| Cleistogenes songorica, Peganum multisectum and Bassia dasyphylla are important native plant species in North-west desert grassland of China.The two plants are high quality food-stuff,and they play an significant role in pasture production and vegetation restoration.The seeds of C.songorica ,multisectum and B.dasyphylla were collected from Alashan desert,Inner Mongolia,and a serious laboratory test were,therefore,conducted to study germination response of the three species to temperature at optimum water and water stress at optimum temperature.The results of this study showed the following important points:1. Regression analysis indicated that germination percentage(y) of three species was significantly binomial curve related to temperature(x)(p<0.01 )from 5℃to 50℃; germination rates(l/t5o) was significantly positive beeline related to temperature(x) from base temperature to optimum temperature,but were significantly nagtively beeline related to temperature(x) (p<0.01) from optimum temperature to ceiling temperature.2. The germination percentage of three desert plants was significantly positive beeline related to osmotic potential (p<0.01) ,but the germination percentage of P. multisectum was not up to 50%,the germination rates(l/t5o) of C.songorica and B.dasyphylla was significantly positive beeline related to osmotic potential (p<0.01) as osmotic potential decreased from 0 to -2.1Mpa..3. The optium temperature of C.songorica, P. multisectum and B.dasyphylla was 23,34 and 21℃;the base temperature was 6,21 and 3℃and the ceiling temperature was 43,48 and 42℃. we can know the sequence of the base,optimum and ceiling germination temperature of the three species is Pmultisectum>C.songorica> B.dasyphylla.4. At a range of temperature,the hydrotime constant(θ_H) was relative to temperature,for example,at 15℃,theθ_H of C.songorica and B.dasyphylla were 8.16 and 4.32Mpa.d,at 30℃,were 3.4 and 3.92Mpa.d.5. At a range of water stress,the thermaltime(θ_T) was B.dasyphylla < C.songorica.
|
PDF Full Text Request