Effect of Different Preceding Crops and Crop Rotations on Yield of Winter Oil-seed Rape (Brassica napus L.)

To determine the effect of different preceding crops and crop rotations on the grain yield of oil-seed rape, a long-term rotation experiment was conducted at the Hohenschulen experimental station in Kiel, NW Germany. Additional factors included the nitrogen fertilization and the fungicide application. The results reported herein are based upon the harvest years 1988 to 1993. Averaged over the different rotations and husbandry treatments, the grain yields in the 6 experimental years varied between 2.71 t ha^?1 and 3.99 t ha^?1. In contrast, the effect of the different husbandry treatments was smaller and non significant. Averaged over 6 years, only the fungicide application caused small yield increase of 0.2 t ha^?1. The highest grain yields of 3.77 t ha^?1 or 3.65 t ha^?1 occurred when oil-seed rape was directly following peas. Low yields between 3.15 tha^?1 and 3.33 tha^?1 were obtained when oil-seed rape was grown after oilseed rape. The lowest grain yield of 3.13 t ha^?1 was produced with oil-seed rape grown in monoculture only. In rotations with oil-seed rape following a preceding cereal crop (wheat or barley), the grain yields averaged between 3.22 tha^?1 in a two course rotation and up to 3.44 tha^?1 in a four course rotation. In general, the yields of oil-seed rape increase with the length of the rotation and the length of the break between two oilseed rape crops. The yield component number of seeds per m² was affected by the previous cropping accordingly, whereas the thousand seed weight did not respond to the cropping history. Based upon disease assessments in the first years of this experiment, we argue that an increase in the incidence of fungal diseases has considerably contributed to the yield decrease of oil-seed rape in short rotations.     

Effect of Integration of Fertilizer and Green Manure Nitrogen on Yield Attributes, Nitrogen Uptake and Yield of Lowland Rice (Oryza sativa L.)

Field experiments were conducted at Tamil Nadu Rice Research Institute, Aduthurai, India, during the wet seasons of 1992 and 1993 to study the effect of full and partial substitution of fertiliser N with green manure N (Sesbania rostrata) on nitrogen uptake, yield attributes and yield of rice. The experiment consisted of eight treatments with two levels of N (100 and 200 kg ha⁻¹) and three sources of N application viz., fertilizer, integrated (1:1 fertilizer and green manure N) and green manure N compared to the recommended practice (150 kg fertilizer plus 6.25 t ha⁻¹ (72 kg N) green manure) and a no N control. Nitrogen application markedly increased the N uptake. Combined use of the two N sources at 200 and 222 kg N ha⁻¹ and of single fertilizer N at 200 kg N ha⁻¹ recorded the maximum N uptake, increased the yield attributes such as number of panicles per unit area, weight per panicle, number of total and filled grains per panicle and test weight. At 200 kg N ha⁻¹ full substitution of N by green manure reduced the grain yield but only partial substitution of N by green manure resulted in almost similar yield as single fertilizer N. Thus 200 kg N ha⁻¹ applied in equal proportions of fertilizer and green manure N can be recommended for medium duration rice cultivars.     

Effect of Different Crop Densities of Winter Wheat on Recovery of Nitrogen in Crop and Soil within the Growth Period

Previous experiments have shown that, at harvest of winter wheat, recovery of fertilizer N applied in early spring [tillering, Zadok’s growth stage (GS) 25] is lower than that of N applied later in the growth period. This can be explained by losses and immobilization of N, which might be higher between GS 25 and stem elongation (GS 31). It was hypothesized that a higher crop density (i.e. more plants per unit area) results in an increased uptake of fertilizer N applied at GS 25, so that less fertilizer N is subject to losses and immobilization. Different crop densities of winter wheat at GS 25 were established by sowing densities of 100 seeds m^–2 (S_low), 375 seeds m^–2 (S_cfp= common farming practice) and 650 seeds m^–2 (S_high) in autumn. The effect of sowing density on crop N uptake and apparent fertilizer N recovery (aFNrec = N in fertilized treatments ? N in unfertilized treatments) in crops and soil mineral N (N_min), as well as on lost and immobilized N (i.e. non‐recovered N = N rate ? aFNrec), was investigated for two periods after N application at GS 25 [i.e. from GS 25 to 15 days later (GS 25 + 15d), and from GS 25 + 15d to GS 31] and in a third period between GS 31 and harvest (i.e. after second and third N applications). Fertilizer N rates varied at GS 25 (0, 43 and 103 kg N ha^–1), GS 31 (0 and 30 kg N ha^–1) and ear emergence (0, 30 and 60 kg ha^–1). At GS 25 + 15d, non‐recovered N was highest (up to 33 kg N ha^–1 and up to 74 kg N ha^–1 at N rates of 43 and 103 kg N ha^–1, respectively) due to low crop N uptake after the first N dressing. Non‐recovered N was not affected by sowing density. Re‐mineralization during later growth stages indicated that non‐recovered N had been immobilized. N uptake rates from the second and third N applications were lowest for S_low, so non‐recovered N at harvest was highest for S_low. Although non‐recovered N was similar for S_cfp and S_high, the highest grain yields were found at S_cfp and N dressings of 43 + 30 + 60 kg N ha^–1. This combination of sowing density and N rates was the closest to common farming practice. Grain yields were lower for S_high than for S_cfp, presumably due to high competition between plants for nutrients and water. In conclusion, reducing or increasing sowing density compared to S_cfp did not reduce immobilization (and losses) of fertilizer N and did not result in increased fertilizer N use efficiency or grain yields.     

The Effect of Different Preceding Crops on the Development, Growth and Yield of Winter Barley

Reliable estimations of the yield response of winter barley to different preceding crops are necessary for the design of crop rotations.
The grain yield and yield components of winter barley (cv. Tapir ) following either rapeseed, oats, wheat or barley were determined in five years of field experiments on a sandy loam (Luvisol) at the Hohenschulen experimental station near Kiel, Germany, F.R. The growth, development and incidence of take-all ( Gaeumannomyces graminis var. tritici ) was measured in a total of three years. On average over the five years barley grown after oats yielded 0.8 t per ha (11 %) more than barley following wheat which was mainly due to a higher number of ears per m². Barley following either oats or rapeseed produced a higher dry weight and a larger number of tillers per m² compared with barley grown after wheat or barley. This effect was already-present at the sampling date before winter. Take-all ratings were constantly higher in barley following a susceptible crop, but only reached a severe level late in the season and therefore could not explain the observed differences in growth, development and subsequently grain yield. Since no other pathogens affected the development other non-pathogenic causes must be considered as main causes for the described observations and yield differences.     

The Effect of Seeding Rate and Nitrogen Fertilization on Barley Yield and Yield Components in a Cool Maritime Climate

Soil and climatic conditions in Newfoundland are on the margins of agricultural capability, and almost all feed grain is imported. The overall objective of this work was to develop guidelines for the production of barley in Newfoundland, with the goal of establishing modern cropping recommendations. We conducted a 4-year study near St. John's to examine the effect of seeding rate and topdress ammonium nitrate (N) fertilization rate on Chapais six-row barley ( Hordeum vulgare L.) yield components and grain yield. Increasing seeding rate from 200 to 380 seeds m^–2 did not alter grain yield in any year. Increasing topdress fertilization from 0 to 60 kg N ha^–1 increased spike density m^–2 at harvest, resulting in linear increases in grain yield in all years. Highest N rates had greatest lodging in two years. Based on our results, agronomic recommendations for eastern Newfoundland now include barley seeding rates of 250 ± 50 seeds m^–2, with topdress applications up to at least 30 kg N ha^–1.     

Effect of a Winter Cereal or Legume Crop on the Yield and Nutrient Uptake by Summer Maize/Cowpea Fodder

A field experiment conducted at the Indian Agricultural Research Institute, New Delhi brought out that summer maize green fodder yield was 31.8 t/ha to 34.1 t/ha, while that of cowpea fodder was only 15.5 to 16 t/ ha. Maize fodder and crude protein yield and NPK uptake was more after a winter legume (lentil) than after a winter cereal (wheat).     

The Effect of Nitrogen and Phosphorus Fertilization on the Nitrogen Absorption by Sunflowers

Little is known about the effect of fertilization on the N uptake of sunflowers. A 4² factorial trial with 0, 60, 120 and 180 kg N ha⁻¹ and 0, 15, 30 and 45 kg P ha⁻¹ was conducted over three years. The N content and concentration of leaves, stems and capitula were determined at three growth stages. High N levels increased the N content and concentration of all plant parts at all growth stages sharply. High P levels increased the N content of all plant components through better growth. P has an inconsistent effect on N concentration but tended to decrease it. After flowering the crop assimilated 20 to 25 % of the total N. This implies that N applied can still be applied and utilized by the crop at a late stage. This should be substantiated by further research.     

Effect of Nitrogen Rates at Different Growth Stages on Corn Yield and Common Smut Disease [Ustilago maydis (D.C.) Corda]

The effect of N fertilizer rates and time of N application on plant growth, N %, N uptake, smut index and yield response of corn were investigated in the field during the summer seasons 1988 and 1989. Increasing N rate from 30 to 60 and/or 90 kg/acre produced greater response on the studied parameters, followed by a limited response at 120 kg N/acre. Opposite results were detected on yield losses, owing to the severity of smut infection. Single application of N at planting was the least productive for DM and grain yields, compared with 2-split or 3-split N treatments. On the other hand, splitting N application at planting and 16-leaf growth stages produced limited smut infection with greater increase in grain yield and lowest DM and N accumulations. The results also showed that 3-split N treatment acted to accelerate the vigour growth and N uptake to a greater extent, creating more favourable conditions for stimulating smut infection, with an attendant increase on yield losses. Because of the advantage of applying 90 kg N/acre over the N treatments on the measured parameters, with particular reference to yield potential and smut performance, attention was given to splitting N fertilizer at planting and 16-leaf growth stages.     

氮肥调控对小麦/玉米产量、氮素利用及农田氮素平衡的影响

为了实现小麦/玉米高产高效生产,采用田间小区试验方法,研究了不同氮肥管理措施对小麦/玉米产量、氮素利用及农田氮素平衡的影响。结果表明,小麦季在农民常规施肥的基础上适当减少追氮量不会对小麦产量产生明显影响,在施氮总量195 kg/hm2基础上配施调控剂处理小麦增产8.3%~24.6%,氮肥偏生产力、表观利用率和农学效率及氮肥贡献率均得到相应提高。在玉米季,以一次性基施适量氮肥同时配施抑制剂的氮肥管理方案为最佳,在施氮240 kg/hm2水平上与不添加抑制剂等氮量一次性基施和基追结合处理相比,增产幅度分别为7.4%~9.6%和13.9%~16.2%,氮肥贡献率、肥料偏生产力和农学效率亦得到显著提高;经过一个轮作周期后,农田土壤氮素盈余量为63.94~126.83 kg/hm2。在总施氮量435 kg/hm2的情况下,与单施尿素相比较,配施氮素调控剂的氮素盈余量降低了27.4%~44.2%,其中脲酶与硝化抑制剂配施效果最佳。但在总施氮量480 kg/hm2的情况下,即使施用了氮素调控剂,氮素平衡盈余率仍在20%以上,存在较大的环境风险。     

The Effect of Nitrogen and Phosphorus Fertilization on the Phosphorus Absorption by Sunflowers

Little is known about the effect of fertilization on the P uptake of sunflowers. A 4² factorial trial with 0, 60, 120 and 180 kg N ha⁻¹ and 0, 15, 30, and 45 kg P ha⁻¹ was conducted over three years. The P content and concentration of leaves, stems and capitula were determined at three growth stages. High N levels increased the P content and concentration of all plant components in early growth stages only. High P levels increased the P content and concentration of all plant components sharply almost throughout. Plants seem to recover some lost growth towards the end of the season so that at physiological maturity there are no significant differences in P content among N levels. The translocation of P from the stems is very effective but P can accumulate in the leaves if a luxury quantity of P is present in the plants. In terms of seed yield a significant N × P interaction was found, indicating a sharp response to both N and P only in the presence of a sufficient quantity of the other element. The response of seed yield was in agreement with the P absorption by the plants.     

Effects of Two Underseed Species, Medicago polymorpha L. and Scorpiurus muricatus L., on the Yield of Main Crop (Durum Wheat) and Subsequent Crop (Teff) Under Humid Moisture Regimes in Ethiopia

Mixed cropping of leguminous underseed species and cereal crops may increase productivity and serve some additional purposes. Two leguminous weed species which are widely distributed in annual crops of the Ethiopian highlands have been studied with varying coverage in greenhouse trials in Ethiopia with regard to their suitability as underseeds and with wheat ( Triticum turgidum [L.] Thell. var. durum [Desf.] MacKey) as a main crop. The competitive effects of Scorpiurus muricatus L. on the grain yield of wheat were smaller than those of Medicago polymorpha L. (-14.1 % and -23.6 % respectively, compared with the underseed free control) which is mainly ascribed to differences in their speed of development and shoot height. The residual effects of the underseed's root masses on the grain yield of the successive teff crop (Eragrostis tef [Zucc] Trotter) were significantly higher with Scorpiurus muricatus (+99.3 %) than with Medicago polymorpha (+63.6 %). The results are discussed with regard to the specific site conditions in the cereal-dominated cropping systems of the Ethiopian highlands.     

有机肥C/N优化及钾肥运筹对烤烟钾含量及香气品质的影响

利用大田试验研究了有机肥C/N优化及钾肥运筹对烤烟钾吸收及香气品质的影响。采用裂区试验设计,主处理为利用猪厩肥与腐熟花生饼肥混合配制不同碳氮比(m:m)的有机肥,设3个C水平,C1:饼肥420 kg/hm~2,猪厩肥2 250 kg/hm~2;C2:饼肥300 kg/hm~2,猪厩肥3 750 kg/hm~2;C3:180 kg/hm~2,5 250 kg/hm~2;副处理为3个K(K2O)水平,K_低:120 kg/hm~2;K_中:240 kg/hm~2;K_高:480 kg/hm~2。结果表明:C1、C3水平时,随钾用量增加中部叶生物量增加,K_高处理上部叶生物量高于K_低;C3水平时,供钾量对上、中部叶生物量无显著影响;C2水平时,钾量增加提高烟叶生物量;相同碳水平时,随生育进程烟叶钾含量呈降低趋势,随钾量增加呈增加趋势;相同钾供应下,C1、C2对烟叶钾含量无显著性影响;现蕾期、成熟期时,与C1相比,K_中、K_高处理时C2水平增加烟叶钾含量,而C3水平降低烟叶钾含量。不同部位烟叶钾含量为C2C3C1处理;解钾菌在团棵期-旺长期呈增加趋势,现蕾期-成熟期呈降低趋势;K_中、K_高处理解钾菌高于K_低处理;C2水平时,K_中、K_高处理解钾菌随生育期呈增加趋势,且C2水平时K_中、K_高处理显著高于其他处理时;K_中、K_高时C3与C1处理时无显著差异,显著高于K_低处理;各处理烟叶常规化学成分在C2处理时K_中、K_高处理中部叶总糖含量25.39%~25.27%,还原糖22.75%~25.73%,总氮1.67%~1.72%,氮碱比0.79,糖碱比10.78~11.80,烟碱含量2.11%~2.18%,表明有机肥碳氮比优化下,钾肥用量增加提高了烟叶中总烟碱、蛋白质及总氮量,改善糖碱比及优化氮碱比值,增加烟叶中钾离子含量;所有处理烟叶中性致香物质种类相同(28种),K_低处理其总量低于K_中、K_高处理,且部位间差异显著;上部叶总量低于中部叶;K_中、K_高处理提高烟叶致香物质总量,C2处理上部叶提高幅度最大。由此可见,通过花生饼肥300 kg/hm~2与猪厩肥3 750 kg/hm~2(中碳水平)的碳氮比优化下,施钾量增加对提高烟叶中性致香物质效果最佳,特别对上部叶。     

The Effect of Moisture Stress on the Yield and Yield Components of Several Wheat Cultivars and their F1 Hybrids

The effect of moisture stress on yield and yield components of five winter wheats and their F₁, hybrids were investigated by maintaining the material at 80 % and 50 % field capacity respectively. Yield, kernel number, and kernel mass of the secondary tillers were affected severely by moisture stress. Kernel number and kernel mass of both primary and secondary tillers were correlated to yield significantly (r > 0.75) at both moisture levels. The rankings of the characters most significantly correlated to yield remained much the same at moisture levels despite a significant cultivar X moisture level interaction.     

玉米/大豆间作条件下根瘤菌与氮肥互作对大豆产量和品质的影响

通过大豆与玉米间作,研究根瘤菌与氮肥互作对大豆产量和品质的影响。研究结果表明,合理运筹氮肥和大豆种子拌根瘤菌均可提高间作大豆产量、品质和效益;大豆种子拌根瘤菌还可增强玉米/大豆间作系统的互补促进效应,减少施氮量,增加复合系统总效益;大豆高产、优质、高效等不同指标对应的最大需氮量不同,在确定大豆最佳施氮量时应考虑施氮量与根瘤菌互作效应的影响。     

长期施肥对不同类型土壤中作物产量及土壤剖面硝态氮累积的影响

在潮土、褐土、砂盖黑土3种土壤上,分别自1980和1981年选点布置了氮、磷、钾定位试验。在各个处理中分别从0－20,20－40,40－60,60－80,80－100cm5个剖面层次中垂直取土样,然后进行室同内分析。结果表明：在不施肥处理、单施氮处理、氮磷配施处理、氮磷钾配施处理,NO3^--N累积量以砂盖黑土为最多,潮土次之,褐土最少。硝态氮在土壤中分布不仅与施氮量有关,而且还与土壤类型有直接关系。不同土壤类型直接影响硝态氮在土壤剖面中的移动。     

Effect of Relative Sowing Time on the Growth and Yield of the Component Crops in Okra/Maize and Okra/Cowpea Intercropping Systems

The effects of variations in the relative sowing time of component crops in okra/maize and okra/cowpea intercropping systems were examined in 1990 and 1991 cropping seasons. Okra was either sown the same day as, or two weeks before or after maize or cowpea. Intercropping reduced the growth and yield of okra, maize and cowpea relative to their sole crops. However, okra yield was depressed more by maize than by cowpea, especially when okra was sown two weeks after maize. Comparative assessment of okra/maize and okra/cowpea mixtures suggests that it is better to grow okra and cowpea together than intercropping okra and maize because yield advantages were always higher in okra/cowpea (67% and 59% in 1990 and 1991 respectively) than in okra/maize (15% and 29%). The results were discussed in light of competitive abilities of the various components in the mixtures.     

某些内部和外部因子对蔬菜中硝酸盐含量的影响

本文对蔬菜中硝酸盐积累的内部和外部因子作了综合评述.不同蔬菜的种、品种、部位和年龄之间,硝酸盐含量差别很大.一般来讲,叶菜类和根菜类蔬菜积累的硝酸盐高于茄果类蔬菜.就叶菜类的可食部分而言,硝酸盐积累量为根>茎>叶柄>叶片.外部因子,诸如氮肥用量、氮素形态、光照、温度、水分、栽培方法以及收获时期和方法等,都不同程度地影响了蔬菜中硝酸盐的积累.根据影响硝酸盐积累的各种因子,提出了减少硝酸盐积累的几条措施.     

The Effect of Nitrogen Fertilization and Population Density of the Field Bean (Vicia faba L. minor) of Indeterminate and Determinate Growth Habit on the Symbiosis with Root Nodule Bacteria and on the Seed Yield

Field beans of indeterminate (cv. Nadwiślański) and determinate (cv. Tibo) growth habits were grown on field plots with a density of 20, 40 and 80 plants m⁻² at two levels of nitrogen fertilization: low (20 kg N ha⁻¹) and very high (150 kg N ha⁻¹). At the phase of intense pod growth the number and the dry matter weight of root nodules as well as their nitrogenase activity and some features of the plants growth were determined, and in the period of ripeness the components of seed yield were established.
It was found that increased density of sowing as well as the high level of nitrogen fertilization inhibited the growth and development of root nodules and limited their nitrogenase activity in both cultivars. Plants of both varieties were characterized by a similar potential of forming the root nodules, however, in plants of the cv. Tibo the nitrogenase activity of nodules was much lower than in the cv. Nadwiślański.
Increased population density of the plants has in both varieties given increased seed yield when calculated per m² of the soil, compensating in excess the depression of the seed yield from one plant. Such compensation did not occur in the case of the depression of nitrogen fixation under intense nitrogen fertilization.     

水氮配置对华北冬小麦-夏玉米种植体系氮素利用及土壤硝态氮残留的影响

针对华北平原冬小麦-夏玉米轮作体系存在过量的水、氮投入问题,本研究于2008 -2010年在河北吴桥设置了传统水氮、传统水氮调整、节水减氮和最少水氮4个水氮模式,以分析减少水氮投入后冬小麦-夏玉米体系的产量、氮素利用和土壤氮残留情况.结果表明:与传统水氮相比,节水减氮模式的氮肥投入量下降55％,水分投入量下降36.6％...     

The Effect of Chilling Temperature on the Permeability of Membranes to K+, Mg2+, Ca2+ ions and on the Electric Potential of Leaves in the Seedlings of Maize (Zea mays L.)

The relations between the extent of injuries in seedlings caused by a few day-long exposures to chill (5°C) and the leakage of K⁺, Mg²⁺ and Ca²⁺ ions from the leaves as well as the electric potential in seven maize hybrids, were investigated. The permeability of cells to ions was defined based on their absolute concentration in a water diffusate (C_t) and concentration expressed in relation to the total ion content in the leaves (IL index).
At lowered temperature the hybrids of higher resistance to chilling temperature were characterized by a lower value of the IL index for K⁺ and Mg²⁺ ions than the chill-sensitive hybrids. On the other hand, absolute concentration of the ions (C_t) Mg²⁺ and Ca²⁺ leaking from the leaves before chill exposure of the seedlings was positively and highly correlated with the extent of injuries in hybrids caused by 4 day-long exposures to chill. This observation is evidence that the chill injuries were predetermined through increased cell permeability to the mentioned ions at room temperature.
Changes in the electric potential of leaves in conditions of lowered temperature preceded the injuries of leaves, which became apparent after a longer period of exposure to chill. Thus, as the leakage of Mg²⁺ and Ca²⁺ ions occurs, changes in the electric potential may supply early information about the predisposition of the particular maize hybrids to chilling injuries. Leakage measurements of Mg²⁺ and Ca²⁺ ions from the leaves at room temperature may find application in the selection of chill-tolerant maize genotypes.