干旱胁迫下杏叶片中茉莉酸积累的作用

以耐旱的山杏和非耐旱的龙王帽实生苗为试材, 研究干旱胁迫下茉莉酸( JA) 的作用机制。结果表明: 在停水后第12天, 即植株将衰老时, 山杏叶片JA含量升高3倍。整个干旱过程中山杏和龙王帽根中内源JA含量都变化不大。自然干旱时杏的脂氧合酶(LOX) 活性表现为叶片升高, 在根中无显著变化。用外源50 mmol·m^-3 JA喷洒山杏叶片后促进了叶绿素的降解, 加速了叶片衰老过程。同时在旱后复水时发现叶子完全干枯的山杏又能长出新叶而复活, 而叶片延迟衰老的龙王帽却不能复活。因此推测JA在干旱胁迫下是通过促使叶片衰老而使植物减少水分散失、以此来抵抗逆境的。     

板栗短雄花序异常死亡的超微结构观察

板栗(Castanea mollissima Bl. ) 短雄花序发育过程中, 花序上部变黄, 弯曲, 最后枯死脱落,而基部花序正常发育。利用透射电镜观察花序上部发育中的细胞超微结构发现: 细胞呈现有序的死亡变化,细胞核内发生染色质凝聚, 继而核仁消失, 核质降解, 核膜破裂, 核解体; 液泡内吞现象明显, 形成很多小液泡; 叶绿体和线粒体也逐渐解体; 花序上部衰亡过程中所有细胞器在膜包裹下有序地降解, 表现出植物细胞程序性死亡的典型形态学特征。     

基于VAR模型的北京市西瓜市场的替代与整合

西瓜是我国重要的鲜活农产品之一。利用北京市批发市场中香蕉、梨子、哈密瓜、菠萝4种典型水果的价格数据,建立向量自回归模型探究香蕉、梨子、哈密瓜、菠萝4种水果在水果市场对西瓜的替代作用和动态影响,进而分析各种水果对西瓜的替代效果与水果市场的整合效应。结果表明:在不考虑季节因素的影响时,哈密瓜、香蕉、梨子与西瓜之间存在着较强的替代关系,强弱依次为哈密瓜>香蕉>梨子,而菠萝对西瓜不具有明显的替代作用。当价格受到正向的外部冲击时,西瓜自身价格会上涨,以分担这种压力,哈密瓜、香蕉和梨子这些存在替代关系的水果对西瓜价格分担上涨压力的贡献率比没有替代关系的水果高。在推动北京市西瓜市场发展的同时也要顾全整体水果市场的大局,充分考虑到各种水果之间的相互影响的替代关系。     

都市型薄皮甜瓜品种比较试验

为筛选出适宜在北京种植的优质都市型薄皮甜瓜品种,选取8个品种的薄皮甜瓜为试验材料,对比分析其田间长势及果实品质.结果表明:8个参试品种田间长势及果实品质均有显著差异,其中梨形瓜中丘比特果实大,外观好,果肉最厚,心糖最高,综合果实品质最优秀;长筒形瓜中博洋9号果实外观及品质较优秀,单果质量最大,果形指数好,心糖最高.综合...     

‘西伯利亚’百合花香随开花进程变化及日变化规律

 采用动态顶空套袋-吸附技术,采集东方百合‘西伯利亚’不同花期和一天不同时间点释 放的花香,并利用自动热脱附-气质联用（ATD–GC/MS）技术分析花香成分和释放量。结果表明：‘西 伯利亚’百合花香成分主要包括萜烯类、醇类、醛类、酮类、酯类、芳香族类和烷烃类7 大类;其释放 量和化合物数量在初开期较少,半开期逐渐增加,盛开期最高,衰败期急剧下降。在4 个时期分别检测 出12、46、55 和20 种成分,其中萜烯类化合物最多,释放量最大;在一天当中其释放量和化合物数量从 早到晚同样表现出先增加后减少的变化,15：00-16：00 时间段总释放量最高,成分最多,而在7：00- 8：00 和19：00-20：00 这两个时间段成分及释放量明显减少;从7：00 到20：00 的7 个时间段释放的 花香中分别检测出27、42、51、57、45、40 和16 种化合物,萜烯类化合物最多,释放量最大。花香成 分中含量最高的芳樟醇、β–罗勒烯和β–月桂烯等萜烯类化合物可能是‘西伯利亚’百合花香的主要致 香成分,而光强的变化是引起‘西伯利亚’百合花香日变化的重要原因。     

板栗早熟新品种‘京暑红’

 ：‘京暑红’是实生选育的板栗早熟新品种,在北京地区4 月中旬萌芽,6 月中旬盛花,8 月 22 日左右成熟,果实发育期约75 d。总苞呈椭圆形,每苞平均含坚果2.1 个,苞皮较薄,刺密,出实率 为41.2%。坚果红褐色,果面光滑美观,平均单粒质量8.2g,果肉含水量57.2%,灰分2.0%,脂肪4.5%, 蛋白质5.6%,总糖20.4%,淀粉38.2%,氨基酸1.5%。内果皮易剥离,果肉黄色,质地细糯,风味香甜。 嫁接后第3 年株产可达2.5 kg,在北京板栗产区为极早熟类型。适宜密植栽培,株距2 ~ 3 m,行距3 ~ 4 m。 授粉树配置以‘燕山红栗’、‘燕山早丰’为宜。     

一串红新品种‘紫衣仙子’

‘紫衣仙子’是经实生苗系统选育得到的一串红新品种。株高55~62 cm,冠幅68~78 cm,花序长18~24 cm,花轮数14~21,花轮间距1.1~1.8 cm,整株花序67~110枝。花萼白色带淡紫色晕,花冠淡紫色。花期6—10月,盛花期8—9月。抗性强,具有一定的耐热性,不易发生疫病和花叶病。适宜在北京地区种植。     

苹果属观赏海棠McANS基因克隆与不同叶色品种间表达差异分析

以苹果属观赏海棠品种‘王族’叶片总RNA为模板,通过RT-PCR与RACE扩增,获得一个1 350 bp的花色素花青苷元合成酶（anthocyanidin synthase,ANS）基因的cDNA序列,其基因编码区共1 074 bp,编码357个氨基酸,命名为McANS（登录号FJ817488）。基因组序列全长1 268 bp,有1个内含子,内含子的剪切位点均符合真核生物“GT-AG”规则。使用实时荧光定量PCR和紫外可见光分光光度计法,对3种不同叶色的观赏海棠品种‘火焰’（叶片绿色）、‘绚丽’（新叶红色）和‘王族’（叶片紫色）幼叶和功能叶中的McANS表达量、花青苷和类黄酮含量进行测定分析,结果表明：McANS在3个品种的幼叶和功能叶中均有表达,在幼叶中表达量显著高于功能叶,在‘绚丽’中表达量相差达到23.82倍。花青苷含量的变化与McANS相对表达量变化趋势具有一致性,而类黄酮含量的变化与McANS相对表达量无明显相关。说明McANS在苹果属观赏海棠叶片花青苷代谢及色泽形成过程中具有重要作用。     

Variation in cytosine methylation in Clementine mandarin cultivars

Summary

Clementines are an important group of citrus cultivars. However, little is known about their genetic diversity. In this study, methylation-sensitive amplification polymorphism (MSAP), based on the application of isoschizomers (Hpa II and Msp I), was used to analyse cytosine methylation patterns in 18 Clementine cultivars. Conventional AFLP analysis showed only two polymorphic bands out of a total of 1,822 AFLP bands generated using 28 primer pairs. Three types of bands were generated by MSAP using 27 pairs of primers. Type I were present in both Eco RI + Hpa II and Eco RI + Msp I gels. Type II or Type III were present only in Eco RI + Hpa II, or Eco RI + Msp I gels, respectively. The total numbers of these three Types of bands were 1,377, 98, and 93, respectively. Among these three Types of bands, the number of polymorphic bands were 76 (5.5%), 30 (30.6%), and 15 (16.1%), respectively. Of these, non-reproducible polymorphic bands in duplicated samples were 27 (35.5%), 18 (60.0%), and 9 (60.0%). Each Clementine cultivar had specific and relatively fixed methylated CCGG sites, which could be revealed from their specific MSAP patterns. The reproducible polymorphic bands in duplicated samples were used to analyse the extent of variation in methylation. The diversity of the cultivars revealed by the resulting dendrogram suggests that DNA methylation may be one of the main factors accounting for the difference in agronomic traits between Clementine cultivars.     

Influence of a pre-harvest reflective orchard mulching film on lipid peroxidation and anti-oxidant activity in apple fruit during post-harvest storage

Summary

Studies have shown that applying a reflective film to the floor of an orchard enhances fruit colouration. Here we assessed whether this practice also prolonged the post-harvest storage life of apple (Malus domestica Borkh cv. Fuji and Malus prunifolia [Willd.]) fruit. Strips of reflective mulching film (RMF) were placed beneath the apple trees and RMF-treated fruit were compared with those from untreated control (CK) trees. Enzymes involved in reducing lipid peroxidation such as superoxide dismutase (SOD) and catalase (CAT) are associated with delaying fruit senescence. Their activities, as well as malondialdehyde (MDA) concentrations, were quantified as indicators of physiological changes related to lipid peroxidation and membrane damage in the peel and flesh of RMF-treated or control apple fruit during 50 d of post-harvest storage at 4ºC. SOD activities increased in the peel and flesh from RMF-treated fruit during the first 40 d post-harvest, but declined significantly during the final 10 d of storage. RMF treatment resulted in increases in CAT activities of 5 – 14% and 16 – 29% in the peel and flesh of RMF-treated apples, respectively, compared with untreated CK fruit. Conversely, MDA concentrations were 7 – 23% and 14 – 30% lower in the peel and flesh, respectively, of RMF-treated fruit than in CK fruit over the 50 d storage period. Similarly, RMF treatment resulted in reductions of 7 – 20% and 3 – 10% in saturated fatty acid (SFA) concentrations in the peel and flesh, respectively, compared to CK fruit, while the corresponding polyunsaturated fatty acid (PUFA) concentrations increased by 2 – 10% and 3 – 7%. In conclusion, the use of RMF in apple orchards appears to be an effective technique to delay post-harvest senescence in apple fruit.