Effects Of Storage Conditions, Time And Environmental Factors On Seed Germination And Seedling Growth Of Pterocarya Stenoptera C.DC.

Pterocarya stenoptera C.DC. is one of the deciduous, fast growing and dominant native species in China, which is widely distributed in valley and bank. As a pioneer species, P. stenoptera not only can enrich the simple coniferous forest and species diversity, but also can establish an ecological system to control Oncomelania hupensis. Thus, the study of seed germination and seedling establishment of P. stenoptera under different environmental factors can provide the basis of conservation and restoration of the damaged wetland vegetation. In order to find optimum condition for seed germination and seedling growth, five factors were set up to investigate the effect of environmental factors (light intensity, temperature, storage condition and duration, ground water level and burial depth) on seed germination and seedling growth of P. stenoptera at this research.Seed germination of P. stenoptera on different light conditions were studied. Five treatments were set up with light conditions from100%,75%,50%,35%and15%natural light. The results showed that germination rate and germination index of P. stenoptera were highest at75%,50%and35%natural light. The germination rate and germination index of P. stenoptera decreased when the light intensity was too strong or too weak. It could be summarized that an appropriate light intensity could promote seed germination.Seed germination of P. stenoptera on different temperatures were studied. Six temperature gradients (5℃,10℃,15℃,20℃,25℃and30℃) were set up in this research. The results showed that seed germination rate and germination index were significantly effect by temperature. Seeds could germinate in the range of10℃-30℃and the optimum temperature was at25℃to30℃. As the temperature decreased, germination rate and germination index decreased significantly. The germination rate decreased and the time to start germination delayed when temperature was below15℃.Seed germination of P. stenoptera on different storage conditions were studied. Seeds were stored under four conditions(dry at10℃-15℃, moist at10℃-15℃, dry at0℃-2℃, moist at0℃-2℃) for two months before germination. The results showed that less time to start germination and higher germination rate and germination index were occured under moist at0℃-2℃. There were little seeds germinated under dry storage conditions.Seed germination of P. stenoptera on different storage time were studied. Seeds were stored at wet-cold and germinated after2weeks,5weeks,2months,3months,4months and8months. The results showed that the increased storage time caused higher germination in initial three storage times, but the germination rate decreased after4months. When seeds were storaged for2months to8months, seed germination rate were all exceeded51%.Seed germination and seedling growth of P.stenoptera on different under ground water levels were studied in a greenhouse. Seven treatments were set up from submergence to2cm of the soil surface, water level at soil level,-2cm,-4cm,-6cm,-8cm and-10cm below the soil surface. The results indicate that under ground water level had significant effect on germination percentage, morphological traits, biomass accumulation and biomass allocation patterns of P.stenoptera. With the-4cm-0cm treatment, germination percentage were significantly higher than other treatment. Plant height, leaf number, stem diameter and biomass production were significantly higher than those of-2cm,0cm treatments. The results indicated that P.stenoptera having been stored in wet-cold for2-8months had higher germination percentage and shorter time needed to start germination. Water level on-4cm-0cm would be suitable for germination of P.stenoptera but-6cm for seedlings.Seed germination and seedling growth of P.stenoptera on different burial depths were studied in a greenhouse. Seven treatments were set up with0cm,1cm,2cm,3cm,4cm,5cm,6cm beneath sand. The results showed that the percentage of seedling decreased, the time to start germination delayed and belowground biomass increased while burial depth increased with increasing burial depths. The stem height of seedlings at0cm burial depth was tallest after seven weeks while stem height had no significant difference among burial depths eleven weeks later. The fact that seeds with no burial always suffer with drying, freezing and being consume. Thus, the optimal burial depth of P.stenoptera was in the range of a shallow burial depth of lcm-3cm.