氮肥基因型差异对玉米吸氮量的反应

田间试验研究了11个玉米杂交种在不同施氮条件下的吸氮量。结果表明,玉米吸氮量具有明显的基因型差异。在低氮(N2)处理中,子粒、秸秆、地上部吸氮量高低品种相差分别为1.060、0.134、1.125g/kg,在高氮(N4)处理中,分别为0.836、0.154、0.954g/kg。不同基因型玉米的吸氮量差异低氮条件比高氮条件更大。施氮量对玉米吸氮量有显著的影响。玉米子粒、秸秆、地上部吸氮量和相应的产量呈极显著的正相关     

Effects of Salicylic Acid on the Development and Root Nodulation of Soybean Seedlings

Salicylic acid (SA) is recognized as an endogenous regulator of plant metabolism, mainly involved in induction of systemic acquired resistance (SAR). Exogenous SA can also induce a SAR reaction and SAR gene expression. Excessive SAR-related activity can be an overall cost to the plant in terms of energy and materials expended unnecessarily. Elicitation of plant defence responses might also block beneficial plant-microbe interactions and result in negative effects on plant growth. The objective of this study was to investigate the effects of SA concentration (5, 1, 0.5, 0.1 and 0 m m ) on soybean seedling growth and nodulation by watering of soybean seedling roots or soaking of seedling leaves with SA solutions. It was found that 5 m m SA had negative effects on soybean seedling development, but other concentrations of SA did not affect the development of soybean seedlings. In addition, there were no negative effects on seedling development due to SA soaking of seedling leaves. Soybean seedling growth in sterile soil was reduced due to repressed nitrogen uptake following addition of 5 m m SA, indicating that some concentrations of SA can alter the N nutrition of seedlings. A model is presented that ties SA to nodule formation and plant growth.     

施氮量对超级稻‘松粳9号’产量及氮肥利用率的影响

为了探讨施氮量与‘松粳9号’干物质积累、产量、氮肥利用率之间的关系,明确最佳氮肥施用量,使其在生产中真正发挥超级稻的增产潜力。以超级稻‘松粳9号’为材料,通过田间小区对比试验,研究了不同氮肥施用量对超级稻‘松粳9号’产量及氮肥利用率的影响。结果表明,在水稻齐穗期,地上部植株干物质积累量和吸氮量都随着施氮量的增加而增加;成熟期地上部植株干物质积累量和吸氮量都随着施氮量的增加出现先增后减的趋势。氮肥利用率随着施氮量的增加而降低。随着施氮量的增加产量出现先增后减的趋势。产量与成熟期稻穗和植株干物重、齐穗期稻穗含氮量、成熟期稻穗和植株含氮量呈极显著正相关,与氮肥生理利用率呈显著正相关。施氮量195 kg/hm²能实现超级稻‘松粳9号’最高产量。     

水稻根系特征与氮吸收利用效率关系的研究进展

植物根系是活跃的物质代谢和吸收器官,对植株生物量积累、养分和水分高效吸收利用具有重要作用。本文主要综述了水稻根系形态、解剖、生理特征与氮吸收利用效率的关系以及不同氮效率品种根系特征的差异,并综述了促进根系生长和提高氮吸收利用效率的栽培调控措施,展望了未来水稻根系的研究方向,为水稻氮肥减施、氮高效栽培管理技术优化和氮高效品种选育提供理论依据。     

Can arbuscular mycorrhizal fungi improve competitive ability of dill + common bean intercrops against weeds?

Competition for soil resources plays a key role in the crop yield of intercropping systems. There is a lack of knowledge on the main factors involved in competitive interactions between crops and weeds for nutrients uptake. Hence, the purpose of this work was to compare the effects of arbuscular mycorrhial fungi (Funneliformis mosseae) colonization in interspecific competitive relations and its effect on nutrients uptake and weed control in dill and common bean intercropping. Two field experiments were carried out with factorial arrangements based on randomized complete block design with three replications during 2013–2014. The factors were cropping systems including a) common bean (Phaseolus vulgaris L.) sole cropping (40 plants m⁻²), b) dill (Anethum graveolens L.) sole cropping at different densities (25, 50 and 75 plants m⁻²) and c) the additive intercropping of dill + common bean (25 + 40, 50 + 40 and 75 + 40 plants m⁻²). All these treatments were applied with (+AM) or without (-AM) arbuscular mycorrhiza colonization. In both cropping systems, inoculation with F. mosseae increased the P, K, Fe and Zn concentrations of dill plants by 40, 524, 57 and 1.0 μg kg⁻¹ DW, respectively. Intercropping increased Mn concentration in common bean (4.0 μg kg⁻¹ DW) and dill (3.0 μg kg⁻¹ DW), and also seed yields of both crops (198 g m⁻² and161 g m⁻², respectively). AM colonization improved seed yields of dill and common bean by 169 and 177 g m⁻² in 2013 and 2014, respectively. Moreover, AM application enhanced competitive ability of dill + common bean intercrops against weeds at different intercropping systems. Intercropping significantly changed weed density compared to sole cropping, as weed density was decreased in the dill + common bean intercropping. Diversity (H), Evenness (E) and richness of weed species of weeds for intercrops were higher than those for sole crops.     

Short time effects of biological and inter-row subsoiling on yield of potatoes grown on a loamy sand,and on soil penetration resistance,root growth and nitrogen uptake

Soil compaction, especially subsoil compaction, in agricultural fields has increased due to widespread use of heavy machines and intensification of vehicular traffic. Subsoil compaction changes the relative distribution of roots between soil layers and may restrict root development to the upper part of the soil profile, limiting water and mineral availability. This study investigated the direct effects of inter-row subsoiling, biological subsoiling and a combination of these two methods on soil penetration resistance, root length density, nitrogen uptake and yield. In field experiments with potatoes in 2013 and 2014, inter-row subsoiling (subsoiler) and biological subsoiling (preceding crops) were studied as two potential methods to reduce soil penetration resistance. Inter-row subsoiling was carried out post planting and the preceding crops were established one year, or in one case two years, prior to planting. Soil resistance was determined with a penetrometer three weeks after the potatoes were planted and root length density was measured after soil core sampling 2 months after emergence. Nitrogen uptake was determined in haulm (at haulm killing) and tubers (at harvest). Inter-row subsoiling had the greatest effect on soil penetration resistance, whereas biological subsoiling showed no effects. Root length density (RDL) in the combined treatment was higher than in the separate inter-row and biological subsoiling treatments and the control, whereas for the separate inter-row and biological subsoiling treatments, RLD was higher than in the control. Nitrogen uptake increased with inter-row subsoiling and was significantly higher than in the biological subsoiling and control treatments. However, in these experiments with a good supply of nutrients and water, no yield differences between any treatments were observed.     

叶片吸收雾滴过程中雾滴覆盖面积的变化规律

为了给气雾培、叶面施肥以及植保机械的研究提供进一步的理论依据,研究了作物组织吸收雾滴的过程．建立了一个相对湿度为100％,温度为20 ℃的环境控制室,以蒸馏水为载体,利用Matlab图像处理技术研究了雾滴在活体植物猩猩木叶片表面不同位置其覆盖面积随时间变化的规律．首先,为了消除雾滴蒸发对试验的影响,分别用直径为23877,22992,21260 μm的雾滴来验证其蒸发率:在600 s内的蒸发率分别为14％,28％,31％．因此假设雾滴在前600 s内几乎无蒸发．之后,选取直径分别为540,340 μm的雾滴进行雾滴覆盖面积变化的研究．利用雾滴发生器将不同直径的雾滴喷射到叶面不同的位置,利用图像采集系统获得雾滴的照片,观察雾滴覆盖面积的变化情况．叶片吸收雾滴的试验表明:叶片表面不同位置覆盖面积的变化是不同的,雾滴在叶片表面的覆盖面积前期变化缓慢,到后期变化迅速,而且越往后期变化越明显;雾滴的覆盖面积越大,雾滴吸收速度越快．     

控制性隔沟交替灌溉玉米根系吸水模型的试验研究

以影响根系吸水强度的三大要素即作物蒸腾强度、土壤含水率和根系分布密度为影响因子,结合土壤水动力学理论得到的根系吸水率,建立了控制性隔沟交替灌溉条件下玉米的二维根系吸水模型,并进行验证得到较好的结果。模型对预报控制性交替灌溉具有重要的理论及实用价值。     

镁水平对不同类型土壤大豆生长、养分吸收以及产量的影响

在温室条件下,采用土壤盆栽方法研究了镁施用水平对3种不同类型土壤大豆生长、养分吸收以及籽粒产量的影响。试验结果表明,施用60mg/kg镁肥对3种不同类型土壤大豆种植生长,籽粒、茎秆和根部中氮、磷、钾和镁养分吸收量,以及籽粒产量都具有显著的影响。当镁肥施用量为60mg/kg土时,种植在褐土性土、栗褐土和潮褐土土壤上的大豆籽粒产量分别比对照增产15.53％、11.48％和15.52％。当镁肥施用量增加到180mg/kg土时,潮土的大豆籽粒产量比对照增产19.83％,而其它两种土壤大豆籽粒产量没有明显增加。从3种不同类型土壤对施用镁肥的响应来看,潮土表现好于栗褐土和褐土性土。本研究表明,在合理施用氮、磷和钾肥基础上配合施用适当的镁肥对交换性镁含量相对较高的土壤仍有一定的增产潜力。     

不同水氮供应对水稻产量、吸氮量及水氮利用效率的影响

通过两年在宁夏引黄灌区田间小区试验,以宁粳28号为材料,研究了3个不同灌水量与4个施氮水平对水稻产量、吸氮量及水氮利用效率的影响。结果表明,在相同灌水量条件下,两年水稻的籽粒和秸秆产量均随着施氮量的增加呈增加的趋势。不同灌水量对水稻产量影响不大,但施氮量却显著地影响着其产量和地上部吸氮量。灌水量或施氮量对水稻的株高、穗长、穗数和千粒重均无显著影响。05年和06年水稻氮肥利用率分别在5.1%~37.6%和14.1%~25.0%之间。相同施氮水平下,05年水稻氮肥生理利用率随着灌水量的增加而增加,06年水稻表现出相反的趋势。两年水稻的氮肥农学利用率在8.3~19.3 kg/kg之间。氮肥偏生产力在同一灌水水平下,都随着施氮量的增加而降低,在同一施氮水平下,灌水量处理间差异并不大。相同施氮水平下,水稻的灌水生产率随着灌水量的增加而降低。从产量、吸氮量及水氮利用效率等因素考虑,本试验水氮合理配比是灌水量控制在1.2×104 m3/hm2左右,施氮量240 kg N/hm2左右。