苹果优良砧木资源--变叶海棠

变叶海棠(Malus toringoides(Rehd．)Hughes)的形态特征、种质特性、分布的生态环境具有极其复杂的多样性，也是苹果属植物中具有多种高抗性的种类。作苹果砧木利用，嫁接亲和性好，嫁接树半矮化，进入结果期早，果实品质好，是极重要的苹果砧木资源。变叶海棠种群是变叶海棠与陇东海棠和花叶海棠3个种的杂交复合体，由于杂种的全部或部分能育子代中发生的基因重组和增加基因的突变率，丰富了物种的基因库，从而深入的揭示了变叶海棠具有高抗性的遗传机理。变叶海棠是横断山脉地区特有种，是极珍贵的种质资源。因此,对变叶海棠及其近缘种(陇东海棠和花叶海棠)的保护，对于研究物种生物学理论以及资源利用都具有重要的科学意义和应用前景。

MALUS TORINGOIDES (REHD.) HUGHES - A PROMISING STOCK FOR APPLE TREES

Malus toringoides (Rehd.) Hughes, highly diverse in morphological characters, germplasms and distribution habitats and highly resistant to adverse conditions, is an important germplasm resource in the genus Malus. As an apple stock, it tends to dwarf the fruit tree grafted onto it and promote early fruiting. The population of M. toringoides (Rehd.) Hughes represents a hybrid complex of 3 species: M. toringoides (Rehd.) Hughes, M. kansuensis Schneid and M. transtoria Schneid. Gene recombination and increased genetic mutation rate occurring in the fertile or partially fertile descendants of the hybrids enriched the gene bank of the population, thus revealing the genetic mechanism of the high resistance of M. toringoides (Rehd.) Hughes. This species is unique to the Hengduan Mountains and a valuable germplasm. Therefore, it is of great significance for the theoretical study in species biology and for practical resource exploitation to conserve this species and its close relatives, M. kansuensis Schneid and M. transtoria Schneid.