Attempts to overcome partial incompatibility between Hordeum vulgare L. and H. bulbosum L.

Summary Partial incompatibility has already been reported between Hordeum vulgare and H. bulbosum during the course of doubled haploid production, and in this paper attempts to overcome the breeding barrier are described. The methods which seem to offer most success are those of environmental adjustments and the adoption of new genotypes of H. bulbosum. Further cultivars of H. vulgare exhibiting this phenomenon are also noted.     

Scale-Dependent Influence of Topography-Based Hydrologic Features on Patterns of Woody Plant Encroachment in Savanna Landscapes

Rainfall in drylands is erratic. Topographic features of landscapes can dampen or amplify temporal variability by spatially influencing patterns of water loss and accumulation. The extent to which portions of a landscape may differentially capture or retain scarce water and nutrient resources is an important determinant of vegetation patterns, particularly with respect to the distribution of woody plants. We therefore hypothesized that historic changes in woody cover on landscapes experiencing similar climate and disturbance regimes would vary with catena-to-catena (hillslope-to-hillslope) variation in topography-based hydrologic features. We tested this hypothesis by comparing topographic wetness index (TWI) values on replicate landscapes where woody plant abundance has increased over the past 100 yr. These landscapes are characterized by savanna parklands on coarse-textured upland portions of catenas that grade (1–3% slopes) into closed-canopy woodlands on fine-textured (lowland) portions of catenas. TWI values for woody and herbaceous communities were comparable within uplands, suggesting factors unrelated to surface/subsurface hydrology determine patterns of woody cover in these catena locations. TWI values for upland savanna parklands were significantly lower than those of closed-canopy woodlands occupying catena footslopes. Furthermore, uplands adjoining historically static woodland boundaries had lower TWI values than those where woodland boundaries had moved upslope 2.1 m yr⁻¹ from 1976 to 1995. Results suggest runoff–runon relationships influence patterns of woody plant cover and change at the catena scale and may override constraints imposed by soil texture. As a result, changes in woody cover potentially accompanying changes in disturbance regimes, climate or atmospheric chemistry are likely to be constrained by topoedaphic settings. Models of vegetation dynamics may therefore need to explicitly account for rainfall–topography–soil texture relationships and associated scale-dependent mechanisms to accurately predict rates and patterns of change in woody and herbaceous plant abundance.     

二十八个冷季型草坪草品种的耐盐性比较

在干旱区的硫酸盐型土壤上,采用田间小区试验法,对28个冷季型草坪草品种的耐盐性进行比较,草坪型黑麦草品种间的耐盐性差异不显著,耐盐性最强,草坪型高羊茅品种次之,紫羊茅品种普通的耐盐性较？“派尼”强,草地早熟禾品种“公园”,“橄榄球2号”,“亨特”相对较耐盐,参试种幼苗的耐盐性次序为草坪型高羊茅,细弱剪股颖＜草坪型黑麦草＜匍匐紫羊茅＜草地早熟禾＜硬羊茅,以出苗率,保苗率和空隙率为指标,综合评价28个草坪草品种的耐盐性,佳丽2号,三A,高帽,凌志,贝克,未来2000E,爱神特,博士的耐盐性最强;美洲虎3号,矮星2号,小野马,飞思达2号,猎狗5号,交战2号次之,橄榄球2号,公 羊1号,亨特,美洲王,普通,高地,派尼,公园再次,康尼,优异,斯巴达,纳苏,抢手股,齿塔基最差。     

Resistance to ACCase-inhibiting herbicides and isoproturon in UK populations of Lolium multiflorum: mechanisms of resistance and implications for control

Herbicide-resistant Lolium multiflorum (Italian rye-grass) was first reported in the UK in 1993 and had been confirmed on 25 farms by 1999. In this study, resistance to five herbicides belonging to the aryloxyphenoxypropionate, cyclohexanedione and phenyl-urea classes was determined in six populations of L multiflorum from the UK under glasshouse and simulated field conditions. Glasshouse conditions tended to exaggerate the degree of resistance, but experiments performed in both environments detected resistance in four populations of L multiflorum. Four populations (Essex A1, Lincs A1, Wilts B1, Yorks A2) were resistant to diclofop-methyl, fluazifop-P-butyl, tralkoxydim and partially resistant to isoproturon, but only the population from Yorkshire (Yorks A2) showed resistance to cycloxydim. Biochemical analyses of acetyl coenzyme A carboxylase (ACCase) activity, oxygen consumption by thylakoids, diclofop metabolism and glutathione S-transferase activity showed that, in three of the resistant populations, an enhanced rate of herbicide metabolism conferred resistance. This is the first report world-wide of an enhanced metabolism mechanism of diclofop resistance in L multiflorum. In the Yorks A2 population, an insensitive ACCase was detected (target-site resistance) which also conferred cross-resistance to all of the other ACCase inhibitors investigated.     

根茎禾草发育过程中糖含量与能值分配规律的研究

研究表明根茎类禾草含糖量和能值分配存在明显的发育时期、发育器官和植物根茎类型的差异。一般根茎类禾草含糖量在地上部呈单峰曲线 ,前营养期高于后营养期 ;地下部呈“S”型曲线 ,后营养期高于前营养期。根茎类禾草总含糖量和地上部含糖量是 :短根茎大于长根茎 ;地下部含糖量是 :长根茎大于短根茎 ;穗部是 :短根茎大于长根茎。根茎类禾草有性生殖器官的能值分配较低 ,一般在 5～ 1 0 %之间 ,短根茎高于长根茎 ;地上部的能值分配较高 ,一般在 40～ 80 %之间 ,短根茎明显高于长根茎 ,前营养期高于后营养期。地下部的能值分配一般在 1 0～ 50 %之间 ,短根茎明显低于长根茎 ,后营养期高于前营养期。根茎类禾草在生育期内 ,地上部与地下部的能值分配存在明显的互补性 ;在前营养期地上部营养器官与生殖器官的能值分配存在明显的一致性。糖含量与生长发育相关分析达极显著或显著正相关 ,这表明糖含量与根茎类禾草的生长发育有较高的一致性。     

晋西王家沟小流域产流产沙分析

王家沟流域是晋西黄土丘陵沟壑区水土保持综合治理典型示范流域。流域产流产沙是降雨和流域下垫面相互作用的结果。降雨对土壤侵蚀的影响包括降雨量影响和降雨强度影响两个方面,流域在治理措施规模不大的初级治理阶段,输沙量只是随降雨的变化而变化。坡耕地、沟头Ｖ形沟、村庄道路、红土沟坡、沟道小流域、矿区是王家沟流域主要产沙源地。控制流域产流产沙,综合治理中须实行退耕还林还草。     

林草植被生态效益计量调查的探讨

文章重点探讨林草植被在涵养水源、水土保持、防风固沙、防护农田等方面的生态效益的调查内容及计量方法 ,为效益评价数量化提供依据。     

新麦草有丝分裂及核型分析

研究新麦草的核型,观察其有丝分裂过程,结果表明,新麦草的核型公式为２ｎ＝１４＝１０ｍ（２ＳＡＴ）＋４ｓｍ（ＳＡＴ指随体）,核型属２Ａ型,染色体基数为７,属二倍体。     

扎赉特旗浅翻改良羊草草场实践经验

由于自然生态环境的变化和社会因素的影响,草地退化日趋严重,特别是经济价值较高的羊草草地退化更为严重,草地生产力水平明显下降,为了遏制退化,保持生态平衡,提高草地生产力,从而达到永续利用的目的,我盟在扎赉特旗太赉化草场进行浅翻改良退化羊草草地试验工作,因为笔者曾参加过该项工作,就羊草草地植被演替变化规律和改良羊草草地的配套技术,进行试验总结。     

石灰岩山地天然灌木植被的定向培育

通过对石灰岩山地主要灌丛、灌草丛植被类型的特征、植物组成、生物量的调查和测定,得知石灰岩山地广泛分布的灌丛有8个类型,灌草全有5个类型。对236块野外标地资料的分析表明,不同立地上灌木生物量差异悬殊。提出了不同立地上灌木植被的培育方向。