松嫩平原羊草草甸植物的生态及分布区型结构分析

松嫩平原羊草草甸穿越吉林省西部和黑龙江省西南部约 12 9万 hm2的范围 ,是蒙古植物区系、东北植物区系、兴安植物区系、华北植物区系 4个植物区系相汇集的区域 ,在全区所设的 36个调查样地中 ,共有 16 2种植物 ,隶属于 36个科 ,6个株生长型 ,5个根生长型 ,6个生活型 ,5个水分生态类型 ,15个分布区型和 6个经济价值类型。其中 ,菊科种类最多 ,占 2 4 .1% ,豆科和禾本科分别占 11.1%和 10 .5 % ;株生长型结构以分枝型种类最多 ,占 31% ,直立型和丛生型分别为 2 2 %和 2 0 % ;根生长型结构以直根型的种类最多 ,占 5 4 % ,刷状根型和根茎型分别为 2 3%和 19% ;生活型结构以地面芽植物最多 ,占 4 2 % ,地下芽植物次之 ,占 2 6 % ,地面 -地下芽植物占 9% ;水分生态类型结构以中生型种类最多 ,占 5 8% ,中旱生型次之 ,占 2 5 % ;分布区型结构以蒙古 -东北 -兴安 -华北分布区型的种类最多 ,占 2 6 % ,东北 -华北分布区型次之 ,占 17% ;经济价值类型结构以中、低等质量的种类最多 ,所占比重高达 5 0 % ,而优、良牧草种类只占 2 2 %。松嫩平原羊草草甸具有温带草本群落的植株和根系的特点 ,典型的温带地面芽植物气候特征 ,中生生境条件 ,复杂的分布区型结构和多样的经济价值类型。

尼勒克喀什河国家湿地公园植物组成结构及其与环境的关系

于2019和2020年对尼勒克喀什河国家湿地公园植物组成结构及其与环境的关系进行了调查,结果表明:共记录到高等维管植物180种,隶属53科140属。进一步分析不同生活型植物的生长型和水分生态类型组成发现,地面芽植物普遍具有分枝型、直根型和中生的生长和生态特征,是阳性草地的主要类群;地下芽植物则普遍具有直立型、根茎型和湿生的生长和生态特征,是湿草甸和沼泽的主要类群;一年生植物具有分枝型、刷状根和中、旱生的生长和生态特征,为沙地、干旱坡地等生境的主要类群;地上芽植物则以分枝型、直根型和旱生性为表征,是极旱生境的主要类群。尼勒克喀什河国家湿地公园植物群落组成具有典型的温带植被特征,但同时也叠加了土壤水分条件的作用,形成以温带地面芽植物为主、湿生成分和一年生荒漠成分并重的格局。未来应加强湿地生境管理,提升湿地属性,增强湿地功能。

伊犁河谷湿地镰叶锦鸡儿群落的植物组成分析

伊犁河谷湿地镰叶锦鸡儿群落调查样方中,共有64种植物,隶属于29个科,6个株生长型,3个根生长型,6个生活型,5个水分生态类型。其中,菊科和禾本科种类最多,各占14.0%,豆科占12.5%;株生长型结构以直立型种类最多,占39.0%,分枝型和丛生型分别为25.0%和22.0%;根生长型结构以直根型的种类最多,占50.0%,刷状根型和根茎型各占25.0%;生活型结构以地下芽植物最多,占42.0%,地面芽植物次之,占33.0%,一年生植物占12.5%;水分生态类型结构以中生型种类最多,占57.8%,中旱生型和中湿生型分别为14.0%和12.5%。以上结论表明,伊犁河谷湿地镰叶锦鸡儿群落具有中温带群落植株和根系特点,典型的中温带地下芽植物气候特征和中生生境条件特征。

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、伞形科、松科、虎耳草科、蓼科、唇形科植物占优势,占68%以上;长期放牧草地植被区以菊科、百合科、毛茛科、禾本科、蔷薇科、堇菜科、蓼科、十字花科植物占优势,占63%以上。2个植被区的镶嵌群落均以分枝植物和直立植物为主,其次为莲座植物。在Raunkiaer生活型谱中,2个植被区均以地面芽植物和地下芽植物的比例最大。长期放牧草地植被区高位芽植物比例很小,仅占3.2%。

The BUD2 mutation affects plant architecture through altering cytokinin and auxin responses in Arabidopsis

The ratio of auxin and cytokinin plays a crucial role in regulating aerial architecture by promoting or repressing axillary bud outgrowth. We have previously identified an Arabidopsis mutant bud2 that displays altered root and shoot architecture, which results from the loss-of-function of S-adenosylmethionine decarboxylase 4 （SAMDC4）. In this study, we demonstrate that BUD2 could be induced by auxin, and the induction is dependent on auxin signaling. The mutation of BUD2 results in hyposensitivity to auxin and hypersensitivity to cytokinin, which is confirmed by callus induction assays. Our study suggests that polyamines may play their roles in regulating the plant architecture through affecting the homeostasis of cytokinins and sensitivities to auxin and cytokinin.

The δ^15N response and nitrate assimilation of Orychophragmus violaceus and Brassica napus plantlets in vitro during the multiplication stage cultured under different nitrate concentrations

Natural nitrogen isotope composition(δ^(15)N) is an indicator of nitrogen sources and is useful in the investigation of nitrogen cycling in organisms and ecosystems. δ^(15)N is also used to study assimilation of inorganic nitrogen. However, the foliar δ^(15)N of intact plants, which is a consequence of nitrate assimilation occurring in the roots and shoots, is not suited for studying nitrate assimilation in cases where nitrate is the sole nitrogen source. In this study, Orychophragmus violaceus(Ov) and Brassica napus(Bn) plantlets, in which nitrate assimilation occurred in the leaves, were used to study the relationship between foliar δ^(15)N and nitrate assimilation.The plantlets were grown in vitro in culture media with different nitrate concentrations, and no root formation occurred for the plantlets during the multiplication stage.Nitrogen isotope fractionation occurred in both the Ov and the Bn plantlets under all treatments. Furthermore, the foliar nitrogen content of both the Ov and Bn plantlets increased with increasing nitrate concentration. Foliar nitrogen isotope fractionation was negatively correlated with foliar nitrogen content for both the Ov and Bn plantlets. Our results suggest that the foliar nitrogen isotope fractionation value could be employed to evaluate nitrate assimilation ability and leaf nitrate reductase activity.Moreover, high external nitrate concentrations couldcontribute to improved foliar nitrogen content and enhanced nitrate assimilation ability.

Components of Liquid Media on the Production of High Spore Concentrations of Lecanicillium lecanii （Zimm.） Gams and Zare

Two Lecanicillium lecanii isolates, ATCC26854 and V3, were evaluated for spore production in liquid media. Both isolates have interesting known properties for the production of high concentrations of chitinases （ATCC26854）, and an outstanding pathogenic activity against the green cabbage aphid, Brevicorine brassiacae （L.）. The isolates were grown on thirteen different liquid media, which had been used to produce other entomopathogenic Hyphomycetes. Experiments were carried out at 27 -4- 1 ℃ with a 12：12 photoperiod using shake flasks. The production of spores was quantified during a seven days period, and the effects of the media were evaluated by determining spore concentration and morphology. Submerged conidia yields were higher with ATCC26854 than with V3 in all thirteen media, while higher concentrations （5.3×10^9, 4.6 ×10^9 and 3.4 ×10^9 conidia/mL） were found with ATCC26854 isolate in the Camaron, Minerales and Jenkins-Prior medium, respectively; lower yields （2.3 ×10^8, 2.2 ×10^8 and 2.3 ×10^8 conidia/mL） were found with the V3 isolate in Catroux, TKI and Camaron media, respectively. Spore production curves were adjusted to different sigmoid models. The process was better explained by the Richards model （r^2 = 0.99）. Concerning conidia morphology, submerged conidia seemed to look like aerial conidia, but they were different in size （ATCC26854 2.73-6.99 μm and V3 5.28-14.29 μm）; however, the dimensions fall within the ranges reported for L. lecanii. The analysis of shake flask cultures with the Richards model allowed selecting two low-cost liquid medium, Camaron and Jenkins-Prior, for scaling up conidia production for use in aphid biological control programs.