Effects of gamma irradiation on in vitro pollen germination of different Cucumis species

Summary Pollen grains of 14 Cucumis accessions were irradiated with 0, 1, 2, 3 or 4 kGy acute gamma rays and germinated in vitro directly afterwards. Pollen germination was significantly reduced by increasing irradiation dose for all species, except C. melo var. agrestis. Pollen tube growth was generally reduced likewise. Pollen of two C. anguria subspecies was most sensitive to irradiation. Sensitivity of the pollen with respect to pollen tube growth in relation to irradiation dose was inversely related to total DNA amount per nucleus. In vitro germination was not related to DNA amount per nucleus. Results show that the examined Cucumis species, especially C. melo var. agrestis, are sufficiently resistant to irradiation to be used as donor species for in vivo egg cell transformation of the cucumber.     

Weibull and percentile models for lidar-based estimation of basal area distribution

Abstract

The aim of this study was to assess the accuracy of basal area distributions of sample plots in coniferous forest derived from small-footprint airborne laser scanner data, and to compare the accuracy of two methods for derivation of such distributions based on: (1) two percentiles of a two-parameter Weibull and parameter recovery, and (2) a system of 10 percentiles defined across the range of observed diameters. The 12 percentiles were derived from the empirical basal area distributions of 141 plots with size 300–400 m². Regression analysis was used to relate the percentiles to various canopy height and canopy density metrics derived from the laser data. On average, the distance between transmitted laser pulses was 0.9 m on the ground. The plots were divided into three strata according to age class and site quality. The stratum-specific regressions explained 7–91% of the variability. Total plot volume predicted from the estimated distributions was used to assess the accuracy of the regressions. Cross-validation of the regressions revealed a bias of ?1.2 to 2.1% between predicted and ground-truth values of plot volume. The standard deviations of the differences between predicted and ground-truth values of plot volume were 15.1–16.4%. Neither bias nor standard deviation differed significantly between the two validated methods.     

The Use of Antigen-capture Enzyme-linked Immunosorbent Assay (ELISA) for the Diagnosis of Rinderpest and Peste des Petits Ruminants in Ethiopia

Rinderpest had been reported in most parts of Ethiopia when the Pan African Rinderpest Campaign (PARC) was launched. As a result of intensive disease investigation and strategic vaccination, most parts of the country are now considered provisionally free, and widespread vaccination has been replaced by clinical and serological surveillance. Details of any episodes of disease are recorded and followed up after laboratory confirmation of suspected cass using antigen-capture ELISA. This paper is based on observations on the performance of the antigen detection ELISA compared to the agar gel immunodiffusion (AGID) test, which also differentiates rinderpest from peste des petits ruminants (PPR). The stability of the specific viral antigen was monitored for 4 days, and rinderpest and PPR antigens were still detected, depending on the type of specimen. Antigen capture ELISA is more rapid, sensitive and virus specific than the AGID. Even if the cold chain of the specimen is compromised for a day or two during sample collection and submission, the specimen may still be suitable for testing by ELISA.     

Pacific sand lance of the Port Moller estuary, southeastern Bering Sea: an estuarine^dependent early life history

Three waves of spawning Pacific sand lance (Ammo-dytes hexapterus) entered the Port Moller estuary from mid-January to late May 1990. Each wave laid its eggs on sand in lower Moller Bay with the center of egg distribution about 14 km inside the estuary. After incubation for 45 to 94 d, each cohort of eggs hatched out over a 41- to 63-d period. Larvae moved at a rate of 0.21 knvd“¹ toward a deep fjordlike basin at the head of Herendeen Bay inside the estuary about 20 km southwest of the center of hatch. The basin has the lowest flushing rate of the estuary, and unlike the rest of Port Moller, it is vertically stratified, which allows the development of a spring-summer zooplankton community with greater biomass than any other location in the estuary. Larvae may have moved to the basin to enhance growth or to avoid offshore transport to areas of low food abundance, but we cannot demonstrate a direct link between growth and habitat. We conclude that the Port Moller sand lance stock has an estuarine early life history that evolved in response to the unique physical conditions of the Port Moller estuary–a shallow, well-mixed site with sandy substrate that is suitable for incubation of demersal eggs next to a deep, vertically stratified fjord with a rich zooplankton community that is suitable for rearing of larvae.     

林木生长与养分动态模型研究Ⅲ.生长方程的假设与前提

结合实例对吴和胡提出的杉木直径、高和蓄积生长方程的基本假设和边界条件进行了详细的说明和论证,并在直径和高生长方程的基础上给出了杉木径高比系数的动态方程．径高比系数随树龄增长而递减的规律表明杉木直径和高的生长速率递减存在不同步现象,产生这一现象的主要原因是林木生长的平面限制效应大于高度限制效应,因此,森林蓄积增长的主要限制因子是树木的直径生长速率．     

陕北风沙滩区胡萝卜标准化栽培技术

为了确保并发掘陕北风沙滩区胡萝卜的产能优势,克服近年来随着种植面积的扩大,生产中出现的费工、费水、费肥,产品商品率及销售价格偏低,种植效益不显著等严重的问题,榆林市农业科学研究院从新技术应用、高标准管理入手,对胡萝卜生产过程中的茬口安排、播前准备、机械化播种、田间管理、病虫害防治、采收贮藏等方面进行了规范与总结,集成了一套陕北风沙滩区胡萝卜标准化栽培技术,用于指导风沙区域胡萝卜生产,促进胡萝卜产业的提质增效,从而实现农民的增产增收。     

Evaluating naturalness and functioning of urban green infrastructure

Evaluating the state of urban green infrastructure (UGI) is a basic step to reach urban sustainability. Two indicators were used to evaluate 89 UGI sites in Zaragoza, a medium-sized city in NE Spain: Naturalness (Nat), related to the area covered by natural components; Functioning (Fun), related to the area showing natural hydro-geomorphological features. Complementarily, 15 biophysical and social variables were used to characterize these sites. A principal component analysis (PCA) was performed to group variables and types of UGI, while linear regressions and ANOVAs were applied to identify relationships between UGI characteristics, Nat and Fun.The Zaragoza UGI was dominated by artificial regular sites. Most sites (73%) have low-medium values of Nat and Fun. They were mostly flat urban parks with very regular forms located in the most densely urbanized zones, and 20% of the sites have high values of Nat and Fun, corresponding to well-conserved natural areas, either unchanged or slightly transformed. Only 3 sites displayed high Nat values and low Fun values. No sites had high Fun values and low Nat values. These groups of UGI sites were mostly distributed along the first axis of the PCA which represented the natural and heterogeneous forms versus regularity and flatness features. The UGI sites scattered throughout the second axis represented a gradient from paved to vegetated sites. Both Nat and Fun were positively correlated with area, natural subsoil and the area covered by vegetation but negatively with artificial soil, regularity and flatness after the linear regressions and ANOVAs.These results show that Nat and Fun are effective indicators to assess UGI sites. Minimizing regularity of design, preserving the natural topological relief, and restricting the area covered by artificial components are suggested to achieve a balanced representation of ecosystem processes, functions, and services within the UGI network of a city.     

Effects of Dietary Ampitheoe sp. Powder on Growth and Lipid Contents of Litopenaeus vannamei北大核心CSCD

This experiment was conducted to investigate the effects of dietary Ampitheoe sp. powder on the growth and the contents of astaxanthin, triglyceride (TG), total cholesterol (TCHO) and fatty acids of Litopenaeus vannamei. A total of approximately 6 777 L. vannamei with an initial body weight of (1. 80 ± 0.72) g were randomly divided into 3 groups, and there were 3 replicates (753 shrimp per replicate) in each group. Those shrimp fed diets containing 0 (D0 group), 8. 25% (D8. 25 group) and 33% (D33. 00 group) Ampitheoe sp. powder, respectively. The feeding trial lasted for 40 days. The results showed as follows: 1) the final body weight, weight gain rate, specific growth rate, yield and survival rate in D33.00 group were significantly higher than those in D0 group (P <0.05), whereas the feed conversion ratio was significantly lower than that in D0 group (P <0.05) . However, there was no significant difference between D33.00 group and the D8. 25 group in those indexes (P >0.05) . 2) The astaxanthin content in carapace, hepatopancreas and muscle of L. vannamei in D8.25 and D33. 00 groups was significantly higher than that in D0 group (P < 0. 05); that in D33.00 group was significantly higher than that in D8. 25 group (P < 0. 05) . 3) TG content in haemolymph, hepatopancreas and muscle in D8. 25 and D33. 00 groups was significantly lower than that in D0 group (P < 0.05); the TCHO content in hepatopancreas in D8. 25 group was significantly higher than that in D0 and D33.00 groups (P <0.05); TCHO content in muscle in D33.00 group was significantly higher than that in D0 group (P <0.05) . 4) The contents of eicosapentaenoic acid (EPA) and arachidonic acid (AA) in hepatopancreas in D33.00 group were significantly higher than those in D0 group (P <0.05) . The EPA content in muscle in D33.00 group was significantly higher than that in D0 group (P < 0. 05) . In conclusion, adding Ampitheoe sp. powder into the diet can improve the growth performance, the contents of astaxanthin, EPA and AA in L. vannamei, and affect the accumulation of TG and TCHO, which can be used as a functional diet in aquaculture. Considering the cost, the supplementation level of 8. 25% Ampitheoe sp. powder is more appropriate. © 2023 Chinese Journal of Pediatric Surgery. All rights reserved.     

贵州省万峰湖库区农业面源污染防治技术集成研究

采用多学科的综合性集成技术是治理万峰湖水体面源污染的根本措施。通过技术的实施，使人畜粪便基本得到有效处理，坡耕地水土流失得到有效控制，化肥、农药施用量及作物秸秆利用更趋合理，网箱养鱼方式的转变使饲料过量投放得到有效控制，水体污染风险显著降低。农民的经济及生态效益明显提高，生活环境显著改善。     

植物生长物质对黄瓜植株性别分化的影响

综述了植物生长物质如乙烯、赤霉素、生长素、多胺和油菜素内酯等对黄瓜性别分化的影响,同时介绍了黄瓜性别分化的分子机理研究概况,并提出了今后的研究方向。