C/N比对好氧堆肥中NH3挥发损失和含氮有机物转化的影响

利用牛粪和不同比例玉米秸秆的混合,设置5个不同C/N比处理(T1=15、T2=20、T3=25、T4=30、T5=35),研究其对条垛式好氧堆肥过程中的NH₃挥发损失和含氮有机物转化的影响。结果表明:在肥堆前24 d有11.1%～23.1%的总氮损失,堆体C/N比越低,总氮损失率越高。堆肥结束时,T1～T5处理的总氮损失率为10.1%～24.1%,其中由NH₃挥发造成的氮损失占总氮损失的30.9%～40.5%。堆肥过程的NH₃挥发主要发生在升温期和高温期,此期的NH₃挥发量占总挥发量的95%以上,是总氮损失的主要途径。堆肥前6 d各处理堆体铵态氮积累并达到最高值,导致pH值迅速升高,是造成堆肥NH₃挥发的直接原因。堆体C/N比越低,pH值越高,NH₃挥发量越大,由此造成的氮损失占总氮损失的比例越大。堆肥材料总氮的90%以上为有机氮,其降解主要发生在堆肥前24 d,堆体初始C/N比越低,有机氮矿化越快。不同有机氮组分的降解速率不同,以氨基酸态氮和酰胺态氮的降...     

Responses of plant community to the linkages in plant-soil C:N:P stoichiometry during secondary succession of abandoned farmlands,China

Succession is one of the central themes of ecology;however,the relationship between aboveground plant communities and underground soils during secondary succession remains unclear.In this study,we investigated the composition of plant community,plant-soil C:N:P stoichiometry and their relationships during secondary succession after the abandonment of farmlands for 0,10,20,30,40 and 50 a in China,2016.Results showed that the composition of plant communities was most diverse in the farmlands after secondary succession for 20 and 50 a.Soil organic carbon and total nitrogen contents slightly decreased after secondary succession for 30 a,but both were significantly higher than those of control farmland(31.21%-139.10%and 24.24%-121.21%,respectively).Moreover,C:N ratios of soil and microbe greatly contributed to the changes in plant community composition during secondary succession of abandoned farmlands,explaining 35.70%of the total variation.Particularly,soil C:N ratio was significantly and positively related with the Shannon-Wiener index.This study provides the evidence of synchronous evolution between plant community and soil during secondary succession and C:N ratio is an important linkage between them.     

Community structure and carbon and nitrogen storage of sagebrush desert under grazing exclusion in Northwest China

Overgrazing is regarded as one of the key factors of vegetation and soil degradation in the arid and semi-arid regions of Northwest China.Grazing exclusion(GE)is one of the most common pathways used to restore degraded grasslands and to improve their ecosystem services.Nevertheless,there are still significant controversies concerning GE’s effects on grassland diversity as well as carbon(C)and nitrogen(N)storage.It remains poorly understood in the arid desert regions,whilst being essential for the sustainable use of grassland resources.To assess the effects of GE on community characteristics and C and N storage of desert plant community in the arid desert regions,we investigated the community structure and plant biomass,as well as C and N storage of plants and soil(0-100 cm depth)in short-term GE(three years)plots and adjacent long-term freely grazing(FG)plots in the areas of sagebrush desert in Northwest China,which are important both for spring-autumn seasonal pasture and for ecological conservation.Our findings indicated that GE was beneficial to the average height,coverage and aboveground biomass(including stems,leaves and inflorescences,and litter)of desert plant community,to the species richness and importance values of subshrubs and perennial herbs,and to the biomass C and N storage of aboveground parts(P<0.05).However,GE was not beneficial to the importance values of annual herbs,root/shoot ratio and total N concentration in the 0-5 and 5-10 cm soil layers(P<0.05).Additionally,the plant density,belowground biomass,and soil organic C concentration and C storage in the 0-100 cm soil layer could not be significantly changed by short-term GE(three years).The results suggest that,although GE was not beneficial for C sequestration in the sagebrush desert ecosystem,it is an effective strategy for improving productivity,diversity,and C and N storage of plants.As a result,GE can be used to rehabilitate degraded grasslands in the arid desert regions of Northwest China.     

不同灌溉量梯度下胡杨和新疆杨苗期的抗旱性比较

在新疆和田地区墨玉县选取两年生的胡杨和新疆杨实生苗,栽植于苗圃进行不同灌溉水量的处理。不同处理下土壤的含水量分别为田间持水量的85%,70%,47%和24%。测定不同处理水平下胡杨和新疆杨在不同时刻的叶片水势,结果表明:胡杨和新疆杨的水势在一天中的变化趋势呈"V"字型,胡杨的水势日平均值高于新疆杨。利用Licor-6400便携式光合仪对两种杨树的净光合速率和蒸腾速率进行了测定,结果显示相同处理下胡杨的净光合速率和蒸腾速率的日平均值大于新疆杨,胡杨的瞬时水分利用效率高于新疆杨。此外,还测量了两种杨树的叶片的稳定碳同位素比率,结果显示胡杨的δ13C值显著大于新疆杨(p<0.05),表明它的长期水分利用效率较高。运用隶属函数综合各个指标的比较结果来看,胡杨的抗旱性强于新疆杨。     

中稻新组合C两优华占展示试验初报

通过多穗型杂交中籼组合C两优华占与中晚熟品种扬两优6号及中早熟组合丰两优香一号的展示对比试验,结果表明:C两优华占的在随州市平均生育期140d左右,比扬两优6号早7d左右,比丰两优香一号晚4d左右;株叶型态好,植株生长稳健,有效穗多,结实率高,综合抗性好,产量高,最高产量可达904kg/667m2,适合鄂北地区气候条件推广种植。     

蚊耐氯菊酯C6/36细胞构建及耐药相关基因PR-XP1的表达分析

建立蚊耐氯菊酯C6/36细胞,并探讨PR-XP1基因与蚊C6/36细胞对氯菊酯的耐药性之间关系。采用逐步诱导法筛选蚊耐氯菊酯C6/36细胞,观察耐药细胞形态变化、生长状态,测定生长曲线和半数致死剂量;利用荧光实时定量PCR鉴定PR-XP1基因在敏感细胞与耐药细胞中的表达差异。获得耐400μg/m L氯菊酯的C6/36细胞;实时定量PCR检测发现抗药基因PR-XP1在蚊耐氯菊酯C6/36细胞中表达量明显上升。表明构建蚊耐氯菊酯C6/36细胞是研究蚊虫氯菊酯耐药性的有效方法,初步证明PR-XP1基因表达升高可能与蚊虫对氯菊酯的耐药性具有一定的相关性。     

维生素C在家禽生产中的使用及效果

维生素C是动物生长发育、生产及繁殖过程中必不可少的一种营养素,同时也是生物学中一种重要的活性物质,参与动物体内多种代谢过程。     

国外提高蛋鸡产蛋量的几种方法

1 饲料中添加不同的营养成份法 1.1 维生素C 俄罗斯研究结果表明:鸡舍在17.8～44.4℃气温下,用每千克添加40mg维生素C的饲料喂产蛋鸡,3个月可增产约6%的鸡蛋.     

太阳能热水器"家电下乡"山东中标企业名单公布

伴随着“太阳能下乡”,太阳能热水器越来越受广大农村消费者喜爱,挑选一款好的太阳能也日益为消费者重视。为此,专家给出了一些诀窍,让您轻松识别优质热水器。、专家提醒：选购太阳能时,不要轻信商家的过度夸张,也不要迷信广告的泛泛宣传,更不要误听推销人员的无据杀戮,考究产品的品牌一切都必须要求商家亮出证据进行证实。以政府下设的权威部门下发的“ISO9001国际产品质量管理体系认证”、“3C认证”、“饮用水卫生安全认证”等高权威、高质量的保障认证为主,兼看产品的发展史、产品材料、产品的制作,以及产品的品位档次等,对不同产品综合比较,从而选择出自己满意的名牌产品。     

廉价的饲料添加剂——桔皮

桔皮大多被废弃．造成浪费。研究认为．桔皮作为一种生物资源．其所含的胡萝卜素、维生素C、维生素P比果肉含量高,同时还含有硫胺素、核黄素、挥发油等营养成分：其味苦、辛,性温,有理气健脾、燥湿化痰等功效。将桔皮晒干、粉碎作畜禽饲料添加剂．对增加食欲、减少疾病、促进生长效果显著：用桔皮粉饲喂鸡、鸭、鹅等家禽．不仅增加产蛋量．还可使蛋黄颜色加深．