Abstract:

Aims Suaeda aralocaspica is an annual halophyte native to the inland salt desert of the Junggar Basin, Xinjiang, China. It produces two clearly defined types of fruits and seeds on the same plant. Our objective was to investigate reproductive allocation and fruit-set pattern of this species.
Methods We randomly selected 11 plants of S. aralocaspica in a population and measured the canopy diameter, shoot length, and root length and biomass allocation. We randomly selected 30 primal branches, 30 secondary branches and 30 tertiary branches, and then counted the fruit number for different node sites. We also determined the position of each fruit (seed) in the infructescence for three consecutive growing seasons.
Important findings Suaeda aralocaspica had high biomass allocation to reproductive organs and a regular fruit-set pattern that is a cautious strategy. The reproductive allocation of biomass in S. aralocaspica plants reached 56%, which is much higher than that of most annual and perennial plants. A greater proportion of biomass was allocated to oblate brown seeds (opportunistic germination strategy) than to elliptical black seeds (cautious germination strategy). The inflorescence (dichasium) may contain from one to fifteen fruits in one to four orders. The first order contains a single fruit, the second order two fruits, the third four and the fourth eight. Suaeda aralocaspica allocated resources first to black-seeded fruits. Thus, S. aralocaspica has high reproductive allocation and a cautious reproductive strategy that is adapted to the salt desert.

Key words: fruit-set pattern, halophyte, reproductive allocation, seed heteromorphism, Suaeda aralocaspica