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.     

麻类纤维在非织造领域的应用

本文阐述了麻类纤维在我国非织造行业新用途的开发和拓展，对麻类纤维在非织造领域的利用符合国家农业可持续性发展的方向。     

Growth of triploid oyster, Crassostrea madrasensis (Preston)

The performance of I and II meiotic triploids and control oysters (Crassostrea madrasensis) reared at Tuticorin Bay was compared to determine if the improvements in the growth of edible oysters were additive to faster growth in triploids. After a grow‐out period of 12 months, both mean whole weights and shell heights were in order I meiotic triploid>II meiotic triploid>control. Mean whole weights and shell height of different oyster lines were all significantly different (P<0.05). On an average, larger morphological traits indicated that growth improvements from triploids were additive, and throughout the study triploid oysters maintained faster growth rate than their diploid siblings. Condition index and adductor muscle diameter of both triploids were higher than those of control.     

关于核密度具有间断点的Cauchy主值积分

讨论在实轴上核密度具有无穷个间断点的Ｃａｕｃｈｙ主值积分的性质，在一定条件下，得到了一些结果。     

Relating Kirtland's warbler population to changing landscape composition and structure

The population of male Kirtland's warbler (Dendroica kirtlandii) in the breeding season has averaged 206 from 1971 to 1987. The Kirtland's warbler occupies dense jack pine (Pinus banksiana) barrens from 5 to 23 years old and from 1.4 to 5.0 m high, formerly of wildfire origin. In 1984, 73% of the males censused were found in habitat naturally regenerated from wildfire or prescribed burning. The rest were in plantations (11%) or in harvested, unburned jack pine stands stocked by natural regeneration (16%). Twenty-two percent (630 of 2,886) of the Kirtland's warbler males counted in the annual censuses from 1971 through 1984 were found in 26 stands that were unburned and naturally regenerated following harvest. From 1982 to 1987, suitable regenerating areas were barely sufficient to replace currently occupied maturing stands, so population growth was impeded. Ecosystems of suitable size and regeneration characteristics (wildfire and plantation) doubled in area by 1989. In response, the population of Kirtland's warblers increased from 167 to 398 males between 1987 and 1992, but they withdrew almost entirely from the unburned, unplanted barrens by 1989 when the area of more suitable regeneration types increased. Minimum (368 males) and maximum (542 males) population estimates for 1996 were calculated based on 1984 average density (1.9 males per 40 ha) and peak population in burns (2.8 males per 40 ha).     

Growth,Meat Yield,and Economic Responses of Broilers Provided Three- and Four-Phase Schedules Formulated to Moderate and High Nutrient Density During a Fifty-Six-Day Production Period

This study examined growth responses and meat yield of broilers provided a 3- or 4-phase feeding schedule formulated to moderate or high nutrient density. Four dietary treatments were implemented consisting of high or moderate nutrient density diets that were provided for the duration of 3 phases (1 to 17, 18 to 35, and 36 to 56 d) or 4 phases (1 to 17, 18 to 35, 36 to 46, and 47 to 56 d).Provision of a 3-phase schedule did not alter growth performance, meat yield, or diet cost per final BW. Broilers receiving high nutrient diets had improved growth rate and feed conversion from 1 to 35 d. In the 3-phase schedule, birds given the high nutrient density diets had advantages in BW gain and pectoralis minor breast weight. Market changes in meat prices impact differences in gross feeding margins between diets formulated to high or moderate nutrient density more than variation in diet cost.     

Reproductive roles predict sexual dimorphism in internal and external morphology of lake whitefish,Coregonus clupeaformis

Abstract – The different reproductive roles of the sexes can predict the direction and magnitude of sexual dimorphism of external and internal morphology. Males should have enlarged structures that enhance the acquisition of mating opportunities, whereas females are predicted to have enlarged organs that are associated with the production of eggs. We tested these predictions in male and female lake whitefish, a species in which both sexes have similar overall body size and shape. After controlling for body size, male lake whitefish had significantly longer jaws and pectoral and pelvic fins, larger hearts, and more muscle than females. Sexual dimorphism in relative muscle mass may be one of the most fundamental morphological differences between males and females. Females had relatively heavier livers than males. Because the liver is important for the breakdown of fats and vitellogenesis, selection should favour an enlarged liver in females for the processing of energy and the production of large numbers of eggs.     

Evaluation of Five Most Commonly Grown Cotton Cultivars (Gossypium hirsutum L.) Under Mediterranean Conditions: Productivity and Fibre Quality

Studies were conducted in four regions of central Greece (Larisa, Karditsa, Livadia, Thiva), to evaluate the productivity and fibre properties (fibre strength and fibre length) of the five most commonly grown cotton cultivars in these regions. The experiments lasted for 6 years (1995–2000). All the characteristics tested were strongly influenced by the factors ‘year’, ‘cultivar’ and ‘region’. Significant cultivar × region, year × cultivar, region × year and cultivar × region × year interactions occurred for all the characteristics studied. The cultivar Alegria had the highest seed‐cotton and lint yield, while Aria had the lowest ones. Both cultivars gave the highest mean lint percentage but the lowest mean boll weight (MBW). Alegria had the lowest fibre strength, while Aria had the highest. The Acala‐type cultivars, Acala SJ2 and Zeta 2, had intermediate seed‐cotton and lint yield, while Vered 171 had high seed‐cotton and satisfactory lint yield. The three cultivars mentioned above had the highest MBW and very good fibre strength. Positive correlation was observed between fibre strength and length. In spite of the fact that mean fibre length was statistically the same in all cultivars, it was influenced by the factor ‘year’, as a result of different weather conditions. The year 1996 was the most unfavourable one for seed‐cotton yield and MBW, because it was characterized by lower than average air temperatures and rather dry conditions for all study sites. The factor ‘region’, a combination of different climatic conditions and cultural practices, influenced significantly all the parameters studied.     

夏直播花生规范化栽培密度与氮肥优化配置研究

采用二次饱和D—最优设计建立了密度和N肥用量与夏直播花生产量的数学模型。进一步分析表明，密度与N肥用量呈负交互效应，肥料用量增加，花生密度可适当减少。密度与N肥用量的最优组合为每公顷播15．36万穴，施纯N99．6kg，最高产量可达到5527．0kg。公顷产量在4500~5527kg范围内的措施组合为：每公顷播15．O～18．7万穴，施纯N65．1～124．4kg。     

In situ radiometric mapping of soil erosion and field-moist bulk density on cultivated fields

Abstract. Recent developments in in situγ ray spectrometry offer a new approach to measuring the activity of radionuclides such as ¹³⁷Cs and ⁴⁰K in soils, and thus estimating erosion or deposition rates and field moist bulk density (ρ_m). Such estimates would be rapid and involve minimal site disturbance, especially important where archaeological remains are present. This paper presents the results of a pilot investigation of an eroded field in Scotland in which a portable hyper pure germanium (HPGe) detector was used to measure γ ray spectra in situ. The gamma (γ) photon flux observed at the soil surface is a function of the ¹³⁷Cs inventory, its depth distribution characteristics and ρ_m. A coefficient, Q_Cs, derived from the forward scattering of ¹³⁷Cs γ ray photons within the soil profile relative to the ¹³⁷Cs full energy peak (662 keV), was used to correct the in situ calibration for changes in the ¹³⁷Cs vertical distribution in the ploughed field, a function of tillage, soil accumulation and ρ_m. Based on only 8 measurements, the agreement between in situγ ray spectrometry and soil sample measurements of ¹³⁷Cs inventories improved from a non significant r²=0.05 to a significant r²=0.62 (P<0.05). Erosion and deposition rates calculated from the corrected in situ¹³⁷Cs measurements had a similarly good agreement with those calculated from soil cores. Mean soil bulk density was also calculated using a separate coefficient, Q_K, derived from the forward scattering γ photons from ⁴⁰K within the soil relative to the ⁴⁰K full energy peak (1460 keV). Again there was good agreement with soil core measurements (r²=0.64; P<0.05). The precision of the in situ¹³⁷Cs measurement was limited by the precision with which Q_Cs can be estimated, a function of the low ¹³⁷Cs deposition levels associated with the weapons testing fallout and relatively low detector efficiency (35%). In contrast, the precision of the in situ ρ_m determination was only limited by the spatial variability associated with soil sampling.