Abstract:

Taken typical natural sabina przewalskill forests at the eastern section of southern slope of Qilian mountains as research objects,the daily variation curve of net photosynthetic rate(P_n) was measured by Li-6800 portable photosynthetic system,radial growth was measured by growth cone method,natural regeneration and soil seed bank were studied by sample method,cutting seedling method was used to study the cutting seedling optimization.The results showed that:1) the diurnal curve of net photosynthetic rate showed a single-peak curve in May and October,there wasdouble-peak curve from June to September,the morning peak was greater than that in the afternoon; the order of monthly average photosynthetic rate was:September>August>June>July>May>October.2) the cumulative radial growth increment continued to rise,it increased from 274μm in 2015 to 565μm in 2019,incremental rate 106.20%,the growth rate in the early growth stage(262.86%) was higher than that in the late growth stage(149.60%).3) the natural regeneration was poor,the seedling density was only 231 plants/hm²,most of them were randomly distributed,the population was in a declining state; soil seed density was 9.58 grains/m²,distributed within the crown width of the mother plant,majority was in the 0~5cm layer,in the postmature stage of dormancy physiology.4) different concentrations and time gradients of ABT6^# rooting powder&2% sucrose mixture solution treatment,the rooting response of the cuttings was different,the best way to root cuttings was the treatment of 200mg/L mixed solution for 3 hours.

Key words: Sabina przewalskill, photosynthetic rate, radial growth, cutting seedling, Qilian mountains