化肥有机替代对连作花生产量和根瘤固氮的影响

为了探究蚓粪和生物有机肥部分替代化肥对连作花生产量和氮素吸收固定的影响,通过花生两年连作定位试验,设置蚓粪替代化肥处理（VM）、生物有机肥替代化肥处理（BF）、单施化肥处理（CF）3个施肥处理,另设不施肥处理（CK）作为对照,研究化肥有机替代对花生产量和氮素吸收利用的影响。结果表明,VM处理可以提高花生收获指数和植株干物质积累,VM、BF处理的花生产量较 CK 分别提高 63.18%、33.51%。CF 处理显著降低了根瘤数和根瘤鲜质量,降幅分别为 18.78%~50.82% 和 24.29%~34.74%,BF和VM处理较CF处理根瘤数、根瘤鲜质量分别提高53.20%和69.56%、63.90%和66.31%。BF和VM的根瘤固氮酶活性分别是CK的1.16倍和1.20倍,是CF的1.15倍和1.19倍。施肥处理的花生籽粒、叶、茎、根的氮素含量和氮素积累量均高于CK,其中,VM处理最高,BF处理次之。花生氮素分配比率表现为籽粒大于叶、茎、根。VM提高了根瘤固氮酶潜力和氮素向籽粒分配比率的同时降低了氮素向根的分配比率,而 CF结果相反。VM的氮肥农学效率分别是 BF和 CF处理的 1.85倍和 5.08倍。VM（5.02kg·kg^-1）和BF（4.11 kg·kg^-1）的氮肥偏生产力显著高于CF（3.43 kg·kg^-1）和CK（3.08 kg·kg^-1）,与CF和BF相比,VM表现出了更强的氮素吸收利用能力。综合来看,蚓粪替代化肥后增强了花生光合同化产物转化为经济产品的能力,表现出较强的产量优势。单施化肥表现出明显的“氮阻遏”效应,而有机肥（特别是蚓粪）替代化肥后具有缓解“氮阻遏”的作用,主要归因于蚓粪替代化肥可通过提高花生根瘤固氮酶活性来保持根瘤的固氮潜力,并改变花生植株氮素分配,最终使花生植株氮素吸收利用能力增强。     

土著花生根瘤菌田间试验研究

于鄂东三地同时对花生(Arachis hypogaea Linn.)进行接种土著根瘤菌(Rhizobium)HG-5菌株的田间试验。结果表明,接种处理对花生饱果率、百果干重和单株根瘤数等性状均有明显的促进作用,最终表现为花生产量增加,与对照组相比,平均增产14.54%。HG-5菌株可作为当地生产上推广应用的优选菌株。     

低硼胁迫对根系调控及生理代谢的影响研究进展

硼作为植物的必需营养元素,对植物的许多生理过程起着重要的作用。根系是植物地下的营养器官,决定着地上部及整个植株的生长发育。本文对近年来国内外学者在植物根系方面硼素营养的一些研究成果进行综述,着重阐述了低硼胁迫下植物调控根系生长和养分吸收的机制,以及硼对根系细胞壁结构的形成及稳定、豆科植物根瘤的生长发育及根瘤菌的固氮能力等方面的重要作用,最后提出了应加强硼元素在植物根系方面研究的问题与展望。     

不同含油量大豆的结瘤特性与农艺性状比较分析

为明确大豆脂肪含量与根瘤的关系,以不同含油量大豆品种（延11、长农16、长农21、吉育202）为试验材料,研究不同含油量大豆品种在不同生育期的结瘤特性、植株高度、根部长度、根瘤新鲜重、根部干燥重、结荚数以及粒数等农艺性状。结果表明：在各生育期高油大豆和超高油大豆的根部比较发达,根瘤数、根瘤鲜重及根部干燥重都比对照增加。超高油大豆和高油大豆的产量比对照无明显增产。     

大豆育成品种与双亲根部性状间的关系

1983—1986采用盆栽的方法对九个不同类型的品种和品系及七个组合的大豆材料进行了根量、瘤量、瘤数、固氮酶活性的分析研究,所测的资料表明,不同类型的大豆品种在不同的生育期中其根部性状表现有较大的变异。育成品种和双亲在所测定的根部性状方面是遵循数量性状的遗传动态而表现的。在今后的大豆育种工作中,不但要注意对材料的地上部分性状的选择,而且可以按数量性状的遗传特点来对双亲的根部性状进行选配及杂种的选择。从而更有利于创造出综合性状良好的材料。     

豇豆根瘤亚细胞组分中ASAL的分段盐析

68．5％的腺苷酸琥珀酸裂解酶(ASAL)活性和62．2％的5-氨基-4-咪唑-N-腺苷酸羧基酰胺核糖核苷酸(SAICAR)裂解酶活性分布在豇豆根瘤亚细胞的可溶性组分中。亚细胞可溶性和颗粒组分的ASAL和SAICAR裂解酶活性回收率均在50％-55％(NH4)2SO4饱和度分段盐析沉淀中出现1个峰值。但在颗粒组分提取液的60％-65％(NH4)2SO4饱和度分段盐析沉淀中,分别另有一个小的ASAL和SAICAR裂解酶活性回收率峰值出现。讨论了ASAL是1个双功能酶及其同工酶存在的可能性。     

Biodiversity of endophytic bacteria which colonize red clover nodules, roots, stems and foliage and their influence on host growth

The aim of this study was to identifiy the endophytic bacteria recovered from the foliage, tap roots and nodules of red clover plants (Trifolium pratense L.); and to assess the effects of the nodule bacteria, alone and in combination with Rhizobium spp., on the growth and development of red clover seedlings. Thirty-one bacteria species from 14 different genera were recovered from within the foliage, roots and nodules of red clover plants cv. AC Charlie. Genera diversity and species number were greatest in foliage tissues. Pantoea agglomerans (59.6%) was the most frequent species recovered in foliage tissues, Agrobacterium rhizogenes A in the tap root (49.2%) and Rhizobium leguminosarum BV phaseoli and R. loti B in the nodules (27.2% each). Recovery of Rhizobium species was not restricted to the nodules, and species of this genus were systemic throughout the plant. Clover root nodules were host to 12 bacteria species other than rhizobia, of which 8 were specific to this tissue. Using non-selective media, R. leguminosarum BV trifolii constituted only 8.8% of all the root nodule bacteria recovered. In root bacterization experiments, species of nodule bacteria promoted growth of red clover more often when applied in combination with R. leguminosarum BV trifolii than when applied singly. However, Bacillus megaterium, Bordetella avium and Curtobacterium luteum consistently promoted growth either individually or in combination with R. leguminosarum BV trifolii. Nodulation was promoted when R. leguminosarum BV trifolii was coinoculated with Bacillus insolitus, B. brevis or A. rhizogenes A. Single isolate applications of Rhizobium species to roots always led to the depression of clover growth, but mixtures of R. leguminosarum BV trifolii and R. leguminosarum BV phaseoli resulted in growth promotion. The latter is considered further evidence of the beneficial allelopathic side effect of strain competition for the same ecological niche. Received: 27 June 1996     

Variation in Nitrate Tolerance of Nitrogen Fixation in the Pea/Rhizobium Symbiosis

The short-term effects of nitrate on symbiotic nitrogen fixation were studied in six cultivars of pea (Pisum sativum L.) using two strains of Rhizobium leguminosarum. Plants grown symbiotically for three weeks, in order to eliminate the effect of NO₃ on nodule formation, were exposed to nil, 5 or 15 mM NO₃ for a period of seven days. Nodule mass, nitrogenase activity by acetylene reduction and the NO₂ and NO₃ concentrations in nodules were determined. Exposure to nitrate reduced the total acetylene reduction activity (ARA) in all cultivars, and a significant cultivar × nitrate treatment interaction was found. Nitrate influenced the components of N₂ fixation, nodule mass and specific ARA (ARA/mg nodule), differently within and among cultivars. Nodule mass was reduced in all cultivars, but a variation among cultivars in the degree of reduction was found. Nitrate also reduced the specific ARA to different extents in the cultivars- The specific ARA of nodules from NO₃-treated plants, expressed as per cent of the specific ARA of nodules from plants grown without NOT₃ was negatively correlated with the concentration of NO₃ in nodules. No relationship was found between the reduction of N₂ fixation and the nitrite concentration in nodules. The results indicate that it is possible to improve the nitrate tolerance of symbiotic N₂ fixation of the established pea/Rhizobium symbiosis by selection of suitable host plants.     

白花草木樨半同胞家系的生物固氮性状评价

以不同的白花草木樨(Melilotus albus)半同胞家系为试验材料,分别种植于甘肃临泽和榆中,测定其根干重、根瘤数、根瘤重、叶全氮、叶全磷和生物固氮百分率,以此评价其生物固氮能力。结果表明,白花草木樨在两个地区表现出的各项固氮指标变异系数均大于15%,主成分分析后,可将半同胞家系划分为4组,组1白花草木樨家系的根干重、根瘤数、根瘤重、叶全氮、叶全磷和生物固氮百分率分别高出对照当地白花草木樨品种(RX-02)4%、26%、10%、17%、24%、11%,其中生物固氮百分率的最大值和最小值分别为58%和43%。本研究筛选出的优良生物固氮性状的后代家系,可为进一步选育生物固氮能力强的新品种奠定基础。