Evaluation and Exploration of Citrus Germplasm Resources in the Origin of Shatangju(Citrus flamea Hort.ex Tseng Shiyueju)

[Objectives]To protect the local rare citrus germplasm resources and further develop and cultivate new citrus varieties.[Methods]The germplasm resources of Shatangju(Citrus flamea Hort.Ex Tseng Shiyueju)in Sihui City of Guangdong Province and other 8 citrus varieties from the same origin were evaluated.The appearance characteristics of tree shape,the length and thickness of shoot at each shoot stage,the appearance characteristics of leaves and the fruit quality of each variety were investigated.[Results]Through the comparison of various citrus varieties grafted with sour mandarin,the results showed that the overall advantages of the length and thickness of the shoots of Shatang tangerine in summer and autumn were more prominent,which was conducive to fruit setting.The sprouting time of the three shoots of each variety was different,and there were sporadic sprouting phenomena in different seasons,so the growth was different,and the length and thickness of the shoots were different in different seasons.There were significant differences in shoot length and diameter among different varieties in the same season.The coefficient of variation of Shatangju's leaves was low,and the traits were stable;leaf shape,leaf base shape,leaf margin and other indicators among the three shoots of the same variety and the differences among the same shoots of different varieties were compared.All varieties had strong flavor,separately sweet and sour,sweet and sweet taste.Shatangju has many segments,orange pericarp,rough texture,easy peeling,and high oblate fruit shape.The orange pericarp was favored by the participants,while the rough and thick peel was not favored by the participants.[Conclusions]Based on the improvement of local varieties,it is recommended to improve the smoothness of pericarp,reducing the thickness of pericarp and improving the flavor of fruit will be conducive to increasing sales.In the cultivation process of various quality resources,especially in the period of fruit growth and development,the plan of nutrition and fertilization should be formulated according to the rules of fruit growth and development,the rules of yield formation and the rules of quality composition,so as to establish the integrated nutrient management system of various varieties.

无子沙糖橘(十月橘)的选育

采用芽变选种的方法,在四会市石狗镇选出了无子柑橘新品种—无子沙糖橘(十月橘)。果略小,单果重平均40g左右,单果平均种子数0.5粒以内,达到柑橘无子的标准。果实扁平,皮橘红色,薄而脆;果肉橙黄色,味清甜,可溶性固形物13%以上,肉质爽脆化渣,品质上等。早结丰产性好,发梢能力强,3月上中旬开花,12月上旬果实开始成熟。

“十月桔”黄化与正常植株的矿质养分及果实品质比较

广东省"十月桔"(沙糖桔)叶片黄化现象目前有增加的趋势。以同一果园中正常树和严重黄化树为试材,测定分析其根际土壤和叶片矿质养分、叶片养分的DRIS值及果实品质。结果表明,与正常树果实相比,黄化树果实变小,着色变差,可滴定酸、维生素C和还原糖的含量提高,风味偏酸;供试果园土壤偏酸并处于缺镁、缺钙和缺锌状态,正常树与黄化树根际土壤矿质元素差异以有效钙最大;黄化树叶片中钙与锌的含量显著低于正常树,其余无显著差异;在叶片镁明显不足的背景下,再严重缺钙和一定程度缺锌是导致黄化的主要原因。

ICP-AES法测定砂糖橘中的矿质元素含量

以市售广西砂糖橘为材料,采用微波消解法处理样品,以电感耦合等离子体发射光谱仪（ICP-AES）检测砂糖橘中Cu、Fe、Zn、Mn、Na、K、Ca、Mg、P等14种矿质元素的含量,结果表明,砂糖橘果皮和果肉中K、Ca、Mg、P等元素的含量较高;果肉中K含量尤其高,达到9 082.23 ug/g,而Na含量则很低,果肉中仅含80.45ug/g,元素Cr在果皮和果肉中均未检出;Sr在果肉中未检出,在果皮中含量为10.24ug/g;在砂糖橘果皮中B、Ca、Mg、Fe、Mn、Si、Zn 7种元素含量均高于果肉。加标回收率实验表明,各元素的相对标准偏差（RSD）为0.18%～4.77%,各元素的回收率在95.15%～106.1%之间,说明该方法测定广西砂糖橘中矿质元素具有较好的精密度和准确度。

砂糖桔全长cDNA文库的构建及病程相关蛋白基因的克隆与分析

为从分子水平上了解影响砂糖桔生理代谢、生长发育、病虫害抗性和品质的众多基因，以无籽砂糖桔幼叶为材料，应用SMART技术构建了cDNA文库，检测文库发现其库容量达到1．36×10^6，重组率为95％，插入片段绝大多数分布在0．6～2kb之间，有36％的插入片段是全长cDNA。随机挑选224个克隆进行测序，获得了1个病程相关蛋白基因的全长cDNA序列。将基因序列提交GenBank，编号为KJ000019。基因的CDS长429bp，5’UTR为43bp，3’UTR为235bp，编码长度为143个氨基酸残基的蛋白。基因位于第8染色体上，有1个长度为193bp的内含子，基因编码的蛋白质分子量为15．4ku，等电点为6．96。该蛋白N端含有长度约为22aa的信号肽序列，指导蛋白分泌到细胞外；剩余部分是一个典型的Barwin保守结构域，具有几丁质酶的活性，在受到细菌、真菌侵染时可以分解部分真菌和细菌的细胞壁，发挥抗病作用。