Tagging quantitative trait loci for dormancy, tuber shape, regularity of tuber shape, eye depth and flesh colour in diploid potato originated from six Solanum species

Potato breeding aims at breeding diversified cultivars not only suitable for different purposes, but also resistant to diseases, such as late blight caused by Phytophthora infestans , which is a major constraint in potato production. Resistance to P. infestans has been previously introduced into the diploid hybrid population 98-21 from Solanum verrucosum and Solanum microdontum . In the present study, we assessed the segregation of tuber dormancy, tuber shape, regularity of tuber shape, eye depth and flesh colour in this population. Quantitative Trait Loci (QTLs) affecting these important quality traits were tagged using the genetic map developed for this population to locate QTLs for late blight resistance. The most prominent QTL for dormancy was detected on chromosome II and explained 7.1% of the variance. The most important QTLs for tuber eye depth, flesh colour, shape and shape regularity were identified on chromosomes X ( R ² = 14.7%), IV ( R ² = 5.8%), II ( R ² = 8.0%) and III ( R ² = 10.4%) respectively. All traits were also affected by minor QTLs. The obtained results improve our understanding of the inheritance of traits relevant for variety development in potato.     

Regional mixed-effects height–diameter models for loblolly pine (<Emphasis Type="Italic">Pinus taeda</Emphasis> L.) plantations

A height–diameter mixed-effects model was developed for loblolly pine (Pinus taeda L.) plantations in the southeastern US. Data were obtained from a region-wide thinning study established by the Loblolly Pine Growth and Yield Research Cooperative at Virginia Tech. The height–diameter model was based on an allometric function, which was linearized to include both fixed- and random-effects parameters. A test of regional-specific fixed-effects parameters indicated that separate equations were needed to estimate total tree heights in the Piedmont and Coastal Plain physiographic regions. The effect of sample size on the ability to estimate random-effects parameters in a new plot was analyzed. For both regions, an increase in the number of sample trees decreased the bias when the equation was applied to independent data. This investigation showed that the use of a calibrated response using one sample tree per plot makes the inclusion of additional predictor variables (e.g., stand density) unnecessary. A numerical example demonstrates the methodology used to predict random effects parameters, and thus, to estimate plot specific height–diameter relationships.     

北京市园林植物个体大小及株数分布等相关特性的研究

采用抽样调查方法,设置了138个样点,调查了2 789株样木的胸径(地径)、树高、冠幅直径等指标,对北京市城区现有园林植物的个体大小(胸径、树高、冠幅)、平均状况、按直径株数分布、按树高株数分布、径高关系模型、直径冠幅模型等进行了研究,探讨了园林植物与自然条件下植物截然不同的统计特性。     

平原地区杨树人工林阳性冠幅与胸径关系的研究

通过对100株中林46杨树人工林的调查,研究了平原地区杨树人工林阳性冠幅与胸径之间的关系。结果表明:两者之间存在着相当紧密的线性相关关系,其相关线性模型为y=-2.254+0.432x,相关系数为0.9043。     

湖北恩施种源红椿不同家系育苗试验初报

为了给湖北乡土树种红椿资源保护及开发利用提供基础数据,本研究以湖北恩施的6个红椿半同胞家系为材料,对其1年生实生苗木进行了生长量调查和分析,结果表明,6个不同红椿家系间当年生苗高、地径、叶长、叶宽、叶长宽比的差异均达到了显著水平,其中表现较好的是红椿2和3号家系.本研究取得的苗期生长数据在一定程度上客观反映了恩施红椿种源在武汉地区的适应性,可为今后武汉周边地区发展利用红椿提供良好借鉴.     

陕西地区马陆的发生规律及防治技术

通过对陕西地区马陆的形态特征及生物学特性进行概述,分析其危害特点和发生规律,从农业防治、人工防治、化学防治三方面给出综合防治的措施和建议.     

氮磷钾配比施肥对银杏幼苗生长的影响

为了筛选我国北方地区彩叶树种银杏生长中较好的施肥配方,开展了氮磷钾3因素3水平的施肥正交试验,结果表明:氮磷钾不同配比处理对银杏树高、地径、叶片生长等生长因子有着明显的促进作用,其中纯N 4.6 g·株^-1、纯P 6.4 g·株^-1、纯K 1.1 g·株^-1的处理组合对苗高以及单株叶质量增加效果最好,纯N 9.2 g·株^-1、纯P 3.2 g·株^-1、纯K 1.1 g·株^-1的处理组合对地径以及单叶质量的增加效果最明显。     

黑木相思17号无性系在桂东地区早期生长表现

为丰富桂东地区速生树种多样性以及为生态敏感地区桉树改造提供新的树种,2017年5月在桂东地区试种黑木相思17号无性系20hm^2,分别在造林后第8个月和14个月调查试验林不同海拔、坡向、坡位的林分生长情况,试验结果表明:黑木相思17号无性系在桂东地区造林成活率85%以上,造林后第8个月成活率、地径和树高分别为92%,3.1cm和2.3m,造林第14个月地径、胸径和树高分别为7.4cm,5.8cm和5.0m;黑木相思造林后8-14个月,上坡生长表现优于下坡,海拔200m生长表现优于海拔320m。说明黑木相思17号无性系适合在桂东地区生长,避开谷底和山脚等光照不足地块、及时抚育是黑木相思在桂东地区造林成功的关键。     

大悟县板栗雪片象甲发生规律及防治初报

板栗雪片象甲每年发生一代，为害板栗桑苞、票实、幼芽和嫩叶等；可人工收集烧毁落艺和使用甲胺磷等药物防治。     

Canopy density in stands of Picea abies and Pinus sylvestris after different thinning methods

Altogether 82 plots (261 estimations) of Picea abies (L.) Karst, and 193 plots (360 estimations) of Pinus sylvestris (L.) stands were estimated by a vertical tube. The “crown free projection”, CFP, of stands thinned in three methods with different thinning grades was measured: unthinned, heavily and very heavily thinned, heavily thinned delayed first thinning, extra heavily thinned and thinned from the top. Basal area (m²ha^?1) density (stems ha^?1) and diameter sum (m ha^?1) were plotted against CFP. Basal area was the best practical measure of stand in this study. Generally Scots pine stands have higher CFP and the curves are steeper than in Norway spruce stands. Depending on the grade of thinning, heavily and very heavily thinned spruce stands, delayed first thinning included, have CFP values of 10–15% and stands thinned from the top, 20–40%, compared with 30–80% and 30–60% respectively in pine stands. Extra heavily thinned stands have the highest CFP, 20–80% in spruce and 50–90% in pine stands. The CFP levels after thinning are too high in pine stands for avoidance of sucker and sprout production of aspen and birch. In dense Norway spruce stands thinned from the top or heavily and very heavily thinned, the CFP values are low enough (≤30%) to diminish the production of suckers.