不同播期夏玉米二代玉米螟幼虫为害特点与防治对策

系统调查表明 ,不同播期夏玉米上二代玉米螟幼虫为害情况存在一定差异 ,由此根据玉米螟发生期与玉米生育期的对应情况 ,提出了 3种类型田玉米螟的防治对策     

Effect of Crop Rotation on Meloidogyne spp. and Pratylenchus spp. Populations in Strawberry Fields in Taiwan

Changes in population levels of Meloidogyne hapla, M. incognita, Pratylenchus coffeae, and P. penetrans were studied in 12 strawberry fields in the Dahu region of Taiwan. Ten potential rotation crops and two cultural practices were evaluated for their effect on nematode populations and influence on strawberry yield. Rotation with rice or taro and the cultural practice of flooding and bare fallowing for four months were found to reduce nematode soil populations to two or fewer nematodes per 100 ml soil. Average strawberry yields increased between 2.4% to 6.3% following taro compared to the bare fallow treatment. Corn suppressed M. incognita and M. hapla populations and resulted in an increased in strawberry yield compared to bare fallow. Other phytopathogens also present in these fields limited taro as the rotation choice for nematode management. Results of this research and economic analysis of the input requirements for various rotation crops, corn and bare fallow were recommended as the most appropriate rotation strategies for nematode management in strawberry in this region.     

Simultaneous saccharification and fermentation and economic evaluation of ultrasonic and jet cooking pretreatment of corn slurry

The potential of ultrasonics to replace hydrocooking in corn-to-ethanol plants was examined in this study. Batch and continuous experiments were conducted on corn slurry with sonication at a frequency of 20 kHz. Batch mode used a catenoidal horn operated at an amplitude of 144 μm peak-to-peak (p–p) for 90 s. Continuous experiments used a donut horn operating at inner radius amplitude of 12 μm p–p. Jet-cooked samples from the same ethanol plant were compared with ultrasonicated samples. The highest starch-to-ethanol conversion was obtained by the jet-cooked samples with a yield of 74% of the theoretical yield. Batch and continuous sonication achieved 71.2% and 68% conversion, respectively, however, statistical analysis showed no significant difference between the jet cooking and ultrasonication. On the basis of the similar performance, an economic analysis was conducted comparing jet cooking and ultrasonic pretreatment. The analysis showed that the capital cost for the ultrasonics system was ~10 times higher compared to the capital cost of a hydrocooker. However,due to the large energy requirements of hydrocookers, the analysis showed lower total overall costs for continuous ultrasonication than that for jet cooking, assuming the current energy prices. Because of the high utility cost calculated for jet cooking, it is concluded that ultrasonication poses as a more economical option than jet cooking. Overall, the study shows that ultrasonics is a technically and economically viable alternative to jet cooking in dry-grind corn ethanol plant.     

结冷胶固定化保加利亚乳杆菌及在玉米秸秆连续发酵d-乳酸中的应用

秸秆生物炼制化学品是解决秸秆资源利用附加值低、减轻秸秆焚烧带来的环境污染的主要方法之一。本研究制备了结冷胶固定化保加利亚乳酸杆菌(Lactobacillus bulgaricus)T15凝胶珠(结冷胶-T15凝胶珠),并对其性质进行表征,建立了结冷胶-T15凝胶珠固定化细胞循环连续发酵产D-乳酸发酵工艺。结冷胶-T15凝胶珠的断裂应力为(91.68±0.11) kPa,较海藻酸钙固定化T15凝胶珠(海藻酸钙-T15凝胶珠)提高了125.12%,表明结冷胶-T15凝胶珠的强度更强。以结冷胶-T15凝胶珠为出发菌株,葡萄糖为发酵基质,10批次循环(720h)发酵,其D-乳酸最高批次产量为(72.90±2.79)g/L,较海藻酸钙-T15凝胶珠提高了33.85%,较游离T15提高了37.70%。将葡萄糖更换为玉米秸秆酶解液,使用结冷胶-T15凝胶珠进行10批次循环(240 h)发酵,D-乳酸生产强度可达(1.74±0.79)g/(L·h),远高于游离菌。10批次循环发酵后结冷胶-T15凝胶珠磨损率小于5%,表明结冷胶是一种细胞固定化的良好载体,可广泛应用于细胞固定化工业发酵领域。本研究为细胞...     

First Report of Corn Whorl Rot Caused by Serratia marcescens in China

Whorl rot is a novel disease of corn found in the Huang‐Huai‐Hai Plain, China. Common symptoms of the disease in fields include yellowing and water‐soaked brown necrosis of young leaves in the whorl of corn plants, which often results in rot of the whorl. Bacterial streaming was always observed from diseased samples. Bacterial isolates were obtained from symptomatic tissue and further confirmed to be the casual agent of the disease using Koch's Postulates. Sequence analysis of 16S rDNA, housekeeping gene groES‐groEL and BIOLOG tests revealed that the isolate B3R3 belongs to the bacterium Serratia marcescens. None of the corn cultivars evaluated showed acceptable resistance to the disease. To our knowledge, this is the first report on corn whorl rot caused by Serratia marcescens.     

甜玉米种子活力测定及其田间成苗能力的评估

室内和田间条件下检测18种基因型甜玉米种子活力状况的结果表明:不同甜玉米种子基因型间的活力差异显著,但均以品种京科甜116较佳.用电导率、糖含量、脱氢酶活性、醛含量、穿纸和老化发芽率均可评估田间出苗率,且前三者还可评估出苗速度,尤以电导率最佳.建立回归方程可对田间成苗能力进行预测.     

半干旱区旱地不同覆盖种植方式玉米田的土壤水分和产量效应

为探讨半干旱区旱地不同种植方式玉米(Zea mays)田的土壤水分动态特征, 测定了全膜双垄沟播(PMF)、全沙覆盖(SM)和裸地(CK) 3种不同处理0-200 cm土壤水分季节变化、垂直变化及年际变化。结果表明: PMF明显改善玉米拔节前0-200 cm土壤的水分条件, 有利于玉米前期生长; 随着玉米生育进程的推进, 3种处理的耗水量依次为: PMF﹥SM﹥CK, 而土壤贮水量表现为CK﹥SM﹥PMF; 在相同降雨条件下, PMF处理0-200 cm土壤水分降雨入渗补给深度最大, SM次之, CK最小。随着种植年限增加, PMF的耗水量和耗水深度增加, 两年种植期间耗水深度从20-120 cm向120-200 cm推移; 连续种植两年后, 3种处理40-120 cm土壤含水量下降至9.0%以下, 其中PMF下降最快(7.9%), 土壤含水量接近萎蔫系数7.2%, 玉米只能靠当年降水生长, 如种植年限继续增加, 土壤极有可能形成干层。3种处理之间耗水量、产量、水分利用效率都存在显著差异, PMF最高, SM次之, CK最低。因此, 在半干旱区采用全膜双垄沟播种植玉米可显著提高产量, 但连续种植可导致土壤贮水量显著降低, 对农田可持续生产能力造成不利影响。     

Miniprimer PCR assay targeting multiple genes: a new rapid and reliable tool for genotyping Pantoea stewartii subsp. stewartii

Aim: Development of a ‘miniprimer’ PCR assay for genotyping Pantoea stewartii subsp. stewartii, the causal agent of the Stewart’s bacterial wilt on maize. Methods and Results: Four 10‐nucleotide (10‐nt) ‘miniprimer’ sets were designed and evaluated in the presence of Titanium Taq DNA polymerase. Under optimal reaction conditions, the miniprimer pair Uni‐BacF‐10/Uni‐BacR‐10 reproducibly generated identical banding patterns among 10 strains of P. stewartii subsp. stewartii, different patterns from strains of P. stewartii subsp. indologenes, other Panteoa species, Clavibacter michiganensis, Pectobacterium spp., Pseudomonas spp. and other bacterial species. The amplicons of Pantoea stewartii subsp. stewartii were cloned and sequenced to identify genes or DNA fragments that are targeted by the miniprimer PCR assay. Of the 14 ‘clone types’ identified, sequences of a 1·23‐kb fragment had a 99·8% similarity to part of the Pantoea stewartii zeaxanthin diglucoside biosynthetic operon ( AY166713 ). Other dominant cloned fragments included a 411‐bp amplicon that exhibited 99·8% similarity to the psaU gene (syn:ysaU; GQ249669 ), a type III protein‐secretion system complex of P. stewartii subsp. stewartii strain DC283, and a 548‐bp fragment showed 63% homology to the Asp/Glu racemase encoding gene in Erwinia tasmaniensis strain ET1/99. Conclusion: The miniprimer PCR assay reported here is highly discriminatory and reproducible in genotyping Pantoea stewartii subsp. stewartii. Significance and Impact of the study: This miniprimer PCR assay could be a new reliable and rapid tool for fingerprinting the Stewart’s wilt pathogen of maize.     

地膜覆盖对旱作春玉米农田土壤微生物碳源代谢的影响

土壤微生物碳源代谢特征是评价土壤质量变化的重要指标。依托山西省东部晋中市寿阳县农业环境与作物高效用水科学观测试验站,采用Biolog-ECO微孔板技术探究覆膜（FM）与裸地不覆膜处理（LD）对旱作春玉米拔节期、灌浆期和收获期3个关键生育期不同土层深度下（0-10 cm、10-20 cm和20-30 cm）土壤微生物碳源代谢的影响。结果表明：1） FM措施可以显著增加土壤微生物对碳源的利用能力,显著提高了土壤微生物的优势度指数,但降低了土壤微生物的均匀度指数。2）在0-10 cm和10-20 cm土层,FM与LD处理土壤微生物碳源利用情况均表现为灌浆期较高,而20-30 cm土层,表现为收获期较高,差异均主要体现在碳水类、羧酸类、氨基酸类3大类碳源上。3）拔节期和灌浆期0-10 cm土层中FM处理的土壤微生物碳源利用能力显著高于LD处理;然而收获期0-10 cm土层中恰好相反,呈现出LD处理下土壤微生物碳源利用能力显著高于FM处理。4）此外,Pearson相关分析表明,FM处理土壤微生物对碳水类碳源和羧酸类碳源2大类碳源的利用能力主要与土壤有机碳（SOC）和全氮（TN）含量相关性较好,呈现出正相关关系;对氨基酸类碳源的利用能力主要与土壤含水量、pH、SOC、NH₄⁺-N和NO₃^--N含量相关性较好。LD处理下,土壤微生物对碳水类、羧酸类和氨基酸类碳源的利用能力与土壤中TN含量的相关性较好,且呈现正相关关系。