中国豆科1个新记录种——沼生田菁

本文报道了海南岛发现的豆科(Fabaceae)田菁属(Sesbania Scop.)新记录种1个,沼生田菁(Sesbania javanica Miq.).在海南东方和昌江临海沼泽湿地中分别发现沼生田菁3个种群,凭证标本保存于中国热带农业科学院植物标本室(ATCH),现予以报道.     

Droë massaproduksie van vyf eenjarige Medicago‐genotipes in die sentrale oranje‐vrystaat,soos beinvloed deur planttyd

Uittreksel

Bogrondse droë massa‐opbrengste (DM) van Medicago truncatula, cvv. Cyprus en Jemalong, M. aculeata var. inermis, cv. SA 4438, M. orbicularis, cv. SA 2552 en M. rugosa, cv. Paragosa wat op ses verskillende datums gevestig is, is in ‘n veldproef onder besproeiing bepaal. Die plantdatums was c. 15 dae gespasieer, vanaf middel Februarie tot einde April, DM is op drie stadiums bepaal naamlik drie weke na opkoms, begin blomstadium en met die aanvang van peulverkleuring toe finale DM ongeveer bereik is. Uiteindelik is peul‐ en saadopbrengs ook bepaal.

Die DM op drie weke het in alle gevalle sterk afgeneem namate later geplant is en die temperature gedaal het, terwyl die opbrengs met blom en peulverkleuring grootliks bepaal is deur die tydsverloop vanaf plant tot die betrokke stadiums. Die gemiddelde finale DM oor die ses plantings was 11,5; 10,7; 8,4; 6,7 en 5,0 t/ha vir Jamalong, SA 4438, Cyprus, Paragosa en SA 2552 onderskeidelik. Die gemiddelde saadopbrengste het gewissel van 650 kg/ha by Paragosa tot 2460 kg by SA 2552.     

田菁种子发芽条件研究

通过温水及浓硫酸浸泡处理,以及采用不同的发芽床,观察田菁[Sesbania cannabina(Retzius)Poiret]种子的发芽势和发芽率的变化规律。结果表明:温水浸泡各处理间达到显著差异,其中30℃、12 h的发芽势和发芽率最高,分别达到56%和75%;浓硫酸浸泡各处理间差异不显著,其中处理15 min的发芽势和发芽率最高,分别达到73%和84%;不同发芽床间的差异不显著,其中纸床的发芽势和发芽率最高,分别达到64%和75%;本试验中,以浓硫酸处理种子效果最佳。     

Impact of simulated erosion on the abundance and activity of indigenous vesicular-arbuscular mycorrhizal endophytes in an Oxisol

Summary The influence of simulated erosion on the abundance and activity of indigenous vesiculararbuscular mycorrhizal (VAM) populations was evaluated in an Oxisol. Surface-soil losses in excess of 7.5 cm were generally associated with significant decreases in the numbers of total and active VAM propagules and in the symbiotic effectiveness of the active propagules. Surface-soil removal not exceeding 7.5 cm was associated with decreased propagule abundance without adverse effects on VAM colonization of roots and symbiotic effectiveness of the fungi. The extent of VAM colonization of roots and the degree of symbiotic effectiveness observed at this level of simulated erosion were significantly higher than those observed in the soil not subjected to simulated erosion. This stimulation is attributed to the removal of antagonistic biotic factors as the top 7.5 cm of soil was removed. It is concluded that propagules lost during erosional soil losses must be replaced before legumes grown on relatively highly weathered and severely eroded tropical soils could appreciably benefit from the VAM symbiosis.Hawaii Institute of Tropical Agriculture and Human Resources Journal Series No. 3234     

High differentiation among populations of the woody legume Sesbania sesban in sub-Saharan Africa: Implications for conservation and cultivation during germplasm introduction into agroforestry systems

Cultivation of the woody legume Sesbania sesban in agroforestry systems has been widely promoted for soil fertility improvement in Africa. Despite the existence of natural populations in eastern Zambia, considerable seed originating from Kenya has been introduced to the area, while further introductions from Malawi are planned. Large-scale anthropogenic seed dispersal raises concerns regarding genetic management, which were addressed here by random amplified polymorphic DNA (RAPD) analysis. Eleven populations of Sesbania from southern and East Africa were assessed, including S. sesban populations already or likely to be introduced into eastern Zambia and reference taxa. Seventeen primers revealed a very large number of polymorphisms (538) in surveyed material. Differentiation among S. sesban populations was unusually high for a woody perennial (70% of variation among populations), with all individuals stringently assigned to specific populations in cluster analysis, even for geographically proximate sites. High differentiation, combined with the unusually large number of polymorphisms determined, resulted in the identification of a number of population-diagnostic markers. High differentiation may reflect the restricted ecology of S. sesban, human disturbance and frequent natural fluctuations in niche availability. Hydrochory, posited as a mechanism for gene flow between populations located along the same drainage system, appears to be discounted. Geographic proximity was not always a good guide for genetic similarity among S. sesban populations. In particular, rather proximate populations from Zambia and Malawi appeared highly differentiated genetically, while Zambian populations were relatively similar to a geographically distant population from Namibia. Differentiation was consistent with the presence of two botanic varieties in the southern Africa region, vars. nubica and zambesiaca. Estimates of Nei's genetic diversity suggested that S. sesban populations from East Africa were most diverse. Overall, population diversity estimates were low, possibly due in part to frequent bottlenecks, short longevity and a short juvenile phase. The unusually large number of polymorphisms detected here provided an opportunity to test for data redundancy and primer selection methodologies during RAPD analysis. Combined data from a subset of eight primers selected according to three different approaches provided a very good overall fit to the complete data set (r_M > 0.95). Different primer selection approaches influenced the reliability of clustering and diversity analysis, with a minimum of eight primers required for reliable ranking of diversity estimates. The implications of our data for conservation, cultivation and monitoring of S. sesban in the southern Africa region are discussed. Caution is advised during the introduction of germplasm into eastern Zambia from both distant (Kenya) and relatively proximate (Malawi) sources.     

Differences in physiological responses to NaCl between salt-tolerant Sesbania rostrata Brem. & Oberm. and non-tolerant Phaseolus vulgaris L.

Sesbania rostrata ( S. rostrata) Brem. & Oberm., a member of the Fabaceae family, has been used as a promising halophytic plant to ameliorate soil salinity in north-east Thailand. To obtain information regarding the mechanism of salt tolerance, the physiological responses of S. rostrata to NaCl was compared with those of the salt-susceptible species, kidney bean ( Phaseolus vulgaris L. cv. Meal). Seedlings were grown hydroponically with 0, 50, 100 and 150 m m NaCl for 10 days and their effects on growth, chlorophyll content, fluorescence yield ( F _v/ F _m), inorganic elements and amino acid content were determined. The results showed that tolerance to NaCl was clearly different between the two plants. At the highest concentration (150 m m ), the dry weight of S. rostrata was more than 50% greater than the control, whereas the kidney bean could not survive. Chlorophyll a content drastically reduced only in the kidney bean. The F _v/ F _m of S. rostrata did not change with increasing concentrations of NaCl, but that of kidney bean decreased. Greater percentages (≥80%) of absorbed Na⁺ and Cl^– were translocated and accumulated in the shoots of S. rostrata , but remained largely in the roots of kidney bean. The enhancement of contents of amino acids, including proline, with increasing NaCl was observed in both species. These results strongly suggest that the salt tolerance of S. rostrata is associated with the ability of the plant to translocate and sequester Na⁺ and Cl^– in the shoot cells.     

田菁（Sesbania rostrata）cosmid基因组文库的建立和豆血红蛋白基因序列的克隆

利用mini-Ti质粒和λ噬菌体cos位点构建的植物cosmid载体,建立了茎瘤田菁cosmid基因组文库,并分子克隆了茎瘤田菁豆血红蛋白基因片段。改进了原有的方法,得到了植物大分子DNA片段和高效价的λ噬菌体体外包装物,为植物cosmid基因组文库的建立提供了关键的条件。菌落原位杂交筛选1.0×10#+5菌落,获得4个含有茎瘤田菁豆血红蛋白基因序列的阳性克隆。质粒DNA点杂交和Southern blot杂交进一步证明了田菁豆血红蛋白基因序列的克隆。     

适宜在安徽推广种植的田菁品种的筛选与评价

为了筛选适宜于安徽地区推广种植的绿肥种质资源,采用田间试验和盆栽试验,于2011—2013年对53个田菁品种进行评价,记载各品种的根、茎、叶、花、荚果及种子的形态特征、生长特性、产量和干物质积累效率,测定各品种在盛花期的叶片光合效率、根瘤量和氮、磷、钾养分含量。结果表明:早熟品种的全生育期约为3个月,迟熟品种的全生育期约为7个月;早熟品种光合效率和干物质积累效率较高,而迟熟品种的干物质积累总量较大;盐菁胶1号的叶片光合效率和干物质积累效率最高;泸早田菁根瘤最多,根瘤量可达地下部总重的24.1%,其种子产量也最高;三亚田菁产青量和干物量最大,其固氮和富集磷、钾的能力最强。从光合效率、产量、养分富集能力和生育期等方面综合考虑,初步认为盐菁胶1号、庆丰田菁、三亚田菁、泸早田菁等4个品种适宜在安徽种植推广。     

Establishment of Azorhizobium caulinodans in the rhizosphere of wetland rice (Oryza sativa L.)

 Azorhizobium caulinodans strongly colonized the rhizosphere of rice plants after incorporation of Sesbania rostrata in a field trial throughout the growing season and during the fallow period until 19 weeks after incorporation of S. rostrata. A. caulinodans became well established in the rhizosphere (7.17 log cfu g^–1 dry rice root) and colonized subsequent S. rostrata test plants. Three traditional and three improved high-yielding rice varieties were inoculated with A. caulinodans under gnotobiotic conditions. In none of the combinations did acetylene reduction activity significantly increase. Ethylene production on colonized rice roots only started after the growth medium had been supplemented with an extra C source (0.1 to 0.25% Na-lactate). This indicates that the bacterial nitrogenase activity is limited by energy supply. Four possible inoculant-carriers (peat, coir dust, bagasse, rice straw) were compared for long-term survival of the bacterial strain. Independent of the storage temperature (26  °C or 4  °C), the survival of A. caulinodans in peat and coir dust was very high during a 12-month period (>8 log cfu g^–1 dry carrier), whereas the bagasse and rice straw carriers showed a serious decline from 3 months onwards. Received: 6 April 1999