Effect of herbicides and annual weeds on the yield and seed quality of lathyrus (Lathyrus sativus L.)

Field research conducted over six location years has indicated that lathyrus (Lathyrus sativus L.) is a poor competitor with annual weed species. Failure to control annual weeds reduced lathyrus seed yields by 54–95%, depending on the weed species present and their density. Weed competition also reduced thousand-seed weight. Preplant soil-incorporated applications of trifluralin and postemergence applications of sethoxydim controlled wild oat (Avena fatua L.) and green foxtail (Setaria viridis (L.) Beav.). Trifluralin failed to control wild mustard (Sinapis arvensis L.), an important broad-leaved weed in western Canada, but this weed was controlled by both preplant soil-incorporated and postemergence applications of metribuzin. Lathyrus exhibited excellent tolerance to these herbicides, which are currently registered for use on high-acreage crops in Canada.     

Pre-transplant herbicides for weed control in irrigated onion (Allium cepa L.) in northern Nigeria

Field trials were conducted at Samaru in the northern Guinea and at Bakuta and Kadawa in the Sudan Savanna ecological zones of Nigeria to identify suitable herbicides for weed control in irrigated onion. The herbicides tested were chlorthal-dimethyl, fluorodifen and oxadiazon. In the trials each herbicide treatment was compared with an identical treatment which received supplementary hand-weeding. The results of these experiments show that oxadiazon at 1·0–2·0 kg a.i./ha, with or without supplementary hoe-weeding at 6 weeks after transplanting, combined effective weed control with high bulb yields in irrigated dry season onions. While fluorodifen at 1·5 kg a.i./ha followed by supplementary hoe-weeding may be effective at sites with low weed infestation, a higher rate (3·0 kg/ha) may be desirable at sites with a higher broad-leaved weed infestation. Chlorthaldimethyl at 10·0 kg a.i./ha effectively controlled weeds at all the sites and gave high onion yields at sites with 6–12% clay; the selectivity was, however, lower at Bakura with very light soil. Uncontrolled weed growth caused 49–86% reduction in the bulb yields compared with the best herbicide treatments.     

Evaluation of post-emergence herbicides for the control of wild oat (Avena fatua L.) in wheat and barley in Argentina

Wild oat (Avena fatua L.) is the most troublesome weed in cereal crops in Argentina. With the aim of studying the effects of different herbicides, doses, and wild oat growth stage at application on weed control and crop yield, field experiments were conducted in wheat and barley crops during three growing seasons in the south of Buenos Aires Province, Argentina. Treatments were post-emergence applications of new herbicide, pinoxaden + cloquintocet mexyl (5%-1.25%), at doses that ranged from 20 g to 60 g a.i. pinoxaden ha⁻¹, applied at two to three leaves and the beginning of tillering of wild oat. In addition, standard treatments were included and applied at the same wild oat growth stages. Diclofop methyl at 511 g a.i. ha⁻¹ and fenoxaprop-p-ethyl at 55 g a.i. ha⁻¹ were applied in barley. In wheat, diclofop methyl was replaced by clodinafop-propargyl + cloquintocet mexyl (24%-6%) at 36 g a.i. clodinafop-propargyl + 9 g cloquintocet mexyl ha⁻¹ and in 2008/09 wheat experiments, iodosulfuron plus metsulfuron methyl (5%-60%) at 3.75 g a.i. ha⁻¹ + 3 g a.i. ha⁻¹ also was included. In both crops, pinoxaden at 30 g a.i. ha⁻¹ and at higher rates, fenoxaprop-p-ethyl and clodinafop-propargyl gave the best control of wild oat. In 2006/07 wheat crops, treatments applied at tiller initiation provided better control than the early timing averaged across herbicides. However, wheat yield generally was greater with early application. In barley, wild oat control and crop yield were similar regarding time of application. Variations in crop yield were correlated with grain number m⁻² both in wheat and barley, but relationships between both grain number and spikes m⁻² and with grains per spike were identified only in wheat.     

Influence of different tillage methods and pre-emergence herbicides on weed control in cowpea (Vigna unguiculata (L.) Walp.)

In the early and late cropping seasons of 1983, three different methods of tillage (minimum tillage, conventional tillage, and tilled and ridged) were evaluated for their influence on the performance of some pre-emergence herbicides used during the production of cowpea. Four varieties of cowpea (Ife Brown, H 144-1, TVx 3236, and Black-eyed bean) were planted in the early season while five varieties (Ife Brown, H 144-1, TVx 3236, H64/3 and Vita-5) were planted in the late season. A single spray application of 3·0 kg/ha alachlor, 3·0 kg/ha metobromuron + metolachlor and 3·5 kg/ha metolachlor was carried out one day before planting. Cyanazine at 3·0 kg/ha was included in the late season trial. The plots were either minimally tilled, conventionally tilled or tilled and ridged at the Teaching and Research Farm of the University of Ife. Results showed that the performance of all three herbicides used in the early season, as measured by weed control and grain yields, was best on the conventionally tilled, while the performance of the four herbicides in the late season was best on tilled and ridged plots. Metobromuron + metolachlor performed consistently better than each of the other herbicides irrespective of the method of tillage during both seasons. Conventional tillage enhanced the performance of metobromuron + metolachlor over minimum tillage plots and tilled and ridged plots in the early season; however, in the late season, the performance of metobromuron + metolachlor was best on tilled and ridged plots. Alachlor did not effectively control competing weeds in both seasons but did not injure any cowpea line. On the other hand, cyanazine did not control weeds effectively but was phytotoxic to Ife Brown variety of cowpea. In both seasons, the control of the broad-leaved weeds Ageratum conyzoides, Amaranthus spp., Euphorbia heterophylla, Ipomoea spp., Spigelia anthelmia, Synedrella nodiflora and Talinum triangulare was not adequate. The control of the grassy weeds Brachiaria deflexa, Cynodon dactylon, Imperata cylindrica and Eleusine indica was, however, effective.     

Assessment of allelopathic potential of barnyard grass (Echinochloa crus-galli) on rice (Oryza sativa L.) cultivars

Laboratory, greenhouse and field studies were conducted to assess the allelopathic potential of 44 rice cultivars (Oryza sativa L.) on barnyard grass (Echinochloa crus-galli P. Beauv. var. oryzicola Ohwi). Rice cultivars exhibited marked differences in the inhibition of barnyard grass growth and development. In the laboratory, Gin shun rice cultivar extracts exhibited the greatest activity on the weed seedling growth, reducing dry weight by 61%, while Kasarwala mundara cultivar extracts exhibited the greatest activity on seed germination, reducing germination by 23% and germination speed by 46%. In a greenhouse study of a residue mixture, the Philippine 2 cultivar showed the greatest inhibition percentage on seedling emergence (57%), total seedling length (74%) and dry weight (73%). In the field study, the Juma 10 cultivar demonstrated the most inhibitory effect by reducing barnyard grass tiller number (80%), leaf area (49%) and leaf (61%) and stem (74%) dry weight (68%). These results suggest that there are differences among the varieties for allelopathic inhibition of barnyard grass, and that the development of barnyard grass suppressive rice cultivars that have greater allelopathic potential may be possible.     

可可蔗糖磷酸合成酶基因家族进化及组织表达分析

在高等植物中,蔗糖磷酸合成酶（Sucrose phosphate synthase,SPS）是蔗糖合成的限速酶。在多种植物中都发现了SPS基因,而可可中尚未见相关报道。通过分析可可基因组数据库,鉴定出4个SPS候选基因,依次命名为TcSPS1、TcSPS2、TcSPS3和TcSPS4。4个基因的编码区（CDS）长度在3 075~3 228 bp之间,外显子数目为12~14,预测蛋白的平均分子量为118.15 ku,等电点均小于7。进化分析结果表明SPS基因家族分成3个亚族;TcSPS1和TcSPS2属于ClassⅠ亚族,TcSPS3和TcSPS4分别属于ClassⅡ亚族和ClassⅢ亚族。实时荧光定量PCR分析结果表明,TcSPS1与TcSPS2在树皮和果实中高量表达,TcSPS3和TcSPS4主要在叶片中表达。伴随着叶片和花蕾生长发育,各TcSPS基因表达量均呈现出上升的趋势,表明其与主要光合产物--蔗糖的合成或再合成有密切联系,参与可可“源库”器官中光合产物分配。     

20个小粒种咖啡种质生长量及根系形态差异分析

以20个小粒种咖啡种质为试验材料,通过盆栽试验,分析咖啡种质苗期生长量和根系形态差异。结果表明,各种质苗期株高、叶片数、分枝数差异显著,通过苗期株形分析,把小粒种咖啡种质分成高干、中等和矮生3个类型。M13、M14可作为高干型,CATUAI为矮生型鉴定的标准品种;CA ZHONGⅢ、M13为高干、多叶、多分枝品种,CATURRA、T8667为株高中等、多叶、多分枝品种,热引2号为矮生、多叶、多分枝品种;各种质主根长除了CA ZHONGⅡ较小以外,其他种质间差异不显著,各种质主根直径差异不显著;M13侧根长、根体积、根表面积显著大于CATUAI,参试的小粒种咖啡种质绝大部分都具有细而且数量较多的侧根,各种质间差异较小。侧根直径与侧根长为显著的负相关,地上部干物质累积量与地下部干物质累积量间呈显著的正相关,长势强壮,枝叶繁茂的植株,根系发达;各种质地下部和地上部生长相协调的根冠比在0.40~0.35。     

Evaluation of some weed control treatments for long season weed control in maize (Zea mays L.) under zero and minimum tillage at Samaru, in Nigeria

The effect of weed control treatments for long season control of weeds in maize under zero and minimum tillage was evaluated at Samara in northern Nigeria. Among the weed control treatments evaluated, soil ridging plus application of either 2,4-D or atrazine at 1.5 kg a.i/ha performed well as they effectively controlled weeds and resulted in better growth and a grain yield that was comparable to the hand weed control. Maize production under minimum tillage was better than under zero tillage.     

小麦种质资源耐深播性评价体系研究

为建立准确、简单易行的种质资源耐深播评价体系,以15份耐深播能力存在不同程度差异的小麦种质为材料,在大田环境下,研究6个播种深度(5 cm、7 cm、9 cm、11 cm、13 cm、15 cm)下小麦出苗率、出苗时间、苗高、地中茎长、胚芽鞘长、胚芽鞘横截面积及初生根长的差异,筛选小麦耐深播评价的最佳播种深度及其密切相...     

长期高温对黄瓜生理生化特性的影响

高温是热带地区夏季黄瓜产量的一个重要限制因子.本试验中以"新泰密刺"为材料,研究了长期高温(32～38℃)和适温(22～29℃)对黄瓜叶片和根生理生化特性的影响.结果表明,高温处理前期的叶片生长比对照快,高温处理后期叶片面积小于对照.长期高温使黄瓜的产量、叶片光合速率、叶绿素含量、叶绿素a/b、根活力都明显降低.在长期高温条件下,叶片和根中SOD活性的降低幅度大于对照,POD活性和MDA含量的增加幅度亦大于对照.14C示踪结果表明,长期高温处理使分配到根中的同化产物也明显低于对照.     

Weed control and sesame (Sesamum indicum L.) response to preplant incorporated herbicides and method of incorporation

Field studies were conducted at two sesame-growing regions of Texas in 2004 and 2005 to determine weed control and sesame response to four dinitroaniline herbicides and their method of incorporation. Ethalfluralin, pendimethalin (formulated as Prowl EC), and trifluralin were applied at the X, 1X, and 2X of the suggested label dose for Gossypium hirsutum L. Pendimethalin (formulated as Prowl H₂O) was applied at the X, 1X, and 1X rate. Two methods of incorporation included rolling cultivator mixing wheels and spring tooth harrow. With rolling cultivator mixing wheels, all herbicides controlled Amaranthus tuberculatus (Moq.) J.D. Sauer at least 74% regardless of dose. The X dose of ethalfluralin and pendimethalin (formulated as Prowl EC), or the X and 1X dose of pendimethalin (formulated as Prowl H₂O) controlled Brachiaria platyphylla (Griseb.) Nash no better than 73% while all other doses of the herbicides controlled B. platyphylla at least 80%. The use of mixing wheels to incorporate the herbicides resulted in better sesame stands and less stunting than the use of the spring tooth harrow; however, sesame stands were reduced as herbicide rate increased when using mixing wheels. Ethalfluralin at the 1X dose, pendimethalin (formulated as Prowl H₂O) at the X dose, and trifluralin at the X dose produced the highest sesame yield while ethalfluralin at the 2X dose produced the lowest yield.     

辣椒恢复系选育及三系配套研究

利用辣椒雄性不育系与恢复源材料杂交,以其F1及后代高可育株作母本,再与优良辣椒自交系进行连续回交,在不育细胞质的基础上,将自交系的优良性状逐步转育到恢复源中,选育出新的具有不育系细胞质基因"S"的辣椒强优恢复系,并实现辣椒"三系配套".     

Effects of nitrogen fertilizer and weed control on nutritive quality of carrots (Daucus carota L.)

The nutritive quality of carrots, obtained from different herbicide-treated plots and under different levels of nitrogen application ranging from zero to 80kg nitrogen/ha, was compared. There were significant differences in carotene content, T.S.S. (total soluble solids) and organolptic characteristics under the influence of different treatments. The maximum carotene content, T.S.S. and organoleptic characteristics were observed with the application of 80 kg. nitrogen/ha and fluchloralin herbicide at 0.90 and 1.20 kg/ha.     

小麦GRAS基因家族的全基因组鉴定与分析

GRAS基因是一类转录因子基因,在植物的生长和发育中起关键作用。本研究利用最新的小麦基因组数据,对小麦GRAS基因进行了全基因组鉴定和分析。结果从小麦中鉴定出153个GRAS基因,这些基因不均匀分布在小麦21条染色体上。系统发育分析将这些基因分为12个亚家族,片段复制和串联重复是导致该基因家族扩张的主要原因。蛋白质序列分析发现不同亚家族间氨基酸数目、分子量存在一定差异;二级结构预测表明,小麦GRAS基因的氨基酸序列均以α-螺旋、随机卷曲为主要组成部分。通过对小麦GRAS基因在不同组织和不同逆境胁迫下的表达分析发现,GRAS基因在不同组织和逆境胁迫下存在明显的差异表达,表明GRAS基因具有组织或器官表达特异性,且可能在对逆境胁迫的响应中起重要作用。这些结果为进一步研究小麦GRAS基因的功能奠定了基础。     

小麦β-酮脂酰CoA合成酶基因KCS的克隆与酵母表达

超长链脂肪酸是生物体内众多重要物质的合成底物。KCS基因编码β-酮脂酰CoA合成酶,该酶具有底物特异性,参与超长链脂肪酸延伸的缩合反应,是超长链脂肪酸合成的限速步骤。为了探究小麦KCS基因在超长链脂肪酸合成中的功能,采用同源克隆的方法从小麦(Triticum aestivum L.)中克隆出KCS基因后,利用生物信息学对其编码序列进行分析,并在酿酒酵母(Saccharomyces cerevisiae)中对其进行真核表达。结果表明,小麦TaKCS6基因的开放阅读框为1 287bp,编码428个氨基酸残基。结构域预测结果显示,TaKCS6蛋白含有III型聚酮合酶脂肪酸延伸酶和C末端3-酰基ACP合酶III结构域,属于KCSs蛋白家族。序列比对分析结果显示,TaKCS6氨基酸序列与拟南芥及其他植物的KCS6氨基酸序列在两个功能结构域上和活性位点保守。酵母表达结果显示,TaKCS6基因编码的蛋白参与C24以上超长链脂肪酸的延伸。     

Economic analysis of chemical weed control in irrigated garlic (Allium sativum L.) in Sudan Savanna Ecology, Nigeria

An economic analysis on the use of herbicide to control weeds in garlic production in 2002/2003 and 2003/2004 dry seasons indicated a considerable reduction in the cost of weed control and labour demand with the application of herbicide. Although the hoe weeding and the herbicide gave comparable bulb yield in 2002/2003 dry season, the net return per hectare was higher with herbicide application in both seasons. Similarly, the value of labour saved through herbicides use was positive throughout and increased significantly in 2003/2004 dry season.     

玉米纹枯病研究进展

玉米纹枯病已成为我国玉米主产区的一种重要病害,其危害日趋严重.系统地综述了玉米纹枯病的症状表现、病原菌及致病因子、发病传播、危害损失、玉米对纹枯病的抗性研究及综合防治等方面的研究进展.选育、鉴定综合性状好、高抗的玉米品种是防治玉米纹枯病的重点和难点.我国应加强玉米纹枯病抗性机制及其遗传规律的研究,加强玉米纹枯病抗病基因的定位、克隆的研究,同时广泛开展抗病性鉴定,为选育包括纹枯病在内的多抗性玉米杂交种提供依据。     

Diclofop resistance in sterile wild oat (Avena sterilis L.) in wheat fields in Greece and its management by other post-emergence herbicides

In 2009, a survey was conducted of cereal fields in five prefectures of Greece to establish the frequency and distribution of herbicide-resistant sterile wild oat (Avena sterilis L.). In total, 104 sterile wild oat accessions were collected and screened in a field experiment (conducted in 2009 and repeated in 2010) with several herbicides commonly used to control this weed. Most of the sterile wild oat accessions (89%) were classed as resistant (or developing resistant) to the ACCase-inhibiting herbicide diclofop, while resistance to other ACCase-inhibiting herbicides was markedly lower. The results of the pot experiments showed that some of the sterile wild oat accessions were found to have a very high level of diclofop resistance (resistance index up to 28.6), while cross-resistance with other herbicides was common. The levels of resistance and cross-resistance patterns varied among biotypes with different amount and time of selection pressure, indicating either more than one mechanism of resistance or different resistance mutations in these sterile wild oat biotypes. LA14, which had the highest diclofop resistance level (28.6 resistance index), showed resistance to all APP herbicides applied and non-ACCase inhibitors. Alternative ACCase-inhibiting herbicides, namely tralkoxydim and pinoxaden remain effective on 86 and 92% of the tested sterile wild oat populations, respectively. For the ALS-inhibiting herbicide mesosulfuron + iodosulfuron, nearly all the sterile wild oat accessions were susceptible (97%), with only 3 of them classed as developing resistance. Therefore, there is an opportunity to effectively control sterile wild oat by selecting from a wide range of herbicides and other cultural practices. Early post-emergence herbicide application is strongly suggested, since it could decrease the number of resistant seeds in the field and slow down the dispersal of this major problem.     

Variability in essential oil content and composition of Origanum hirtum L., Origanum onites L., Coridothymus capitatus (L.) and Satureja thymbra L. populations from the Greek island Ikaria

Plants belonging to four “oregano” plant species (Origanum hirtum L., Origanum onites L., Coridothymus capitatus L., and Satureja thymbra L.) were collected during flowering from 33 sites located in the eastern part of the Greek island of Ikaria in the Eastern Aegean during April, May and July 2008. C. capitatus and O. hirtum were mostly observed in higher altitudes, whereas O. onites and S. thymbra in lower ones. The spatial distribution of all species was depicted on a GIS map. All four species exhibited essential oil concentrations higher than those reported in earlier literature, namely O. onites 3-4.3%, S. thymbra 4-6.5%, C. capitatus 3.7-5.6% and O. hirtum 5.5-10.0% (v/w). Carvacrol was the main constituent of the essential oils of all species, followed by γ-terpinene, p-cymene and caryophyllene, while thymol was not detected. All constituents varied remarkably among the four species, with carvacrol exhibiting the lowest variation. Carvacrol content varied between 72.3 and 89.2% in O. onites; 46.5 and 58.0% in S. thymbra; 82.9 and 90.9% in C. capitatus; and 84.4 and 93.8% in O. hirtum. By applying hierarchical cluster analysis on the basis of the essential oil constituents two main groups, divided into four subgroups of the taxa were evident. The first group consisted of O. onites and S. thymbra, while the second one of C. capitatus and O. hirtum. The results are discussed in terms of topography and climatic variation.     

The critical period for weed control in three corn (Zea mays L.) types

Knowledge of the crop-weed competition period is vital for designing effective weed management strategies in crop production systems. Field studies were conducted at the Agricultural Research Institute, Kahramanmaras, Turkey in 2013 and 2014 to determine the critical period for weed control (CPWC) in three corn (Zea mays L.) types (field corn, popcorn, and sweet corn). A four parameter log-logistic model described the relationship between relative crop yield to both increasing duration of weed interference and length of weed-free periods. The relative yield of corn was influenced by duration of weed-infested or weed-free period, regardless of corn types. Increasing periods of weed interference significantly reduced corn yields in both years. In field corn, the CPWC ranged from 175 to 788 growing degree days (GDD) in 2013 which corresponded to V2–V12 growth stages, and 165–655 GDD (V1–V10 growth stages) in 2014 based on the 5% acceptable yield loss (AYL) level. In popcorn, the CPWC ranged from 92 to 615 GDD (VE–V10 growth stages) in 2013 and 110–678 GDD (V1–V10 growth stages) in 2014. In sweet corn, the CPWC ranged from 203 to 611 GDD in 2013 (V2–V10 growth stages) and 182–632 GDD (V2–V10 growth stages) in 2014. The practical implication of this study is that weed management should be initiated around V1 stage and maintained weed-free up to V12 stage in all corn types to prevent yield losses greater than 5%. These findings could help corn producers improve the cost effectiveness and efficacy of their weed management programs.