Pollen Viability of Five Sympatric Tamarix Species in Different Blossom Periods
In order to explore the ecological adaptability of Tamarix pollens to their environments,five sym-patric Tamarix species that blossom at different periods were taken as the research objects,including T.laxa,T.elongata,T.gansuensis,T.ramosissima and T.hispida.The optimum culture conditions were examined by setting three temperature gradients(25,30,35℃),two different boric acid concentrations(5,10 mg/L)and five sucrose concentrations(50,100,150,200,250 g/L).In addition,the pollen viabilities of the five species at six blossom stages(the primary flower bud stage,the middle bud stage,the initial blos-som stage,the full blossom stage,the withering stage and the primary fruiting stage)were also observed.The results showed that 1)except that T.ramosissima(flowering in summer and autumn)had the highest pollen germination rate at 35℃,yet the other four species were all at 30℃.2)The optimum pollen culti-vation media of the five species were slightly different:"10 mg/L boric acid+250 g/L sucrose(T.laxa),"5 mg/L boric acid+200-250 g/L sucrose"(T.elongata),"5 mg/L boric acid+150 g/L sucrose"(T.gansuensis and T.hispida),and,"5 mg/L boric acid+200 g/L sucrose"(T.ramosissima).3)All the pollen viability were weak at the primary flower bud stage and reached the highest at the full blossom stage for the five Tamarix species.The values of pollen viability of T.laxa,T.elongata,T.gansuensis,T.ramosissima,and T.hispida at full blossom stage were 96.24%,90.04%,64.24%,46.68%and 43.21%,respectively.The pollen viability decreased sharply at the withering stage.The significant differ-ences of pollen viability in the five sympatric Tamarix species could ascribe to the genetic factors,solar radiation,natural temperature or the other factors.
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