花期提前对雌雄桑树花部形态及其生物量的影响

Effects of Advancing Flowering Date on Floral Morphology and Biomass in Male and Female Mulberry

桑树(Morus alba L.)是我国重要的经济和生态恢复造林树种,近年来已观测到其开花时期提前的现象。作者通过比较桑树在1月下旬(提前开花期)和3月中旬(正常开花期)间雌雄植株的花序特征、单花形态以及生物量积累的差异,分析花期提前对桑树的繁殖器官带来的潜在影响。结果发现:1)在花序特征方面,与正常花相比,提前开花显著降低了雌雄桑树花序长,而对花序柄长及单花总数无显著影响;2)在单花形态方面,提前开花显著降低了雌花子房大小、花被片大小、柱头宽,但显著增加了雄花花粉数量;3)在生物量积累方面,提前开花显著降低了雌雄单花干重、花序干重;4)此外,还发现雌花序干重与子房大小、花被片大小和单花干重均呈显著正相关,花序长与子房大小、花被片大小和单花干重呈显著正相关;雄花序干重分别与单花干重和花被片大小呈显著正相关。结果表明,提前开花会减小桑树雌株的部分花部性状特征及雌雄株的花部生物量积累,增加雄花花粉数量,并且雌株的变化率大于雄株,这种雌、雄株之间的不对称响应是桑树为保证生殖成功而形成的适应性机制。

In recent years, the phenomenon of advancing flowering date （ AF） caused by global climate change is observed in the Mulberry （Morus alba L. ） sp ecies ,an important economic and ecological restoration species in Chi-na. To evaluate the potential effects of AF on the reproductive organs of Mulberry,the floral morphology and biomass in male and female Mulberry in late January （ advancing flowering date, AF） or mid - March （ normal flowering date, NF） were investigated. The results showed that： 1 ） inflorescence length in AF was significantly lower than that in NF,while inflorescence stalk length and number of single flowers per inflorescence were not significantly different between AF and NF; 2 ） compared to flowers in N F , the ovary siz e, tepal size and stigma width of female flowers in AF were lower,but the pollen number of male flowers in AF were higher; 3 ） dry mass of single flower and inflores-cence of female and male flowers in AF were significantly lower than that in NF ; 4 ） in ad dition,inflorescence dry mass in female plants was positively correlated with ovary size,tepals size and dry mass of single flowers,and inflo-rescence length was positively correlated with ovary size,tepals size and dry mass of single flowers;in male plants, inflorescence dry mass was significantly positively correlated with dry weight of single flowers and tepal size. The re-sults suggest that part traits of female floral morphology and biomass of female and male flowers in AF were lower than that in NF, while the pollen number of male flowers in AF were higher, and flowers suffered more negative effects in morphology and biomass than males in AF. The asymmetric responses between female and male flowers of Mulberry by AF may ensure its reproductive success.