A review of composting as a management alternative for beef cattle feedlot manure in southern Alberta, Canada

Composting is gaining increased acceptance as a management alternative for the large volumes of manure produced by southern Alberta's beef cattle feedlots. Research on windrow composting of feedlot manure was initiated at the Lethbridge Research Centre of Agriculture and Agri-Food Canada in 1996. Early studies looked at physical and chemical changes during composting. Studies have also been conducted on greenhouse gas emissions during composting and the effect of composting on reduction of pathogens, parasites and weed seed viability. The quality of commercially-produced composts at southern Alberta feedlots has been examined as has the mineralization rates of soil-applied composts. This paper reviews results from our feedlot manure composting research program.     

荸荠营养器官的发育与解剖学研究

荸荠同化茎起源于肉质主茎倒２或倒３叶的叶腋内。同化茎基部着生二鞘状叶,鞘状叶对早期同化茎穿出土面具保护作用。匍匐茎大多起源于同化茎基部鞘状叶的叶腋内。当植株开始抽生花茎时,地下匍匐茎顶端开始膨大。球茎的膨大是匍匐茎顶端５－６节的基本组织经细胞有丝分裂,增加细胞数目,然后由细胞体积的扩大来实现的。球茎具足够的营养物质供来年顶芽萌发的需要,故属水生植物冬芽的性质。     

三种核型多角体病毒核酸同源性的研究

用分子杂交技术研究了黑点银纹夜蛾(Arqyrogramma agnata Stgr,)单粒包埋型核型多角体病毒(简称A,A,SNPV),斜纹夜蛾(Prodenia litura)多粒包埋型核型多角体病毒(简称PL MNPV)以及用A,A,SNPV感染斜纹夜蛾幼虫所获得的多粒包埋型核型多角体病毒(暂称PoI MNPV)三种病毒核酸的同源性,用SDS-Tris酚法分别提取病毒核酸,用内切酶Eco RⅠ酶解,比较了病毒核酸的酶解图谱及分子量,用〔α-~(32)P〕dATP标记的三种病毒核酸Eco RⅠ酶解片段作探针,分别与各病毒核酸的Eco RI酶解片段杂交,结果表明PoI MNPV与PL MNPV的病毒核酸同源,而A,A,SNPV DNA不与PoI MNPV DNA、PL MNPV DNA杂交,无同源序列。     

岭南垛基果林湿地土壤碳组分特征

岭南垛基果林湿地是珠三角地区典型的湿地类型之一,其对土壤碳汇的贡献值得关注。为探讨果林种植类型对土壤有机碳的影响,对广州垛基果林湿地内种植黄皮(Clausenalansium)(HP),龙眼(Dimocarpuslongan)(LY)、杨桃(Averrhoa carambola)(YT),龙眼和黄皮间种(LH),杨桃、龙眼和黄皮间种(YLH)共5种种植类型下的表层(0～20 cm)土壤碳组分进行研究。结果表明,不同的植被类型对土壤的总有机碳(SOC)、可溶性有机碳(DOC)、微生物生物量碳(MBC)、易氧化有机碳(ROC)、惰性碳(NLC)含量都有影响,LY的SOC含量最高(22.6 g/kg),显著高于YLH (P<0.05),且NLC含量显著高于LH和YLH (P<0.05)。NLC含量与土壤养分呈正相关,与土壤容重呈负相关。YT的MBC含量显著高于LY、HP、LH (P<0.05),且MBC/SOC显著高于HP、LY(P<0.05)。YLH模式下,土壤DOC含量和DOC/SOC显著高于其他植被类型(P<0.05)。LH的ROC/SOC显著高于HP和L...     

中国黄颡鱼的线粒体DNA多样性及其分子系统学

基于体侧色斑、背鳍前部形态、吻长及尾柄长的差异, Ng和Kottelat(2007)将分布于中国的黄颡鱼群体划为两个物种: 北方群体为Pseudobagrus sinensis, 南方群体为P. fulvidraco。本研究通过对70个黄颡鱼标本相关形态特征的测量及对线粒体cyt b基因序列的分析, 探讨了P. sinensis物种的有效性问题。结果表明: 依据体侧色斑和背鳍前部形态的差异, 可将黄颡鱼分为对应于P. sinensis和P. fulvidraco的两种形态类型, 但对尾柄长、吻长的测量发现二者没有差异。对70条cyt b基因序列的分析结果为: 两种鱼类有1个共同的单倍型; 两种鱼类的单系性在系统发育分析中都没有得到重现, 而二者聚在一起形成获得100%支持率的单系群; 两种鱼类群体之间存在持续的基因交流(Nm = 4.7); 两种鱼类在单倍型的巢式支系分析(nested clade analysis, NCA)中没有形成各自独立的进化谱系, 所有的单倍型以不超过5步的突变全部被纳入同一个进化网络中。因此我们认为P. sinensis不是有效物种, 而应被视为黄颡鱼的一种形态类型。基于cyt b基因的序列变异, 本研究对黄颡鱼群体的遗传多样性和种群结构作了初步分析。群体的核苷酸不配对分布及Tajima’sD中性检验表明, 约在10.1-14.1万年前, 黄颡鱼在其分布范围内经历过群体扩张, 推测这可能是导致黄颡鱼群体单倍型多样度高(h = 0.857 ± 0.0014)而核苷酸多样度低( π = 0.0023 ± 0.0003)的主要原因。此外, 分析结果显示黄颡鱼群体缺乏明显的地理结构, 推测原因可能是历史上水系的连通促进了不同地理群体之间的基因交流。     

甘南地区二氧化碳施肥效应对生态系统的影响

陆地生态系统是全球第二大碳库,其碳收支一直是气候变化研究的热点领域,而研究二氧化碳（CO₂）施肥效应又是全球变化碳循环领域较为关注的前沿部分。CO₂与生态系统关系复杂,当前仍无法厘清CO₂对陆地生态系统碳循环的影响作用。基于太阳辐射数据、气温数据及归一化植被指数数据等,利用光能利用率遥感模型,模拟2019年甘南地区的碳循环,选取三个指标,即GPP （陆地生态系统总初级生产力）、NPP （净初级生产力）和NEP （净生态系统生产力）来分析甘南地区植被固碳的时空变化特征及CO₂施肥效应。结果表明：（1）甘南地区2019年植被固碳总量约为2611 tC。甘南地区生态系统GPP、NPP和NEP季节性特征明显,其值均在夏季达到最高;而在空间上,GPP、NPP表现为东高西低的特征,NEP呈现出北高南低的分布特征。（2） CO₂对GPP、NPP存在正向的施肥效应,分别增加了14.4%和14.3%;而对NEP具有负向反馈效应,使其减少了0.3%,并且CO₂对NEP的影响整体也表现为北高南低的特征。研究揭示出：虽然CO₂在提升GPP和NPP时,正向的施肥效应明显,但是对甘南地区的NEP,即固碳量来说,CO₂的影响却很有限。因此在研究CO₂施肥效应时不应一概而论,生态地理环境对其的影响不可忽视。研究可以为揭示陆地生态系统碳循环的动态机制提供一定的理论依据。     

The CYP19 RS4646 Polymorphism IS Related to the Prognosis of Stage I–II and Operable Stage III Breast Cancer

Purpose

Aromatase, encoded by the CYP19 gene, catalyzes the final step of the conversion of androgens to estrogens. Given the critical role of CYP19 in estrogen synthesis, the potential influence of CYP19 rs4646 polymorphism on breast cancer survival, deserves further study.

Methods

Genotyping for CYP19 rs4646 variants was performed on 406 Chinese women with stage I–II and operable stage III breast cancer. Associations were evaluated between CYP19 rs4646 genotypes and disease-free survival (DFS).

Results

In premenopausal patients, women who are homozygous for the minor allele (AA) have a longer DFS compared with those carrying the major allele (CC or AC) (87 months versus 48.7 months; Hazard ratio (HR) = 0.56, 95 % CI = 0.318-0.985, P = 0.041). These differences were further demonstrated by a multivariate analysis (HR = 0.456, 95 % CI = 0.249-0.836, P = 0.011). Conversely, the same variant (AA) was estimated to be associated with a poorer DFS in postmenopausal women (AA versus AC or CC: 13.7 months versus 56.3 months; HR = 2.758, 95 % CI = 1.432-5.313, P = 0.002). Furthermore, the differences were confirmed by the COX proportional hazards model (HR = 2.983, 95% CI =1.494-5.955, P = 0.002).

Conclusions

The present study indicates that CYP19 rs4646 polymorphism is related to DFS in early breast cancer and that the prognosis index of the homozygous for the minor allele (AA) may depend on menopause status. The findings are novel, if confirmed, rs4646 genotypes may provide useful information for routine management in breast cancer.     

Determining critical values of soil Olsen-P for maize and winter wheat from long-term experiments in China

The critical value of soil Olsen-P is the point above which the probability of crop yield response to fertilizer P is small or nil. Determining this critical value is fundamental when making appropriate P fertilizer recommendations. In this study, the critical values were determined for continuous maize (Zea mays L.)-winter wheat (Triticum aestivum L.) cropping systems from a 15-year field experiment across three sites in China using linear-linear, linear-plateau and Mitscherlich models. The mean critical values for maize using the three models ranged from 12.1 to 17.3 mg P kg^?1 (average 15.3 mg P kg^?1) and for winter wheat from 12.5 to 19.0 mg P kg^?1 (average 16.3 mg P kg^?1) among study sites. The mean critical value for maize was approximately 7% lower than that for winter wheat across all sites based on the three models. Critical values identified by the Mitscherlich model were 1.4 to 2.1 times those from linear-linear and 1.3 to 1.9 times of those from linear-plateau and were crop and site dependent. There was a significant negative correlation (P?<?0.05) between the mean critical value from the three models and the observed P uptake by either maize or wheat. Our study shows that the critical values can vary with sites, crops and models used, and thus caution should be taken when selecting the most appropriate one when making P fertilizer recommendations for agronomic return and to minimize chances of negative environment impact from overfertilization.