Adaptive Significance Of Seeds Germination Heterochrony For Four Annuals (Salsola L.) In Junggar Basin

Salsola L was a large genus of arid desert and mainly distributed in the Junggar basin of China withimportant ecological function and economic value. The habitat types of S.affinis C. A. Mey most grew ingravelly soil and saline soil and they were the most widely distributed range. S.korshinskyi Drob grew inthe saline soil, S. nitraria Pall. grew in sandy soil. S. brachiata Pall. were most distributed in gravelly soilof former mountain zone, the habitats were the narrowest distribution. We tried to study that features,heteromorphic seeds of four species and the germination specificity and difference among species underdifferent temperature, soil water content and sand burying, difference of water absorption characteristics,and seedling desiccation tolerance with the dry time to analysis of relationship between germinationcharacteristics and species distribution of four Salsola plants. The main results were as follow:(1)Four species all had the highest germination rate and germination potential at0/10℃, the germinationrate and germination potential decreased with the increase of temperature. However, the magnitude ofchange of germination rate among the four species and the germination rate of S. Nitraria Pall.was thehighest (26.2%), the germination rate S. brachiata Pall. was the lowest(0.73%) at20/35℃.(2)The four types seeds of S. affinis C. A. Mey, S. Korshinskyi Drob.and S. Nitraria Pall. had the highestgermination rate at the lowest temperature. The germination rate of type A, B and C seeds weredecreased when the temperature increased, and type A and B seeds were the dominant position at all thetemperature. The germination rate of type C seed was between type A, B and D. The germination rate ofD type seeds in the three species were very low, about10%and the differences were insignificant,which also had the lowest germination potential in four temperature regimes. The germination rate ofthe four types seeds of S. brachiata Pall. did not change significantly with the same temperature.(3)Water absorption time of S.affinis and S. Nitraria could be to stabilize at around2–3h, water absorptiontime of S. Korshinskyi could be to stabilize20h at least to a stable, water absorption time of S. brachiatawas significantly longer than the other three Salsola.(4)Germination rate S. affinis was reduced with soil moisture content decreasing. Seed germination rates ofA, B, C, D types of S. Nitraria was not significantly different at each soil moisture gradient. Seedschange from A to D of the two plants, seed germination rate decreased at the same moisture gradient.Different types of S. Korshinskyi had a higher germination rate in15%and20%soil water content.Seed germination rate of B, C–type seeds were higher than A–type seeds at low moisture.(5)With the longer drying time of four Salsola seedlings were, the weaker seedling desiccation tolerancewere. Seedlings of S. affinis, S. Korshinskyi and S. Nitraria had a strong desiccation tolerance,Seedlings of S. brachiata resisting drying characteristics was the weakest. When seedlings dehydrationrehydration after drying14days, seedling survival rate of the three Salsola could be20%, whileseedlings of S. brachiata were dead completely.(6)Sand burial significantly inhibited the seed germination of four species, there was the greatest impact onS. brachiata. Germination of A type seeds affected by sand burial were more serious than B type seedsin the four Salsola species.These results suggested that four species all had four types of A, B, C, D, they could germinatecontinuously in growth season, but the four types seeds had highest germination rate under the lowesttemperature in early spring which was the best season of germination. There ware differences seedimbibition, effects of sand burial on seed germination and seedling desiccation tolerance between species.At the same time, we found that habitat habitat had an important effect on the germination characteristics,shaping the different adaptation characteristics of species and populations and also forming differentdistribution patterns whether among or within species, so the special germination strategy was an importantfactor of the annuals (Salsola L.) that was widely distributed in arid desert region.