Growth of individual tillers and tillering rate of Lolium perenne and Bromus stamineus subjected to two defoliation frequencies in winter in Argentina     

G. D. Berone  F. A. Lattanzi  M. G. Agnusdei  N. Bertolotti 《Grass and Forage Science》2008,63(4):504-512

The aims of the experiment were to (i) test whether the higher leaf elongation rate per tiller (LER_T) of Bromus stamineus D. than Lolium perenne L. at moderately low temperatures was maintained at high defoliation frequencies and (ii) explore responses in tiller dynamics during the onset of the cool season in the south‐east of the humid Pampas region in Argentina. The following treatments were applied: defoliation frequency at the 3·0‐leaf stage (i.e. one‐leaf lifespan), which is considered optimal, and higher defoliation frequency at the 1·5‐leaf stage (i.e. half‐of‐a‐leaf lifespan). The higher defoliation frequency reduced leaf elongation rate in both the species but it did not affect the leaf appearance rate. This confirms previous studies on several C₃ grasses, suggesting a similar pattern of response. Changes in tiller size are proposed as a possible mechanism to explain such long‐term defoliation effects on leaf elongation rates. Responses in tiller production depended on the species considered. The higher defoliation frequency caused a reduction in site‐filling which led to lower tiller production rates in L. perenne but not in B. stamineus. Thus, B. stamineus maintained the advantage in LER_T over L. perenne and its tiller production was not affected when defoliated at frequencies higher than those considered optimal.  相似文献   

Analysis of geographical and breeding-related distribution of hybrid necrosis genes in bread wheat (Triticum aestivum L.)     

V.A. Pukhalskiy  S.P. Martynov  T.V. Dobrotvorskaya 《Euphytica》2000,114(3):233-240

Using the Information and Analytical System of Wheat Genetic Resources GRIS 3.2, the peculiarities of distribution of hybrid necrosis genes in bread wheat in different regions of the world were analyzed. Considerable variation in frequencies of the Ne1 and Ne2 genes in regions with different moisture and heat supply was revealed. A significant effect of breeding on frequency dynamics of different genotypes Ne1ne2, ne1Ne2 and ne1ne2 was confirmed. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Genetic analysis of grain mould resistance in coloured sorghum genotypes     

S. Audilakshmi  J.W. Stenhouse  T.P. Reddy 《Euphytica》2000,116(2):95-103

Grain moulds are a major constraint to sorghum production and to adoption of improved cultivars in many tropical areas. Information on the inheritance of grain mould reaction is required to facilitate breeding of resistant cultivars. The genetic control of grain mould reaction was studied in 7 crosses of 2 resistant sorghum genotypes. P₁, P₂, F₁, F₂, BC₁ and BC₂ families of each cross were evaluated under sprinkler irrigation for field grade and threshed grade scores and subjected to generation mean analysis. Frequency distributions for grain mould reaction were derived and F₂ and BC₁ segregation ratios were calculated. Grain mould reaction in crosses of coloured grain sorghum was generally controlled by two or three major genes. Resistance to grain moulds was dominant. Significant additive gene effects were also found in all cross/season combinations. Significant dominance effects of similar magnitude to additive effects were also observed in five out of ten cross/season combinations. Gene interactions varied according to the parents with both resistant and susceptible parents contributing major genes. Choice of parents with complementary resistance genes and mechanisms of resistance will be critical to the success of resistance breeding. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Variability in Azolla sporulation in response to phosphorus application     

P. P. Kar  S. Mishra  D. P. Singh 《Biology and Fertility of Soils》2000,32(6):458-462

 Phosphorus application decreased the sporulation frequency and number of sporocarps per plant in all the three Azolla species and 21 A. pinnata strains evaluated in this study. The number of megasporocarps tended to be more depressed than the number of microsporocarps. Nevertheless, the sporulation of A. caroliniana was less sensitive to P than that of A. pinnata and A. microphylla. Its sporulation frequency in the mineral medium did not decrease at 2.5 μg P ml^–1 and remained unaffected between 5 and 20 μg P ml^–1. The sporulation frequency and sporocarp number in this species in the soil culture also were not significantly affected by an increase in the dose of P from 10.7 to 21.4 or 21.4 to 32.1 mg pot^–1. Large variations in the degree of inhibition of sporulation due to the application of P (21.4 mg pot^–1) also occurred among the A. pinnata strains tested. Received: 20 October 1999  相似文献   

DPJH型单片机仿真频率自动减负荷装置研究     

陈岑  孙业才  高平  张国良 《中国农村水利水电》2000,(10):48-49

ＳＺＨ－１型低频率继电器接线复杂设备老化,现场使用时拨轮开关接触不良,为此用十六位单片机８７９８对该装置进行了仿真研究,仿真后的装置不但解决了上述问题,而且接线简单,提高了调整的精度和灵活性。  相似文献   

实测洪水系列在洪水频率分析中的重要作用     

杨力行  郑祖国 《新疆农业大学学报》2000,23(3):1-5

没有考古洪水,靠外延P-Ⅲ型频率曲线推求三峡工程稀遇设计洪水就非常困难。针对此问题,本研究提出了X-Ⅲ1型乘法频率曲线的原理、方法和算例,其数值计算结果显示：好的算法贵在信息利用,无论有无考古洪水,实测洪水系列在洪水频率分析中都具有重要作用。  相似文献   

基因频率随机过程模型的形成与发展     

张立岭  钱宏光 《内蒙古农业大学学报(自然科学版)》2000,21(4):102-108

基因频率变化规律是群体遗传学研究的核心,也是理解生物进化的关键。近１个世纪以来,许多遗传学家做出了重要贡献。在许多遗传学著作中,常常提到基因频率的Ｈａｒｄｙ－Ｗｅｉｎｂｅｒｇ平衡定理,并把此定理作为群体遗传学的核心,不适当地夸大了这个定理的作用。而真正对群体遗传学的基本理论,特别是群体遗传学数学理论有开拓性贡献的遗传学家,当属Ｒ．Ａ．Ｆｉｓｈｅｒ,Ｓ．Ｗｒｉｇｈｔ,Ｊ．Ｂ．ＳＨａｌｄａｎｅ,Ｔ．Ｄ  相似文献   

3种家用化学品的微核效应研究     

叶亚新 《农业环境科学学报》2000,19(5)

应用蚕豆根尖微核技术对家用化学品 (洗洁精、洗发水、洗面奶 )进行诱变性试验 ,结果表明 ,3种家用化学品均能诱发蚕豆根尖细胞微核率增高。对其进行剂量效应测定 ,结果表现良好的剂量效应关系。显示3种家用化学品均具有一定程度的诱变活性。  相似文献   

气力式油菜精量排种器田间漏播检测方法     

李明  丁幼春  廖庆喜 《农业工程学报》2010,26(13):27-31

针对气力式油菜精量排种器排种性能漏播检测的问题,提出了一种基于排种频率的检测方法。通过测频装置对不同转速、不同数量型孔堵塞的气力式排种器出口的排种频率测量试验,获得了不同转速下界定漏播严重程度的频率划分区域,即正常区、弱漏播区与严重漏播区。设计了田间漏播检测方法,即对排种器转速测量值经平滑滤波后通过插值运算得到界定漏播严重程度的频率阈值,对排种频率测量值经中值滤波后与频率阈值比较实现漏播严重程度的检测。在试验台上测试表明：排种频率法能有效实现漏播程度的检测,无漏播时检测准确率为100%,当量型孔堵塞8孔以上时判定为漏播的准确率为100%,能够有效地屏蔽因偶尔的漏播引发的频繁报警问题。  相似文献   

基于RFID技术的生猪产业链信息采集研究   总被引：2，自引：0，他引：2  

赵颖文  李晓 《湖北农业科学》2012,51(9):1886-1889,1894

将无线射频识别(RFID)技术应用于畜产品信息可追溯系统的个体识别已经成为一种必然的趋势.以生猪产业链的信息采集规范研究为例,重点分析了生猪养殖、屠宰、加工、运输及销售环节的信息化流程,对生猪产业链中各信息采集点的信息采集流程和信息采集内容加以规范,为日后建立畜产品信息采集规范和畜产品信息可追溯体系提供了一定的借鉴.  相似文献