珠江河口及其附近水域银鲳生长与死亡参数估计

对珠江河口及其附近水域银鲳的生长与死亡参数进行估算,得von Bertalanffy生长方程的相关参数为：L∞=36．0cm,K=0．230,t0=-1．137;根据生长方程进一步计算得到自然死亡系数为0．586;20世纪9H0年代捕捞死亡系数为0．944,是20世纪80年代的近2倍;根据等渔获量曲线图分析,若在当前的捕捞规格(开捕叉长为12．0cm)下仍维持现行的捕捞强度(捕捞死亡系数),资源将受到破坏,而且不符合经济效益的要求。依据性成熟特征,开捕叉长最小应为15．0cm;综合考虑性成熟特征、当前可能的捕捞强度及经济效益,在提高产量而不破坏资源的前提下,建议珠江河口及附近水域银鲳的开捕叉长应由12．0cm增加至15．0cm。     

莱州湾芙蓉岛人工鱼礁区鮻资源分布特征及其与环境因子的相关性分析

为研究环境因子对人工鱼礁区鰉分布的影响,实验以莱州湾芙蓉岛人工鱼礁区鰉为对象,根据2014—2017年春季和秋季礁区三重刺网调查数据,主要应用GAM模型研究了水温、盐度、pH、溶解氧、饵料生物和人工鱼礁等环境参数以及年份、月份对鰉单位捕捞努力量渔获量(CPUE)和各站位平均体长的影响。结果显示,春季礁区和非礁区CPUE差异不显著,秋季礁区CPUE高于非礁区,是非礁区的3.53倍。礁区和非礁区体长差异不显著。三因素方差分析表明,鰉CPUE受到年份、月份、人工鱼礁、年份和月份的交互作用影响,平均体长则主要受到年份的影响。Delta GAM模型表明,人工鱼礁和水温对CPUE影响显著,鰉在人工鱼礁区出现的概率大于非礁区,随着水温的升高,鰉出现的概率降低;CPUE呈现先升高后降低的趋势,并在8°C达到最高值;饵料浮游植物丰度和浮游动物丰度是影响鰉平均体长的关键因子,当硅藻丰度小于3×10~5个/m~3时,鰉平均体长随硅藻丰度上升而下降,随后趋于稳定;鰉平均体长随浮游动物丰度增加而呈现降低趋势。研究表明,鰉主要分布在秋季水温较低时的人工鱼礁区,体长较大的鰉主要出现在硅藻丰度和浮游动物丰度较低的区域。     

水稻矮杆小粒突变体dsg1的表型鉴定及粒形基因精细定位

粒形是评价水稻产量和品质性状的重要指标之一,其分子机制研究对水稻（Oryza sativa）遗传改良及品种培育有重要意义。利用EMS诱变粳稻品种TB309获得了一个矮杆小粒的突变体dwarf and short grain (dsg1)。与野生型相比,突变体dsg1株高较野生型显著降低20.35%,其矮化表型由穗长和节间长度缩短缩短所致。突变体的籽粒粒长、粒宽和粒厚分别减少15.53%、10.45%和7.26%。将突变体dsg1与9311进行杂交,获得F2群体进行表型考察和遗传分析,F2代出现表型分离,正常粒长与dsg1突变体的粒长比例符合3:1,说明该粒长突变基因是由隐性单基因控制。利用图位克隆的方法,将突变基因定位于水稻第4染色体分子标记ID2798与ID2803之间52.28 kb的区间内,并利用Gramene数据库对定位区间进行基因预测,发现该区间存在11个基因,这为该突变基因的克隆和功能分析奠定了基础。     

Production of high yielding red raspberry long canes in a Northern climate

Techniques for the production of raspberry long canes with high yield potential were studied on a research station and in two commercial nurseries in South Norway. Potted ‘Glen Ample’ plants were grown in the open and in polyethylene greenhouses during two seasons in order to optimize cultural practices. Dates of propagation and transfer to the production sites were varied. Following cold storage from December to early June, the canes were tipped (cut) at 160 cm height and grown in open plastic tunnels in the fruiting season for the evaluation of growth and yield performance. Remarkable berry yields of 1.5–3.8 kg per plant (cane) were regularly achieved. When grown in the open, later starts than June 1 (June 15 and July 1) successively reduced yields. On the other hand, an earlier start involves risks of growth cessation due to low spring temperature. When grown in greenhouses, high yields were still possible when plants were transferred from propagation conditions as late as July 1, although optimal yields of nearly 4 kg per plant were obtained with transfer on June 15. In a year with unusually high summer temperatures, the yields of canes produced in the open and in greenhouses did not vary significantly, whereas in the second year with normal summer temperatures, canes produced in greenhouses consistently out-yielded those produced in the open by about 1 kg per cane. Regression analyses revealed that high yields were associated with fruiting cane architecture traits such as cane height, number and length of laterals, and a low proportion of dormant buds. The single most important component was lateral length which alone accounted for 82% of the yield variation. Since lateral lengths increased from the shoot tip towards the base, cane heights in excess of 2 m are required for the attainment of top yields as the uppermost nodes with short and low-yielding laterals then can be eliminated by tipping.     

Root development of Thuja plicata in peat-substitute rooting media

In this study we investigated the potential usefulness of different substrates produced from gorse (Ulex europaeus L.) for propagating cuttings of Thuja plicata ‘Atrovirens’. The gorse was composted by different methods, to produce four types of compost. These composts were then used as such (100% compost) or in mixes with coarse sand and pine bark compost (25% compost, 25% coarse sand and 50% pine bark compost, v/v/v) to prepare eight different substrates. The substrates were compared in cutting propagation trials carried out in a greenhouse, with a standard rooting medium consisting of 25% Sphagnum peat moss, 25% coarse sand and 50% pine bark compost (v/v/v). Cuttings were taken from a garden hedge in March 2003, and comprised shoots of the previous year's growth. The bases of the cuttings were treated with a 0.4% solution of IBA rooting hormone, then inserted into cells filled with the corresponding substrate and placed on a propagation bench. Rooting percentage and visual rooting score were determined in July. The quality of roots was evaluated, as total root length and number of root tips, in July, September and November 2003, by use of a Delta-T Scan system. The rooting success of the cuttings ranged from 75% to 90%, except when the substrate comprised the pure composted gorse, obtained after the shorter period in an enclosed composting system with addition of fertilizer and reuse of leachates. Most of the cuttings in this substrate died and only 4% of the cuttings rooted successfully. Physicochemical characteristics of this rooting medium included very high electrical conductivity, low C/N ratio and high water retention. Addition of coarse sand and pine bark compost to the composted gorse significantly increased the rooting success. The root quality variables differed depending on the substrate considered and date of harvest. The results showed that substrates made from gorse compost are of potential use as a peat substitute for propagating cuttings of T. plicata ‘Atrovirens’. The physicochemical properties of the composted gorse should be determined before its use to establish whether it can be used pure as a substrate for rooting or whether it should be mixed with other substances.     

水稻粒长遗传及其功能基因研究进展

随着人民生活水平的提高,稻米需求呈现多样化趋势,在产量仍作为重要指标的同时,稻米品质也越来越受到重视.提高产量、改良稻米品质是现代水稻育种的两个主要目标,而水稻粒长不仅是影响水稻产量的重要农艺性状,还与外观品质性状密切相关,细长粒稻米通常表现较好的外观品质,且世界上的大多数地区的消费者更偏爱于长粒型的稻米.因此,改良水...     

楸树杂种无性系幼龄期材性遗传变异1）

以11个楸树杂种无性系3年生幼树树干为材料,分析了木材材性的26个性状。结果表明：木材的基本密度、气干密度、纤维长度、木纤维比量和导管比量等材性性状在无性系间存在极显著差异,且重复力较大,受遗传控制较强,其遗传变异系数（ GCV）分别为21．77％、34．09％、5．51％、7．52％、19．58％;因此在进行楸树无性系早期材性选择时,只需要分析木材密度、纤维长、木纤维比量、导管比量即可做出对无性系材性的初步评价。通过主成分和聚类分析可知,11个无性系在材性性状方面具有4个类型,第一类为无性系002－1、004－1的木材,密度大、纤维长,但胸径生长量小;第二类为无性系008－1,生长量中等,木材密度相对较小;第三类为无性系015－1、1－2、1－3、1－4、2－1、2－2、9－1、013－1,生长量、木材密度和纤维长度处于中等水平;第四类为无性系001－1,生长量最大,但木材密度和纤维长度中等。     

施氮方式对玉米根系生长、产量和氮素利用的影响

【目的】垄植沟灌技术在西北内陆地区应用广泛,但往往施氮方式单一,在大田常规沟灌条件下,研究不同施氮方式对春玉米根系生长及产量和氮素利用效率的影响,揭示不同施氮方式下根系的生长分布及产量和氮素利用规律,探求西北内陆干旱、半干旱地区沟灌条件下合理施氮方法。【方法】以金穗4号春玉米为供试材料,连续两年在大田条件下,采用垄植沟灌技术,设均匀沟氮（CN,即两侧沟同时均匀施氮）、交替施氮（AN,即两侧沟交替施氮）和固定施氮（FN,即始终给一侧沟施氮）3种处理。各处理施氮量均为200 kgN•hm-2,氮肥选用尿素,分3次开沟施入,基施50%,大喇叭口期和抽雄期各追肥25%;磷肥选用过磷酸钙,作为底肥开沟前均匀撒施,施磷量45 kgP2O5 •hm-2。灌溉定额3 750 m3•hm-2,分别在播后、拔节期、大喇叭口期、抽雄期和灌浆期灌水,灌水定额相同。分别在抽雄期、灌浆期和成熟期监测0-100 cm土层各层（每20 cm一层）植株下方、植株左侧和右侧的玉米根系长度,并根据采样土体折算根长密度。收获后测定产量及植株全氮量,折算氮素利用效率。【结果】玉米根系主要聚集在植株下0-40 cm土层,随着土层深度增加,根长密度呈递减趋势。监测期内,根长密度大小表现为：均匀沟施＞交替施氮＞固定施氮。0-40 cm土层根长密度以均匀施氮较大,60-100 cm土层中根长密度以固定施氮较大。固定施氮下,植株两侧根长密度值差异明显;均匀施氮和交替施氮下,植株两侧根长密度值相近。均匀施氮下,两年平均氮素吸收量、产量和氮素利用效率的值分别为217.8 kgN•hm-2、10 318 kg•hm-2和47.3 kg•kg-1N。较固定施氮和交替施氮,氮素吸收量平均提高了4.3%和2.5%;产量平均提高了8.5%和4.4%;氮素利用效率平均提高了4.1%和1.9%。【结论】均匀施氮在监测生育期内维持了较大根量,植株左右两侧根系分布最均匀;固定施氮下,根系在植株左右两侧分布差异明显;交替施氮表现介于均匀施氮和固定施氮之间。在维持玉米根系的生长和产量形成方面,均匀施氮表现最好,交替施氮次之,固定施氮最差。常规沟灌条件下,氮肥均匀撒施在两侧沟内为较好的施氮方式。     

河蟹养殖生态、气象影响因子观测研究

基于2011~2012年河蟹养殖生态、气象观测资料,对河蟹不同生长断面的体重、水温、蟹龄之间的相互关系进行分析,利用多元回归方法建立了河蟹平均体重预测模型。根据不同层次水温与气温的相关关系,建立了利用气温预测水温的模型。研究结果表明:(1)在相同管理措施下,水温是河蟹生长快慢的影响因子,河蟹生长最快的时期对应的平均水温为25~28℃,这也是河蟹进化过程中适应自然季节变化的结果;(2)4~8月份河蟹平均体重与水温相关性较好,采用回归方法,可构建河蟹不同生长期平均体重预测模型;对2012年的预测结果与实际观测资料对比分析表明,预测值与实测值较为接近;(3)前3日滑动平均气温与各层水温的线性相关关系最好,可利用该指标预测各层水温,进而预测河蟹不同生长期平均体重。     

水稻穗伸出度及若干茎秆叶片性状的遗传变异和相关

选用籼、粳、爪哇稻品种(系)100个,研究了穗伸出度等12个茎秆叶片性状的遗传变异和相关.结果表明:穗伸出度和最下部节间长的遗传变异系数最大:各茎秆叶片性状的广义遗传力均在95%以上;穗伸出度与叶片长、宽,第3、4节间长的遗传相关不显著.通径分析表明,对穗伸出度作用最大的是第1节间长度,其次为第2节间长,且与第3、4节间长和倒二叶长的遗传通径均为负效应.育种上,在选育利于异交的长穗颈、短冠层叶片性状的同时,可兼得降低基部节间长度,从而不因增长穗颈长度而降低抗倒性.