Dwarfi ng apple rootstock responses to elevated temperatures: A study on plant physiological features and transcription level of related genes

The aim of this study was to investigate the impact of heat stress on physiological features, together with endogenous hormones and the transcription level of related genes, to estimate the heat resistance ability and stress injury mechanism of different dwarfing apple rootstocks. Among the six rootstocks, the rootstocks of native Shao series（SH series） showed better heat stress resistance than those of Budagovski 9（B9）, Cornell-Geneva 24（CG24）, and Malling 26（M26） from abroad. Among SH series rootstocks, SH1 and SH6 showed higher heat stress resistance than SH40. M26 demonstrated the lowest adaption ability to heat stress, showing higher leaf conductivity and lower liquid water content（LWC） with the increase in temperature. Heat stress also resulted in the suppression of photosynthesis, which showed no significant restoration after 7-day recovery. It should be noted that although a higher temperature led to a lower LWC and photosynthetic efficiency（P_n） of CG24, there was no significant increase in leaf conductivity, and 7 days after the treatment, the P_n of CG24 recovered. The extremely high temperature tolerance of SH series rootstocks could be related to the greater osmotic adjustment（OA）, which was reflected by smaller reductions in leaf relative water content（RWC） and higher turgor potentials and leaf gas exchange compared with the other rootstocks. Determination of hormones indicated multivariate regulation, and it is presumed that a relatively stable expression levels of functional genes under high-temperature stress is necessary for heat stress resistance of rootstocks.

新型苹果矮化砧木——SH_1的选育

SH1苹果矮化砧是从国光×河南海棠的杂交实生苗中选育而成。经30 a的田间调查及区试鉴定表明,其做中间砧与基砧八棱海棠、山定子和红星、红富士等苹果品种亲和性好、树体矮化、结果早,尤其是果实着色、风味品质、耐贮性及抗逆性等主要经济性状均超过了M26。SH1矮化砧适宜在黄土高原或气候类似的苹果产区栽培。

SH系矮砧苹果园节水灌溉比较

为了研究出一套适宜山西省自然条件的SH系苹果矮砧果园配套栽培技术模式,结合SH系矮化砧木特性,借鉴国内M26苹果矮砧集约高效栽培模式、乔砧果园节水灌溉方式,对矮砧苹果园进行了大水漫灌、起垄覆膜小沟灌溉、生物基质覆盖、树下生草覆盖4种方式的灌溉处理,调查与测定了4种灌溉处理方式下果园的树体灌溉量、树体枝量生长及枝类组成、树体叶片生长情况、树体叶片叶绿素含量、果实品质。结果表明:对矮砧‘红富士’苹果园进行起垄覆膜小沟灌溉方式处理后,灌溉费用较少,树体枝条结构比例较好,100片叶的干重、厚度、面积、叶绿素含量都好于其他处理,经济效益较高,果园产量高,果实品质较好。因此,起垄覆膜小沟灌溉方式较适宜山西省气候、立地等条件。

苹果矮化砧木SH_1选育及配套栽培技术研究

我国自育本土苹果矮化砧木SH1由山西省农业科学院果树研究所以国光和河南海棠进行种间杂交,历时32 a选育而成,2010年通过了山西省林木品种委员会审定。几十年的区域试验和生产实践已证实,SH1苹果矮化砧木在早果、丰产、耐旱、耐寒、抗抽条、抗倒伏等方面明显强于M26,非常适宜在我国苹果主产区黄土高原和华北平原应用。

基质及营养液对苹果矮砧组培苗移栽后生长的影响

以苹果矮化砧木SH28、SH29生根组培苗为试材,研究了不同草炭土与蛭石基质配比、草炭土处理方式及3种营养液浇灌(MS、园试配方、霍格氏配方)对移栽组培苗生长的影响。结果表明:以草炭土与蛭石1∶2或1∶1配比为移栽基质,组培苗移栽成活率较高,分别达90.77%和88.24%,显著高于草炭土与蛭石2∶1配比;同时草炭土与蛭石1∶1配比处理还可有效提高幼苗生长量。草炭土经灭菌处理后,组培苗单株叶面积及单叶片面积显著增加,苗木生长更健壮。基质中添加0.1%枯草芽孢杆菌对幼苗生长量未见显著作用。MS、霍格兰、园试3种营养液浇灌40d后,均可使移栽幼苗生长量显著大于对照,综合效果以MS营养液促苗效果最佳。

苹果矮化砧木SH系的SSR标记鉴定

对山西省果树研究所、北京市林业果树研究所和北京市昌平果树研究所保存的28份SH系苹果砧木进行鉴定,结果表明:山西果树所的SH9与北京林果所的SH9,相似性高达100%,属于同名同物;山西果树所的SH17、SH18、SH40与北京昌平的SH17、SH18、SH40的相似性分别为68.9%、55.1%和65.6%,属于同名异物;山西果树所、北京林果所及北京昌平的SH38,三者间最高相似性为61.2%,均为不同材料;山西的SH18与SHb(100%),北京昌平的SH17与山西的SHd,山西的SHa与山西的SHe,山西的SH18(28)与山西的SH40,相似性均在99%以上,属于同一种材料,而相似性比较高的还有昌平的SH18与昌平的SH38(98.4%),并且山西的SH12与山西的SH17及SH29三者相似性在97.2%～98.9%之间;不同保存地的SH1、SH3、SH6、SH8-11、SH9-hf、SH19、SH28、SH29、SHc、SHd和SHf为异名异物材料。