The impacts of sand burial on seedling development of Caragana intermedia
沙埋对中间锦鸡儿幼苗生长发育的影响

Sand burial is one of the main factors that affect seedling survival in sand land.Caragana intermedia is a psammophilous shrub and one of the commonly occurred species in fixed and semi-fixed sand dunes in the Otindag Sand Land and the Mu US Sand Land.In order to investigate the impacts of sand burial on seedling survival and growth of the species,seed-originated seedlings of Caragana intermedia grown in greenhouse for a month were buried by sand with four experimental treatments: T_C,control;T_1,one third of the above ground section was buried by sand;T_2,half of the above ground section was buried by sand;and T_3,all of the above ground section was buried by sand.The growth of the seedlings in different treatments was examined by harvests performed once a week during a period of four weeks.The results showed that: During the four weeks,there was no seedling decease in T_C,T_1 and T_2,but 20% seedlings died in T_3.Sand burial had significant effects on biomass accumulation,root/shoot(R/S) ratio,root mass ratio and stem mass ratio of seedlings.Root/shoot(R/S) ratio and root mass ratio decreased with the increasing of depth of burial.There was no significant difference among leaf mass ratios in the four treatments.Sand burial had not significant effect on leaf area of seedlings.Leaflet area of seedlings was significantly larger in T_2 and T_3 than in T_C at the first harvest.Comparing with control,T_1 and T_2 treatments did not have significantly effect on leaflet area of seedlings,but T_3 treatment did at the other three harvests.Leaflet area of seedlings trended to decrease with age in all four treatments.Sand burial had significant effects on relative growth rate(RGR) and net assimilation rate(NAR) of seedlings.RGR and NAR of seedlings were significantly lower in T_3 than in the other three treatments at the end of experiment,but no significant difference existed among T_C,T_1 and T_2 treatments.These results suggest that partial sand burial of above ground section(T_1and T_2) may not affect growth and development of Caragana intermedia seedlings,whereas full sand burial of above ground section may do.Caragana intermedia could be a sand burial tolerant species.