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.     

Die Wurzelentwicklung von Zuckerrübenpflanzen auf einem Sandlöß-Standort und ihre Bedeutung für die Stickstoffernährung

Root development of sugar beet plants on a sandy loess site with regard to nitrogen nutrition.
Root development of sugar beet plants in a sandy loess soil (Haplic Phaeozem) was observed from the early seedling stage up to harvest by measuring at first the greatest vertical and lateral extension of the root systems of single plants and later the rooting density of the whole plant stands (auger method, profile wall method).
During the seedling stage not only the subsoil, but also large parts of the topsoil between the plants remained unoccupied by the root systems. In this phase the greatest lateral extension of single roots reaches nearly the length of the greatest leaf of the plant. With the closure of the canopy the rooting density in the topsoil accounts to 1–2 cm cm⁻³.
In summer roots penetrate to a depth of 100–150 cm with rooting densities of 0.1 to 1 cm - cm⁻³. Thus, the plants gain not only access to water reserves, but sometimes meet remarkable amounts of nitrate which under the relatively dry conditions of the region tends to accumulate in 60–120 cm depth and – when taken up by the beet plants in the late stage of growth – affects crop quality negatively.     

Long-term application of animal slurries to grassland alters soil cation balance

Abstract. Soil samples from a 32-year grassland field experiment were taken from 0–5, 5–10, and 10–15 cm soil depths in February 2002. Plots received annual treatments of unamended control, mineral fertilizer, three rates of pig slurry and three rates of cow slurry, each with six replicates. Samples were analysed for cation exchange capacity (CEC), exchangeable cations (Na⁺, K⁺, Ca²⁺, Mg²⁺), pH and Olsen P. Exchangeable sodium percentage (ESP) was calculated as a sodicity indicator. Mean ESP was generally greater for slurry treatments than the control, with a trend of increasing ESP with application rate. This was particularly marked for cow slurry. At 0–5 cm depth ESP increased from 1.18 in the control to 1.75 at the highest rate of pig slurry and 5.60 at the highest rate of cow slurry. Similar trends were shown for CEC, exchangeable Na⁺, K⁺ and Mg²⁺, Ca²⁺ and Olsen P. The build-up of soil P due to slurry applications, together with this combination of physical and chemical factors, may increase the risk of P loss to surface waters, particularly from soils receiving high rates of cow slurry.     

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.     

温度和砷对不同品种水稻幼苗生长和砷吸收的影响

为明确温度和外源砷对水稻生长发育的影响,选取江苏地区常见的8个水稻品种为试验材料,通过添加不同浓度外源砷[0(As0)、0.5(As0.5) 和1 mg?L-1(As1)]和模拟不同温度[白天/夜晚分别为30 ℃/25 ℃（T0）和35 ℃/30 ℃（T1）],在人工气候箱内进行了发芽和苗期培养试验,并分析了8个品种水稻种子萌发、幼苗生长及砷含量状况。结果表明,外源砷对水稻的芽长和活力指数具有抑制作用,与对照（T0As0）相比,T0As1处理使不同品种水稻的芽长和活力指数分别降低13.69%~43.34%和28.14%~52.88%。 而温度对水稻种子萌发的影响与水稻品种有关。在T1处理下,盐两优1618的发芽率、芽长和活力指数均优于其他品种。温度和外源砷的共同作用显著降低了不同品种水稻的芽长（P<0.05）。与T0As0相比,T1As1使水稻芽长显著降低5.66%~43.34%。水稻根长和根系活力显著受到温度和外源砷的单一因素的影响。与T0As0相比,T0As1处理使水稻根系活力降低3.01%~58.21%。温度和外源砷的共同作用抑制了水稻根长和根系活力,其中T1As1使水稻根系活力显著降低53.80%~89.01%。不同品种水稻的苗高和根系活力在相同温度或外源砷处理下具有显著差异（P<0.05）,其中盐两优888的苗高和根系活力均处于较高水平。水稻茎叶砷含量在外源砷处理下显著增加,在增温处理下却降低。与单一的砷处理相比,温度和外源砷的共同作用降低了水稻茎叶的砷含量。综上可知,温度和外源砷影响水稻的生长及砷吸收,但水稻生长状况具有明显的品种间差异,其中盐两优888和盐两优1618在增温和外源砷共存条件下的种子萌发和生长状况优于其他水稻品种。     

An aggregation index (AI) to quantify spatial patterns of landscapes

There is often need to measure aggregation levels of spatial patterns within a single map class in landscape ecological studies. The contagion index (CI), shape index (SI), and probability of adjacency of the same class (Qi), all have certain limits when measuring aggregation of spatial patterns. We have developed an aggregation index (AI) that is class specific and independent of landscape composition. AI assumes that a class with the highest level of aggregation (AI =1) is comprised of pixels sharing the most possible edges. A class whose pixels share no edges (completely disaggregated) has the lowest level of aggregation (AI =0). AI is similar to SI and Qi, but it calculates aggregation more precisely than the latter two. We have evaluated the performance of AI under varied levels of (1) aggregation, (2) number of patches, (3) spatial resolutions, and (4) real species distribution maps at various spatial scales. AI was able to produce reasonable results under all these circumstances. Since it is class specific, it is more precise than CI, which measures overall landscape aggregation. Thus, AI provides a quantitative basis to correlate the spatial pattern of a class with a specific process. Since AI is a ratio variable, map units do not affect the calculation. It can be compared between classes from the same or different landscapes, or even the same classes from the same landscape under different resolutions.     

广西糯玉米品种种质构成及穗部性状选育探讨

对2011-2022年广西审定的173个糯玉米品种进行分析,研究广西糯玉米品种种质来源、构成,探析品种选育路径。结果表明,广西糯玉米主要种质由A (宜山糯)类、B (京科糯2000)类、C (万糯2000)类、D (燕禾金2000)类、E (中糯1号)类、F (中糯2号)类、G (衡白522)类、H (华珍)类、I (花甜糯179)类、J (NA群体)类、K (NB群体)类等11类种质构成,A、B类种质是广西糯玉米品种的基础种质。根据亲本主要种质类型,排除年份间的环境变化因素,可将93个品种归入AB等15个群组。各群组穗部性状相关分析表明,穗行数、穗粗与产量及其他穗部性状分别呈显著负效应及无显著效应,群组相关性受到种质组合及组配模式共同影响,通常情况下种质组合的影响力更强,涉及F类种质的群组则相反。因此,穗部性状选育重点要根据亲本主要种质类型确定。     

利用SNP芯片对部分黄淮海玉米自交系遗传多样性分析

利用4 434个SNP标记对47份玉米自交系进行种质遗传多样性和杂种优势类群研究。采用Admixture软件对自交系的遗传结构进行分析,采用Treebest软件对自交系进行聚类分析和类群划分。结果表明,47份自交系分为6个类群,分别为瑞德群、兰卡斯特群、塘四平头群、PB群、旅大红骨群和自330亚群。10个自选系组配的杂交种主要利用的杂种优势模式为PB×塘四平头和瑞德×塘四平头,均为近年来黄淮海地区主要利用的杂种优势模式。     

美洲斑潜蝇空间分布型研究

通过采用聚集度指标的方法,对美洲斑潜蝇在茄子、豆角田空间分布起先了系统研究,测定结果呈聚集分布,为田间调查及防治提供了依据。