Ontogenic Changes in Growth and Assimilate Distribution as Influenced by N Supply in Rapeseed-mustard

Brassica juncea , cv. Pusa Bold, and Brassica campestris , cv. Pusa Kalyani, were raised under field conditions with varying levels of N fertilization, i.e. 0, 40, 80 and 120 kg N ha⁻¹. Changes in dry matter accumulation in various plant parts as influenced by N supply were measured throughout the crop ontogeny. N supply up to 120 kg had an increasing effect on the growth of leaves, stem and pods during the entire period till maturity. Analysis on the assimilate distribution pattern revealed that 84–87% of the total was accumulated during the post-flowering phase. Dry matter partitioning profile during the ontogeny indicated that about 72–83 % of the total DM was accumulated in the leaves, while 17–28 % in the stem, in the preflowering phase. This trend was found nearly opposite during the postflowering phase. At maturity, however, stem and pods accounted for nearly equal amounts of dry matter accumulation. Among the genotypes, Pusa Bold recorded significantly higher DM accumulation and seed yield over Pusa Kalyani which, on the other hand, exhibited a better assimilate-partioning ability than the former. Nitrogen levels had a favourable effect on LAI, LAD and CGR in both genotypes. Highly significant correlations were obtained between seed yield vs. LAI, LAD and CGR. N fertilization up to 120 kg ha⁻¹ was found beneficial in enhancing growth and yield of rapeseed-mustard.     

Effect of Gibberellic Acid Spray and Basal Nitrogen and Phosphorus on Productivity and Fatty Acid Composition of Rapeseed-Mustard

Two field experiments were conducted during] 994-95 to study the effect of spray of 10⁻⁵ M GA3 at 40 days after sowing on mustard ( Brassica juncea (L.) Czern & Coss.) cv. Varuna grown with basally applied 0, 40, 80 and 120 kg N ha⁻¹ (Expt. 1) and 0,15, 30 and 45 kg P ha⁻¹ (Expt. 2) on pod number per plant, seeds per pod, 1000 seed weight, seed yield, biological yield, harvest index and fatty acid composition of oil. No significant difference between water and GA3 spray was found when basally applied nitrogen was 0 or 40 kg N ha⁻¹. N₈₀ proved to be the best for yield characteristics. In another experiment on phosphorus, GA₃ and 30 kg P ha⁻¹ individually enhanced the yield, but interaction of GA₃ and P remained non-significant. The fatty acid composition of oil in both experiments was significantly affected only by nitrogen and phosphorus treatments for oleic acid and erucic acid. It was found that return in the form of yield was more for every kg applied fertilizer under GA, spray treatment. The response was more for N fertilizer in comparison to P. GA₃ at a low level of fertilization significantly increased the return from fertilization.     

土壤联合固氮菌的研究进展

面临人类社会普遍出现的粮食、人口、环境、能源、资源等问题的困扰,从可持续发展的角度出发,生物固氮逐渐引起了各国科学家的重视,测试技术的进步及细胞工程与基因工程等技术的出现使生物固氮的研究日趋深入。通过阐述生物固氮中细胞联合固氮的研究现状及其方法与手段,为与之相关的研究者提供了参考。     

粉状物质定量取料给料实验装置设计

根据有关机械原理设计出了一种新型的粉状物质定量取料给料装置,该装置结构简单,定量准确、快速,并且可以重复地取料给料。实验证明,该装置稳定可靠,具有一定的实际应用价值和推广价值。     

转Bt基因棉新棉33B叶片氮素代谢特征及其化学调控潜力

新棉33B 在开花期间 ,叶片硝酸还原酶活性呈现递减趋势 ,蛋白酶活性和叶蛋白含量呈增加趋势 ,全氮、氨基酸含量与硝酸还原酶活性呈正相关。蕾期至盛花期毒蛋白含量呈马鞍形变化。缩节安系统化控处理使功能叶片硝酸还原酶、蛋白酶的活性、叶片蛋白含量、氨基酸和全氮的含量以及叶片毒蛋白的含量均有提高 ,最终提高单株结铃数和单铃重     

Nitrogen application method for improving yield and protein content of “Kitanokaori”, a new variety of winter wheat for bread use in Hokkaido

(Jpn. J. Soil Sci.Plant Nutr., 77, 273–281, 2006)

“Kitanokaori” is a new variety of winter wheat (Triticum aestivum L.) for bread use bred at the National Agricultural Research Center for Hokkaido Region. The grain protein content of wheat for bread use should be higher than 120 g kg?1. Much nitrogen application is necessary to obtain high grain protein content. Therefore, it is necessary to determine the optimum amount of nitrogen to obtain the required protein content and to prevent nitrogen from remaining in the soil. Field experiments were conducted for four years from sowing in 2000 to study the effect of the amount of nitrogen and the time of top-dressing. In the experiment in which sowing was carried out in 2003, nitrogen treatments were 40, 40–60, 40–60–0–60, 40–60–0–60–30, 40–60–0–60–60, 40–60–60–60, 40–60–60–60–30, 40–60–60–60–60, 40–60–30–30, 40–60–30–30–30 and 40–60–30–30–60 (each value showing the amount of applied nitrogen at sowing · re-growing stage · panicle formation stage · flag leaf stage · full heading stage, kg ha?1). The experiments were conducted in Andosol, which has moderate nitrogen fertility, and in Histosol, which is fertile soil.

Kitanokaori did not lodge with high-applied nitrogen, and both yield and protein content increased with an increase in applied nitrogen. In a moderate climate, Kitanokaori reached a protein content of 120 g kg?1 when the amount of absorbed nitrogen was about 190 kg ha?1, and the yield was about 7·8 Mg ha?1 at that time.

The top-dressing at the panicle formation stage was effective to raise the yield and the top-dressing at the full heading stage was effective to raise the grain protein content. It is recommended that the amount of applied nitrogen should be 160 kg ha?1 until the flag leaf stage, and additional nitrogen should be applied at the full heading stage to obtain a grain protein content of more than 120 g kg?1. Nutritional diagnosis at the full heading stage will be necessary to determine whether more nitrogen is needed to achieve the required protein content.

When the amount of total applied nitrogen did not exceed 220 kg ha?1, the amount of absorbed nitrogen was over 90% of applied nitrogen, and there was little inorganic nitrogen in the soil after harvest. Therefore, it was considered that the residue of nitrogen in the soil was small within 220 kg ha?1 of nitrogen application, while favorable growth and high yield were obtained.     

土壤水分含量与施肥量对辣椒产量与品质的影响

通过盆栽大方线辣椒,研究了土壤水分含量与施氮量对辣椒果实产量和品质的影响。结果表明,土壤水分含量和施氮量对产量影响显著,其中W2N2(土壤水分下限为60%Q,0.2gN/kg干土)产量最高;同一土壤水分含量,施氮能显著的增加辣椒素、维生素C、干物质和可溶性糖等物质含量,但施氮过多,辣椒素、维生素C含量下降;同一施氮量,土壤水分含量下降辣椒素、维生素C含量显著增加。综合来看,W2N2产量最高,品质较好。     

Nitrate leaching losses under Miscanthus grass planted on a silty clay loam soil

Abstract. Nitrate leaching under newly planted Miscanthus grass was measured for three years. The crop received either no fertilizer-N or an annual spring application of 60 kg or 120 kg N ha^-1. During three winters soil water was collected from porous cup probes installed 90 cm deep. Nitrate leaching was calculated from the mean drain flow recorded in two drain gauges multiplied by the mean nitrate-N concentration in the soil water solutions collected. In the first year soil water nitrate concentrations were high on all treatments and N losses were 154, 187 and 228 kg ha^-1 respectively on the unfertilized treatment and those that received 60 or 120 kg N ha^-1. Leaching losses in the second and third years were, in turn, 8, 24 and 87 kg ha^-1 and 3, 11 and 30 kg ha^-1 for the unfertilized treatment and for the 60 and 120 kg N ha^-1 treatments respectively. Leaching losses were closer to those recorded under extensively managed grassland than arable land. The large losses in the first year were probably due to the previous agricultural management at the site and excessive inputs of N on the fertilized plots. In the second and third year, lower drainage volumes may also have influenced losses. The results show that Miscanthus , once established, can lead to low levels of nitrate leaching and improved groundwater quality compared with growing arable crops.     

基于有限体积法的含无压段泵站水锤模拟及调压井优化

针对含无压段的泵站输水工程水锤模拟常采用特征线法，且往往忽略动态摩阻和有压-无压相互干扰影响的问题，该研究建立了考虑动态摩阻的二阶有限体积法模型，进行有压段-无压段实时联合计算。首先，采用二阶Godunov格式分别对有压流、无压流流动控制方程进行求解，同时考虑了动态摩阻效应以准确模拟水力瞬变过程中的能量耗散，并进行试验验证。进一步地，对有压段、无压段交接处采用变时步法传递数据，结合实际工程对阻抗式调压井的尺寸、位置进行了敏感性分析。结果表明：考虑动态摩阻效应后模型模拟结果与试验结果基本一致，阀门处水锤压力误差最大值仅有4.58%；与特征线法相比，二阶Godunov格式稳定性更高，库朗数小于1时水锤压力只有轻微的数值衰减。本文建立的有压段-无压段实时联合计算方法能够充分考虑有压段出水池水位变化以及无压段倒流的影响。针对水泵失电工况，对阻抗式调压井进行的优化研究表明，随连接管直径增大，系统内最大压力水头、调压井最高涌浪水位和水泵最大反转转速增大，调压井最低涌浪水位降低；随调压井直径增大，最高涌浪减小，最低涌浪增高，最大压力在连接管直径较小时一直降低，在连接管直径较大时先减小后增大；当连接管管径 3.5 m，调压井直径 15 m 时， 既能满足系统控制参数要求，也能减少工程量。调压井位置离泵站越近，最大压力、反转转速、最高涌浪越大，最低涌浪越小，当调压井布置在泵后1.0 km时，最高涌浪水位会达到172.35 m，不满足控制标准要求。综上，建立的模型具有较高的准确性、稳定性和适用性，研究结果可为含无压段泵站输水工程的水锤模拟提供参考。     

浅议开关电源的干扰源

开关电源由于其在体积、重量、功率密度、效率等方面的诸多优点,已经被广泛地应用于工业、国防、家用电器等各个领域。随着开关电源工作频率的不断提高,印制电路板的走线和元件的布局不当等原因。所产生的电磁干扰和低频噪声辐射将会对周围环境以及存在于周围空间中的设备、仪器带来危害。了解开关电源的干扰源,可以方便设计人员采取有效的措施来降低开关电源的干扰程度和提高其抗干扰的能力。