Molybdenum reserves of seed,and growth and N2 fixation by Phaseolus vulgaris L.

Summary Plants grown from seed with high (1.5–7.3 g Mo seed^-1) and low (0.07–1.4 g Mo seed^-1) Mo contents were grown in the presence and absence of Mo in growth media (perlite) or in a flowing-solution culture, in a controlled environment. Neither the high (1.5 g Mo seed^-1) nor the low (0.1 g Mo seed^-1) Mo content in seed from a small-seeded genotype (BAT 1297) was able to prevent Mo deficiency (reduced shoot, root and nodule dry weight, N₂ fixation and seed production) in growth media without an external supply of Mo, whereas both the high (7.3 g Mo seed^-1) and the low (0.07 g Mo seed^-1) contents in seed were able to prevent Mo deficiency in a large-seeded genotype (Canadian Wonder). Responses to Mo treatment by the Two genotypes were inconsistent between the growth media and solution culture experiments. Seed with a large Mo content (3.5 g Mo seed^-1) from the Canadian Wonder genotype was unable to prevent Mo deficiency (reduced shoot and nodule dry weight and N₂-fixation) in a solution culture without an external source of Mo, whereas both the large (1.7 g Mo seed^-1) and the small (0.13 g Mo seed^-1) contents in seed prevented a deficiency in BAT 1297. Growing plants from seed with a small Mo content, without additional Mo, reduced the seed Mo content by 83–85% and seed production by up to 38% in both genotypes. Changes in seed size and increases in shoot, root and nodule dry weight occurred, but varied with the genotype and growth conditions. These effects were also observed in some cases where plants were grown with additional Mo, demonstrating that the amount of Mo in the seed sown can influence plant nutrition irrespective of the external Mo supply. Nodule dry weight, total N content of shoots and seed production were improved by using seed with a small Mo content (1.64–3.57 g Mo seed^-1) on acid tropical soils in Northern Zambia. Plants of both the large- and small-seeded genotypes grown from seed with a small Mo content (<1.41 g Mo seed^-1) had a smaller nodule weight, accumulated less N and produced less seed. The viability of seed with a small Mo content was lower (germination up to 50% less) than that of seed with a large Mo content.     

The Influence of Day Length on Plant and Nodule Development of Fababeans (Vicia faba L.) and Grasspeas (Lathyrus sativus L.)

The valuation of the influence of different day length (DL) on plant and especially nodule development of fababeans ( Vicia faba L.) and grasspeas ( Lathyrus sativus L.) was the aim of these experiments. For that, experiments in growth chambers (Exp. 1) with DL of 10, 13, 16 and 19 hours and an experiment in vegetation boxes (Exp. 2) with DL of 7, 10, 13 hours and natural DL as control (CON) were conducted. The development of plants was studied by 6 and 7 harvests (HA) respectively beginning at 27 and 31 days after emergence (DAE) respectively, as well as consecutive determinations of leaf area, dry matter (DM) of the different plant organs and nodule number.
Total- and pod-DM of both species increased with higher DL (19 h, CON). Nodule-DM was positive influenced by longer assimilation duration and bigger leaf areas of the higher DL treatments. With onset of pod ripening, which occurred early under higher DL, lower nodule-DM was determined due to the beginning of nodule senescence. Under 19 h DL the fababeans established highest nodule-DM, 1,100 mg/plant, whereas the grasspea 410 mg only. Nodules under shorter DL (7 h, 10 h) showed less intensive red tissue and less nodules > 6 mm diameter. The grasspea established more bigger nodules than the fababeans. Total nodule number was not unequivocal affected by DL, however, it increased with the course of vegetation. Senescence of nodules was most evident at time of highest growth rates of the pod-DM.     

土壤中铁锰结核的研究进展

通过对国内外近几十年关于土壤铁锰结核研究的文献进行系统梳理,总结了土壤中铁锰结核的成因、物质组成、形态构造及其与环境变化的关系等方面研究成果。发育于土壤中的铁锰结核形成过程受到环境条件的严格限制,因此各种理化性质都是环境的产物,是反映环境变化信息的良好载体。然而,目前对土壤铁锰结核的研究尚存在如空间分异的规律及机理不清、年代学薄弱等不足。     

沙冬青植物群落特征及其根瘤多样性研究

沙冬青是西北荒漠地区珍稀常绿阔叶灌木.该文在其分布区内,综合土壤、水分条件,选定宁夏中卫县沙坡头、内蒙古阿拉善左旗、内蒙古磴口县、内蒙古乌拉特后旗4个地区作为调查样区,研究了沙冬青植物群落和沙冬青根瘤的特征.结果表明:沙冬青植物群落组成较为丰富;因水分、土壤类型及地形差异,不同样区内沙冬青群落成分、结构有一定变化,水分是沙冬青植物群落的决定性生态因子;沙冬青根瘤的最佳采集时间是在结果期之前,根瘤的外部形态呈现多样性,不同样区根瘤的着生部位有差异;水分是根瘤菌侵染沙冬青根系并形成根瘤的主要限制因子;沙冬青群落其他豆科植物的根瘤与沙冬青根瘤具有相似的外部形态.      

2,4-D诱导固氮螺菌在玉米根部结瘤及固氮效果的研究

采用 2 ,4 -D诱瘤法诱导固氮螺菌在玉米根部结人工根瘤并且固氮。最佳的 2 ,4 -D诱瘤浓度为0 9mg/kg。用乙炔还原法和15N2 示踪法均测到了固氮酶活性 ;并且在用乙炔测定固氮酶活性时发现了 4h延迟期的存在。用 2 ,4 -D加固氮螺菌处理的玉米比未加 2 ,4 -D只用固氮螺菌处理的玉米可以忍耐更高的氧压 ,这说明 2 ,4 -D诱发的人工根瘤的形成为固氮螺菌提供了一个屏氧场所     

寒地野生三叶草形态特征及抗寒性研究

通过对寒地野生三叶草开发利用,研究了野生三叶草的形态特征与抗寒性.结果表明:野生三叶草成坪速度快、抗寒性优于进口同类草,观赏期比进口同类草长10余天,野生红三叶能在寒冷地区越冬,填补了东北地区园林绿化无红三叶的空白.     

小豆根瘤菌接种结瘤条件分析

设计不同的小豆根瘤菌及菌液浓度、侵染时间和接种方式接种小豆推广品种京农5号和京农6号,研究其对小豆结瘤数的影响。根瘤菌BAU73042菌液浓度0.6 OD接种,单株平均结瘤数最多;BAU11017菌株菌液浓度0.2 OD接种,单株平均结瘤数最多。BAU73042侵染京农6号15 min单株结瘤数最多,BAU11017侵染京农5号45 min单株结瘤数最多。菌液浇灌接种方式优于菌液侵染接种;不同品种接种不同根瘤菌的结瘤反应不同。该研究为小豆固氮研究及利用和根瘤突变体筛选鉴定奠定了基础。     

黎塘岩溶区铁锰结核背景下的土壤研究

对黎塘岩溶区铁锰结核背景下的土壤进行了分析。结果表明：研究区土壤以硅质土为主,土壤发育呈幼年性。土壤多呈中性,对土壤肥力的发挥及旱地作物的生长较为有利;有机质含量A层多为中等（Ⅲ级）或丰富（Ⅳ级）,B层为缺乏（Ⅱ级）;全N含量A层多为中等（Ⅲ级）,B层多为缺乏（Ⅱ级）,有效N含量A层多为丰富（Ⅳ级）或甚丰富（V级）,B层多为中等（Ⅲ级）或缺乏（Ⅱ级）,A、B层养分含量的差异说明农耕区土壤受表层耕作、施肥影响较为显著。土壤有效P整体表现为缺乏或甚缺乏,可能已成为旱地作物生长的主要限制因子,阳离子交换量多表现为保肥力中等。     

青海胡卢巴植物根瘤形态结构与发育研究

[目的]对青海胡卢巴植株根瘤的形态结构与发育情况进行研究。[方法]选取西宁、大通、乐都等农田栽培的豆科植物胡卢巴植株10～15株,进行生态学特征描述;在西宁市连续采集胡卢巴根瘤,对根瘤的生长发育进行观察记录。[结果]从青海省大通、乐都和西宁各城区所采集的豆科植物胡卢巴植株根瘤在表型上表现出较大的差异。随着植株的生长,根瘤的数量、大小都有所增长。植株根瘤的显微切片表明,所有根瘤都由4个部分组成,不同时期根瘤的各部分细胞层数不同,中心组织占根瘤总面积的百分比及侵染细胞占中心组织总细胞数的百分比在不同生长时期也有差异。[结论]该研究可为青海省胡卢巴等栽培作物的根瘤及根瘤菌资源保护和开发利用提供理论与实践依据。     

Karyotype Analysis of Sesbania rostrata Brem.

The karyotype of Sesbania rostrata, a species endemic to West Africa, which produces nitrogen fixing, nodules on stem and branches, was analysed. The somatic chromosome number was 12 with two pairs of long, submetacentric and four pairs of short, metacentric chromosomes. The chromosome number in another species S. aculeata, which is well adapted as a green manure crop in India but not capable of stem nodulation, was also 2n = 12. The similarity between the chromosome complements of the two species indicates that they may be cross compatible.