Temporal variation in mineral nitrogen in soil as influenced by incorporation of legume or cereal residues under submergence or well drained conditions

A laboratory study was conducted at the Indian Agricultural Research Institute, New Delhi on a sandy clay loam soil of pH 7.9 and organic C content of 0.34% to study the effect of incorporating Sesbania or Vigna legume residues or wheat straw at 15 and 30t ha^?1 on temporal variation in ammoniacal and nitrate‐N in soil under submergence and well drained conditions. Under submergence most mineral N was present as ammoniacal‐N, while under well drained conditions it was present as Nitrate‐N. The content of ammoniacal N in soil was the highest after 30 days of incubation and declined thereafter under submergence. On the other hand under well drained conditions the mineral‐N (mostly nitrate) content in soil at 30 DAI was very little and showed increases only later, reaching the highest level at 90 DAI. Application of wheat straw specially at 301 ha^?1 level resulted in immobilization of native soil‐N. These results show that rice which is grown under submergence can be transplanted soon after incorporation of legume residues, but for wheat or other crops which are grown under well drained condition a time interval of 30 days or more needs to be provided before sowing the crop.     

黄河三角洲地区田菁种植密度对其生长发育及籽粒产量的影响

[目的]为了研究不同品种和密度对田菁籽粒产量及其相关性状的影响。[方法]比较田菁在不同密度下植株的株高、茎粗、地上部鲜重、结荚数、结荚枝数、秕粒率等指标。[结果]各密度下同一品种田菁生长性状、结荚特征具有明显差异,籽粒产量虽变化不大,但以7.5万株/hm2密度下秕粒率最低,籽粒更饱满;不同田菁品种间籽粒产量差异较大。[结论]通过选育品种、合理调节田菁种植密度等措施,可获得品质更高的田菁籽粒,并实现高产,为黄三角地区田菁胶的工业化生产提供丰富的原料。     

The reproductive biology of three perennial Sesbania species (Leguminosae)

Summary The reproductive biology of Sesbania sesban, S. goetzei and S. keniensis (Leguminosae; Papilionoideae) was studied. Fifty percent flowering was observed at 102 to 153 days after germination for S. sesban accessions; 96 to 146 days for S. goetzei and 131 to 176 days for S. keniensis accessions. Flowers opened in the afternoon and remained fresh for 2–3 days. Bee species including Xylocopa sp., Apis mellifera, Megachile bituberculata and Chalicodoma sp. visited the flowers. Hand pollination experiments showed that all three species were self and cross compatible. The percentage of fully developed seeds was greater in pods formed after cross pollination compared to self pollination. No evidence was found for stigmatic or stylar self incompatibility. Outcrossing is probably the common method of reproduction under natural conditions, although in isolated trees substantial seed set by selfing might occur. Pod production under natural conditions was 34% for S. sesban; 49% for S. goetzei and 39% for S. keniensis. Considerable variation was found in pod production under open pollination between accessions of the same species. Selective abortion was observed within pods, with more mature seeds formed at the distal end of the pod.     

Light-stimulated 14CO2 uptake and acetylene reduction by bacteriochlorophyll containing stem nodule isolate BTAi 1

Summary Bradyrhizobial strain BTAi 1 nodulates both stems and roots of Aeschynomene spp. Previous work has shown that it contains bacteriochlorophyll a and forms photosynthetic reaction centers, and has provided indirect evidence of photosynthesis by bacteroids within stem nodules. Here we report physiological and biochemical characteristics of BTAi 1 ex planta, which also suggest the presence of photosynthetic activity. Light-stimulated uptake of ¹⁴CO₂ by BTAi 1 was detected at all stages of growth. Inhibitors of photosynthesis, 1,10-orthophenanthroline and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), and the uncoupler NH₄Cl, immediately suppressed light-driven ¹⁴CO₂ uptake and increased O₂ uptake. BTAi 1 is strictly aerobic and was unable to grow without organic C even in the light; also, it was unable to grow chemoautotrophically in an atmosphere enriched with H₂ and CO₂. In micro-aerobic conditions, strain BTAi 1 expressed acetylene reducing activity ex planta in an N-free medium. The highest rates of light-stimulated ¹⁴CO₂ uptake and acetylene-reducing activity occurred during the exponential and early stationary phases of growth. Acetylene-reducing rates at a low glucose concentration were increased following a light-dark cycle in comparison with continuous dark conditions.     

Amelioration of calcareous saline sodic soils through phytoremediation and chemical strategies

Abstract. The worldwide occurrence of saline sodic and sodic soils on more than half a billion hectares warrants attention for their efficient, inexpensive and environmentally acceptable management. These soils can be ameliorated by providing a source of calcium (Ca²⁺) to replace excess sodium (Na⁺) from the cation exchange sites. Although chemical amendments have long been used to ameliorate such soils, the chemical process has become costly during the last two decades in several developing countries. As a low‐cost and environmentally acceptable strategy, the cultivation of certain salt tolerant forage species on calcareous sodic and saline sodic soils, i.e. phytoremediation, has gained interest among scientists and farmers in recent years. In a field study conducted at three calcareous saline sodic sites (pH_s=8.1–8.8, EC_e=7.8–12.5 dS m^–1, SAR=30.6–76.1) in the Indus Plains of Pakistan, we compared chemical and phytoremediation methods. There were four treatments; two involved plants: Kallar grass (Leptochloa fusca (L.) Kunth), and sesbania (Sesbania bispinosa (Jacq.) W. Wight). The other two treatments were uncropped: soil application of gypsum and an untreated control. All treatments were irrigated with canal water (EC=0.22–0.28 dS m^–1). The plant species were grown for one season (5–6 months). Sesbania produced more forage yield (34 t ha^–1) than Kallar grass (23 t ha^–1). Phytoremediation and chemical treatments resulted in similar decreases in soil salinity and sodicity, indicating that phytoremediation may replace or supplement the more costly chemical approach. The soil amelioration potential of sesbania was similar to that of the Kallar grass, which suggests that moderately saline sodic calcareous soils can be improved by growing a forage legume with market value.     

Influence of green manuring with Sesbania rostrata and Aeschynomene afraspera or urea on dynamics and uptake of nutrients by wetland rice

Nutrient concentrations in the soil and crop uptake from incorporated green manure and urea in flooded rice was studied in field experiments. Release of plant-available nitrogen (NH₄ ⁺-N) from green manure was slightly delayed compared with that from prilled urea (PU) because Sesbania rostrata L. and Aeschynomene afraspera L. released the N gradually after their decomposition, whereas N became available immediately after PU application. Exchangeable NH₄ ⁺-N concentration in soil peaked at 163 mg kg^–1 in the transplanted rice (TPR) and 198 mg kg^—1 in broadcast-seeded rice (BSR) at 0 and 1 week after PU application. Broadcast-seeded rice depleted NH₄ ⁺-N faster than did TPR because of the crop‘s vigorous growth in the former during the early stage. Soil solution NH₄ ⁺-N followed a similar trend to that of soil NH₄ ⁺-N. Incorporation of S. rostrata and A. afraspera increased the concentration of P, K⁺, Fe²⁺ and Mn²⁺ in soil solution more than did the application of PU. However, zinc concentration decreased in all treatments. Both PU and green manure increased the N status of the rice plants and enhanced the uptake of P, K, Fe, Mn and Zn by the rice crop. This suggests that application of green manures improves the uptake of these nutrients by the crop. The highest apparent N recovery was obtained with PU followed by green manure. Received: 11 November 1996     

黑龙江省地产田菁的化学成分及其纤维形态的分析研究

本实验研究是对黑龙江省近年来引种的田菁植物原料进行化学成分的分析和纤维形态的观测。结果表明,我省产田菁主要成分的含量与山东省产田菁相差不大,含木素为14.06％,多聚戊糖14.45％、综纤维素73.61％。与芦苇等相比,木素和多聚戊糖的含量较低,而纤维素含量则相近。纤维平均长度为0.942mm,优于稻草、山杨等,与芦苇、白皮桦等相近。而且田菁秆部细胞壁较薄,壁腔比较小,作为造纸原料与同等纤维长度的其它原料相比会有较好的结合力。因此,黑龙江省产田菁作为造纸原料是适宜的,该省引种田菁必将取得较好的社会效益和经济效益。     

田菁及其与硫铵混合施用时水稻对肥料氮和土壤氮的利用

应用标记15_M的田菁和硫铵进行一季水稻盆栽试验的结果表明,1.田菁和硫铵单独施用,田菁氨素的17.6％和41.8％分别为稻秆和谷粒利用,硫铵氨素的分别为15.1％和29.0％。这两种肥料氮在谷粒中分布的比例较大,稻杆和谷粒对田菁氨的利用率都高于硫铵氮.2.施用硫铵有促进水稻吸收土壤氨素的作用,比不施氨对照增加71.8％;相反,施用田菁减弱了水稻对土壤氨的吸收,比对照减少37.1％。3.田菁和硫铵混合施用,除了可使水稻对田菁氨的吸收增加(5.2％)。对硫铵氨的吸收减少(5.3％)外,亦有促进水稻增加吸收土壤氨素的作用,4.与硫铵单独施用的结果相比,这两种肥料混合施用,可以在消耗较少量土壤氨素的基础上,更好地维持水稻生长所需的氨营养供应。     

Effect of crop‐residue management on the production and agronomic nitrogen efficiency in a rice–wheat cropping system

The rice–wheat cropping system (RWCS), producing about 5–10 Mg ha^–1 y^–1 of grain, is the backbone of food‐crop production in South‐East Asia. However, this system shows signs of fatigue as indicated by declining yields, negative nitrogen (N) balances, and reduced responses to applied fertilizer at some research centers. The return of rice and wheat residues can recycle up to 20%–30% of the N absorbed by the crops. However, their wide C : N ratio can temporarily immobilize native and applied N. To overcome this immobilization, wheat‐straw application was supplemented with the incorporation of Sesbania green manure and mungbean residues, and their effects on productivity, agronomic N efficiency, and system's apparent N balances were studied. Combining the application of wheat straw with Sesbania green manure or mungbean residues increased cereal grain yield and agronomic N efficiency and improved the generally negative apparent N balances. The combined use of wheat straw and mungbean produced an additional 0.5–0.6 t ha^–1 protein‐rich grain and thus appears to be the most promising residue‐management option for rice–wheat cropping systems in South Asia, provided that the transition cropping season between wheat harvest and rice transplanting is long enough.     

普通田菁根瘤菌及其类菌体的碳源研究

普通田菁(Sesbania cannabina)根瘤菌属快生型,24小时形成菌落,杆状,大小为0.28～0.47μm×1.3～2.5 μm,运动,具两根侧生鞭毛,类菌体形态与其培养基上形态相似。能广泛利用碳源。产能基质试验结果表明,类菌体不能利用蔗糖,丙酮酸是最有效的能源,其次是葡萄糖、α-酮戊二酸、延胡索酸、琥珀酸、草酰乙酸、乳酸和苹果酸,果糖利用较差。类菌体的固氮酶活性从 10 m mol·L~(-1)始随基质浓度递增而增加,琥珀酸和丙酮酸分别在 200和300mmol·L~(-1)时达最高活性,而葡萄糖达 500 mmol·L~(-1)时乙炔还原活性还在上升,未出现抑制现象。葡萄糖为产能基质要求低氧浓度,当氧浓度为反应瓶气体体积的2％时,类菌体乙炔还原活性最高,6％时活性很低,而丙酮酸,琥珀酸为基质,类菌体适应氧浓度范围比较宽,在6％时固氮酶活性最强。