鲜食玉米大斑病经济阈值及品种抗性分级标准

【目的】明确福建省鲜食玉米大斑病田间病情与玉米产量损失的关系,为福建省鲜食玉米大斑病的合理防控提供理论依据。【方法】在玉米大斑病自然发病条件下,利用不同施药次数人为造成田间不同病情梯度,建立病情指数与玉米产量损失率模型,制定适合福建省鲜食玉米大斑病的经济阈值。同样条件下,以病情指数与产量损失率模型推算不同抗性玉米品种科学用药时期和次数,制定鲜食玉米品种抗性分级标准。【结果】采用逐步回归分析建立了玉米大斑病全部叶片病情指数与种植天数的回归方程。玉米产量损失率与玉米大斑病全部叶和功能叶病情指数均呈显著正相关关系,建立了基于玉米全部叶和功能叶病情指数与产量损失率的模型。在用药次数依次为1,2,3和4次条件下,基于全部叶病情指数乳熟期（R3）玉米大斑病经济阈值分别是14.63,17.88,18.72和22.06,基于功能叶病情指数分别是7.74,10.43,12.24和16.80。基于建立的回归方程、经济阈值及玉米籽粒建成期（R2）功能叶病情指数（DI）,建议玉米品种抗性分级标准为：DI≤15为抗病（R）,15＜DI≤30为中抗（MR）,30＜DI≤45为中感（MS）,DI＞45为感病（S）。【结论】建立了福建省鲜食玉米大斑病田间病情消长动态理论模型和病情指数与产量损失率的模型,制定了玉米大斑病的经济阈值和不同玉米品种对大斑病的抗性分级标准。     

大豆蛋白肽-玉米淀粉复合物的制备及其性质研究

以玉米淀粉为原料,采用了压热-酶法并加入一定量的大豆蛋白肽（5%、10%、15%和20%, W/W）制备了大豆蛋白肽-玉米淀粉复合物,研究了复合物的理化性质和体外消化性。结果表明,玉米淀粉颗粒为椭球形或多棱角形,而复合物形貌受到了严重的破坏,为大小不一的片状结构。复合物红外光谱的-OH向低波数处移动,说明和玉米淀粉相比,复合物分子的有序性升高。玉米淀粉的结晶结构为A型,经过压热-酶处理后的复合物结晶结构发生了明显改变,变为B+V型结构。复合物的熔融温度最高为126.81 ℃,说明复合物的崩解温度很高,结晶结构紧密并且热稳定性更高。复合物的体外消化性显著降低,抗性淀粉含量大幅提高,并且随着大豆肽添加量的增加抗酶解性逐渐升高。大豆蛋白肽与淀粉之间主要的相互作用力为氢键,相互作用产生的复合物性质发生了很大的改变,对其特性进行研究可以为在食品领域的应用提供理论依据。     

北京春玉米生产经营现状分析——基于9区县的调查

通过对北京地区春玉米生产经营的成本收益等情况进行调研,发现农户生产中面临着规模化水平低、机械化水平低、效益低和种植意愿总体不强等问题。建议通过促进土地规模经营、提高机械化和社会化服务水平等,保护春玉米种植者生产积极性,提高北京地区的春玉米生产能力。     

不同生长调节物质浸种对玉米种子萌发生长及水分利用效率的影响

通过室内培养试验、砂培试验和土培试验研究了不同生长调节物质浸种对玉米种子发芽、幼苗生长及水分利用效率的影响。室内培养试验和砂培试验表明,低浓度矮壮素(2.5gk/g和5.0gk/g)和6-BA(0.010gk/g)处理提高了农大108的发芽率、发芽势和幼苗及根系干重,高浓度处理则表现出明显的抑制作用。土培试验表明,使用CCC、6-BA及其配合均不同程度提高了农大108和陕单902玉米叶片叶绿素SPAD值和光合作用速率,促进了根系生长和干物质的累积。用生长调节物质浸种对玉米水分利用效率的影响与玉米品种及水分供应水平有关。且水分胁迫下的水分利用效率增幅明显高于正常水分下,正常水分和水分胁迫下农大108的水分利用效率提高为1.83%～4.57%和2.31%～7.51%,陕单902分别为2.84%～12.80%和11.05%～15.26%。     

糯玉米新品种山农花糯1号的选育与利用

山东农业大学农学院选育的糯玉米新组合Wxn×Wxa,2001年4月经山东省农作物品种审定委员会审定,定名为山农花糯1号.该品种夏播鲜穗采收期80 d,子粒成熟期92 d,鲜穗产量达15 000～18 000 kg/hm2,子粒产量7 500～12 000 kg/hm2.同果穗子粒颜色有多种,商品价值高.该品种株型紧凑,抗大小叶斑病、抗青枯、抗倒伏,是优质的青食玉米。     

EFFECT OF DELAYED EMERGENCE ON CORN (ZEA MAYS L.) GRAIN YIELD

Uneven crop stands result in a reduction in corn yield production. This study was conducted to determine the effect of delayed emergence on corn yields and the effect of nitrogen (N) applications to compensate for yield reductions. The design used was a randomized complete block, with 4 sequences of delayed planting (0,4,7,and 10 days after planting) and 3 rates of nitrogen fertilizer (0, 40, 80 kg N ha^?1). At maturity, individual plants were tagged in sets of three and hand harvested. Corn ears were shelled, and yield per plant calculated. Grain yield of the delayed plant compared to that of the neighbors was reduced by 27, 8, 20 and 12 kg ha^?1day^?1 for 2007 LCB1, 2007 LCB2, 2010 LCB1 and 2010 LCB2, respectively. Over locations and years, the mean grain yield decrease of the delayed plant versus neighboring plants for each day delay was 122 kg ha^?1.     

EFFECTS OF MYCORRHIZAL FUNGI ON TOLERANCE CAPABILITY OF CORN GROWN UNDER SALT STRESS CONDITION

A greenhouse experiment was conducted to determine the effect of salinity on the efficacy of two arbuscular mycorrhizal fungi (AMF), Glomus mossea and natural mycorrhiza, of Glomus species, was investigated in terms of growth and nutrition of corn plant (Zea mays L). Plants were grown under different salinity levels imposed by 2.0, 2.5, 3.5, 5.0, 8.0, 12.0 dS m^?1of Hoagland's Solution [sodium chloride (NaCl), sodium sulfate (Na₂SO₄)_, Calcium dichloride (CaCl₂), and magnesium sulfate (MgSO₄) 7:9:3:1 ratio, respectively]. Both types of mycorrhizal fungi did not display significant protection in the host plant against the detrimental effects of the soil salinity. The effect of inoculation on growth varied only with the level of salinity. Maximum root colonization and spore numbers were observed in plants cultivated with low salinity levels. It was found that significant interaction between AMF x Salinity level for calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), and manganese (Mn) of shoot, and for Zn and Mn, of root.     

Chemical and spectroscopic characteristics of humic acid from a clay loam soil in Ontario after 52 years of consistent fertilization and crop rotation

Long-term fertilization and crop rotation can influence both organic C sequestration as well as the C composition of soils and the more resistant organic C compounds contained in humic acid(HA). This study examined the effects of fertilization and cropping type(monoculture corn(MC) and Kentucky bluegrass sod(KBS) and corn-oat-alfalfa-alfalfa rotation(RC)) on the HA composition of soil from a 52-year field study in southern Ontario, Canada. Humic acid samples were extracted from soil, and elemental analysis, infrared spectroscopy, solid state 13C nuclear magnetic resonance spectra, and electron paramagnetic resonance methods were used to determine the influence of the cropping type on the characteristics of HA. Both fertilization and cropping type affected the chemical characteristics of HA. Fertilization led to a 5.9% increase in C, a 7.6% decrease in O, and lower O/C and(N + O)/C ratios in HA as compared to the corresponding non-fertilized treatments. Rotation resulted in a lower proportion of C(48.1%) and a greater(N + O)/C ratio(0.7) relative to monoculture cropping. Infrared spectroscopy analysis showed that HA contained more C-O groups in fertilized soil than in non-fertilized soil under MC and KBS. Fertilization increased the O-alkyl-C, phenolic-C, and free radical contents of HA relative to non-fertilization treatments. Rotation decreased the aliphatic and carboxyl groups and increased the O-alkyl, carbohydrate, aryl, and phenolic groups and free radicals, relative to MC and KBS. Both long-term crop rotation and fertilization dramatically modified the soil HA composition. Significant relationships were observed between the molecular composition of HA and soil organic C. Hence, humic acid characterization could be used as an indicator of the long-term sustainability of crop management practices.     

Soil micromorphological and physical properties after application of composts with polyethylene and biocomponent-derived polymers added during composting

Composts are considered to be one of the best soil amendments. However, the effects of composts with added polymeric materials on soil physical,hydraulic, and micromorphological properties have not been widely discussed. Changes in soil physical properties influence the numerous services that soils provide. We studied the impacts of composts with the addition of three different polymers(F1–F3) produced from polyethylene and thermoplastic corn starch on the physical, hydraulic, and micromorphological properties of two soils, a Cambic Phaeozem and a Luvic Phaeozem. Applying composts with polymers had limited or no significant effect on soil bulk density and porosity, but increased the field water capacity by 18%–82% and 3%–6% and the plant-available water content by 15%–23% and 4%–17% for the Cambic Phaeozem and Luvic Phaeozem, respectively. The application of composts with polymers had a greater effect on the Cambic Phaeozem than on the Luvic Phaeozem. It was suggested that the use of modified composts led to changes in soil physical properties and micromorphological features and this effect was dependent on the compost application rate. Composts made with the addition of composite synthetic and natural material-derived polymers during composting were found to be a composite mixture that can be successfully used in agriculture.     

磁化水灌溉对土壤水盐分布和春玉米产量的影响

以春玉米为研究对象,通过磁化水灌溉试验,研究磁化水灌溉条件下不同灌水量(4 200,4 800,5 400 m~3/hm~2)对土壤水盐分布、玉米干物质量积累、产量及生长特性的影响,以探寻3 500 Gs磁化强度磁化水灌溉条件下适宜的灌水量,为促进塔里木盆地农业资源高效利用提供相关数据支持。结果表明:不同灌水量下磁化水灌溉均能提高土壤含水量,40—60 cm土层土壤盐分淋洗效果优于0—20 cm土层;磁化水灌溉可促进玉米植株生长及产量增加,各处理磁化水灌溉玉米产量较非磁化处理增加了2.11%～19.31%;磁化水3 500 Gs磁化强度灌溉4 800 m~3/hm~2处理产量均最佳,水分利用效率及灌溉水利用效率均达到最大,分别为2.64,2.86 kg/m~3。因此,与非磁化灌溉相比,适宜的磁化水灌溉量可改善玉米穗部干物质积累,有利于提高玉米的产量及水分利用效率。