The Life-history Strategies Of Several Chenopodiaceae Annuals

In this paper, the phonological features, fruit-development characteristics of several Chenopodiaceae annuals such as Petrosimonia sibirica (Pall.)Bunge, Ceratocarpus arenarius L., Salsola brachiata Pall,S. affinis C. A. Mey., Atriplex aucheri Moq. and the seed dimorphism, seed germination, reproductive output and reproductive allocation of P. sibirica were studied. The main results were as follows:(1)The characteristics of phenology and fruit-development:①The seeds germinated early; the life history was long; the cotyledon duration and the persistent flowering period was long;②The length, width and weight of fruits experienced the changing regulation of "slow-fast-slow" and they presented "S" type of growth curve during the process of fruit-development;③Fruits placed in the condition of "stagnate development" in the6-7month, it developed rapidly at the end of August and matured in October.(2)The germination characteristics of fruits (seeds):①The fruits (seeds) of P. sibirica have dimorphism and the two types of seeds were significantly different in shape, size and color;①The two types of seeds have different germination characteristics. The germination percentage of green seeds was>80%at four alternative temperatures and they have quick germination ability; However, the yellow seeds germinated slowly and the final germination percentage was lower (<30%). The scarification of fruit coat or seed coat can significantly increase the seed germination percentages, and it shows that the yellow seeds may have physiological dormancy.(3)The size of individuals and their reproductive characteristics:①In natural population, P. sibirica have different sized individuals and they show great plasticity and have significant differences in plant’s dry weight, plant height, the number of branch classes and nodes;②The number of green seeds and yellow seeds increased with the augmente of individual and significant differences were showed in their respective proportion. The proportion of green seeds and yollow seeds were about84%-91%and9%-13%, respectively;③There were no significant differeces between different sized individuals in the case of single weight of green seeds, but the ingle weight of yellow seeds was increased with the augmente of individuals;④There were no significant differences among reproductive allocation of different sized individuals of green seeds, yellow seeds and total seeds, therefore, it was not size-dependent.