中晚粳品种寒丰的选育及其特性研究

<正> 选育株型好,生育期中等,耐寒性强,又能抗稻瘟病的品种是后季稻育种的重要课题。1974年秋用垦桂/科情3号//黎明复交,经二次海南岛异地加代,F_5时进行初步产量鉴定,亩产1001斤,比对照嘉农15增产2%,但仍有分离。以后又进行株系提纯,其中以7号株系产量最高,亩产1080斤,比对照嘉农15增产5.4%。1980～82年参加上海市后季     

Effects of dietary dl‐methionyl‐dl‐methionine (Met‐Met) on growth performance,body composition and haematological parameters of white shrimp (Litopenaeus vannamei) fed with plant protein–based diets

A 10‐week feeding trial was conducted to evaluate the effects of supplementing different levels of dl ‐methionyl‐dl ‐methionine (AQUAVI^® Met‐Met) in plant protein–based diets on Litopenaeus vannamei. The positive control (PC) and negative control (NC) diets were designed with 20% and 8% fishmeal respectively, and other six diets were formulated with graded levels of Met‐Met from 0.05% to 0.30% with a 0.05% increment on the basis of NC diet (MM 0.05–MM 0.3). Six replicates were randomly assigned to each diet with 50 shrimp each having initial weight of 0.98 ± 0.02 g. The variation of FM concentration from 20% to 8% and supplemented with graded levels of Met‐Met did not affect the survival rate, feed conversion ratio, protein efficiency ratio, whole body and muscle proximate compositions (p > 0.05). However, diets with ≤0.20% Met‐Met supplementation resulted in significantly increased weight gain and specific growth rate, after which both parameters reached plateau. Shrimp fed the NC diet showed significantly lower total essential amino acid (EAA) content in muscle (p < 0.05). Supplementation of Met‐Met significantly improved apparent digestibility coefficients of dry matter, crude protein, lipid, phosphorus and EAAs (p < 0.05). Based on broken‐line analysis, the methionine requirement for white shrimp was estimated to be 0.87% when using Met‐Met as methionine source.     

长白山区长期放牧草地植物种类动态

通过实地调查,对临江市八里沟老秃岭长期放牧草地和林下草地植物种类动态及其多样性进行了比较分析.结果表明:在长期放牧草地和林下草地中,共出现111种植物,隶属于43科,93属,其中,长期放牧草地(1区)共有植物63种,林下草地中(2区)109种.林下草地植被区以菊科、百合科、毛茛科、禾本科、豆科、蔷薇科、石竹科、堇菜科、...     

Light-sucrose interaction stimulates nitrate uptake by wheat roots

To improve nitrate uptake efficiency and minimize fertilizer waster, nitrate uptake control was investigated. In the previous work, we found that illuminating shoots can stimulate nitrate uptake by wheat (Triticum aestivum cv. “EM18”) roots, which is thought to be via a signal carried through phloem, maybe a sugar. We also found that sucrose could show features of a specific signal of nitrate uptake. A noninvasive technique method with a high-time resolution (minutes) has enabled us to make the comparison between illumination and sucrose supply. Interestingly, the results showed when plants were in the light, the stimulation by external sucrose was less than that in the dark, indicating light affected nitrate uptake co-operatively with externally supplied sucrose. The interaction between light and externally supplied sucrose showed that the mechanism of light effect on nitrate uptake involved sucrose. This work was useful for further investigating its molecular mechanism and ultimately improving nitrogen use efficiency.     

绿色植物基微生态食品的产业化开发——以籽粒苋为例

籽粒苋子实是优质的食品原料,其蛋白质含量高且质量好,尤其是赖氨酸含量高;钙、锌、铁含量丰富,还含有类胰岛素、角鲨烯等医疗保健成分。植物基微生态食品中的籽粒苋酸乳及其复合酸乳已获得两项国家发明专利,该专利产品全部使用植物原料,利用现代生物技术发酵而成。产品在不添加稳定剂的情况下不沉淀、含活菌、低脂肪,无胆固醇及乳糖,风味独特,非常适合“三高”人群食用。籽粒苋在吉林省已初步形成了较完整的技术支撑和推广体系,只要有企业接产,“农户+公司”的产业化格局即可形成,实现公司增效、农民增收。      

外源芘的添加对水稻土微生物群落多样性的影响

采用磷脂脂肪酸(PLFA)生物标记法和聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)技术,研究了外源芘的添加对土壤中微生物群落结构和遗传多样性的影响。结果表明,在培养1~15d内,添加芘的土壤中脂肪酸总量高于未添加芘的对照组;而培养30d时,添加芘的土壤中脂肪酸总量低于对照组。芘的添加增加了土壤中真菌、放线菌和革兰氏阴性菌的脂肪酸含量,减少了革兰氏阳性菌的脂肪酸含量,并改变了土壤中细菌群落的遗传多样性。多样性指数在培养15d时最低,而到培养30d时达到最大值,其变化可能与土壤中外源芘的降解有关。     

妃子笑荔枝LcSAI启动子的克隆及其生物信息学分析

[目的]酸性转化酶在荔枝糖代谢中具有重要作用,克隆和分析荔枝酸性转化酶基因(LcSAI)启动子,以期为LcSAI调控荔枝糖代谢的功能研究提供理论依据.[方法]以妃子笑荔枝果肉为材料,根据荔枝基因组序列信息,克隆LcSAI上游约1500bp的启动子序列,并利用生物信息学工具对启动子序列中的转录起始位点、顺式作用元件及Cp...     

宁夏灌区扁豆农艺及产量性状分析

对宁夏灌区引种扁豆的农艺及产量性状进行分析,结果表明,宁夏灌区引种的扁豆从播种到成熟需要80d左右;株高与生育期、单株荚数呈显著负相关;小区产量与主茎分枝、千粒重均呈显著正相关;主成分分析表现为3个主成分,分别是产量主成分、千粒重主成分和荚粒数主成分;产量及其构成因素分析表明单株荚数、单荚粒数品种间均无显著差异,而千粒重差异显著,产量的变化主要是由千粒重的变化引起的。     

长江三角洲地区土壤环境质量与修复研究Ⅲ.农业土壤不同粒径组分中菲和苯并[a]芘的分配特征

持久性有机污染物在土壤环境中的行为在很大程度上取决于土壤有机质对它们的吸附作用，粒径分组通常用来区分具有不同有机质组成和周转速率的有机质库。本研究利用菲（Phe）和苯并[a]芘（Bap）作为多环芳烃（PAHs）低、高环组分的代表物质，研究了它们在污染区9个农业表层土壤（0～20cm）不同粒径组分（粘粒、细粉粒、粗粉粒、细砂粒和粗砂粒）中的分配特征。结果表明，Phe在不同粒径组分中的平均含量大小顺序为粗砂粒〉细砂粒〉粘粒〉细粉粒〉粗粉粒，Bap为粗砂粒〉细砂粒〉粗粉粒〉细粉粒〉粘粒。Phe和BaP在不同粒径组分中的含量与粒径组分中有机质的含量均呈显著性正相关（P〈0．01）。不同粒径组分中的有机质对Phe富集能力的大小顺序为粗粉粒〉细粉粒〉细砂粒〉粗砂粒〉粘粒，对Bap的富集能力为粗粉粒〉粗砂粒〉细粉粒〉细砂粒〉粘粒。     

Effects of grazing on CO2 balance in a semiarid steppe: field observations and modeling

Purpose

Carbon (C) dynamics in grassland ecosystem contributes to regional and global fluxes in carbon dioxide (CO₂) concentrations. Grazing is one of the main structuring factors in grassland, but the impact of grazing on the C budget is still under debate. In this study, in situ net ecosystem CO₂ exchange (NEE) observations by the eddy covariance technique were integrated with a modified process-oriented biogeochemistry model (denitrification–decomposition) to investigate the impacts of grazing on the long-term C budget of semiarid grasslands.

Materials and methods

NEE measurements were conducted in two adjacent grassland sites, non-grazing (NG) and moderate grazing (MG), during 2006–2007. We then used daily weather data for 1978–2007 in conjunction with soil properties and grazing scenarios as model inputs to simulate grassland productivity and C dynamics. The observed and simulated CO₂ fluxes under moderate grazing intensity were compared with those without grazing.

Results and discussion

NEE data from 2-year observations showed that moderate grazing significantly decreased grassland ecosystem CO₂ release and shifted the ecosystem from a negative CO₂ balance (releasing 34.00 g C?m^?2) at the NG site to a positive CO₂ balance (absorbing ?43.02 g C?m^?2) at the MG site. Supporting our experimental findings, the 30-year simulation also showed that moderate grazing significantly enhances the CO₂ uptake potential of the targeted grassland, shifting the ecosystem from a negative CO₂ balance (57.08?±?16.45 g C?m^?2?year^?1) without grazing to a positive CO₂ balance (?28.58?±?14.60 g C?m^?2?year^?1) under moderate grazing. The positive effects of grazing on CO₂ balance could primarily be attributed to an increase in productivity combined with a significant decrease of soil heterotrophic respiration and total ecosystem respiration.

Conclusions

We conclude that moderate grazing prevails over no-management practices in maintaining CO₂ balance in semiarid grasslands, moderating and mitigating the negative effects of global climate change on the CO₂ balance in grassland ecosystems.