Quantitative genetic parameter estimates for size and growth rate traits in Pacific white shrimp, Penaeus vannamei (Boone 1931) when reared indoors

Heritabilities of size traits and growth rate traits, as well as genetic, phenotypic and environmental correlations were estimated at three ages for a captive population of Pacific white shrimp (Penaeus vannamei) grown indoors. A covariate, mean size or mean growth rate during early growth in individual tanks before tagging and mixing, was introduced in the analyses to reduce the error caused by unique previous growth conditions on variance components. Heritabilities of size traits increased with age, with the h² for TL, AL, TWt and Wi1AS being 0.15, 0.20, 0.20 and 0.22, respectively, at 17 weeks, increasing to 0.28, 0.33, 0.34 and 0.35 at 29 weeks of age. Heritabilities of growth rate traits estimated between consecutive growth periods decreased from the first (h² for ΔTL 0.65, ΔAL 0.71, ΔTWt 0.63 and ΔWi1AS 0.84) to the second period (h² for ΔTL 0.34, ΔAL 0.50, ΔTWt 0.54 and ΔWi1AS 0.52). Phenotypic correlations were always larger than genetic correlations for both, size and growth rate traits. Genetic correlations between size traits within age were high (r_G >0.95), but those between the same size trait at different ages decreased as the age difference increased in spite of a consistently high environmental correlation (r_E 0.80–0.85) between the same trait at different ages. Phenotypic and genetic correlation's between the same growth rate trait at the two different growth periods evaluated were negative or zero (r_G TL –0.26, AL –0.24, Wi1AS 0.00) with the exception of total weight (r_G TW 0.35) and the environmental correlations between growth periods were also low (r_E 0.13–0.32).     

油茶F_1代苗木分级对盛果期生长量的影响初探

选择闽侯桐口林场油茶杂优F1代5个杂交组合,按造林苗木分级标准,同时视成活苗木具体数量将不同杂交组合的苗木分为3或4个等级,进行造林对比试验。在造林18年后的2003、2004、2005和2007年进行生长量调查,并对逐年树高、冠幅乘积和产果量进行方差分析和相关分析,结果表明:不同等级的苗木,对造林18-22年的生长量差异影响不显著,苗木分级与树高、冠幅乘积和产果量的相关性也不显著。     

广西罗城马尾松人工林林下植被生物量与丰富度的关系研究

为了促进生态系统的养分循环、能量流动和保持森林生态系统平衡,通过设立样地调查广西罗城马尾松人工林的丰富度和生物量。结果表明:共记录马尾松林下植物种类34种,隶属于26科31属。生活型以高位芽植物为主。马尾松幼龄林林下植被丰富度与其生物量间存在很好的正相关性,相关系数(R2)为0.853 5,中龄林和近熟林的相关系数分别为0.569 2和0.334 1。     

猪垫料用量对大杯香菇中主要矿物质元素与铅含量关联度的影响

【目的】研究猪垫料栽培大杯香菇子实体中主要矿物质元素含量与铅含量的关系,为大面积栽培铅含量更低的大杯香菇提供依据。【方法】通过在对照培养料(A0,10%)中添加质量分数为10%(A1)、20%(A2)、30%(A3)、40%(A4)、50%(A5)、60%(A6)、70%(A7)的猪垫料,进行大杯香菇栽培试验,采用灰色关联方法,分析各处理大杯香菇子实体中主要矿物质元素含量(铜、锰、铁、锌、钾、钙)与铅含量的关系。【结果】7个处理中,猪垫料用量对铅与各主要矿物质元素含量的关联系数影响顺序从大到小为:A2A3A7A0A6A4A1A5,其中A2处理关联系数最大,为0.811 3,A5处理关联系数最小,为0.485 0。猪垫料栽培大杯香菇子实体中的Zn含量与Pb含量关联度最大,为0.725 9,其次是Mn含量,关联度最小的是K含量。【结论】猪垫料用量对大杯香菇子实体中各种主要矿物质元素与铅含量关联系数有一定的影响,猪垫料栽培大杯香菇子实体中的Zn含量与Pb含量关系密切。     

新疆艾比湖流域耕地面积变化对艾比湖湖面面积的影响分析

基于1950～2009年艾比湖流域耕地面积与湖面面积历史数据和卫星影像数据,研究艾比湖流域耕地面积变化对艾比湖湖面面积的影响。结果表明,艾比湖每年3～4月湖面面积最大,而4月以后特别是7月后,湖面面积减小;2000～2009年艾比湖湖面面积最大的是在2003～2004年,湖面面积最小的是在2008～2009年,且湖面面积呈逐年减小的趋势;艾比湖流域的耕地面积不断增加,且增速逐年增长,以2005～2009年的增加速度最高;相关性分析显示,艾比湖流域耕地面积与湖面面积之间呈线性负相关,且显著相关,表明流域耕地面积的增加会直接导致湖面面积的减少。     

Age trends in the genetic parameters of wood density and the relationship with growth rates in hybrid larch (Larix gmelinii var. japonica × L. kaempferi) F1

Age trends in variance components and heritability of overall wood density, earlywood and latewood density, and latewood proportion were investigated in 29-year-old trees of 19 full-sib families of hybrid larch (Larix gmelinii var. japonica × Larix kaempferi) F₁. The age–age correlation and optimum selection age for these traits were also estimated and genetic and phenotypic correlations between wood density and radial growth rate were calculated for each growth ring. Intraring wood density data were obtained using X-ray densitometry. The coefficient of additive genetic variance was stable over all ages, whereas the coefficient of environmental variances gradually decreased with increasing age, resulting in increases in heritability estimates with age for overall density. The latewood proportion had the highest heritability estimates at all ages, ranging from 0.44 to 0.66. Overall density and its various components at 28 years of age showed strong genetic correlations with their respective traits at all younger ages. Optimum selection ages for the wood density traits ranged from 8 to 14 years, at which point maximum gain efficiencies per year were obtained. There were negative correlations between wood density and radial growth rate at early ages, although these relationships tended to be weaker with increasing age. These results suggest that selection at a young age is effective for wood density, but particular care must be taken in selecting trees with an improved radial growth rate because rapid growth will result in a low-density wood product, especially in the early growth period.     

具有风险相依结构的平衡信度估计

在保险实务中,风险之间具有一定的相依结构. 通过考虑保费的目标估计来对风险保费进行了研究,采用正交投影的方法求解了最优问题,在平衡损失函数下得到了风险等相关的齐次和非齐次信度估计. 结果表明得到的信度估计具有经典信度模型的加权形式.     

不同覆土厚度对伊犁地区公路护坡植被质量的影响

为提高伊犁地区公路建设中的边坡植被防护质量,促进公路建设与生态环境的和谐发展,依托S242线巩留至尼勒克公路开展了实地边坡试验,利用灰色关联度的分析方法,对5 cm、10 cm、15 cm、20 cm四种表土回填厚度处理的边坡植被建植质量进行了研究。结果表明：随着覆土厚度的增加,公路边坡护坡植被质量逐渐增加,土壤砂粒减小了15%~23%,粉粒含量增加了18%~23%,土壤质地由壤土转变为粉砂质壤土;不同处理下的土壤孔隙度、土壤抗蚀指数、土壤抗冲系数差异显著,其对应的灰色关联度值分别为0.74,0.72,0.71,相比其他指标对护坡植被质量的影响更大;覆土20 cm小区的综合评判值G （k）最大（0.83）,说明在本研究中覆土20 cm小区的护坡植被质量最好。