苏北麦田野燕麦两个变种的生态习性及其防治研究

对紫壳野燕麦和白壳野燕麦生态习性的研究表明,麦田野燕麦的发芽、出苗、3叶发育率均与温度呈极显着正相关.以温度为自变量可以预测野燕麦各幼苗阶段的发生期,据此可采取相应防除措施.     

2,4—D丁酯诱导野燕麦不孕的研究

野燕麦(Avena futra L.)是我国农田中一种危害严重的杂草,广布于我国的西北地区。在东北、内蒙、西藏、四川、云南等省、区也有大量分布,对粮食生产带来相当大的影响。在使用2,4-D 丁酯防除麦田阔叶杂草中,人们发现它能引起野燕麦不结实。我     

浙江金衢盆地小麦—杂草群落的研究

用模糊图论中的最大树法,对金衢盆地的小麦-杂草群落进行了分类研究,结果表明,该区小麦-杂草群落分成4个类型,即潮土田上的小麦(Triticum aestivum)-野燕麦(Auena fatua)-春蓼(Polygonum persicaria)一荠菜(Caspsella bura-pas-toria)-猪殃殃(Galium aparine var.teneruml)群落,低丘岗地上的小麦-猪殃殃-野燕麦-波斯婆婆纳(Veronica persica)群落,水稻土田上的小麦-看麦娘(Alopecurusaequalis)-雀舌草(Stellaria alsine)-牛繁缕(Malachium aquaticum)-春蓼群落及烂浸田上的小麦-翅茎灯心草(Juncus alatus)-春蓼-看麦娘-扬子毛茛(Ranunculus sieboldii)群落。分析表明,土壤类型、pH、地形地貌、耕作制度、栽培措施是影响该区小麦-杂草群落结构及分布的主要因素。     

2种杂草水提液对小麦种子萌发及幼苗生长的影响

以2种麦田伴生杂草播娘蒿(Descurainiasophia)和猪殃殃(Galiumtricorne)为供体,以关中地区15个主要的小麦(Triticumaestivum)栽培品种为受体,采用室内生物测定法,比较了2种杂草水提液对不同小麦品种种子萌发及幼苗生长的影响.结果表明:(1)播娘蒿水提液对所有小麦品种的发芽率、发芽势和发芽指数均具有显著的抑制作用,猪殃殃水提液对这3项指标的抑制作用相对较弱,甚至对某些品种的这3项指标没有影响或具有促进作用.(2)2种杂草水提液对供试15个小麦品种的活力指数,以及根长、苗高、根鲜重、苗鲜重等生长指标均表现出抑制作用,且同一种杂草水提液对不同小麦品种的影响程度存在差异.(3)以播娘蒿和猪殃殃的响应指数值(RI)为指标分别将15个小麦品种聚类为强、中、弱三组,并发现2种杂草水提液分别对小偃22和西农979的化感作用均较弱,即这2个品种对播娘蒿和猪殃殃的化感作用均具有较强抗性.     

温度变化对油菜及其伴生杂草种苗生长和幼苗生理特性的影响

以目前大面积栽培的甘蓝型油菜(Brassica napus) ‘秦优10号’和其田间常见的8种杂草播娘蒿(Descurainia sophia)、泽漆(Euphorbia helioscopia)、野燕麦(Avena fatua)、棒头草(Polypogon fugax)、婆婆纳(Veronica didyma)、看麦娘(Alopecurus aequalis)、灰绿藜(Chenopodium glaucum)、反枝苋(Amaranthus retroflexus)为试验材料, 利用人工气候培养箱控温, 研究了10 ℃/5 ℃ (昼/夜)、18 ℃/10 ℃、25 ℃/20 ℃、35 ℃/30 ℃、40 ℃/35 ℃不同温度幅度处理对它们的发芽势、发芽率、幼苗形态及生理指标的影响, 旨在为预测气候变化环境下油菜田恶性靶标杂草的演替趋势提供参考依据。试验结果表明: 不同供试杂草对温度变化表现出明显的适应性差异, 看麦娘、灰绿藜和反枝苋的最适萌发温度偏高, 如反枝苋在高温处理(40 ℃/35 ℃)下种子的发芽率达到最高(91%); 而播娘蒿、泽漆、野燕麦、棒头草、婆婆纳种子的最适萌发温度主要集中于10-18 ℃范围内。进一步测试研究表明, 高温处理(40 ℃/35 ℃)下, 反枝苋幼苗生长旺盛, 体内丙二醛的积累也明显低于低温(10 ℃/5 ℃)处理, 可溶性糖和可溶性蛋白含量以及保护酶活性也较高, 表明反枝苋对高温胁迫有较好的适应性, 灰绿藜对高温的响应与反枝苋相似, 在高温气候年份, 要严防这2种草害加重; 而在低温处理(10 ℃/5 ℃)下, 野燕麦的种子萌发率达到100%, 其幼苗生长旺盛, 体内可溶性糖和可溶性蛋白含量及保护酶活性较高, 播娘蒿对低温胁迫的响应类似于野燕麦, 因此在寒冷年份需加强对野燕麦和播娘蒿草害的预防。供试油菜品种相对于所有供试杂草对温度变化的适应性更好, 其种子在不同温度处理下均保持较稳定的高发芽率, 且幼苗长势良好, 表明‘秦优10号’是一个对温度变化适应性很好的油菜品种。     

安徽省霍邱县夏收作物田杂草群落的数量分析

采用７级目测法,获得安徽省霍邱县夏收作物田６９个样点共８４．３ｈｍ￣２样地杂草种群的草害指数,对其进行数量分析——主成分分析（ＰＣＡ）和聚类分析,并赋以生态学意义的解释,结果显示该地区杂草的种类分布、危害程度与环境因子间的密切对应关系,杂草群落的分布主要取决于：（１）土壤湿度、结构性质;（２）土壤酸碱性。前者可通过样点的耕作制度,后者可通过样点的地理位置定性了解。数量分析的结果将全部样方分成３组——水稻土组、旱地组和偏碱土壤组,每组都对应着相应的杂草优势种。其中看麦娘、日本看麦娘、雀舌草为水稻土组的杂草优势种,猪殃殃、大巢菜、野燕麦为旱地组杂草优势种,偏碱土壤组优势种杂草为粘毛卷耳和牛繁缕。根据这些杂草群落的分布规律,提出了相应的杂草防除策略。     

安徽沿江圩丘农区夏收作物田杂草群落分布规律的研究

作者创用了七级目测调查取样,进行数量分析的方法,对夏收作物田杂草群落进行分类研究,揭示了安徽沿江圩丘农区夏收作物田杂草群落的分布规律主要受土壤类型和轮作制度制约。看麦娘杂草群落分布于水稻土田,猪殃殃,野燕麦杂草群落分布于丘岗区旱地,卷耳、婆婆纳杂草群落分布于灰潮土旱地。首次提出综合草害指数,用以评定杂草群落类型中每种杂草的危害性,从而,提出了不同土壤类型和轮作制度的田块中恶性杂草的定量化指标与防除策略。     

升马唐种群生态及其田间密度调控指标的研究

 研究表明,马唐的生育期为62—111天,需>0℃积温1380—2716。其生殖生长阶段对季节的温度要求严,营养生长阶段宽,生育期长短主要靠营养生长期的长短来调节。马唐种子休眠期一般为150天,休眠期长短和解除休眠速率与种子贮藏条件关系密切,以恒温贮藏最快。种子发芽起点温度为15℃,60%种子发芽的有效积温平均为555.13℃。马唐种子发芽对光照要求不敏感。在农田7cm土层内的种子均能出苗,但以1—4cm层最佳。马唐的再生能力强,试验表明,凡是带有须根和幼芽的任何断节都能发生新的植株。通径分析结果表明,马唐是我国北方夏播粮田的主要杂草。马唐群体水平(x,株／m2)与夏玉米籽粒减产率(y,%)间呈以下关系模式：(1)y=0.1532x1-5574(x≤20株／m2) (2)y=-18.400+11.315lnx(x>20株／m2)与夏玉米共同生长日数对作物籽粒减产率呈以下关系模式：y=54.5956／1+89.7962e-0.1184x根据推算,在石家庄地区夏播玉米田,马唐的允许存在密度即生态经济阈值为5.8株／m2。     

燕麦镰刀菌GD-2毒素对野燕麦的除草活性研究（英文）

评价了燕麦镰刀菌GD-2毒素对野燕麦的除草活性潜力。毒素对野燕麦种子萌发抑制试验表明,当毒素浓度达到5 mg/mL时,对野燕麦种子的萌发抑制效果达77.54%,在相同浓度下,对野燕麦种子胚根的抑制效果高于对胚芽的抑制效果。在温室条件下,毒素处理野燕麦植株后,各个不同处理野燕麦株高和地上部鲜重明显减少,然而,各处理间没有明显差异。用石油醚、氯仿、乙酸乙酯和正丁醇依次萃取燕麦镰刀菌发酵滤液并获得粗提物,其中正丁醇浸提物(5 mg/mL)在离体叶片实验中效果优于其他有机溶剂粗提物。此外,在毒素对10种植物的敏感性实验中,其中稗草和藜表现对燕麦镰刀菌毒素敏感。从燕麦镰刀菌中分离出3个除草活性化合物,且具有相同的紫外吸收峰。当前结果表明燕麦镰刀菌产生的毒素具有开发成为防除野燕麦生物源除草剂的潜力。     

浑善达克沙地黄柳种子发芽和幼苗生长特性的研究

在实验室通过模拟野外自然条件,研究了土壤水分、沙埋厚度和温度对黄柳种子发芽与幼苗生长的影响。结果表明:(1)黄柳种子对水分条件很敏感,发芽的适宜土壤含水量为3%~20%,低于3%或高于20%发芽都会受到抑制;(2)种子萌发需要沙土覆盖,适宜覆沙厚度为0.1~0.4 cm,此条件下第5天种子发芽率达80%以上;但当沙埋厚度超过0.6 cm时,种子出苗就会受到抑制;当沙埋厚度超过1.2 cm时,将不能出苗;(3)种子发芽的适宜温度为15~35℃,当温度高于45℃时种子将不能萌发并最终死亡;(4)幼苗的耐热性较强,40℃处理下幼苗出现热害症状,并且热害症状发展缓慢,60℃处理下90 min后幼苗干枯死亡;(5)种子的寿命为120 d左右。     

PHYCOLOGY IN THE FIELD AND IN THE LABORATORY1

Field and laboratory phycologists are still following different paths. This is regrettable because their labors supplement one another, and only by co-operation can progress be achieved.     

THE DEVELOPMENT OF THE DORSAL AND VENTRAL MAMMALIAN PANCREAS IN VIVO AND IN VITRO

The origin, morphogenesis, and biochemical differentiation of the dorsal and ventral pancreas of the rat embryo have been investigated in order to ascertain the similarities and dissimilarities between the two lobes. We have utilized a culture system in which the primitive gut gives rise to a number of differentiated organs, including the dorsal and ventral pancreas. The two pancreases do not undergo fusion in these cultures, thus allowing independent analyses of the two lobes for comparison with in vivo results. The dorsal pancreas first appeared at the 23–25 somite stage while the ventral pancreas appeared approximately 12 hr later at the 29–30 somite stage. Guts from embryos as young as 12 somites were capable of developing both pancreases in vitro. In spite of the 12 hr difference between the times of their appearance, the dorsal and ventral pancreases exhibited identical patterns of morphological and biochemical differentiation. The two lobes contained the same exocrine enzymes and hormones, at similar levels, differing only in their glucagon content, the dorsal pancreas possessing a fivefold higher glucagon specific activity. The implications of these results are discussed.     

VASCULAR SUPPLY AND STRUCTURE OF THE OVULE AND ARIL IN PEONY AND OF THE ARIL IN NUTMEG

Camp , Wendell H., and Mary M. Hubbard . (U. Connecticut, Storrs.) Vascular supply and structure of the ovule and aril in peony and of the aril in nutmeg. Amer. Jour. Bot. 50(2): 174–178. Illus. 1963.—Examination of the placental region in the carpel of Paeonia indicates a complexity and super-abundance of vascular supply beyond that usually found in angiosperms and certainly more than is necessary for adequate nutrition and water supply of the ovules. From this it is concluded that the ovules once were borne on a larger and more complex structure than the present carpel. Vascular strands leading to the aril and the hypostase are interpreted as being relictual. The large multifid aril of Myristica has a well-developed vascular system composed of several sizes of branched bundles.     

PURIFIED DIPHTHERIA ANTITOXIN IN THE ULTRACENTRIFUGE AND IN THE ELECTROPHORESIS APPARATUS

Ultracentrifugation studies of diphtheria antitoxin showed that: 1. Purified antitoxin of high activity obtained from horse plasma without enzymatic treatment has exactly the same sedimentation constant as the globulin fraction obtained in a similar way from normal horse plasma s ₂₀ ^water = 6.9 x 10^–13. 2. Purified antitoxin obtained with trypsin digestion of the toxin-antitoxin complex has a sedimentation constant of s ₂₀ ^water = 5.5 ± 0.1 x 10^–13, a diffusion constant of D ₂₀ ^water = 5.7₆ x 10^–7, and a molecular weight of about 90,000. Electrophoresis experiments demonstrated that: 1. The trypsin-purified antitoxin has an isoelectric point not far from pH 7.0. 2. The reversible spreading noticed at about pH 7.3 cannot be attributed to heterogeneous preparation. 3. The large increase in the γ-globulin fraction occurring during immunization consists either of antitoxin of various degrees of activity or of some inert protein in addition to the antitoxin.