核桃物候期与叶、果表型可塑性研究

大尺度范围内研究‘清香’核桃的物候期和叶、果表型可塑性,探讨气候变化对核桃物候期的影响,为核桃跨区域优质栽培和理解核桃种群分化提供参考。以中国暖温带栽培区、北亚热带栽培区和南亚热带栽培区的‘清香’核桃为研究对象,观测不同栽培区‘清香’核桃的物候期和复叶、单枝多果率和坚果果面特征等表型可塑性。不同栽培区‘清香’核桃遗传相似系数总体平均值为0.998,说明其纯度较高;从暖温带栽培区到南亚热带栽培区迁移栽培过程中,各区域‘清香’核桃物候期顺序一致,但果实发育时间从125天延长至150天;复叶小叶数从5~9片渐变为5~11片,侧叶由椭圆形叶尖锐尖渐变为长椭圆形叶尖渐尖;单枝多果率从2.22%增加至7.43%;坚果果面刻纹和刻窝逐渐增多增深。‘清香’核桃从暖温带到北亚热带再到南亚热带迁移栽培过程中,生长期延长,叶片逐渐由圆变长,叶尖变尖,单枝坐果数逐渐增多,坚果表面光滑程度减弱,物候期和叶、果均表型出了较强的表型可塑性。由其表现出的核桃向泡核桃转变的趋势推测,核桃和泡核桃2个种的分化可能是由环境因子所致。

Research on Phenological Phase and Phenotypic Plasticity of Leaves and Fruits of Walnut

Research on the phenological phase and phenotypic plasticity of leaves and fruits of walnut ‘Qingxiang’ was carried out, to clarify the effect of climate change on walnut phenological phase in large scale and to provide a basis for high quality walnut cultivation and understanding walnut population differentiation. The phenological phase and phenotypic plasticity of compound leaves, multiple fruit rate on single branch and nut surface of walnut ‘Qingxiang’ from different growing regions of warm temperate zone, northern subtropics and southern subtropics in China were observed. The average genetic similarity coefficient of walnut ‘Qingxiang’ from different regions was 0.998, indicating high purity of the test material. The phenological phase of walnut ‘Qingxiang’ was coincident from warm temperate zone to southern subtropics, but the fruit development time increased from 125 d to 150 d. Leaflet number of compound leaf ranged from 5-9 pieces to 5-11 pieces, lateral leaflet edge shape was from elliptic to narrow elliptic, with tip shape changed from sharp point to gentle point. The multiple fruit rate on single branch was from 2.22% to 7.43%, and lines and pits on nut surface became more and deeper. In the migrating cultivation of walnut ‘Qingxiang’ from warm temperate zone to southern subtropics, its growth period becomes longer, the lateral leaflet edge shape is changing from round to long gradually with more sharp tips, the fruit-bearing number on single branch increases, and the smoothness of nut surface is weakened. So, the phenological phase and phenotypic characteristics of leaves, multiple fruit rate on single branch and nut surface of walnut ‘Qingxiang’ show quite strong phenotypic plasticity. From the transformation trend of Juglans regia to J. sigillata, we speculate that the differentiation of the two species may be caused by environmental factors.