Soil physical changes and maize growth in a structurally fragile tropical soil due to mulching and duration between irrigation intervals

Under tropical meteorological conditions, the volume of soil explored by plant roots is crucial for crop growth as it allows increased water and nutrient use efficiency. We hypothesized that, under different irrigation intervals, leguminous mulch can extend the duration between irrigation events but maintain crop performance, because decreased evaporative fluxes also reduce constraints to root exploration imposed by mechanical stress. We evaluated the combined effects of leguminous mulch and irrigation intervals on soil physical properties to determine whether the growth and productivity of maize were modified in a structurally fragile tropical soil. The experiment involved the following treatments: 4‐day irrigation intervals with soil mulched (4C) or bare (4S), 6‐day irrigation intervals with soil mulched (6C) or bare (6S), 8‐day irrigation intervals with soil mulched (8C) or bare (8S) and 10‐day irrigation intervals with soil mulched (10C) or bare (10S). Mulch decreased soil penetration resistance and increased to 4 days the favourable time for root development in drying soil. Relative to bare soil, mulch with a 6‐day irrigation interval almost doubled nitrogen uptake post‐tasselling, which decreased nitrogen remobilization and increased the crop growth rate during this stage. These conditions had a positive effect on the transpiration rate and stomatal conductance as well as on the growth and yield of maize. A 6‐day irrigation interval with mulch compared to 4 days with bare soil resulted in similar conditions for root development, but greater uptake of nitrogen (102.73–78.70 kg/ha) and better yield (6.2–5.3 t/ha), which means greater efficiency in nitrogen and water use.     

苹小卷叶蛾在6个苹果品种上的发育与繁殖

为探索不同品种苹果对苹小卷叶蛾生长发育和繁殖的影响,在温度(26±1)℃、相对湿度(80±5)%、光周期L∶D=16 h∶8 h的室内条件下,测定了苹小卷叶蛾在小国光、大国光、红玉、祝光、红星和金帅上的发育历期、存活率和产卵量,并组建了其各自的生命周期表。结果显示,苹小卷叶蛾在6个品种上的发育历期差异显著,全世代发育历期以小国光最短(33.95 d),以红玉最长(39.76 d);平均单雌产卵量以红玉最高(107.24粒),小国光次之(85.00粒);而存活率则无显著差异。生命表参数中净生殖率(R0)、内禀增长率(rm)和周限增长率(λ)均以小国光最高,世代平均周期(T)和种群加倍时间(Dt)以小国光最短,表明6种试验品种中小国光是苹小卷叶蛾最适宜的寄主品种。     

Effect of dietary Moringa stem meal level on growth performance,slaughter performance and serum biochemical parameters in geese

Moringa stem meal (MSM) with a high level of crude fibre (CF) might be developed and utilized in herbivorous geese as an unconventional feedstuff. The aim of this study was to investigate the effect of the MSM level in the diet on the growth performance, slaughter performance, breast meat quality and serum biochemical parameters in geese from 22 to 70 days of age. A one-factor completely randomized design was adopted in our study. A total of one thousand eight 21-day-old geese were randomly divided into six groups, with six replicates per group and 28 birds per replicate. The geese were fed diets containing MSM levels of 0, 20, 40, 60, 80 or 100 g/kg during day 22–70. The dietary MSM level had no effect (p > .05) on the final body weight (BW), average daily gain (ADG) or average daily feed intake (ADFI). The feed/gain ratio (F/G) increased linearly (p < .001) as the dietary MSM level increased. No differences (p > .05) were observed in the slaughter performance, meat quality and the relative organ weight (except for thymus) of the geese (p > .05). The relative weight of the thymus in the geese fed diets with supplementation of MSM was higher than that in the non-supplemented MSM control group (p < .05). In addition, 100 g MSM/kg of diet decreased the serum glucose (GLU) level (p < .05) and increased the alanine transaminase (ALT) enzyme activity (p = .03). Dietary MSM levels of no more than 60 g/kg had no effects on the growth performance and slaughter performance, whereas diets with 100 g MSM/kg increased the F/G and serum ALT enzyme activity, as well as decreasing the serum GLU level. Therefore, MSM provided at a reasonable level could be developed as an unconventional feedstuff for geese at the finisher period.     

提高小麦单产的田间排水暗管规格模拟

改进内蒙古河套灌区田间排水系统的规格对灌区提升作物产量和保障粮食生产有重要现实意义,因此,在河套灌区对所构建的分布式SWAP-WOFOST模型进行了参数率定和验证,然后,对2000—2010年灌区春小麦种植条件下适宜的田间排水暗管规格进行探讨,并模拟评价了该条件下作物产量和水分生产力(WP)的时空分布特征。结果表明,所构建的分布式模型在河套灌区具有较高的适应性。春小麦种植条件下,灌区大部分耕地面积推荐采用田间排水暗管的规格为间距100.0m或75.0m,埋深为2.5m。相比现有排水系统,采用推荐的排水暗管规格,春小麦多年平均作物产量提高了18.5%,多年平均WP提高5.2%。研究结果为进一步改进灌区田间排水系统的效果提供了一定的参考。     

基于响应面法和NSGA-II算法的麦弗逊悬架优化

应用响应面法和经过改进的非支配排序遗传算法(NSGA-II)进行悬架结构参数优化.在ADAMS/Insight软件中进行设计参数的灵敏度分析，针对灵敏度较大的设计参数，建立车轮定位参数在车轮跳动过程中最大变化量的2阶响应面近似数学模型对该模型进行稳定性分析，并且应用加入精英保持策略和去除重复个体算法的NSGA-II优化算法对多目标响应面模型进行优化求解.优化结果表明该方法具有较高的精确性与有效性.     

长白和大白猪主要生长性状的遗传参数估计

旨在分析母猪的出生年份、出生季节、初生重、开测日龄等固定效应对长白、大白猪主要生长性状的影响,并对目标生长性状进行遗传参数估计（遗传力、遗传方差、表型相关和遗传相关）,为猪的遗传改良提供基本依据。本试验利用GLM模型分析试验猪群（398头长白猪和1 176头大白猪）的固定效应对猪生长性状的影响,并采用多性状动物模型对目标性状进行遗传参数估计。目标生长性状包括达100 kg体重日龄（age to 100 kg,AGE）、达100 kg背膘厚（backfat to 100 kg,BF）、100 kg平均日增重（average daily gain to 100 kg,ADG）。研究表明,在大白和长白猪中,猪的出生年、出生季、初生重以及开测日龄对生长性状均具有极显著的影响（P<0.001）;长白猪的AGE、ADG和BF的遗传力分别为0.321、0.327和0.324,大白猪对应性状的遗传力分别为0.454、0.469和0.408;长白猪的ADG和AGE之间的遗传相关、表型相关分别为-0.990、-0.995,大白猪的ADG和AGE之间的遗传相关、表型相关分别为-0.993、-0.998,均呈现较强的负相关。长白、大白猪的生长性状（AGE、ADG、BF）均属于中等遗传力性状,其出生年份、出生季节、初生重和开测日龄对猪的生长性状影响较大。在遗传参数估计分析时,提高样本数量并提升表型数据质量,可以增加遗传参数估计的可靠性。本研究中的生长性状遗传参数估计结果较为可靠,可为后续的遗传改良提供参考。     

Molecular characterisation of Theileria equi and risk factors associated with the occurrence of theileriosis in horses of Punjab (Pakistan)

Theileria equi (T. equi) is an obligate intra- and extra-erythrocytic parasite that causes equine theileriosis (ET) in equids. Equine theileriosis is considered a notifiable disease of global significance, a major constraint to the international movement of horses, and endemic in many countries. This disease may be difficult to diagnose, as it can produce variable and nonspecific clinical signs. A cross-sectional study was designed for the molecular characterisation of T. equi and to investigate the associated risk factors of ET accompanied by its consequences on haematological and sero-biochemical parameters. A convenience sampling of 500 blood samples were collected from ET suspect horses from January to December 2017. PCR was performed on all blood samples targeting the 18S rRNA gene of T. equi followed by sequencing; 9% animals tested positive with confirmed sequences. The isolates of this study showed high homology with Cuban, Russian and Brazilian isolates of T. equi (accession numbers KY111762.2 , MG551915.1 and KY952237.1 , respectively). Based on multivariate analysis, the principal risk factors consisted of absence of dogs on the premises and presence of tick infestation. The haemato-biochemical parameters showed a decrease in granulocytes and erythrocytes, and an increase in lymphocytes, monocytes, mean corpuscular volume, mean corpuscular haemoglobin, mean platelet volume, glucose, phosphorus and aspartate aminotransferase in positive horses. This is the first study which identified ET in Punjab (Pakistan) using molecular techniques and risk factors together with the haemato-biochemical variations in horses.     

计算机视觉技术在智慧羊场中的研究进展

智慧羊场具有科学化、标准化管理的优点,是羊场转型发展的趋势。计算机视觉技术是人工智能的核心,可以实现非接触性、自动化、实时监测羊的个体信息。本文总结并分析了计算机视觉在羊场的个体识别方法、行为识别方法、体尺与体重估测、疾病监测的研究现状,并指出计算机视觉在智慧羊场的进一步发展趋势。 [关键词] 计算机视觉|智慧羊场|个体识别|行为识别|体尺与体重估测|疾病监测     

三种荒漠植物叶绿素荧光参数日变化特征

利用Photosynq MultiseQ多功能植物测量仪测定塔克拉玛干沙漠腹地3种主要防护林植物头状沙拐枣、多枝柽柳和梭梭的叶绿素荧光参数日变化,探讨其与环境因子的关系,以揭示3种植物对极端环境的适应策略,为沙漠公路防护林的管护提供理论依据。结果表明：1）3种土壤都呈碱性;0~30 cm土层中的电导率（EC）远高于30 cm以下的土层。1 m内梭梭土层中的含水量高于多枝柽柳高于头状沙拐枣。2）3种植物的光合有效辐射（PAR）、叶片温度和线性电子传递（LEF）及植物周围的大气温度日变化均先升后降,且都在14：00达到最高;而大气湿度、实际光化学效率Y_（II）日变化均呈‘V’型。3）PAR基本上与3种植物的LEF、非光化学淬灭系数（NPQ）、调节性能量耗散量子产量Y_（NPQ）、非调节性能量耗散量子产量Y_（NO）呈显著正相关,与实际光化学效率Y_（II）呈显著负相关;3种植物的Y_（II）与Y_（NPQ）、Y_（NO） 均呈极显著负相关。3种植物的LEF、Y_（II）、Y_（NPQ）的日均值差异不显著,但梭梭与多枝柽柳的NPQ和Y_（NO）日均值差异显著。4）在3种植物的叶绿素荧光参数中,梭梭和头状沙拐枣的LEF、NPQ和Y_（II）要高于多枝柽柳;而多枝柽柳的Y_（NO）要显著高于头状沙拐枣和梭梭。因此,高温和高光均对3种植物造成了不同程度的影响,通过主成分分析表明,3种植物的抗逆性强弱顺序分别为梭梭>头状沙拐枣>多枝柽柳。     

返青期休牧对退化高寒草地植被特征及优势种光合生理的影响

为探讨返青期休牧对退化高寒草地植被特征及优势种光合生理的影响,本研究在祁连山区选择已实施返青期休牧6年的高寒草甸开展了植被特征及优势种光合生理相关指标的调查研究。结果表明：返青期休牧6年后,高寒草甸的植被盖度、地上生物量、地下生物量和土壤含水量较未休牧区分别增加了38.44%,985.00%,209.56%和62.62%,其优势禾草垂穗披碱草（Elymus nutans）株高、叶片净光合速率、光化学量子效率、呼吸速率、叶面积、相对叶绿素含量和叶片氮含量分别提高了965.77%,139.86%,4.92%,269.37%,254.13%,197.02%和96.24%（P<0.05）,其地上地下生物量与除叶温和光化学猝灭系数外的指标显著相关,叶片净光合速率与除叶温外的指标显著相关。因此,返青期休牧可显著增强高寒草地优势禾草的光合作用和呼吸作用,促进植物生长及退化草地的恢复。本研究为推广实施返青期休牧这一措施来恢复退化高寒草地植被提供了理论基础。