Italian Ryegrass (Lolium perenne ssp. multiflorum) and Corn (Zea mays) Competition

Italian ryegrass is an annual/biennial grass that is typically used as a pasture crop or a cover crop along roadsides, rights-of-way, and industrial areas. Glyphosate-resistant (GR) Italian ryegrass populations have been documented around the world, mostly in orchard and vineyard situations. The first evidence of evolved GR Italian ryegrass in row/agronomic crops was reported from Washington County, Mississippi in 2005. GR Italian ryegrass populations can jeopardize preplant burndown options in reduced-tillage crop production systems, thereby, delaying planting operations. The effects of competition of Italian ryegrass on crop growth and yield are poorly understood. A field study was conducted in the 2012 growing season and repeated in the 2013 growing season. GR and susceptible (GS) Italian ryegrass populations were established in the greenhouse and transplanted in prepared corn row beds in the fall of 2011 and 2012 at 0, 1, 2, 3, and 4 plants·meter> of crop row. Italian ryegrass plants overwintered and developed over the following spring-summer. Glyphosate was applied at 1.26 kg·ae/ha (1.5× of labeled rate) in the spring to burndown the Italian ryegrass plants and corn was planted into the ryegrass residue 2 - 3 wk later. Current corn production practices were followed. Corn density (early and late season), height (early season), and yield and Italian ryegrass biomass (early-mid season) measurements were recorded during both years. Corn height was greater in 2012 than that in 2013 at comparable stages of the growing season, due to a cooler and wetter early season in 2013 than that in 2012. Averaged across weed densities, corn density (both early and late season) and yield were higher in the GS than those in the GR population, but Italian ryegrass biomass was similar for both populations. Averaged across Italian ryegrass populations, corn density (both early and late season), and yield were inversely proportional to Italian ryegrass density. In summary, Italian ryegrass significantly reduced corn density and yield and reduction was greater with the GR than that with the GS population. Studies are underway to study inter population competition in Italian ryegrass and investigate allelopathic effects of Italian ryegrass on selected crops.

Molecular identification of asymmetric somatic hybrids between wheat and Italian ryegrass

Sexual incompatibility between common wheat and Italian ryegrass was an obstacle for transferring useful traits from italian ryegrass to wheat. In order to use those desirable genetic resources to improve wheat and to create new cytoplasmic germplasm, the protoplasts of wheat and Italian ryegrass were successfully electrofused and the somatic hybrid plants were regenerated. Examination with 6 restriction enzymes, 13 probes including 9 mtDNA probes (H454, Pst24, B30, Pro I, 490, B342, pHJ2-7-l, B376, 7), 3 cpDNA probes (pHvc p1, pHvc p5 and pHvc p8) and onenuclear DNA probe-pTA71 (rDNA) in total 73 enzyme/probe combinations revealed rich polymorphism between the fusion partners. RFLP analysis indicated that approximately 93.4% of the regenerated plants were true somatic hybrids. AFLP analysis implied that the somatic hybrids were highly asymmetric. The RFLP analysis using mt- and cpDNA specific probes also demonstrated the non-coexistence of mitochondria and chloroplasts from the fusion partners in the

意大利黑麦草菌根际效应研究

研究了水田冬种意大利黑麦草AM形成的规律、稻田中AMF密度变化以及土壤因子对意大利黑麦草AM形成的影响,进而探讨AM对意大利黑麦草生长和发育的影响。结果表明:①翻耕不施肥、不翻耕施肥和不翻耕不施肥处理的意大利黑麦草总感染率上升幅度均达到了显著水平(p<0.05);②土壤中AMF孢子密度随着意大利黑麦草生长时间的增加而增加,与感染率的增长趋势基本保持一致,且二者之间相关性达到极显著正相关(p<0.01);③意大利黑麦草根系AM的感染率与土壤pH值极显著正相关(p<0.01),与土壤温度显著正相关(p<0.05),与土壤含水量极显著负相关(p<0.01),与水解N质量分数显著负相关(p<0.05)。土壤中AMF孢子密度与土壤温度极显著正相关(p<0.01),与pH显著正相关(p<0.05),与土壤有机质质量分数、水解N质量分数、全P质量分数和速效P质量分数显著负相关的(p<0.05);④意大利黑麦草产量与AM感染率(p>0.05)和AMF孢子密度(p<0.05)均呈负相关。

高温高湿条件下意大利黑麦草青贮技术研究

研究以水田冬闲期栽培的意大利黑麦草(Lolium multiflorum)为材料,结合常规的青贮方法进行了小规模控制实验,试验设计了隔水(将青贮过程中产生的渗出液排出)和不隔水,以及不同添加物的青贮处理。青贮结束后,对青贮黑麦草的品质和营养价值进行评定,探讨不同处理对黑麦草青贮的作用效果,以及南方高温高湿条件下青贮黑麦草的合理方法和最佳条件。结果发现,对黑麦草进行隔水添加乳酸的青贮处理从感观评定、pH值和营养成分的分析结果来看,都在一定程度上优于其他处理,由此可以认为隔水添加乳酸的处理相对实现了较稳定和较优质的青贮。

冬闲期种植多花黑麦草对稻田土壤性状的影响

"多花黑麦草(Lolium multiflorum L.; Italian Ryegrass)—水稻(Oryza sativa L.; Rice)"草田轮作(IRR)系统是我国南方农区新型的轮作模式之一。利用冬闲田种植多花黑麦草不仅能够生产大量的优质青饲料,缓解冬季畜禽饲草紧缺的问题,而且可以改善土壤物理和化学性质,提高养分循环效率,并对土壤微生物群落产生积极影响。通过讨论种植多花黑麦草对土壤团聚体结构、容重、pH、腐殖酸、有机质、碳氮比、土壤氮、磷、钾含量和土壤微生物群落等的影响,系统总结了黑麦草在土壤培肥方面的作用效应,并进一步探讨了南方农区利用IRR系统发展"草牧业"的困难与挑战,旨在为IRR系统的进一步推广提供更为全面深入的理论指导。

多花黑麦草根际土壤丛枝菌根真菌对早稻生长的影响

为了探究＂黑麦草（Lolium multifiorum L.）-水稻（Oryza sativa L）＂草田轮作（Italian Reygrass-Rice,简称IRR）系统中冬种黑麦草对土壤丛枝菌根真菌（Arbuscular Mycorrhizal Fungi,简称AMF）的效应,以及该效应对后作水稻生长的影响,在冬种一季黑麦草大田试验地采集土壤,分析种草土和冬闲土土壤理化性状及土壤中AMF的孢子密度,采用湿筛法倾析AMF孢子.对种草土和冬闲土土壤分别进行灭菌、不灭菌和灭菌并回接AMF共六组处理,然后在室内盆栽水稻.结果表明：冬种一季黑麦草对土壤理化性质的影响未达到显著水平（p〉0.05）,但极显著地增加了土壤中的AMF孢子密度（p〈0.01）.冬种黑麦草能够增加后作早稻的株高、叶片数、分蘖数等生长指标,但对早稻的地上部生物量和产量影响不显著（p〉0.05）.灭菌处理显著的提高了早稻的千粒重和产量.无论是种草土和冬闲土,回接AMF都能在一定程度上增加早稻的产量和千粒重.这些结果初步表明土壤微生物群落可能是影响水稻产量的一个重要因素, AMF对水稻生长具有一定的积极作用.冬种黑麦草能在一定程度上提高土壤AMF密度,改良土壤微生物群落结构,进而促进早稻的生长.

冬种意大利黑麦草对蔬菜地土壤理化性质的影响

连作障碍是蔬菜生产可持续发展的瓶颈问题。本研究尝试在蔬菜种植冬季导入一季意大利黑麦草(Lolium multiflorum L.),通过"黑麦草-蔬菜"轮作,探讨冬种黑麦草对蔬菜地土壤理化性质的影响。结果表明,冬种黑麦草能够提高土壤含水量(P<0. 05)、土壤速效磷(P<0. 05)、土壤有机质含量,降低土壤电导率(P<0. 05)、土壤速效钾含量(P<0. 05);并缓解土壤速效氮的流失。试验结束时,种草(冬种意大利黑麦草)区、菜心(菜心连作)区和对照(冬闲)区土壤含水量分别较本底值升高231. 62%、67. 78%和140. 80%;土壤电导率则分别下降86. 36%、66. 67%和71. 43%,种草区和菜心区土壤速效磷含量分别升高11. 28%和3. 88%,而对照区降低1. 22%;土壤有效氮含量分别下降19. 43%、21. 26%和44. 01%;土壤速效钾分别降低71. 5%、2. 73%和48. 37%;种草区和对照区土壤有机质含量升高8. 63%和11. 28%,而菜心区则降低4. 6%。构建"黑麦草-蔬菜"轮作系统是可行的。