Study On Biological Charactersistics Of Autumn Sprout Of Annual Plant Seeds In Junggar Desert,China

Annual plants play an important role in plant community diversity in Junggar desert.Among the 25 autumn germinating species discovered,one-year-old ephemeral plants are dominant,accounting for more than 50%of the total number of ephemeral plants in the desert.Especially with the future climate change,the autumn germinating species showed an increasing trend.Therefore,the main influencing factors of temperature are studied in this study.Based on this,24annual plants,8 perennial plants and 1 biennial plant seeds were selected for indoor germination comparative experiments to understand the response of seeds to different temperature changes.Different seed dormancy types were identified by different breaking dormancy treatments.Combining 33 plant seed characteristics with dormancy types,the dormancy types of autumn germinated seeds were classified to understand seed germination characteristics and systems.The relationship between development,exploring the systematic evolution law of autumn germination in Junggar desert,and analyzing the future evolutionary potential of autumn germination of annual plant seeds in Junggar desert.The results are as follows:?1?Temperature-dependent experiments on Seed Germination showed that the gradient germination rates of Lappula semiglabra,Lepechiniella lasiocarpa,Plantago minuta and Eremopyrum orientale were more than 80%at different temperatures?15/2°C,20/35°C,10/30°C?,while Calligonleucocladum and Cornus corneum were higher than 80%.Seeds of Hypecoum parviflorum and Carex physodes did not germinate at all.Even under suitable conditions,some seeds can not germinate completely,and there is dormancy.Therefore,species that can germinate at all three temperature gradients and at 10/30°C in simulated autumn may germinate in autumn.?2?The experiment of determining seed dormancy types showed that the seeds of 33 species were tested for water absorption,and the seeds with low water absorption were physically dormant and representative leguminous species inhibited by seed coat,while those of Lithospermum family,such as Nnoea caspica and Arnebia decumbens,also had such dormancy.It was found that the seeds of Tetracme recurvata,Malcolmia scorpioides,Malcolmia Africana and Alyssum linifolium increased germination rate significantly by adding GA₃,and there was sleep physiological dormancy in seeds of cruciferous plants..?3?According to the relative frequencies of 33 seed characteristics and distribution,combined with seed dormancy type experiments,the results showed that Schismus arabicus,Erodium oxyrrhynchum,Calligonum leucocladum were the most widely distributed species,with relative frequencies over 70%,and five narrow seeds with relative frequencies less than 8%,including Descurainia sophia.Syrenia siliculosa,Astragalus candidis simus,Hypecoum parviflorum and Silene olgiana.The relative frequency of autumn-germinating species is high and mostly concentrated in the fruit types of horn,capsule and pod.Seven of them account for 21.21%of the total number of species,and there are physiological dormancy and non-dormancy phenomena.Six capsules account for 18.18%of the total number of species,and there are physical dormancy and non-dormancy phenomena.Three pods account for 9.09%of the total number of species,and there are physical dormancy phenomena.?4?The effect of five cruciferous plants on autumn germination was judged by their germination at different storage times.Temperature?0/5°C,10/15°C and 15/25°C?significantly affected seed germination of five cruciferous plants,and the germination rates were relatively high at 10/15°C and 15/25°C,indicating that seeds generally preferred to germinate under high temperature.Seed germination rate first increased and then decreased with storage time.The germination rate of five species was the highest at 6 months,and gradually decreased with the extension of storage time,indicating that most cruciferous seeds had some physiological dormancy and limited seed life.?5?The relationship between seed dormancy types and phylogenetic evolution showed that the main dormancy types of experimental seeds were physical dormancy,physiological dormancy and non-dormancy evolution.Old families with lower phylogenetic trees had higher dormancy rates,whereas those with lower phylogenetic trees had lower dormancy rates.However,Polygonaceae,Caryophyllaceae and Yak Pediatric Miaoke families have higher dormancy ratios at higher phylogenetic tree locations.Among them,the average germination time of Gramineae,Lithospermum and Cruciferae species is short,and the average germination rate of Plantaginaceae,Euphorbiaceae and Gramineae is high.The species of this family can germinate under suitable conditions,with high germination rate and short germination time,and it is easier to germinate in autumn.In summary,based on this,24 annual plants,8 perennial plants and 1 biennial plant seeds were selected for indoor germination comparative experiments.It was found that the seed germination rate of most annual plants was higher than that of perennial plants,and the seed germination rate of biennial plants was in the middle.Combining with breaking seed dormancy experiment,the dependence of 33 species on temperature and the relationship between seed characteristics and dormancy types were distinguished.The results showed that fruit types were horn,pod and caryopsis with physiological dormancy,physical dormancy and non-dormancy characteristics.Species with short average germination time and high germination rate were more likely to germinate in autumn.