Effect of Nitrogen Rate and Stubble Height on Dry Matter Yield,Crude Protein Content and Crude Protein Yield of a Sorghum–Sudangrass Hybrid[Sorghum bicolor (L.) Moench × Sorghum sudanense (Piper) Stapf.] in the Three‐Cutting System

In this study, the effects of nitrogen (N) rate (60, 120, 180 and 240 kg N ha^?1 applied in three equal dressings at seeding and after the first and second cuttings) and stubble height (7, 14 and 21 cm) on the dry matter (DM) yield, crude protein (CP) content, and CP yield of a sorghum–sudangrass hybrid [Sorghum bicolor (L.) Moench × Sorghum sudanense (Piper) Stapf., cv. Pioneer 988] in the three‐cut system was investigated. The N rate had no significant effect in the first and third cuttings, but in the second cutting DM yields increased significantly with increase in N rate. The highest yield of 9.1 t ha^?1 was obtained with 80 kg N ha^?1 for the average of 2 years at the second cutting, but no significant difference was found among the 40, 60 and 80 kg N ha^?1 rates. CP content and yield were not significantly affected by N rate at the first and third cuttings, but CP content and yield were significantly affected by application of N at the second cutting. Stubble height had a significant effect on CP content at the third cutting. However, it had no significant effect on CP content at the first and second cuttings. Stubble height had a significant effect on the CP yield at the first cutting, but no significant effect on CP yield at the second and third cuttings.     

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.     

Differences in Wheat Cultivar Response to N Supply. I: Differences in Grain Yield Formation

Two-year field trials with winter wheat cultivars Batis and Toronto were conducted in Southern Bavaria, Germany, to investigate the possible causes of cultivar differences in response to N supply varying in total amount and time of application. Cultivar-related differences in grain yields were observed in treatments with low and medium N supply. High doses of N supply resulted in grain yield adjustment or grain yield advantage for cv. Toronto. The results of this study revealed a consistent, genotypic pattern in response to N fertilization in spite of strong seasonal effects. Systematic modifications in canopy growth rates in response to N supply were of particular relevance and a main factor for differences in tillering intensity resulting in modified stand densities. In the present study, cultivar differences in spike development and interactions with N supply related more to abortion than to initiation processes for number of spikelets and number of flowers per spikelet. High grain density (grains per m²) of cv. Toronto was evident during reproduction stages even under conditions of medium N supply. However, decreased growth rates during the later part of grain filling in combination with low 1000 grain weight, which was barely modified by N fertilization, allowed only partial utilization of this potential. It is assumed that sink limitations were of particular relevance for grain yield development in cv. Toronto, while cv. Batis combined a less intense response to N supply with more stability in the development of grain yield components.     

镉胁迫下富铁有机肥对芒草生长及镉富集的影响

为了探究镉胁迫下富铁有机肥对芒草生长及镉富集的影响,通过盆栽试验,设置CK（不施肥）、ZCK（施加普通有机肥）和Z2、Z3（施加不同浓度富铁有机肥）处理。结果表明：与CK相比,所有施肥处理均促进了芒草生长,改善了土壤理化性质,抑制了芒草富集重金属,且其中Z2、Z3比ZCK对芒草生长的效果更好。相对于ZCK,Z3的芒草干质量显著增加了131.80%,Z2的芒草根长显著增加了54.22%。此外,Z2地上部的镉含量相比于ZCK显著降低了49.86%,Z3地下部的镉含量相比于CK显著降低了58.94%。研究表明,施加富铁有机肥相对于普通有机肥更能有效促进芒草生长并抑制芒草对镉的富集,该肥料具有对轻度镉污染土壤进行边修复边生产的应用潜力。     

不同氮肥形态对李氏禾铬富集能力的影响

为了优化李氏禾（Leersia hexandra Swartz）铬修复时的施氮效率,通过盆栽试验,研究了5种氮肥形态（硝酸钙、尿素、氯化铵、硝酸铵、硫酸铵）对李氏禾铬修复性能、生长指标和根系指标的影响。结果表明：与对照（不施氮肥）相比,施加的5种形态氮肥均促进了李氏禾生长,提高了根系活力,改变了根系形态特征,有利于提高李氏禾铬含量、铬累积量、富集系数和土壤铬去除率。施加硫酸铵的李氏禾生物量和根平均直径最大,分别为对照的5.54倍和1.51倍,其根系活力比对照增加108%;施加硝酸铵的李氏禾总根表面积和总根体积最大,分别为对照的2.17倍和1.99倍（P<0.05）。相关性分析结果表明,李氏禾的生物量、根平均直径、总根表面积、总根体积和根系活力均与土壤铬修复效率有关。其中,施加硫酸铵处理的富集系数和土壤铬去除率最高,分别为对照的1.45倍和5.56倍。研究表明,施加硫酸铵比其他氮肥形态更有利于提高李氏禾铬污染土壤修复效率。     

水稻田间育秧水肥药变量喷灌装置设计与试验

为解决南方水稻工厂化田间育秧水肥药人工管理作业中存在的灌溉均匀性差、化肥和农药浪费以及劳动强度大等问题,该研究设计了一种水稻田间育秧水肥药变量喷灌装置,阐述了水肥药变量喷灌装置总体结构和工作原理,进行了关键部件设计与试验;以可编程逻辑控制器（programmable logic controller,PLC）为控制核心,构建了注肥量在线调控及整机变量喷灌控制系统。采用Box-Behnken试验设计方法,对装置喷灌均匀性与主要影响因素进行试验研究,应用单目标优化方法对喷灌关键参数进行优化,并通过验证试验,得到最优参数组合为：干管入口水压0.20 MPa、球阀开度90°、喷头喷角80°,此时装置的喷灌均匀性为92.69%;构建了氯化钾肥液质量浓度与电导率（electrical conductance,EC）值的线性模型,开展了装置变量灌溉施肥性能试验,3种喷灌等级下各作业区的肥液EC值分别为1.65、1.66和1.68 mS/cm,平均喷灌强度分别为900.85、1092.04和1263.67 mm/h,施肥均匀系数分别为85.21%、87.86%和91.62%。采用水肥药变量喷灌装置开展水稻育秧田间管理试验,华航51常规稻和广8优165杂交稻的秧苗长势均匀度均高于95%,成毯性良好,各项素质指标满足机插作业要求。所设计的水肥药变量喷灌装置能够满足水稻田间育秧水肥药变量喷灌作业要求,对提高水稻工厂化田间育秧机械化水平、保证秧苗质量具有实际应用价值。     

氮肥对黑小麦“运黑161”产量及氮素利用效率的影响

为了研究不同施肥水平对黑小麦产量和氮利用率的影响,在洪洞县小麦试验基地开展大田试验。试验以“运黑161”为供试品种,采用单因素完全随机设计,设0 kg/hm²（N0）、144 kg/hm²（N144）、192 kg/hm²（N192）、240 kg/hm²（N240）4 个施氮水平,研究黑小麦在不同氮肥水平下的株高、产量、籽粒蛋白质含量和氮利用率的变化。研究表明,与不施肥相比,施氮可增加黑小麦孕穗至成熟期株高。随施氮量的增加,成熟期穗数和穗粒数也增加,产量以施氮量240 kg/hm²最高,达6 048.45 kg/hm²,较其它氮肥提高6.04%~134.30%,但与施氮量192 kg/hm²处理间差异不显著。氮肥农学利用率以施氮量192 kg/hm²最高,达16.26%。总之,施氮量为192 kg/hm²更利于“运黑161”降低氮肥投入,节约成本,实现产量和氮效率的同步提升。     

不同时期一次性施肥对夏玉米产量和氮肥效率的影响

在河南省鹤壁和原阳采用田间试验,研究不施氮(CK)、种肥同播(T1)、5叶期一次性施肥(T2)和10叶期一次性施肥(T3),对夏玉米生长发育、氮素积累转运及产量的影响,明确夏玉米包膜尿素1∶1配施普通尿素适宜的一次性施肥时期。结果表明,鹤壁和原阳T1处理产量最高,分别为12 700 kg/hm²和10 945 kg/hm²,但与T2处理间差异不显著,较T3处理分别提高14.2%和10.9%;干物质积累量较其他处理分别提高5.6%～25.1%和1.6%～21.2%。不同生育期T1处理叶片SPAD值和叶面积指数均达最高。鹤壁和原阳T1氮肥表观利用率最高,分别为35.2%和35.5%,较其他处理分别提高5.6～14.7个百分点和3.2～13.6个百分点;氮素积累量较其他施氮处理分别提高13.8%～34.5%和14.5%～41.5%。T1处理土壤氮素依存率低于T2和T3处理。综上,种肥同播提高了夏玉米产量、氮肥效率、叶片SAPD值和叶面积指数,保持较高的氮素吸收速率,降低了土壤氮依存率,满足夏玉米整个生育期的氮素需求,实现了夏玉米高产和高效施肥。     

液体肥料施用装置设计与试验

针对液体肥料发展迅速和液体肥料施用装置发展不完善的现状,研制了一种可测量液体肥施用装置主要技术性能及参数的试验台,在此基础上对喷头流量影响因素作了三因素二次回归正交旋转试验,得出了液体肥料质量分数、电动机转速及喷头口直径大小对喷头流量的影响规律及主次关系。