The Study Of Apomixis Traits In Walnut

Apomixis was a procreation process that gametophytes directly developed into sporophytes and needn't gametophytes fusion. It only occurred in the process of forming sporophytes without fertilization in the embryo sacs that formed through meiotic and apomeiotic. This research focused on the study of apomixis traits of four walnut varieties through isolation with bags, cytology, embryology, peroxidase isozyme, mineral nutrition. The main results were as follows. (1) Isolation results showed that four walnut varieties had some apomixis abilities. Average apomixis percentage was 15.72% and the highest apomixis percentage was 37.5%. Four varieties had different apomixis percentages that the apomixis percentages of 'Taigu walnut', 'Zhonglin No.1', 'Liaoning No.1', and 'Xinjiang walnut'were 19.65%, 18.75%, 15.3% and 9.2% respectively. The variance analysis results showed that the difference of apomixis ability among four varieties was insignificant, but the annual difference of apomixis ability in every varieties was very signficant. (2) The microspore mother cell meiosis process of 'Taigu walnut'was basically normal. Consistent haploid pollen was formed often the meiosis process. This results showed the inheritance of apomixis ability wasn't accomplished by male gamete. (3) The apomixis embryos of walnut developed from ootid. So it belonged to the parthenogenesis type. Ootid divided spontaneously into 2 and 4 cell proembryo and multicell globular proembryo. In the end it developed into apomixis embryo. (4) The homogeneity of peroxidase isozyme zymogram of apomixis offsprings was higher than natural pollination offsprings'. The higher the homogeneity of peroxidase isozyme zymogram was, the higher the apomixis abilities was. (5) In the mineral elements that were tested, except iron, their contents in the apomixis fruits decreased gradually in the year cycle. But the decreased date of every mineral element was different. The contents of mineral elements in the apomixis fruits decreased more greatly than the control's. The contents of kalium, calcium, magnesium, iron, manganese in apomixis fruits were lower than the control's except cupper, zinc. The results showed that the mineral nutrition level of the apomixis fruits was lower than natural pollination and fertilization fruits'. This was one of reasons that the apomixis fruits could not grow and develop normally.