Arthropod populations and rice yields in direct-seeded and transplanted lowland rice in West Africa

Studies were conducted on the effect of pruning time, host age, urediniospore release and weather parameters on the incidence and intensity of mulberry leaf rust (Peridiopsora mori). Rust severity significantly increased with increasing shoot age, irrespective of pruning time. Maximum disease severity was observed in plants pruned during the third week of October, and minimum severity in plants pruned during last week of November. Apparent infection rate was higher in younger shoots. Infection rate was higher in plants pruned during the last week of November. Urediniospore release was influenced by prevailing climatic conditions. A higher rate of spore release was noticed during sunny days. Maximum spore release was found between 12.00 h and 14.00 h. Spore release was positively correlated with temperature and negatively correlated with relative humidity. Rust severity (34.97%) was higher in January and least (1.03%) during May. Rust severity was negatively correlated with both temperature and rainfall. An exponential model was developed for the prediction of rust severity which was accurate up to 96.60%.     

水稻瘤矮病毒P12蛋白抗血清制备及其应用

为了进一步研究水稻瘤矮病毒(Rice gall dwarf virus,RGDV)P12的功能,将RGDV-GX P12编码区亚克隆至原核表达载体,并导入大肠杆菌诱导表达;重组的P12融合蛋白经Ni-NTA His·Bind Resins纯化后用于免疫小鼠制备抗血清,并进行Western blotting分析。结果显示,约41 kD大小的RGDV P12融合蛋白可在大肠杆菌中高效表达;利用该重组蛋白所制备的抗血清可特异地与融合表达和非融合的P12蛋白发生强烈的免疫学反应。利用该特异性抗血清在病毒粒子样品中检测不到P12蛋白,而在病株总蛋白样品中可检测到1条与预期大小一致的明显条带,表明RGDV P12是一种非结构蛋白。     

Dissemination of weeds with rice seedlings

Abstract

Dissemination of weed seeds, weed seedlings, and shoots of perennial weeds along with transplanted rice (Oryza sativa L.) seedlings was observed in farmers’ fields in Guimba, Nueva Ecija, Philippines. The percentage of weed seedlings and shoots in bundles of rice seedlings to be transplanted into the field ranged from 4–5 to 14.2% in the wet season and from 3.0 to 8.7% in the dry season. Grasses comprised 63% of the weed seedlings in the wet season and 81% in the dry season. The number of weed seeds disseminated with the rice seedlings ranged from 271 to 683 per bundle. Mainly sedges and broadleaf weeds were disseminated in this manner. Possible ways of reducing dissemination of weeds with rice seedlings are suggested.     

Changing rice farmers' pest management practices through participation in a small-scale experiment

Asian rice farmers commonly spray insecticides in the early stages of the crop to control leaf-feeding insects. The most common leaf feeder during this period is the leaf folder. Research shows that these sprays are usually unnecessary as the damaged crops mostly recover. It appears that farmers spray to control leaf folder because of misperceptions. We explored the use of farmer participation to change these misperceptions by inviting farmers to test a simple rule-of-thumb or 'heuristic': 'Do not spray against leaf folders for the first 30 days after transplanting (or 40 days after sowing)'. About 77% of the 101 participating farmers reported that yields of rice in their test plots were not significantly different from yields in their control plots. Before participating in the evaluation exercise, about 70% of the farmers applied their first insecticide sprays during the first 30 days after transplanting. In the first year after participation, 20% applied insecticides in the first 30 days and this was further reduced to 11% in the second year. The mean number of insecticide sprays was reduced from 3.2 to 2.0. Farmers' attitudes towards leaf-feeding insects has also changed. Before participation, farmers believed these insects cause yield loss (87%), severe damage (77%) and had to be sprayed early in the season (62%). After participation, these were reduced to 9%, 28% and 10%, respectively. Through information from research distilled into a 'high science-low tech' decision rule, farmers can readily derive a test hypothesis from it, evaluate itusing a simple experiment, learn its results and change perceptions and practices.     

分子标记辅助选育抗稻瘟病水稻新品种‘铁粳16’

稻瘟病是对水稻生产威胁最大的真菌病害,选育抗病水稻品种是防控该病最经济有效的途径。研究表明,聚合多个抗病基因可提高品种的抗性、拓宽抗谱。本研究以携带抗稻瘟病基因Pib的‘辽粳9234’和携带抗稻瘟病基因Pita的‘铁粳7号’为亲本,利用常规育种技术与分子标记辅助育种技术相结合从后代中鉴定到聚合抗稻瘟病基因Pita和Pib的后代。通过连续3年生产试验和米质分析,鉴定到1个同时具有抗稻瘟病基因Pita和Pib的稳定株系A-3,通过辽宁省水稻品种审定,命名为‘铁粳16’。人工接种结果表明‘铁粳16’较其亲本抗谱宽、抗性强。研究结果证实聚合Pita和Pib可提高水稻品种对稻瘟病的抗性,可为抗病基因聚合育种提供参考。     

基于CRISPR/Cas9技术的水稻miR1866突变体构建

microRNA(miRNA)是长度为18~25个碱基的非编码单链RNA,在植物生长发育过程中起着重要的调节作用。水稻是世界上重要的粮食作物之一,近年来调控水稻生长发育的miRNA不断被发掘,但目前关于miR1866的研究还比较少。本研究通过构建miR1866的CRISPR/Cas9表达载体,创制miR1866的突变体,挖掘水稻miR1866的功能。依据CRISPR/Cas9基因编辑技术,设计了miR1866的突变靶点,通过人工合成的方法得到包含突变靶点的特异序列,经过磷酸化修饰和退火后与载体Sg RNA连接进而与Cas9重组得到miR1866的CRISPR/Cas9表达载体,利用农杆菌介导法导入粳稻品种日本晴,获得转基因植株,结合测序结果判断转基因植株突变单株的突变基因型。本研究比较了野生型和突变体(KO1866-1-2和KO1866-2-4)在相同培养条件下苗期的根长、株高、茎基粗、鲜重和干重,结果表明:在营养液培养条件下,突变体的株高、根长、茎基粗、鲜重和干重均显著低于野生型。据此推测,miR1866对水稻的生长发育有一定的调节作用。本研究利用CRISPR/Cas9创制水稻miR1866的突变体,对研究miRNA调控途径,完善水稻miRNA调控的分子机制具有重要的意义。     

机械旱直播对水稻生育进程、光合特性及产量的影响

探讨2种种植方式对水稻生育进程、光合特性及产量的影响,为辽宁省水稻直播栽培提供技术指导。以辽宁省中早熟水稻品种辽星21、旱稻品种旱403和旱9710为试验材料,采用移栽和直播2种种植方式,对水稻生育进程、茎蘖动态、光合特性和产量进行比较分析。结果表明,2种种植方式下,不同品种水稻产量均表现为移栽高于直播,辽星21直播种植产量高于移栽种植的旱403和旱9710;与移栽种植相比,直播种植水稻株高降低,水稻主茎叶片减少约2片,剑叶和倒二叶的净光合速率（P_n）下降,单位面积茎蘖数增加。水稻直播种植宜以主茎成穗为主,优化群体结构,提高光合特性,进而实现产量的增加。     

双季稻栽培对水稻DUS测试标准品种数量性状表达的影响

通过田间试验,对《水稻DUS测试指南》中21个标准品种的13个数量性状进行早晚季性状观测分析,结果表明,受早晚栽培季节影响程度最大的3个性状依次是千粒重、茎秆长和穗粒数,茎秆直径受影响程度最小;各数量性状对应的标准品种受早晚栽培季节影响程度最大的是竹云糯,其次是桂花黄和元子占稻,川7号和矮糯受影响程度最小;单株穗数和结实率对应的标准品种早晚季表现一致性较差,提出将单株穗数代码为7的陆川早1号更换为Tsukushiakamochi,结实率代码为7的Dasanbyeo更换为特矮选的标准品种优化建议;依据晚季水稻的分级范围对部分早季水稻的数量性状进行调整,调整后各标准品种分级代码早晚季水稻表现出较好的一致性。     

秸秆还田对水稻光合物质生产特征、稻米品质和土壤养分的影响

为充分利用秸秆资源,减少秸秆焚烧带来的环境污染,采用大田试验,以水稻品种盐丰47为试验材料,设置秸秆还田（S）和不还田（CK）处理,对水稻干物质积累、分配及转运、产量、稻米品质、土壤全量养分和速效养分含量进行比较研究。结果表明,S处理水稻产量低于CK,差异不显著。与CK相比,S处理显著增加了水稻成熟期叶、茎和鞘的干重及占总干重比例,但各部分干物质输出率和转运率显著降低。S处理极显著地降低了稻米的垩白粒率、垩白大小、垩白度和直链淀粉含量,提高了稻米的食味值,对稻米的糙米率、精米率和整精米率无显著影响。S处理显著提高了水稻主要生育时期土壤的有机碳、全氮、全磷、有效磷和速效钾含量,对土壤的全钾含量和C/N无显著影响。S处理水稻抽穗期土壤铵态氮含量、乳熟期和成熟期土壤铵态氮和硝态氮含量均显著低于CK。说明辽宁地区推广秸秆还田有利于培肥土壤,改善稻米品质,不会显著影响水稻产量。     

银川地区水稻分布遥感制图方法研究

重点介绍水稻分布图的制作方法。在下垫面地物类型分析和卫星资料精地标订正的基础上，通过对研究区域内作物植被指数变化规律分析，选用不同时次、光谱质量较好的植被指数图像，经植被指数积温模式订正、象元分解，绘制出银川地区水稻空间分布图，为水稻面积信息的提取奠定基础，经过抽样调查检验，遥感调查水稻的空间分布与实况基本吻合。