首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 46 毫秒
1.
Utri Rajapan, a rice variety tolerant to the brown planthopper, Nilaparvata lugens, was resistant to rice ragged stunt virus transmitted by N. lugens and to rice tungro virus transmitted by the green leafhopper, Nephottetix virescens. Although some Utri Rajapan plants became infected with tungro virus, symptoms were mild and disappeared as the plant matured. Of the two tungro-associated viruses, only rice tungro bacilliform virus was present in Utri Rajapan. The infected plants thus did not serve as a source of inoculum for transmission to healthy plants, as rice tungro spherical virus must also be present for transmission to occur.  相似文献   

2.
1988—1991四年调查说明,花生矮化病毒(PSV.)引起普通花叶病害,花生条纹病毒(PStV)引起轻斑驳病害是开封花生两种主要病毒病。PSV通过花生种传,测定自花生普通花叶病株收集近4000粒种子,PSV种传率0.025％。刺槐花叶树是花生上PSV另一个初浸染源。PSV开封刺槐分离物(R_3、R_4)在鉴别寄主上反应和血清学性质上和PSV-Mi相一致,但引起花生病害症状较PSV—Mi轻。开封市农科所一带刺槐花叶病树率平均30.7％。四年病害流行程度差异显著。1988和1991年花生生长季雨量少,蚜虫发生量大,分别为PSV严重和中度流行年。1989和1990年雨水较多,蚜虫发生少,病害显著减轻。  相似文献   

3.
In order to preserve virus for identifying the resistance of rice varieties against rice black-streaked dwarf disease, a simple and reliable method was developed, through which virus-free small brown planthopper (SBPH) acquired rice black-streaked dwarf virus (RBSDV) from frozen infected leaves and the virus was transmitted to healthy rice plants. The experimental results showed that SBPH could obtain RBSDV from frozen infected rice leaves and the virus could be transmitted to a susceptible rice variety. For the ability to acquire RBSDV and transmit the virus to healthy plants by SBPH, there was no significant difference between frozen infected leaves and in vitro infected leaves. The novel method could be applied to identification of rice variety resistance to rice black-streaked dwarf disease, facilitating the breeding process for rice black-streaked dwarf disease resistance.  相似文献   

4.
灰飞虱从冷冻病叶获得水稻黑条矮缩病毒方法的研究初报   总被引：2，自引：0，他引：2  
  研究出一种利用灰飞虱从冷冻病叶中获得水稻黑条矮缩病毒（rice black streaked dwarf virus, RBSDV）的方法。以-70℃条件下冷冻保存的RBSDV罹病植株叶片对灰飞虱饲毒,随后接种感病水稻品种,结果发现灰飞虱可从冷冻病叶上获得RBSDV,并传播RBSDV,且获毒能力和传毒能力与新鲜病叶没有差异。这表明从冷冻病叶上获得RBSDV的灰飞虱可以应用于品种抗性鉴定,此法可望加快RBSDV抗病品种的选育进程。  相似文献   

5.
Survival of Pepper mild mottle virus (PMMV) and Melon necrotic spot virus (MNSV) in diseased plant residues of pepper and melon, respectively, was studied in several experiments investigating drying and composting conducted in experimental heaps. The viability of the soil-borne fungus Olpidium bornovanus, the vector of MNSV, in infected melon root residues was also evaluated. Maximum temperatures in the heap reached 61.9–73.8 °C during composting processes. Drying of plant residues reduced the infectivity of MNSV whereas the infectivity of PMMV and O. bornovanus was unaffected by drying. Neither the virus nor the fungus was viable after composting. PMMV antigens where detected by serology after 30 and 60 days composting in the four experiments, but virus infectivity was detected only in one process after 30 days. Our results show that the use of composts using plant residues from PMMV and MNSV-infected crops as organic amendments in SE Spain do not appear to pose a risk of re-introducing pathogens to soil. Environmental conditions in that area are suitable for the adequate elimination of these pathogens from infected vegetable residues through composting even during winter.  相似文献   

6.
Mature leaves of field-grown eddo plants were used for observing hydathode morphology by light and scanning electron microscopies. There were approximately five hydathode pores on the adaxial surface of each leaf tip. A ring structure with two borders around the pore was detected in this study. Further observations revealed a large cavity underneath the pores. The cavity was directly connected to vascular bundles that lacked a bundle sheath, via intercellular spaces among loosely organized parenchyma cells. Many crystal cells were present around the cavity and vascular bundles. To evaluate the role of guttation in sodium excretion under salinity stress, eddo plants were grown in hydroponic solutions containing 0, 1, 4, 8, and 12 mM sodium chloride (NaCl) for 7 d. As the NaCl concentration in the hydroponic solution increased, the sodium contents increased in leaf blades, petioles, and roots but remained unchanged in corms. The sodium concentration in the guttation fluid increased; however, the volume of guttation fluid decreased with increasing NaCl concentrations. Therefore, sodium elimination via guttation decreased with increasing NaCl concentrations. The ratios of the sodium content in guttation fluid to that of leaf blades, leaves, and whole plants decreased with increasing NaCl concentrations. The ratios of potassium to sodium contents in leaves, roots, and guttation fluid also decreased as the NaCl concentration increased. These results indicate that guttation did not eliminate sufficient sodium to play a role in adjusting sodium homeostasis and the ratios of potassium to sodium contents in eddo plants under saline conditions.  相似文献   

7.
Infection of Dactyls glomerata with cocksfoot mottle virus (Cf MV) and of Cynosurus cristatus with cynosurus mottle virus (CyMV) is frequently lethal. However, varieties of each species differ in the proportion of genotypes which survive, and in the damage suffered by these surviving plains. Infected plants of the CfMV-resistant cocksfoot, cv. Cambria, were generally much more aggressive in the competitive environment of the sward than were infected plants of the susceptible cv. S37. Thus, Cambria populations outyielded comparable populations of S37 by only 7% when healthy, but by 40% when infected with CfMV. A few genotypes in the infected Cambria population apparently recovered from the disease, became virus-free and were immune to further infection Resistance to CyMV in C. cristatus takes the form of resistance to systemic spread. A few symptomless and apparently virus-free tillers grow up from the bases of infected tillers. However, these tillers are susceptible to further infection. It is suggested that, in resistant genotypes, CfMV and CyMV trigger the production of antiviral agent(s) which block or restrict virus replication. There is some evidence that CfMV resistance is virus isolate specific, and this could present problems when breeding for durable resistance.  相似文献   

8.
Southern rice black-streaked dwarf virus (SRBSDV) is a recently proposed distinct species in the genus Fijivirus, family Reoviridae. During the past decade, SRBSDV has spread throughout southern China and northern Vietnam, and has become one of the greatest threats to rice production in these regions. We evaluated three common planthopper species affecting rice: white-backed planthopper (WBPH, Sogatella furcifera), brown planthopper (BPH, Nilaparvata lugens) and small brown planthopper (SBPH, Laodelphax striatellus) to determine their virus transmission abilities. It was confirmed that WBPH was an efficient persistent-transmitting vector for SRBSDV. Neither BPH nor SBPH were viral vectors, although a small proportion (3.7%) of tested SBPH acquired the virus from diseased rice. We characterized the virus transmission properties of WBPH. 83% of the tested insects fed on virus-infected rice plants became viruliferous. The minimum virus acquisition and inoculation access periods were 5 and 30 min, respectively, for both WBPH nymphs and adults. The circulative transmission periods of the virus in WBPH ranged from 6 to 14 days, and most viruliferous individuals transmitted the virus in intermittent periods ranging from 2 to 6 days. A single individual of WBPH could infect 8–25 rice plants with the virus in a 5-day period. WBPH could transmit SRBSDV from rice to maize seedlings, but it was barely able to acquire the virus from infected maize. These results improve our understanding of the epidemiology of SRBSDV, and will be useful for development of disease control strategies.  相似文献   

9.
ABSTRACT

Information on comprehensive evaluation of agricultural innovations is often limited. This study provides an overview of multidisciplinary evaluation of a lowland rice variety, WITA 9 (released in Côte d’Ivoire in 1998), with respect to its agronomic performance, grain quality, resistance to diseases, adoption by farmers, impact on productivity and farmers’ income, and marketability. WITA 9 had the highest paddy yield among the tested varieties including an international check (IR 64) and recently developed varieties adapted to this country. WITA 9 had a higher amylose content (26–28%) than others tested. This study confirmed its resistance to bacterial leaf blight, Rice yellow mottle virus (RYMV), and rice blast. A household survey showed that the adoption rate was 24%, its paddy yield advantage was 0.7 t ha–1, and its adoption increased farmer’s income by US$ 91 ha–1 per season. A market study showed that consumers’ willingness to pay was higher for WITA 9 than any other locally produced rice variety and comparable to imported rice in one of two markets. We conclude that WITA 9 is an ideal innovation for enhancing productivity and rice import substitution in Côte d’Ivoire. An effective seed delivery system and enhancing farmers’ and consumers’ awareness of this variety are vital for accelerating impact.  相似文献   

10.
《Field Crops Research》1999,61(2):163-177
Field experiments were conducted over three years to investigate the effects of beet yellows virus (BYV) and beet mild yellowing virus (BMYV) on leaf area dynamics in sugar beet (Beta vulgaris L.). Plants infected with BMYV showed normal leaf area growth and the leaf area index (LAI) was not significantly affected by virus infection. Up to 1.4 m2 (leaf) m−2 (soil) of leaf area was yellow, resulting in a maximum proportion of yellow leaf area of ca. 35%. Yellowing symptoms were only found on mature leaves. Plants infected with BYV showed a reduced formation of leaf area compared to healthy or BMYV-infected plants; leaves appearing after infection remained smaller than in healthy or BMYV-infected plots. As for BMYV, only mature leaves developed yellowing symptoms. The total amount of yellow leaf area on BYV-infected plants was similar to that induced by BMYV, but due to the smaller total leaf area index, the proportion of yellow leaf area was greater, up to ca. 50%. Infection with BYV substantially reduced the life span of infected leaves. Both viruses caused a ±20% decrease of specific leaf area in mature yellow leaves, compared to healthy leaves. As a result of a lower LAI and a greater proportion of yellow leaf area, BYV causes a greater reduction of crop light interception on green leaves than BMYV. In BMYV-infected plots, proportion of soil cover by yellow leaves was generally similar to the proportion of yellow leaf area, but significant differences from this pattern were observed for BYV.  相似文献   

11.
水浇地冬小麦垄作栽培技术研究   总被引：35，自引：12，他引：35  
针对传统种植方式下．大水漫灌所造成的浪费水资源、破坏土壤结构、在高肥水条件下易招致小麦倒伏和病害发生等问题，对小麦垄作栽培进行了研究，旨在为水浇地小麦高产、高效栽培开辟新途径。试验结果表明，小麦垄作栽培下，水分利用效率提高20％～30％，当季氮肥利用率提高10％以上；由于垄作栽培改传统平作的大水漫灌为小水沟内渗灌，消除了传统平作大水漫灌导致的土壤板结现象，改善了根际土壤的理化性状，有利于小麦的健壮生长；由于垄作栽培改变了麦田的地貌特征，从而改善了田间的通风透光条件，不仅降低了田间湿度，显著提高了小麦的抗倒伏及抗病能力，而且极显著地提高了小麦的光能利用率，有利于小麦产量的提高及品质的改善。  相似文献   

12.
Intensive cultivation of rice and wheat in north-west India has resulted in air pollution from rice straw burning, soil degradation and declining groundwater resources. The retention of rice residues as a surface mulch could be beneficial for moisture conservation and yield, and for hence water productivity, in addition to reducing air pollution and loss of soil organic matter. Two field experiments were conducted in Punjab, India, to study the effects of rice straw mulch and irrigation scheduling on wheat growth, yield, water use and water productivity during 2006-2008. Mulching increased soil water content and this led to significant improvement in crop growth and yield determining attributes where water was limiting, but this only resulted in significant grain yield increase in two instances. There was no effect of irrigation treatment in the first year because of well-distributed rains. In the second year, yield decreased with decrease and delay in the number of irrigations between crown root initiation and grain filling. With soil matric potential (SMP)-based irrigation scheduling, the irrigation amount was reduced by 75 mm each year with mulch in comparison with no mulch, while maintaining grain yield. Total crop water use (ET) was not significantly affected by mulch in either year, but was significantly affected by irrigation treatment in the second year. Mulch had a positive or neutral effect on grain water productivity with respect to ET (WPET) and irrigation (WPI). Maximum WPI occurred in the treatment which received the least irrigation, but this was also the lowest yielding treatment. The current irrigation scheduling guidelines based on cumulative pan evaporation (CPE) resulted in sub-optimal irrigation (loss of yield) in one of the two years, and higher irrigation input and lower WPI of the mulched treatment in comparison with SMP-based irrigation scheduling. The results from this and other studies suggest that farmers in Punjab greatly over-irrigate wheat. Further field and modelling studies are needed to extrapolate the findings to a wider range of seasonal and site conditions, and to develop simple tools and guidelines to assist farmers to better schedule irrigation to wheat.  相似文献   

13.
【目的】探讨增氧方式对稻田土壤微生物量碳、氮和土壤酶活性的影响。【方法】以中旱221(旱稻)、中浙优8号(水稻)和IR45765-3B(深水稻)为材料,研究微纳米气泡水增氧灌溉、干湿交替灌溉、淹水灌溉对稻田土壤微生物量碳、氮,土壤氮代谢作用强度和土壤氮素转化相关酶活性的影响。【结果】微纳米气泡水增氧灌溉和干湿交替灌溉可以显著提高稻田土壤微生物生物量碳、氮,中旱221、中浙优8号和IR45765-3B的增氧处理较淹水灌溉处理微生物生物量碳、氮分别增加了30.0%~46.1%和7.1%~92.1%,并且增氧处理降低了3个水稻品种的微生物量碳氮比;与淹水灌溉相比,微纳米气泡水增氧灌溉和干湿交替灌溉有助于提高稻田土壤脲酶、蔗糖酶、过氧化氢酶、蛋白酶、羟胺还原酶活性,降低硝酸还原酶活性和亚硝酸还原酶活性。【结论】微纳米气泡水增氧灌溉和干湿交替灌溉改善稻田土壤的氧化特性,提高土壤酶活性、微生物量碳、氮和硝化强度,有助于改善土壤环境和肥力状况,协调了C、N代谢的平衡。  相似文献   

14.
An alarming rate of ground water depletion and increasing labour scarcity are major threats to future rice production in north west India. Management strategies that reduce the irrigation amount and labour requirement while maintaining or increasing yield are urgently needed. Dry seeded rice (DSR) has been proposed as one means of achieving these objectives, but little is known about optimal water management for DSR. Therefore a field study was conducted on a clay loam soil in Punjab, India, during 2008 and 2009, to investigate the effects of irrigation management on the performance of puddled transplanted rice (PTR) and dry seeded rice. Irrigation scheduling treatments were based on soil water tension (SWT) ranging from ponding/saturation (daily irrigation) to alternate wetting and drying (AWD) with irrigation thresholds of 20, 40 and 70 kPa at 18–20 cm soil depth. Rainfall was above average and well distributed in 2008 (822 mm), and average and less well distributed in 2009 (663 mm).  相似文献   

15.
To clarify the optimal water management in large-scale fields under high temperatures at the ripening period, effective water managements during this period for improvement of yield, appearance quality and palatability were investigated. Compared with intermittent irrigation and flooded irrigation, the soil temperature with saturated irrigation remained low throughout the day, and the decrease rate of the bleeding rate of hills was the lowest. These results suggested that the saturated irrigation maintained root activity. For the three irrigation types, the number of spikelets per m2 and 1000-grain weight were similar, however, saturated irrigation resulted in significantly higher rice yield due to improvement in the percentage of ripened grains. The saturated irrigation produced a high percentage of perfect rice grains and thicker brown rice grain, furthermore, the palatability of cooked rice was excellent because protein content and hardness/adhesion ratio were both low. Thus, under high-temperature ripening conditions, soil temperature was lowered and root activity was maintained when applying saturated irrigation after heading time. The results indicated that saturated irrigation is an effective countermeasure against high-temperature ripening damage.  相似文献   

16.
在高海拔寒冷稻作区,通过晒水池增温进行温水灌溉和垄作栽培提高土壤温度。垄作栽培、温水灌溉在移栽后到有效分蘖临界叶龄期的土壤日平均温差分别比常规栽培(对照)高2.94℃和0.57℃。通过调查有效分蘖临界叶龄期水稻的分蘖发生数量和质量,探讨增加土壤温度对水稻分蘖发生和产量及其构成因素的影响。结果表明,丽粳10号垄作栽培、温水灌溉成穗率比对照分别高14.59和0.14个百分点,大白谷分别高12.08和2.09个百分点。丽粳10号垄作栽培、温水灌溉的产量分别比对照高13.79%和10.82%,大白谷分别高13.35%和11.54%。土壤增温可促进高寒生态区水稻早发和干物质积累,增加有效分蘖,优化群体质量,提高成穗率和产量。  相似文献   

17.
To optimize the use of limited water resources, surface irrigation systems in parts of China have introduced a new water saving irrigation method for rice termed alternate wetting and drying (AWD). The basic feature of this method is to irrigate so that the soil alternates between periods of standing water and damp or dry soil conditions from 30 days after crop establishment up to harvesting. However, many Chinese rice farmers still practice the continuous irrigation method with late- season drying of the soil.A comparative assessment of these two methods of on-farm water management for rice was conducted at two sites within the Zhanghe Irrigation System (ZIS) in Hubei province of China for the 1999 and 2000 rice crops. The objective was to evaluate the impact of AWD on crop management practices and the profitability of rice production. In conjunction with irrigation district officials, two sites within ZIS were selected for study, one where AWD was supposed to be widely practiced (Tuanlin, TL) and one where it had not been introduced (Lengshui, LS). It was found that farmers at both sites do not practice a pure form of either AWD or continuous flooding. However, farmers in TL did tend to let the soil dry more frequently than their counterparts in LS.Because most farmers practice neither pure AWD nor pure continuous flooding, an AWD score was developed that measures the frequency with which farmers allow their soil to dry. This AWD score was not significantly correlated with yield after controlling for site and year effects and input use. AWD scores were also not correlated with input use. We conclude that AWD saves water at the farm level without adversely affecting yields or farm profitability.  相似文献   

18.
冷灌繁殖水稻低温敏核不育系技术研究   总被引：8，自引：0，他引：8  
 通过盆栽和大田试验，研究了籼型低温敏核不育系GD-2S的冷灌繁种技术。结果表明，1)冷灌开始时期以幼穗分化Ⅲ期(二次枝梗和颖花原基分化)为好。但是，GD-2S的温度诱导育性转换的敏感期在抽穗前的第11天至19天，即雌雄蕊形成期(Ⅳ期)至花粉母细胞减数分裂期(Ⅵ期)。冷灌处理开始至植株产生反应之间存在一个启动过程。2)冷灌天数以13 d左右为宜。冷灌处理会导致颖花退化，延缓生育进程，推迟抽穗时间。冷灌开始时期越早或冷灌时间越长，颖花退化越严重(如冷灌20 d的达25.5%)，结实率也降低。3)冷灌深度以12 cm左右(刚浸至生长点)深的结实率最高。  相似文献   

19.
增氧灌溉对水稻生理特性和后期衰老的影响   总被引：11，自引：0，他引：11  
以常规粳稻秀水09、杂交籼稻国稻6号和两优培九为试材,于2007-2008年采用大田试验,研究了增氧灌溉对水稻生理特性和后期衰老的影响。结果表明,与常规灌溉水相比,超微气泡水的溶氧量明显提高而且下降速率慢。增氧灌溉处理土壤氧化还原电位显著或极显著提高,有效穗数、结实率和产量显著提高。进一步分析表明,增氧灌溉处理下秀水09和两优培九叶片光合速率分别较对照提高了4.13%和3.78%;而且增氧灌溉显著提高叶片叶绿素和可溶性蛋白质含量,气孔导度也有较大的增加;此外,增氧灌溉处理还增强了水稻生育后期的根系功能,提高了叶片超氧化物歧化酶活性,降低了叶片丙二醛含量,延缓叶片衰老,延长了叶片功能期从而促进籽粒灌浆结实。  相似文献   

20.
Treated industrial effluents have high levels of nutrients and dissolved organic matter. The irrigation of rice by flooding can increase nutrient uptake and grain yield. Therefore, this study evaluated the nutrient contents in the shoots and grain of the rice crop and also the chemical of the soil after irrigation of the crop with leachate of the treated industrial effluent. A greenhouse experiment was conducted using pots filled with 20 kg of soil in a randomized block design with three replications. The treatments consisted of control (irrigation with distilled water) and four concentrations of the leachate (25, 50, 75, and 100 %) for irrigation. At the end of the experiment, the nutrient contents in tissues of rice plants, sterility of spikelets, and grain mass were evaluated. Results showed that irrigation with the leachate at 25 % content increased the macro- and micronutrients’ concentrations in the shoot biomass and grain, except for potassium and iron. Irrigation with the industrial leachate decreased tillering and grain yield; however, it increased chlorophyll content, sterility of spikelets, and sodium intake at this leachate concentration. The potassium and sodium levels and the electrical conductivity values of soils irrigated with treated industrial leachate were increased. The use of the treated leachate from industrial effluents is an alternative that reuses the nutritional load, but the volume of leachate should be limited and monitored to prevent the sodicity in the soil and problemsdue to eutrophication.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号