共查询到20条相似文献，搜索用时 172 毫秒
1.
水稻粒黑粉病的发生规律和防治的研究 总被引：1，自引：0，他引：1
自七十年代后期以来,稻粒黑粉病的发生日渐普遍,特别是杂交稻三系制种田的不育系受害尤为严重。本病可由种子和土壤传染。经测定,在水稻收获后田间每克表土有冬孢子1666.5—12499.8个,制种田可高达48121.2—109367.3个。菌源可在土壤中积累,致使病害逐年加重。试验表明,病菌可以从花器侵染,因而品种发病差异与品种颖壳开放时间长短有密切关系,开放时间长的品种受病菌侵入的机会多,发病重。防治试验的结果表明,采用10％盐水或泥水选种,防病的效果分别可达93.24％和80.42％;在水稻开花初盛期和盛期喷布多菌灵各1次,可以得到较为明显的防病效果。 相似文献
2.
安庆地区南方水稻黑条矮缩病田间发生特征研究 总被引：1，自引：0，他引：1
对南方水稻黑条矮缩病田间症状类型、症状表现时间、不同时间种植类型水稻发病差异、当前主要发病品种(或组合)、白背飞虱在本地发生规律、田间病丛分布特征等进行了初步研究.结果表明,南方水稻黑条矮缩病的症状有典型和非典型、重症和轻症之分;在双季早稻、中稻、单季晚稻和双季晚稻混栽地区,以中稻、单季晚稻和双季晚稻发生较普遍,早稻发病较轻,这与白背飞虱在本地的发生期同各种时间种植类型水稻易感病生育期吻合程度有关;不同类型水稻发病程度不同,籼型杂交稻发病重于常规梗、糯稻,似与白背飞虱嗜食杂交稻的习性有关;品种间发病程度有差异,如奥两优28、华安3号等部分品种发病严重;病丛(株)在田间呈聚集分布. 相似文献
3.
4.
5.
水稻纹枯病成为原梧州地区水稻严重病害的原因在于连年大面积种植感病品种、菌源积累充足、氮肥使用量超过纹枯病敏感点、栽培技术的改变、适宜发病的田间小气候等,其防治对策应着重于加快选育抗病品种,减少初侵染源,注意栽培防病,适时提早用药防治等综合防治措施。 相似文献
6.
7.
人工接种试验和田间多年自然发病调查发现,目前生产上应用的水稻品种均感稻曲病;但在自然条件下,不同水稻品种稻曲病的发生程度存在较大差异,可以人为的分为多病粒高感品种和寡病粒相对抗病的品种。为了探究水稻穗部性状与其病害抗性间的关系,本文对孕穗期不同阶段的不同水稻品种的穗部性状进行了比较分析。结果发现表型为多病粒的高感多病粒品种与表型为寡病粒的相对抗病的品种之间在穗子大小、小花密度、穗鞘闭合程度和密封性、旗叶面积等方面均存在明显差异,寡病粒相对抗病的水稻品种穗鞘闭合程度优于高感多病粒品种。 相似文献
8.
晚稻品种对水稻细菌性条斑病田间对比抗性测定 总被引：1，自引：0，他引：1
水稻细菌性条斑病（Xanthomonas oryzicola Fang et dl）是水稻植物检疫对象病害。据浙江农大报道,水稻发病后,一般减产15%～25%,轻病田约减产6%～10%,重病田约减产40%～60%。据黄齐望报道,我省1975年在余江县曾有发生。上高县于1990年首次在蒙山乡肖坊村发现该病发生面积约1hm^2,后米历年都有不同程度发生,晚稻比早稻重。为探讨晚稻不同品种间有无抗病差异,2008年笔者选用12个品种,在老病区同块田中进行了抗性对比测定。通过详细调查发现, 相似文献
9.
四川土传小麦黄色花叶病的研究 总被引：1，自引：0，他引：1
小麦黄色花叶病,是近十多年来在四川雅安地区发生的一种新病害。病株叶片表现出短细条褪绿或变黄的花叶和桔黄色至枯黄色边缘不整齐的斑驳和条纹,心叶紧裹或扭曲,严重的在未抽穗前死亡。抽穗的穗短小,籽粒不饱满。病田约减产10-70%。根据几年的试验,证实这是由病毒所引起的一种病害,汁液磨接可引起发病。在田间,它主要由土壤传播,病根也有较强的传病能力,采自病株的种子及田间的昆虫不传病。它为害小麦属的一些植物,黑麦和大麦的个别品种发生过病株,普通小麦的品种间,抗病性有明显的差异,有一些是免疫的。三年的观察,田间小麦发病期的大气日均温不超过17℃,盛发期的最高气温不超过13.7℃。小麦的播种期与发病关系密切,早播的(10月)发病严重,稍迟的(11月)发病减轻,迟播的(12月及以后)基本不发病。根据试验结果,它可能是土传小麦花叶病的一个新株系,暂称为四川黄色株系。在病区大面积使用抗病丰产和耐迟播的小麦品种“繁6”,适当推迟播种期,增施肥料等综合防治措施,已收到了防病增产的良好效果,控制了此病的为害。为了防止病区扩大,严格控制病土及带土苗木外传也是必要的措施。 相似文献
10.
西瓜嫁接防枯萎病的嫁接技术 总被引：6，自引：0，他引：6
枯萎病是西瓜上发生危害最严重的病害。瓜地发生此病轻则减产,重则成片死亡,甚至全园毁灭。对于枯萎病的防治,目前还没有特效药,也没有理想的抗病品种,通过轮作换茬防病,轮作年限太长,土地有限,影响了西瓜生产的发展,挫伤了瓜农的积极性,针对这个问题,我们分别在红壤山地与旱田进行了嫁接防病试验,采用葫芦、南瓜、冬瓜等抗病强的品种做砧木均能达到防病的目的,其中以葫芦做砧木表现最好,抗病率达100%,增产15%～40%,既可耐寒抗病又能节省肥料(砧木强大的根系,吸肥能力强,从而提高了肥料利用率),同时解决了西瓜产区因轮作防枯萎病造成的土地… 相似文献
11.
12.
Summary Heteranthera limosa seeds were buried in flooded and in non-flooded soil and exposed to natural seasonal temperature changes in Lexington, Kentucky, USA. Seeds exhumed after various periods of burial ranging from 2 to 36 months were tested for germination under both flooded and non-flooded conditions. Seeds were dormant at maturity in September and became non-dormant during winter. Seeds buried in non-flooded soil during winter germinated to higher percentages and over a wider range of temperatures when tested under flooded conditions (in light) during spring and summer, than did those buried in flooded soil during winter. Thus, the water regime associated with rice culture (non-flooded in winter and flooded in summer) is optimal for dormancy-break and germination of H. limosa seeds. A portion of the buried seeds exhibited an annual dormancy/non-dormancy cycle, whereas others had a conditional dormancy/non-dormancy cycle. Regardless of the type of cycle, seeds buried in non-flooded soil retained the ability to germinate in light at high temperatures under flooded conditions throughout the summer. Thus, seeds potentially can germinate at any time during the growing season, whenever rice fields are flooded. Flooding fields during winter and/or sowing rice relatively early in the growing season may help in establishing rice before seeds of H. limosa germinate. 相似文献
13.
A mathematical model was developed of the dynamics of a plant virus disease within a spatially-referenced lattice of fields of a host crop. The model can be applied to crops in continuous, contiguous cultivation such as tropical irrigated rice. Disease progress in each field of the host crop was assumed to be logistic and determined by incidence within the field itself as well as incidence in neighbouring fields, depending on the gradient of disease spread. The frequency distribution of planting dates (represented by the proportion of the total number of fields planted in successive months) was assumed to follow a normal distribution and the variance of planting date was used as a measure of cropping asynchrony. Analysis of the model revealed that disease incidence within the lattice (i.e. mean incidence over all fields) depended upon the infection efficiency, the slope of the dispersal gradient, and the variance in planting date. Disease endemicity depended mainly on planting date variance and disease persisted in the lattice if this variance exceeded a certain threshold. Above the threshold for persistence, the response of mean disease incidence to planting date variance was non-linear and the region of greatest sensitivity was closest to the threshold. Thus, disease systems that show moderate rather than high cropping asynchrony are more likely to be influenced by changes in the variance of planting date. Implications for the area-wide management of rice tungro virus disease are discussed. 相似文献
14.
Studies conducted at the deepwater rice research site of the Bangladesh Rice Research Institute during 1989–1992 revealed that bandicoot rats in flooded deepwater rice (DWR) fields can be controlled effectively by the use of live traps. Intensive trapping during the flooding period significantly reduced damage to elongating stems and grain yield. Live traps were found to be superior to snap traps. Traps need to be placed on a float. Trap floats served as roosts for the exhausted rats that swam from the raised areas to the flooded rice fields. Floats made of banana trunk (after fruit harvest) were inexpensive and lasted for 2–3 weeks. Fresh snail flesh or paddy grains were effective trap baits. Field monitoring is an essential part of the trapping programme. The programme should be Initiated at the beginning of stem cutting in the field and continue until its cessation. Collective effort may be useful but not essential, when a DWR field is attacked an individual farmer can adopt the method to control rats. 相似文献
15.
香蕉—水稻轮作联合添加有机物料防控香蕉枯萎病研究 总被引：5，自引：0，他引：5
香蕉枯萎病是一种由尖孢镰刀菌引起的土传病害, 枯萎病的发生对香蕉产业造成严重的冲击本文针对香蕉枯萎病难以防控的难题, 采用水稻轮作同时添加有机物料（椰糠、稻秆和桉树皮）的方法, 研究了其对香蕉枯萎病高发病蕉园土壤中尖孢镰刀菌(FOC)和其他微生物数量的影响及其对香蕉枯萎病的防控效果。结果表明, 轮作水稻可以显著减少土壤中FOC的数量, 从而降低香蕉枯萎病的发病率。其中轮作水稻处理比未淹水未种植水稻处理FOC的数量下降了71.5%, 下茬香蕉枯萎病发病率降低了81.7%; 与未种植水稻但淹水的处理相比FOC数量下降了47.8%, 下茬香蕉枯萎病发病率降低了71.2%; 种植水稻同时添加水稻秸秆能够显著增强病原菌的杀灭效果和对下茬香蕉枯萎病的防控效果, 相比未添加物料轮作水稻处理, 尖孢镰刀菌数量下降了36.2%, 下茬香蕉枯萎病发病率降低了50.0%。同时, 水稻轮作同时添加有机物料处理及其下茬香蕉的种植, 对土壤中可培养细菌、真菌和放线菌数量均具有不同的影响。其中水稻种植期间不同处理的可培养真菌与放线菌数量随着时间的增加整体呈下降趋势, 而在种植香蕉后随时间的增加呈上升趋势; 土壤中可培养细菌的数量在水稻种植与香蕉种植期间随着时间的增加未呈现出规律性。结论：水稻轮作联合稻秆的添加能有效降低土壤中FOC的数量和下茬香蕉枯萎病的发病率。 相似文献
16.
Effect of the burial depth and environmental factors on the seasonal germination of bearded sprangletop (Leptochloa fusca [L.] Kunth ssp. fascicularis [Lam.] N. Snow) 
下载免费PDF全文
下载免费PDF全文 Emine Kaya Altop Husrev Mennan Colin J. Phillippo Bernard H. Zandstra 《Weed Biology and Management》2015,15(4):147-158
Bearded sprangletop recently was introduced to Turkey, where it has adapted to rice cultivation and become an important weed in many regions of the country. Experiments were conducted to determine the effects of light, temperature, osmotic stress, salt stress, pH and flooding on bearded sprangletop germination and emergence. Mature bearded sprangletop seeds were collected from rice fields in August 2008. Approximately 1250 seeds were wrapped in plastic fabric and buried at 2 or 10 cm in pots in flooded or non‐flooded conditions. In this experiment, seed germination in the light from the flooded and non‐flooded treatments began in the spring, peaked in summer and decreased in the fall. This pattern was repeated the following year after exposing the seeds to natural seasonal temperature changes. As either the level of water stress or NaCl concentration increased, cumulative seed germination decreased. No seed germinated when the NaCl concentration exceeded 400 mole. The level of seedling emergence decreased with an increasing burial depth. Under the flooded conditions, emergence began in late April and continued until early July, with peak emergence in the first week of June. Under the non‐flooded conditions, bearded sprangletop emerged later than under the flooded conditions and the overall level of emergence was lower. The depth of burial and water stress appear to be the most important factors that limit seed germination. Germination was stimulated by light, suggesting that the seeds are positively photoblastic. 相似文献
17.
18.
19.
ABSTRACT Seedling disease, caused primarily by several species of Pythium, is one of the major constraints to water-seeded rice production in Louisiana. The disease, also known as water-mold disease, seed rot, and seedling damping-off, causes stand reductions and growth abnormalities. In severe cases, fields must be replanted, which may result in delayed harvests and reduced yields. To develop more effective disease management tactics including biological control, this study was conducted primarily to determine sites of infection in seeds and seedlings; effect of plant age on susceptibility to P. arrhenomanes, P. myriotylum, and P. dissotocum; and minimum exposure times required for infection and seedling death. In addition, the effect of water depth on seedling disease was investigated. Infection rates of seed embryos were significantly higher than those of endosperms for all three Pythium spp. The development of roots from dry-seeded seedlings was significantly reduced by P. arrhenomanes and P. myriotylum at 5 days after planting compared with that of roots from noninoculated controls. Susceptibility of rice to all three species was sharply reduced within 2 to 6 days after planting, and seedlings were completely resistant at 8 days after planting. There was a steep reduction in emergence through the flood water, relative to the noninoculated control, following 2 to 3 days of exposure to inoculum of P. arrhenomanes and P. myriotylum. In contrast, P. dissotocum was much less virulent and required longer exposure times to cause irreversible seedling damage. Disease incidence was higher when seeds were planted into deeper water, implying that seedlings become resistant after they emerge through the flood water. These results suggest that disease control tactics including flood water management need to be employed for a very short period of time after planting. Also, given that the embryo is the primary site of infection and it is susceptible for only a few days, the disease should be amenable to biological control. 相似文献