上海市园林绿地共生固氮植物资源调查

对上海市固氮植物的结瘤状况和固氮效果进行调查分析,采集根瘤寄主分属5科37属,共83种,其中非豆科植物有4科4属12种,豆科植物33属71种。结果表明,有93%的根瘤着生于寄主侧根,大小一般在1～10mm。形状以球形、近球形、柱形为主,颜色多为白色、黄褐色。固氮酶活性为0～10μmol/(g.h)。     

Mycorrhiza and soil fertility effects with growth,nodulation and nitrogen fixation of leucaena grown on a typic eutrustox

Abstract

The rapidly growing, woody perennial legume, Leucaena (Leucaena leucocephala (Lam.) de Wit), is adaptable to a wide range of neotropical soil conditions. Effective Rhizobium inoculation and endophyte mycorrhizal colonization are essential for high levels of production and symbiotic N₂ fixation. The objective of this study was to determine growth, nodulation, nitrogenase activity and nodule composition of inoculated Leucaena as affected by mycorrhizal colonization and factorial soil fertility treatments of a Typic Eutrustox. Highly significant increases in top growth, nodule fresh wt. and nitrogenase activity resulted with Glomus fasciculatum colonization, soil K and linear increases with low‐soluble P fertilization to 300 mg P kg^‐1 soil. Highly significant interactions for increased nodulation and nitrogenase activity resulted with K × mycorrhiza. Interactions of all three factors P, K and mycorrhiza were highly significant for nodule fresh wt. However, responses comparing inoculation with G. fasciculatum and with combined G. fasciculatum, G. microcarpus and G. clavium were not significant. Highly significant increases with applied K levels to 300 mg K kg^‐1 soil resulted with top and root growth, nodulation and nitrogenase when applied with soluble P at 100 mg kg^‐1 soil and 500 mg Ca kg^‐1 soil. Significant and highly significant interactions of P, Ca and K level resulted for all parameters. Plant nutrient element composition of nodules increased with the fertilization treatments for P, Ca and increased K levels. A highly significant inverse relation was apparent with decreased Na resulting with increased K levels. Half or more of total nodule K, P and Mg but less than 20% of Ca and Na were within the nodule cytosol. Sodium, Mg, P, and Ca decreased in the cytosol fraction with increased K content.     

Fiber‐optic spectrophotometry of cowpea nodules treated with nitrate or ammonium

Abstract

Cowpea nodules (Vigna unguiculata [L.] Walp. cv. CB5) were pierced with two opposing optical fibers (280 μm diameter), and absorbance spectra of 0.1 mm of nodule tissue were recorded from 415 to 600 nm using a modified spectrophotometer with a nodule sampling stage.

The nodule spectra exhibited two absorbance bands, a major band in the near‐UV (415–450 nm) and a lesser one in the green‐yellow region (510–585 nm); the latter exhibited a prominent peak at 550 nm. Nodule spectra were consistent with the superposition of the spectra of ferroleghemoglobin (Lb²⁺), oxyleghemoglobin (Lb²⁺‐ O₂), and cytochrome c (550 nm). The detection of leghemoglobin in vivo was confirmed by demonstrating the reversibility of binding of CO to Lb, and by comparing the spectra of live nodules with those obtained from anaerobic leghemoglobin preparations.

The effects on the nodule spectra of two successive applications (36 and 39 days after planting) of 5 and 10 mM NO₃ ^‐ or NH₄ ⁺ to the nutrient solution bathing the nodulated roots were determined. The spectra of NO₃ ^‐‐ and NH₄ ⁺‐treated nodules were indistinguishable; in each case the height of both the near‐UV and green‐yellow absorbance bands decreased with treatment. Treatment with N caused a significant reduction in the area of the green‐yellow absorbance band.

The spectra of green leghemoglobin pigments were obtained from senescent nodules; these exhibited a reduction in the height of the near‐UV absorbance band and a flattening of the green‐yellow band similar to that of nodules treated with N, but the broadening of the near‐UV band was greater in green nodules.     

黄土高原丘陵区柠条根系生长发育特性研究

以陇西黄土高原丘陵沟壑区1～3a柠条荒山直播苗为研究对象,应用挖掘法对其根系的形态、生长发育、分布及根瘤特性进行了观测分析。结果表明,幼龄期柠条主根生长速度远大于株高生长,根冠比值在4～6之间;侧根主要发生在主根的5～15cm段;柠条胚根平均向上伸长5cm,合理的播种深度为3cm;根瘤主要集中在10—30cm土层中主根及一级侧根上;速生、发达的根系和根瘤,使得柠条具有超强的抗旱、耐瘠薄能力和蓄水保土、改良土壤的生态功能。柠条秋播较春播能更大程度地与当地的光、热、水等资源相拟合,应大力倡导秋季直播造林。     

Effect of soil physical properties on soybean nodulation and N2 fixation at the early growth stage in heavy soil field in Hachirougata Polder,Japan

We studied the effect of the soil physical properties on soybean nodulation and N₂ fixation in the heavy soil of an upland field (UF) and an upland field converted from a paddy field (UCPF) in the Hachirougata polder, Japan. Seeds of the soybean cultivar Ryuho were sown in each field with or without inoculation of Bradyrhizobium japonicum A1017. The soybean plants were sampled at 35 (V3) and 65 (Rl) d after sowing (DAS), and then nodulation and the percentage of N derived from N₂ fixation in the xylem sap were determined. The soil physical properties were different between UF and UCPF, especially the air permeability and soil water regime. Nodule growth was restricted in UCPF irrespective of rhizobial inoculation, though rhizobial infection was not inhibited by the unfavorable soil physical conditions. Soybean plant growth was closely related to the nodule mass and N₂ fixation activity, and the inoculation of a superior rhizobium strain was effective only at 35 DAS. These results indicate that soybean nodulation and N₂ fixation was considerably affected by the physical properties of heavy soil, and that it is important to maintain the N₂ fixation activity and inoculate the soybean plants with a superior rhizobium strain at a later growth stage in order to increase soybean production in heavy soil fields.     

Nitrogen fixation of Sesbania rostrata: Contribution of stem nodules to nitrogen acquisition

Abstract

Nitrogen contents, nodule numbers, and nodule dry weights of 6-week-oId Sesbania rostrata plants grown in sand culture with only root nodules, only stem nodules or with both were compared and the root nodules were found to contribute to nitrogen acquisition more significantly than the stem nodules. Similar findings were obtained in ¹⁵N₂-fixing experiments. An 8-week-old plant with both stem and root nodules fixed 1.50 mg nitrogen in a 12 h light period, while the fixation decreased to 1.15 mg nitrogen after the removal of the stem nodules, suggesting that root nodules played major role in nitrogen fixation. However, acetylene-reducing activities per nodule dry weight were higher in the stem nodules. Under flooding conditions, the aerenchyma tissues contributed to about 40% of N₂ transport to root nodules, and 60% was supplied through stem.     

Incorporation of 15N into various nitrogenous compounds in intact soybean nodules after exposure to 15N2 gas

The intact nodules attached to the upper part of soybean roots were exposed to ¹⁵N₂ and the incorporation of ¹⁵N into various soluble nitrogen constituents was investigated. Results indicated that ammonia, a primary product of N₂ fixation, was located in more than two compartments. Ammonia reduced from N₂ gas seemed to be incorporated firstly into glutamine especially amido-group nitrogen. Newly fixed nitrogen was secondly incorporated into glutamic acid and alanine in this sequence. These results suggested that fixed ammonia was assimilated by glutamine synthetase/glutamate synthase pathway. Turn-over rate of allantoin plus allantoic acid and serine was relatively high, although apparently these compounds were not primary products of newly fixed ammonia. ¹⁵N content of allantoin was always higher than that of allantoic acid. ¹⁵N incorporation to aspartic acid and asparagine was relatively slow, especially in early period. In bacteroid fraction there is much amount of ammonia comparing with other compounds, while allantoin and asparagine were presented exclusively in cytosol. ¹⁵N was incorporated into nitrate within a few minutes especially in bacteroids.     

Analysis of regulation site and manner of abundant nodulation in a soybean (Glycine max (L.) Merr.) cultivar,kitantusunte, using grafting techniques

To characterize the regulation site and manner of the abundant nodulation in the soybean (Glycine max (L.) Merr.) cv. Kitamusume, three grafting eperiments were carried out as follows: reciprocal wedge grafting and inter-cultivar approach grafting between Kitamusume and a normal nodulating cultivar, Toyosuzu, as well as wedge grafting of scions of the supernodulating mutant En6500 onto either Kitamusume or Toyosuzu rootstock. In the reciprocal wedge grafting, the number of nodules per shoot dry weight and average weight per nodule in the grafted plants were consistent with those exhibited by the genotype of their rootstocks. Approach grafting did not affect the number of nodules per shoot dry weight on either side of the inter-cultivar approachgrafted plant. Although grafting of the mutant scion resulted in the loss of the autoregulatory response from the roots of both cultivars, difference in the number of nodules per g shoot dry weight still remained between the two cultivars. These results suggested that the abundant nodulation in Kitamusume is controlled by the root in a non-systemic manner and is independent of the autoregulation mechanism.     

劣质地条件下肥料树与绿化牧草混植的效应

研究了劣质地肥料树与绿化牧草混植的效应,比较分析了单植与混植、混植密度、施磷肥对于绿化植物生育的影响。结果表明,混植双方的生育受压,肥料树则伴随着根瘤发育不良受压更加明显,这种状况通过采取少量施磷肥可以得到改善。     

苜蓿接种根瘤菌及丸衣化效果研究初报

种子丸衣化可以提高种子的发芽率以及提高豆科植物的共生固氮作用,对改良退化草地,促进农业可持续发展的起着重要意义。实验选用中苜一号、美国（ML323）、准葛尔和20号4种紫花苜蓿作为实验材料,比较了苜蓿接种根瘤菌的效果。结果表明：在接种“先科”菌剂的比较试验中,美国（ML323）在其接瘤率、瘤重,及产量等方面均有较好的效果。