The Reproductive Ecology On Three Ephemeral Plants Of Brassicaceae

Neotorularia korolkovii (Rgl. et Schmalh) Hedge et J. Leonard, Isatis violascens Bge. and Chorispora sibirica (L.) DC. are three early spring ephemeral plants of Brassicaceae which are common in Junggar Desert, Xinjiang. In this paper, reproductive ecology of three species including the phenology, sex expression characteristics, mating system, fruit-set patterns, reproductive allocation, fruits and seeds dispersal mechanisms was studied both in field and indoor. The main results were as follows:(1) Three species belonged to typical ephemeral plants which escape from the hot and dry summer of Junggar Desert. Seeds germination of theirs was in the below ten days of March, the fruits matured fully between the below ten days of May and the above ten days of June, and the life cycles were 62 days, 71 days, 72 days respectively; In three species the vegetative growth period accounted for 1/3 of life histories, and the reproductive growth period accounted for 2/3.(2) The flowers of three species were bisexual, tetradynamous and the anthesis of each flower was about 1 to 3 days. In three species, the anther of long stamen dehisced earlier than that of short stamen, but per anther had more pollen grains in the short stamen than in the long stamen. Fertility rate of pollen was high in three species, and dynamic curves of pollen viability in long and short stamen were similar. The stigma receptivity of three species was 9.0 hours, 4.5 hours, 10.0 hours respectively. In N. korolkovii and I. violascens, the lasted hours of single flower were highly in accordance with the period of high pollen viability, pollen longevity and the best period of high stigma receptivity. In Ch. sibirica, the lasted hours of single flower was much longer than the stigma receptivity, while it was shorter than pollen longevity. All the way the stigma of Ch. sibirica was higher than the anther before and after flowering.(3) P/O value of three species were 108.07±17.17, 992.10±272.16, 8481.94±2379.56 apart. The investigation results on pollinators, pollen germination, and their fruit-set under the treatments of no emasculation and bagging in three species showed that the breeding systems of both N. korolkovii and I. violascens can be regard as predominantly selfing, but obligate...