Interception of water by pastures of Pennisetum clandestinum Hochst. ex Chiov. and Melinis minutiflora Beauv.

The conversion of montane cloud forests into pastures for grazing cattle is the main cause of important impacts on rivers and streams in most of the Andes. In order to evaluate the effects of vegetation changes we need to understand water fluxes, particularly canopy interception. We measured net precipitation responses by the canopies of Pennisetum clandestinum Hochst. ex Chiov. and Melinis minutiflora Beauv. under simulated rainfall. The samples were taken from grazed pastures during 1 year, digging out round mats of grass, placing them on wire-mesh devices after eliminating soil and underground biomass, and irrigating with different water amounts. The resulting data allow us to present a validated model for each species that predicts percentage of interception at different precipitation intensities taking into account previous canopy wetness within determined biomass ranges. We use these models to estimate 2 years of interception values for pastures of both species in the upper watershed of El Cañadón, Capaz River, Venezuelan Andes. Mean annual precipitation of El Cañadón is 1244 mm and the estimate of pasture interception was 36.5% and 31.8% for P. clandestinum and M. minutiflora, respectively. Interception models, such as the ones derived in this study, provide a basis for quantifying interception rates as a function of previous wetness of canopies and grass species.     

Utility of pearl millet landraces in breeding dual-purpose hybrids for arid zone environments of India

In pearl millet (Pennisetum glaucum (L.) R. Br.), single cross hybrids based largely on exotic germplasm, have found very limited adoption in drought-prone arid regions mainly due to their inadequate adaptation to prevalent extremely harsh agro-climatic conditions. This study tested the hypothesis that the use of restorer parents derived from adapted landrace germplasm could be an alternative strategy in developing suitable hybrids for arid regions. Forty inbred restorer lines developed from two phenotypically diverse landraces were used to develop hybrids evaluated in this study for their performance in five typical arid zone environments between 2003 and 2007. Inbred lines from both landrace populations differed significantly in their combining ability for biomass, harvest index and grain and stover yields. A larger proportion of experimental hybrids, based on selected inbred lines, significantly outperformed the commercial checks for grain and stover yields. Increase in grain and stover yields was achieved primarily due to their higher biomass productivity, with no decline in harvest index. Choice of landrace determined the relative grain and stover productivity of their hybrids. Phenotypic differences observed in parental landraces in tillering and panicle length were also visible in their respective hybrids, indicating that characteristics of landrace parental populations were transmitted in their hybrids.     

体细胞突变体筛选法获得象草耐盐植株

以象草幼穗离体培养诱导产生的胚性愈伤组织为外植体,在愈伤组织继代培养基中添加10～0 g/LNaCl,离体筛选得到的白色颗粒状愈伤组织在分化培养基上再生出植株.再生植株耐盐性鉴定结果:6 g/L海盐的1/2 Hoagland营养液每隔7 d浇灌1次,共浇灌4次,处理24 d时,对照植株全部致死;处理42 d时,24 g/L NaC1离体筛选获得的MN12-1和MN12-2体细胞再生植株生长良好.取MN12-1、MN12-2植株和对照株的节间嫩芽组培苗进行耐盐盆栽鉴定:4 g/L、6 g/L海盐的1/2 Hoagland营养液每隔7 d浇灌1次,共浇灌3次,生长28 d时,MN12-1 和MN12-2植株的叶、茎、根干重显著高于对照植株,MN12-2植株各部分的干重比对照植株提高100%以上,差异极显著.SRAP检测结果表明,MN12-1、MN12-2植株与对照植株在分子水平上存在差异,确认获得了耐盐体细胞突变体.     

象草窖藏与宿根技术

象草在江西气候条件下种植具多功能作用,但不能开花结实,因此做好象草栽培留种和保护宿根越冬是最重要的技术环节。     

盐胁迫下泛菌属内生细菌对杂交狼尾草发芽及生理的影响

内生细菌作为一种宝贵的天然微生物资源,在植物防病、杀虫、促生、耐盐及耐干旱能力等方面具有广阔的应用前景。本研究分析了泛菌属内生细菌(Pantoea sp.)PP04对不同盐浓度胁迫下杂交狼尾草(Pennisetum americanum×P.purpureum)种子萌发及幼苗生长的影响。结果表明,该内生细菌在低(100mmol·L~(-1))、中(200mmol·L~(-1))度盐浓度下,对杂交狼尾草种子的萌发率、发芽指数及胚芽长度都有明显增益作用,增幅分别达10.75%、28.57%和300%。进一步研究发现,在不同浓度的盐胁迫下,内生细菌PP04通过诱导杂交狼尾草不同的抗氧化保护酶活性,从而减少膜脂过氧化作用,降低丙二醛(MDA)的含量。在低、中浓度盐胁迫下,PP04能显著提高杂交狼尾草超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸酶(APX)的活性。其中SOD和POD活性在低盐胁迫下增幅最高,可达64.17%和73.14%;而CAT和APX酶活性在高盐(300 mmol·L~(-1))胁迫下增幅最大,可达160.57%和73.38%。说明该内生细菌菌株可通过缓解氧化胁迫对植物造成的损伤,显著提高植物对盐胁迫的耐受性,具有良好的开发应用前景。     

具有化感作用的植物能增强花生对黄曲霉毒素的抗性（英文）

研究三裂叶蟛蜞菊、香根草、香茅对黄曲霉的化感作用。结果表明,三种植物的水提液均能显著抑制黄曲霉的生长。在培养黄曲霉的培养基中加入上述三种植物的水提液后,培养基上黄曲霉的菌落数显著减少,平均菌落直径变小。利用这三种植物的水提液浸泡被黄曲霉感染的花生种子,其发芽率显著高于清水对照处理;显示这三种植物的水提液能够缓解黄曲霉素对花生种子发芽的抑制作用。在没有黄曲霉侵染的条件下,虽然这三种植物的水提液会降低正在发芽的花生种子某些水解酶和保护酶的活性;但在黄曲霉侵染后,这三种植物水提液浸泡过的花生种子水解酶和保护酶的活性却显著高于对照处理,导致处理种子具有更高的呼吸速率、种子活力和发芽率。在对照土壤里,受黄曲霉侵染的种子长出的花生植株长势很差。分别将三种化感植物剪碎、加入土壤中混匀,平衡一段时间;在这些土壤上种植受黄曲霉侵染的种子长出的花生发现能够有效降低黄曲霉素对花生生长的抑制作用。与对照相比,处理土壤上生长的受黄曲霉侵染的花生植株具有更高的根系活力、叶绿素含量、净光合速率、硝酸还原酶和谷氨酰胺合成酶活性,因而具有更高的株高、叶片氮素含量和干物量。     

刈割频率对皇竹草产量及其光合生理生态的影响

采用每30(T1)、60(T2)、90(T3)、120d(T4)刈割1次4个处理,分析刈割频率与产量的关系以及刈割频率对光合生理生态的影响。结果表明:皇竹草的刈割频率对产量有着至关重要的影响。在湛江地区,不同处理的皇竹草的产量高低为T3T2T1T4,不同处理的皇竹草的同化能力强弱为T3T2T1T4,T3处理的皇竹草产量最高,为最佳刈割频率。     

The Control of Cercospora Leafspot on Groundnuts in Malawi and its Effect on the Parameters of Yield

Abstract

Leafspot is one of the major factors which limits the yield of the groundnut crop in Malawi. The most effective and economical uses of fungicidal dusts and water-based sprays to control the disease, are described. Data are also presented to show how the use of such fungicides affects parameters of yield such as numbers, size, weight and quality of kernels, and weight and quality of haulms.     

Influence of sward botanical composition on performance of cool temperate grassland under contrasting nitrogen fertilization regimes

Kikuyugrass (Pennisetum clandestinum Hochst. ex Chiov.) is an active silicon (Si) accumulator, and Si can reduce the organic‐matter digestibility of forage grasses. Calcium carbonate (crushed coral) applications to a low Si Maile silt loam soil (Acrudoxic Hydrudands) had no effect on the in vitro digestible organic matter (IVDOM) concentration of 3‐week‐old (4.5‐leaf‐per‐tiller stage of development) ‘Whittet’ kikuyugrass regrowth, whereas calcium silicate (wollastonite) applied at the calcium equivalent of the calcium carbonate rates produced a curvilinear (crescent‐shaped quadratic) IVDOM response. Whittet IVDOM decreased when grass Si concentration exceeded about 22 g kg^?1 or when 0.5 M acetic acid–extractable soil Si exceeded about 230 mg kg^?1. Common and ‘Hosaka’ kikuyugrass regrowth on the Maile soil had less Si and greater IVDOM concentrations than those observed for high‐Si Kohala (Humic Dystrustepts) and Waialua (Pachic Haplustolls) silty clay soils. Whittet had greater crude protein and IVDOM concentrations and lesser fiber concentrations than common.     

‘热研4号’王草和五节芒光合特性的比较

【目的】获得生产生物能源的优质原料.【方法】在田间采用LI-6400便携式光合作用测定仪对‘热研4号’王草Pennisetum purpureum×P.americanum cv.Reyan No.4和五节芒Miscanthus floridulus的光合特性日变化进行研究,并分析了其净光合速率(Pn)与主要影响因子的相关性.【结果和结论】‘热研4号’王草和五节芒的净光合速率日变化均呈"单峰型",无光合"午休"现象,且‘热研4号’王草日均Pn(25.45μmol·m-2·s-1)略高于五节芒(25.08μmol·m-2·s-1).2种草的蒸腾速率(Tr)、水分利用效率(WUE)、光能利用率(LUE)和气孔导度(Gs)与Pn一样,最大值均出现在13:00时左右,且‘热研4号’王草的Tr、LUE和Gs也都略高于五节芒,只有WUE略低于五节芒.气孔限制值(Ls)日变化呈正钟型,在11:00时左右达最高值(均为0.86μmol·m-2·s-1),早晚最低,而胞间CO2摩尔分数(xi)日变化趋势与之相反.此外,‘热研4号’王草和五节芒的Pn均与大气CO2摩尔分数(xa)呈显著负相关(P0.05),且分别与空气相对湿度(RH)和Gs呈显著正相关(P0.05).以上结果说明‘热研4号’王草的光合能力比五节芒强.