|SHI, XIAN - Xinjiang Agricultural University|
|WANG, JIAN-CHENG - Xinjiang Agricultural University|
|DAO-YUAN, ZUAN - Xinjiang Agricultural University|
|PAN, BO-RONG - Xinjiang Agricultural University|
Submitted to: Nordic Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/2010
Publication Date: 4/16/2010
Citation: Shi, X., Wang, J., Dao-Yuan, Z., Gaskin, J.F., Pan, B. 2010. Pollen source and resource limitation to fruit production in the rare species Eremosparton songoricum (Fabaceae). Nordic Journal of Botany. 28: 438-444.
Interpretive Summary: Eremosparton songoricum (Litv.) Vass. is a rare, central Asian desert species which shows low seed set. We hypothesized that fruit production was limited by pollen and resources. To determine why the plant is rare, we investigated mating system and pollinators. Mating system experiments showed that the species is self-compatible, but depended on pollinators to set seeds. Results suggested that seed production is affected by insufficient pollen rather than by pollen quantity. Addition of fertilizer helps to improve fruit set. We therefore conclude that reproductive success of E. songoricum is limited by both outcross pollen and available nutrients.
Technical Abstract: Eremosparton songoricum (Litv.) Vass. is a rare, central Asian desert species which shows lower fruit set and seed set (<16%) than most hermaphroditic species. We hypothesized that fruit production was limited by pollen and resources. To evaluate potential fruit abortion due to pollen limitation, supplemental hand-pollination was undertaken, the mating system was investigated and the foraging behavior of pollinators was recorded. To investigate possibile resource limitation, flowers and young pods were artificially removed and fertilization were manipulated. The results showed that under natural pollination, the number of pollen deposited on the stigma greatly exceed the number of ovules per ovary. Mating system experiments showed that the species is self-compatible, but depended on pollinators to set seeds. Supplemental outcross pollination increased fruit set significantly. The most frequent effective pollinator Megachile terminate Morawitz, was observed pollinating many flowers of the same individual plant (74.5±1.3%). These results suggested that fruit production is affected by insufficient outcross pollen rather than by pollen quantity. Removal of 2/3 of the flowers and young pods led to significantly higher fruit set, as did addition of fertilizers (N–P–K: 0.025–0.05–0.013 g, N–P–K: 0.05–0.1–0.025 g) showing that reducing resource acceptors and increasing inorganic resources both helps to improve fruit set. We therefore conclude that reproductive success of E. songoricum is limited by both outcross pollen and available nutrients.