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排序方式: 共有382条查询结果,搜索用时 81 毫秒
81.
Mohammad AmzadHossain YukioIshimine HitoshiKuramochi HikaruAkamine 《Weed Biology and Management》2002,2(2):92-97
Two field experiments each conducted during a 1 year period at the Agricultural Experiment Farm, University of the Ryukyus, Japan evaluated the interval needed between sequential applications of asulam (3 kg ai ha−1 ) for successful control of torpedograss ( Panicum repens L.). Regrowth of torpedograss from rhizomes was lowest when asulam was applied at 40-day intervals. Application at intervals of 70 days or longer completely controlled above-ground shoots but not regrowth from rhizomes. Above-ground biomass of torpedograss regrowth was 7- and 49-fold higher when asulam was applied at 70 and 100 day intervals, respectively, compared with 40-day intervals. Asulam applied three times at 40-day intervals starting 40 days after land preparation provided almost total torpedograss control 1 year after the initial application. 相似文献
82.
MOHAMMAD AMZAD HOSSAIN YUKIO ISHIMINE HITOSHI KURAMOCHI HIKARU AKAMINE 《Weed Biology and Management》2002,2(3):153-158
The present study was undertaken from May 1996 to October 1997 in the glasshouse of the University of the Ryukyus, Okinawa, Japan to investigate standing water (12 cm deep) and shoot removal plus standing water regimes on morphological changes, growth, regrowth and biomass production of torpedograss ( Panicum repens L.). The stem internode was longer in standing-water-treated plants than that in untreated plants. The root-crown was developed from the submerged stem-node. Spike-like tillers and sheath-like leaf blades were observed in water-treated plants. Higher shoot biomass and lower rhizome biomass were obtained in standing-water-treated plants than that in untreated plants. Standing-water-treated plants attained higher total biomass than untreated plants. Standing-water stress was the factor that inhibited regrowth of torpedograss when the above-ground shoot was removed. Rhizomes without shoots of 6-month-old torpedograss did not survive in standing water for more than 6 months. The results indicate that torpedograss can survive in standing water if the shoots remain above the water surface. Shoot removal is one effective way to control torpedograss regrowth in standing water. The results of this study may be dependent on season, day length, water temperature, water pH, water depth and salt concentration in water. 相似文献
83.
马蹄金白绢病发生规律及化学防治技术的研究 总被引:1,自引:0,他引:1
采用系统调查方法和室内外防治试验法对马蹄金白绢病进行研究,结果表明,8月上旬-9月上中旬是马蹄金白绢病发病的高峰期.9月中下旬以后,随着温度的降低,病情指数缓慢下降.通过主成分分析,把6个气象因子转化为3个综合因子,且反映原来因子的信息,彼此之间互不相关.建立了发病普遍率与病情严重度之间的定量关系.4种常用杀菌剂对马蹄金白绢病菌的菌丝均有不同程度的抑制作用,其中代森锰锌毒力最强,防治效果最优.用9种聚集度指数的方法测定了,马蹄金白绢病在草坪间的分布型,结果表明,均呈聚集分布,其分布的基本成分为疏松个体群,数量为2400株,抽样以8~13点为宜. 相似文献
84.
85.
Infestations of pastures by species, such as creeping bentgrass (Agrostis stolonifera), may compromise the white clover (Trifolium repens) content in perennial ryegrass (Lolium perenne) mixtures. However, the interactions between white clover and species other than perennial ryegrass are not well understood. Strategies to prevent creeping bentgrass infestations require an understanding of its interactions with white clover, as the exclusion of white clover from infested pastures could be the result of either direct interaction or niche‐differentiation in response to management. A methodology is presented which enables the segregation of the effects of direct interaction and niche‐differentiation, based on existing dry‐weight‐rank measurements of a number of experimental pastures, subjected to a range of management strategies. Only between the two management extremities, i.e. permanent cutting of silage and lax grazing for long periods, did niche‐differentiation occur between white clover and creeping bentgrass. The white clover content was enhanced under the cutting regime, whereas lax grazing for long periods stimulated the content of creeping bentgrass. White clover was actively excluded from creeping‐bentgrass‐dominated patches by direct interaction, whereas it showed a high compatibility with perennial ryegrass. This direct interaction presents challenges to the prevention of creeping bentgrass by management, as creeping bentgrass and white clover showed nearly identical requirements in terms of environmental conditions and grassland management. 相似文献
86.
农杆菌介导白三叶草高效遗传转化和转基因植株再生 总被引:9,自引:4,他引:9
利用子叶下胚轴为外植体,通过农杆菌Ti质粒介导途径,建立了白三叶草高效遗传转化及转基因植株高频率再生体系。PCR检测及Southern印迹鉴定结果表明,外源T-DNA片段已整合到转基因植株的基因组中,且多以1~2个少数拷贝存在。Northern印迹结果和对报告基因GusA编码蛋白的活性检测结果表明,目的基因在部分转基因植株中高水平表达。适宜条件下外植体遗传转化后的植株再生比例达58.23%~62.12%。与对照相比,转基因植株在外部形态上没有发生改变。 相似文献
87.
Qualitative observations of Hevea spp. resistance to Phyllachora huberi were carried out on 200 clones in a collection and 21 full-sib progenies under natural conditions of infestation. A total
of 42 clones, mostly originating from the natural range of the Hevea genus, and at least two species (H. brasiliensis and H. benthamiana) revealed total resistance to the parasite. For nine of the thirteen `resistant ×susceptible' and `resistant × resistant'
progenies studied, the ratio of susceptible: resistant plants suggested the existence of a total resistance mechanism produced
by a dominant allele at a single locus for the P. huberi race(s) present at the study site. For three of the progenies involving the same resistant parent, it was possible to locate
the gene (called Phr) at 14.7 cm from the adhisozyme locus.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
88.
89.
白三叶叶片解剖可塑性及其对光强的响应 总被引:5,自引:1,他引:4
探讨不同光照强度下白三叶叶片解剖特征,叶片可塑性及其对光强环境的响应。结果表明:白三叶叶片结构具有一定的可塑性,其中表皮和叶肉的可塑性较大,而中脉则相对较为稳定;在全光照条件下,叶片为阳生叶特征,叶片较厚,上表皮外切向壁平展,气孔密度大,栅栏组织发达,栅栏细胞长柱形,排列紧密,海绵组织较薄,细胞较小,排列疏松,中脉较厚;在弱光照条件下,叶片为阴生叶特征,叶片较薄,上表皮细胞凸透镜状,气孔密度较小,栅栏组织极不发达,栅栏细胞不规则或漏斗形,海绵组织发达,细胞较大,排列紧密,中脉较薄;非参数相关性分析结果表明,上表皮厚度、海绵组织厚度与相对光照强度呈显著负相关,而上表皮气孔密度、栅栏组织厚度、栅栏组织海绵组织厚度比、栅栏细胞长宽比和中脉厚度等性状与相对光照强度呈显著正相关。 相似文献
90.