Suppressiveness of steam-exploded biomass of Miscanthus sinensis var. giganteus against soil-borne plant pathogens

Commercial compost is a renewable resource widely used in horticulture as an organic amendment, though its suppression against soil-borne plant pathogens remains limited. Preliminary studies conducted on the disease suppression effect of the biomass waste obtained in a steam explosion plant demonstrated positive results. Steam-Exploded Biomass (SEB) of Miscanthus sinensis var. giganteus, a herbaceous perennial energy crop, is a multifunctional renewable energy resource, which could also be useful in crop protection to find valid alternative to the compost use in horticulture. The purpose of this work was to assess the suppressiveness of SEB against five plant pathogenic fungi that are important in many Italian horticultural cropping systems. Analyses of the microbial inhibitors (furfurals, organic acids and lignosulfonates) present in the SEB were performed by the High Performance Liquid Chromatography technique. Assessment of toxic effect of the furfurals present in the SEB (furfuraldehyde and 5-hydroxymethylfurfural), added to a growing medium at the different concentration ranges, was carried out in vitro on Phytophthora nicotianae, Pythium ultimum, Fusarium oxysporum f. sp. lactucae, F. oxysporum f. sp. melonis and Rhizoctonia solani. The suppressiveness of SEB, added to a potting soil used in horticulture at the different doses, was tested in vivo on tomato/P. nicotianae, cucumber/P. ultimum, lettuce/F. oxysporum f. sp. lactucae, melon/F. oxysporum f. sp. melonis and bean/R. solani. The results showed that furfuraldehyde, 5-hydroxymethylfurfural, lignosulfonates, acetic and formic acid were detected at a concentration of 2.93, 0.28, 4.12, 10.07 and 1.88 g/kg SEB, respectively. The P. nicotianae, P. ultimum and R. solani fungi were highly inhibited by the addition of 3.2 g/L furfuraldehyde and 0.48 g/L 5-hydroxymethylfurfural. Moreover, the inhibitory effect was found not adequate against F. oxysporum at the same concentrations. The SEB increased significantly the suppressiveness level of the peat substrate on P. ultimum in cucumber and R. solani in bean in all the trials. For P. nicotianae in tomato, the SEB addition showed a significant suppression at the 20 and 30% doses, but the change was not significant at the 10% dose. In case of F. oxysporum f. sp. lactucae in lettuce and F. oxysporum f. sp. melonis in melon, the SEB addition showed no suppressive effect with respect to compost in all the trials. In conclusion, the SEB could be used against some soil-borne fungal diseases in place of compost in the potting soil, and its suppressiveness could be related to the concentration of the microbial inhibitors produced during the processing of fresh biomass in the steam explosion plant.     

喀斯特煤矸石山自然恢复植物群落研究

为了解喀斯特地区煤矸石山自然恢复植物群落组成情况,采用经典样方法对六盘水五个煤矿区煤矸石山自然恢复定居植物群落进行了调查,经野外记录、标本采集、拍照和分类鉴定。结果发现:六盘水煤矸石山自然恢复定居植物有26科46属50种,其中优势种为戟叶酸模(Rumex hastatus)、亮叶桦(Betula luminifera)、大叶醉鱼草(Buddleja davidii)、五节芒(Miscanthus floridulus)和斑茅(Saccharum arundinaceum);优势群落是戟叶酸模群落(Rumex hastatus Com.),亮叶桦+戟叶酸模群落(Betula luminifera+Rumex hastatus Com.)和五节芒群落+斑茅(Miscanthus floridulus+Saccharum arundinaceum Com.)。研究表明以上三类自然恢复定居的植物群落能较好地适应喀斯特煤矸石山恶劣生境。     

水库集雨区沟渠湿地耐寒植物五节芒耐淹性研究

选取浙江省长潭水库集雨区上游农田沟渠湿地中生长的耐寒牧草五节芒(Miscanthus floridulus),通过盆栽模拟试验,测定其在涝渍逆境下叶片的光合色素含量、气孔导度、胞间CO2浓度、蒸腾速率和净光合速率,并与生长于堤岸上的五节芒进行比较.结果表明:涝渍逆境虽然造成沟渠湿地生长的五节芒叶片光合色素含量减少、蒸腾速率和净光合速率降低,但与在堤岸中生长的五节芒相比,下降幅度较小.说明生长于沟渠湿地上的五节芒具有较强的涝渍逆境适应性.因此,在浙南山区水库集雨区农田沟渠湿地耐寒植物五节芒能强化沟渠湿地生态效应,降低水库水体富营养化的风险.     

芒草化学成分分析研究

以芒草(芒、五节芒、荻、南荻、奇岗以及芒荻杂种)为研究对象,研究其纤维素、半纤维素、木质素的含量及其在种间(或类型间)的差异。结果表明,半纤维素和木质素含量在不同种间(或类型间)差异分别达到了显著和极显著水平,纤维素含量在不同种间(或类型间)差异不显著。纤维素含量、半纤维素含量的种内变异贡献率大于种间变异贡献率,说明利用种内遗传变异,能够对纤维素含量及半纤维素含量进行遗传改良。     

4种芒属植物的核型分析及亲缘关系探讨

以芒、五节芒、荻和南荻4种芒属植物共36份种质为材料,分别采用流式细胞仪和压片法对倍性及核型进行分析。结果表明:4种芒属植物中,南荻的荧光值最大,其次为芒,荻的荧光值最小,但不同种间无显著性差异;南荻的荧光值变异系数最大(37.73%),五节芒的荧光值变异系数最小(4.41%),说明南荻的倍性最丰富,而五节芒的倍性最稳定;芒属植物染色体基数为19(x=19),36份种质中有33份材料属二倍体(2n=2x=38)型、2份材料属三倍体(2n=3x=57)型、1份材料属四倍体(2n=4x=64)型,表明自然界中芒属植物主要以二倍体存在,偶见三倍体和四倍体;不同种之间的核型参数有差异,但都是由中部和近中部着丝粒染色体组成,且芒和五节芒的核型都为"2B"型,而荻和南荻大部分为"2C"型,说明芒和五节芒亲缘关系近,而荻和南荻亲缘关系近。对核型参数进行聚类分析,可将36份芒属植物材料分为3类:第Ⅰ类为芒类群,主要为芒和五节芒;第Ⅱ类为荻类群,主要包括荻和南荻;第Ⅲ类则为多倍体类群。     

五节芒（Miscanthus floridulus）不同种群对镉积累与转运的差异研究

采用盆栽试验的方法,对比研究了来源于大宝山矿区和惠州博罗非矿区的两个五节芒种群在不同Cd含量土壤中的生长反应、Cd富集能力及对土壤Cd形态的影响。结果表明,来源不同的两个五节芒（Miscanthus floridulus）种群植株对土壤中不同浓度的Cd的生长反应不同,低浓度Cd处理,非矿区种群的地上部生物量即受到显著影响,而矿区种群受到的影响不显著。Cd处理浓度提高时,非矿区种群的地上部生物量为对照的30.17%～42.07%,矿区种群地上部生物量为对照的57.80%～67.04%。非矿区种群根部生物量随处理浓度的增加而降低,为对照的57.75%-64.08%,而矿区种群显著升高,为对照的117.43%～135.56%。五节芒矿区种群地上部和根部的Cd含量随着土壤Cd处理浓度的升高而迅速升高,其升高速度明显快于非矿区种群。五节芒矿区种群根部积累的Cd总量远大于非矿区种群,且随着土壤中Cd添加量的增加而显著增加（P〈0.05）。随着Cd胁迫程度的加重,五节芒两种群转移系数和耐性指数都有不同程度的下降,矿区种群的转移系数和耐性指数明显高于非矿区种群。Pearson相关性分析发现,五节芒根部生物量与地上部生物量极显著正相关,地上部生物量与根部和地上部Cd含量均呈极显著负相关关系,地上部Cd含量与根部Cd含量及转移系数（Translocation Factor,TF）均呈极显著正相关关系,耐性指数（Tolerant Index,TI）与根部和地上部Cd含量均呈极显著负相关关系,反映了根部和地上部Cd的累积对植物产生了毒性,并对五节芒的生长产生了抑制作用。矿区种群表现出对Cd更强的耐性以及富集作用。     

New localities and awn morphology variation in Miscanthus ×ogiformis

Miscanthus ×ogiformis is a hybrid between Miscanthus sacchariflorus and Miscanthus sinensis and its several synonyms indicate the insufficient understanding of the morphological variation of its awn on the spikelet, which is a key characteristic for identifying Miscanthus species. In the present study, all the Miscanthus specimens in 19 herbaria were examined in order to find new localities for Miscanthus ×ogiformis. Thirty‐nine Miscanthus ×ogiformis specimens appeared to be naturally occurring hybrids, as their callus hair length, awn length, and callus‐to‐spikelet ratio differed from those found in the parental species. Therefore, new Miscanthus ×ogiformis individuals with morphological variations are likely to be discovered and these strains might be useful as new genetic resources for this biomass crop.     

五节芒茎秆微观构造及结晶度研究

 为更好地研究和利用五节芒Miscanthus floridulus茎秆,并为五节芒工业化利用奠定基础,研究了五节芒茎秆微观构造及茎秆去髓原料的纤维素相对结晶度。结果表明：五节芒茎秆皮部为茎秆最外层不含维管束的部分,木质部为皮部内圈维管束较多且紧密分布的部分,髓部为茎秆中部呈白色、含少量维管束的部分。茎秆表皮层由表皮膜、长细胞、短细胞和气孔器构成,长细胞长边边缘多呈锯齿形,且长、短细胞内含硅质。维管束由木质部、韧皮部、纤维细胞组成。原生木质部含环纹导管或螺纹导管。后生木质部的导管类型有网纹导管和孔纹导管。基本组织薄壁细胞主要特点是壁薄, 壁上有纹孔,且内含淀粉粒。五节芒去髓茎秆梢部纤维相对结晶度为43.21%,中部为42.08%,基部为44.49%,基本相似,没有表现出明显的规律性。图2 表1参15     

Effect of the Organic Residues of Miscanthus × giganteus on the Soil Organic Matter Level of Arable Soils

During a complex investigation programme on the evaluation of the long-term ecological impact of cropping Miscanthus , the substrate composition of residues in 4–8-year-old stands of Miscanthus × giganteus and the contribution of Miscanthus residues to soil organic matter (SOM) were investigated. Only about 50 % of the above-ground biomass produced yearly was suitable for harvest because of pre-harvest losses and harvesting residues. The potential supply to SOM was therefore 3.1 t ha⁻¹ carbon annually accumulated by the litter, and 9.1 t ha⁻¹ carbon accumulated by rhizomes and roots in the long term. These organic residues mineralized differently in laboratory experiments at generally high rates of decomposition. Analysis of soluble portions of the organic substance of these biomass components by hydrolysis with hot water, 2 % HCl and 80 % H₂SO₄ confirmed the results. Setting the SOM effect of an equivalent farmyard-manure (FYM) supply to 100 %, Miscanthus residues reached 60 % (stubble, rhizomes), 80–90 % (pre-harvest losses) and 100 % (roots). Established Miscanthus stands are able to produce about 8.2 t ha⁻¹ organic substance, which is comparable with FYM in terms of SOM impact. This kind of calculation showed higher values for Miscanthus than for the agricultural crops investigated to date. An SOM increase of about 0.5 % on sandy soils and 0.2 % on silt soil was determined after 6–8 years of cropping Miscanthus × giganteus .     

分株和遮荫对花叶芒生长的影响

 盆栽条件下研究了分株和遮荫对观赏植物花叶芒(Miscanthus sinensis‘Variegatus’) 生长的影响, 为种苗快速扩繁和应用配置提供技术依据。分株试验有4个处理, 初始分蘖数分别为2～3、5～6、10～12和20～23个/盆, 结果表明初始分蘖数对植株生长有明显影响, 分株生长6个月后, 植株的茎数、花序数、冠幅和地上生物量随初始分蘖数的增加而显著提高, 但对植株高度没有影响。初始分蘖数为20～23个/盆时, 繁殖系数最低, 仅为2.1, 而初始分蘖数为2～3个/盆时繁殖系数最高, 为6.7, 是前者的3.2倍。通过覆盖不同层数的黑色尼龙网形成了4个遮荫度, 分别为0, 25% , 50%和75%。遮荫度对花叶芒的生长有显著的影响, 25%~50%遮荫度下, 花叶芒的株高、茎数、花序数、地上和地下生物量以及叶绿素含量都显著高于全光照条件下的, 但遮荫度增加到75%时, 这些指标又明显降低, 由此得出25% ～50%的遮荫度适合花叶芒生长, 高于50%的遮荫度不利于其生长。