enhancing world crop production and food availability. The objective of this study, carried out in India on 20 durum wheat cultivars, under three water regimes (full irrigation, limited irrigation and residual soil moisture) and during two seasons, was to investigate the potential use of plant traits (particularly carbon isotope discrimination, Δ, and ash content, m_a) to predict grain yield and WUE in wheat. WUE components were estimated using a soil water balance model (Budget) allowing comparison of environments in data scarce situations. A highly significant correlation was noted between grain yield and grain Δ across water regimes. However, the associations between grain yield, Δ and m_a were found to depend highly on the water regime and environmental conditions. The association between grain yield and grain Δ was significant under full irrigation in season 1 and under residual soil moisture in season 2. Significant positive correlations were noted in both seasons between grain yield and leaf Δ under residual soil moisture and between grain yield and leaf ash content at anthesis under limited irrigation. A significant correlation was found across environments between grain and leaf Δ and T, the quantity of water transpired during the growth cycle, as estimated by the soil water balance model. T also significantly correlated to grain and leaf m_a. Variation in WUE across environments was driven more by runoff, drainage and soil evaporation than by harvest index and transpiration. The associations between WUE and transpiration, runoff and Δ were negative but not significant. WUE was significantly correlated with leaf and grain m_a at maturity. The study indicates that Δ and m_a can be used as indirect selection criteria for grain yield and suggests that m_a is a good predictor of transpiration, grain yield and WUE across environments. The use of mechanistic models that allows differentiating between cultivars should permit in a next future to analyze the relationships between WUE, Δ and m_a across cultivars and evaluate the possibility to use these traits as predictors of WUE in wheat breeding programs.     

春大豆鼓粒期冠层翻叶原因及翻叶对叶片净光合速率和粒重的影响

为明确春大豆鼓粒期冠层翻叶原因及翻叶对粒重的影响。在大田条件下,以28份大豆品种为材料,采用随机区组试验设计,研究了鼓粒初期植株顶部4片叶的单叶面积、比叶重、叶型指数、叶片含水量与翻叶率的关系;比较了翻叶与对照叶片的净光合速率、百粒重及粒重的差异。结果表明,不同大豆品种间翻叶率在0~26.5%之间,且差异显著,其中以‘中黄313’、‘中黄42’和‘中黄13’最高;单叶面积在46~151 cm²之间,其中以‘中黄39’、‘中黄42’和‘中黄13’最大;比叶重在0.536~1.64 mg/cm²之间,其中以‘中黄322’、‘中黄313’和‘中黄13’最低;叶型指数在1.35~3.51之间,其中以‘中黄70’、‘中黄80’和‘中黄42’最低。供试大豆品种分为3个类群,第I类群品种单叶面积小,比叶重高,叶型指数大,翻叶率为1.03%;第III类群品种单叶面积大,比叶重小,翻叶率高达19.7%;第II类群共4个品种,单叶面积、比叶重、叶型指数、翻叶率介于第I类和第III类群之间。翻叶后显著降低叶片净光合速率,平均降幅31.7%,粒数较多的‘新大豆27号’百粒重降低10.38%~22.4%,而粒数少的‘吉育60’粒重没有降低。大豆上层叶片单叶面积大、比叶重小及叶型指数低的叶片翻叶率高,翻叶降低叶片净光合速率,进而降低同节位百粒重及单节粒重,不利于大豆高产。     

旱种水稻结实期茎中碳同化物的运转及其生理机制

以杂交水稻汕优63和籼稻扬稻6号为材料，研究了旱种(地膜覆盖栽培)水稻结实期茎中碳同化物的运转及其生理机制。结果表明，抽穗至成熟期旱种水稻标记14C从茎中向籽粒的再分配、茎中非结构性碳水化合物(NSC)的运转率及其对籽粒的贡献率均显著高于水种(常规栽培)水稻。水稻旱种后籽粒中的蔗糖合成酶和酸性转化酶活性、茎中α-淀     

不同施肥条件对鱼腥草碳氮代谢生理指标的影响

【研究目的】结合前期对产量、品质的研究，探讨不同施肥条件下鱼腥草叶片主要碳氮代谢指标的变化及其与产量形成的关系。【方法】采用单因子随机区组设计进行施肥实验，测定鱼腥草叶片光合速率、硝酸还原酶活性、叶绿素和粗蛋白的含量。【结果】各施肥处理中以较低施肥水平人粪尿处理的鱼腥草叶片含叶绿素总量最高，达2.552 mg/gFW，以中等施肥水平鸭粪的净光合速率最高，为8.306μmol/(m2·s)。施用不同肥料的鱼腥草叶片硝酸还原酶活性大小为：鸭粪>猪粪>常规施肥>化肥>人粪尿，各处理以中等施肥水平的猪粪处理的硝酸还原酶最高，达46.2μg NO2-/(h·g)FW；粗蛋白以施用较高水平化肥的最高（13.31%）。【结论】施用有机肥能显著提高鱼腥草叶片的碳代谢，这有利于其产量的形成；但施用人粪尿不利于提高鱼腥草叶片硝酸还原酶活性和蛋白质的形成与积累。     

六种稻田土壤冬季种植黑麦草功能效应研究

选取我国亚热带地区6种主要成土母质发育的水稻土,通过定位试验研究了黑麦草产量、碳氮环境效应和土壤微生物量变化。结果表明,6种稻田土壤冬季均适合生长黑麦草,黑麦草地上部和根系干物质产量,在河沙泥田表现最好,分别为11 324.8 kg hm^-2和8 227.3 kg hm^-2。6种稻田土壤黑麦草地上部和根系碳蓄积量均存在显著差异(P＜0.05),地上部分碳蓄积量在河沙泥田最高,为4 495.3 kg hm^-2;根系碳蓄积量在河沙泥田和麻沙泥田表现最好,分别为2 799.6 kg hm^-2和2 711.8 kg hm^-2;黄泥田最低,为1 852.9 kg hm^-2。而黑麦草氮蓄积量,在河沙泥田最高,地上氮蓄积量为238.1 kg hm^-2,地下氮蓄积量为60.1 kg hm^-2。6种稻田土壤微生物量碳和土壤微生物量氮,在种草区和冬闲田间差异均达到了显著水平(P＜0.05),除灰泥田外种草区均大于冬闲田,冬季种植黑麦草增加了土壤微生物商。     

Environmental impacts from herbicide tolerant canola production in Western Canada

The commercial production of herbicide tolerant (HT) canola began in Western Canada in 1997. With more than a decade of use, the actual farm-level environmental impact of HT canola can be evaluated. This article reports on a spring 2007 survey of nearly 600 canola farmers in the three prairie provinces of Western Canada. Producers were asked about their crop production experiences for 2005 and 2006 and expected crop planting for 2007. A reduction in the total number of chemical applications over the 3-year period was reported, resulting in a decrease of herbicide active ingredient being applied to farmland in Western Canada of nearly 1.3 million kg annually. Fewer tillage passes over the survey period were reported, improving moisture conservation, decreasing soil erosion and contributing to carbon sequestration in annual cropland. An estimated 1 million tonnes of carbon is either sequestered or no longer released under land management facilitated by HT canola production, as compared to 1995. The value of this carbon off-set is estimated to be C$5 million. Comparisons with similar studies and against non-adoption of HT canola can guide future decisions about HT canola adoption.     

不同施肥条件下微生物对棕壤团聚体和碳分布的影响

以北京市延庆县绿富隆有机肥蔬菜研究基地长期定位肥料试验地为试验平台,利用湿筛法获得不同粒级的团聚体,通过16SrDNA-PCR-DGGE技术进行测序分析,研究不同施肥条件下微生物群落对棕壤土团聚体和碳分布的影响。结果表明,有机肥(OF)处理的0.25～2 mm水稳性团聚体增加,增加幅度为109.0%;0.053～0.25 mm和小于0.053 mm粒级团聚体的含量均下降,与CK(不施肥)相比分别下降了31.9%和142.1%。OF处理对土壤各粒级团聚体中碳含量均有显著提高,与CK相比,提高15.2%～46.9%,其中大于2 mm团聚体中碳含量提高了46.9%。棕壤碳含量与大于2 mm粒级团聚体含量呈正相关;与0.25～2 mm粒级团聚体呈极显著正相关;与0.053～0.25 mm粒级团聚体含量呈极显著负相关;与小于0.053 mm粒级团聚体呈显著负相关。