海水盐度对两种红树植物胚轴萌发的影响

EFFECTS OF SEAWATER SALINITY ON HYPOCOTYL GROWTH IN TWO MANGROVE SPECIES

对采自广西海岸的木榄 (Bruguiera gymnorrhiza)和红海榄 (Rhizophora stylosa)胚轴进行品质检测 ,相关数据可作为该地区胚轴评价的参考指标。不同盐度海水水培和淡水沙培试验的结果表明 :较之海水盐度为 2 0‰和30‰的高盐度海水 ,10‰以下的低盐度海水对木榄胚轴萌根和发芽有明显促进作用 ,使始萌根日缩短一半时日 (6d) ,平均萌根日数快 7.1～ 4.8d,萌根率提高 2 0 %～ 30 % ,并且较早开始发芽。红海榄胚轴萌根的最佳盐度条件为2 0‰左右的高盐度 ,此时的萌根率和平均萌根率分别达到 90 %和 6 8% ,淡水条件下红海榄的萌根率只有 40 %。试验还发现木榄胚轴连续萌根率具有双峰值现象 。

The quality of Bruguiera gymnorrhiza and Rhizophora stylosa hypocotyl budding and rooting in water of different salinities (expressed relative to normal sea water) was studied in seeds from the Guangxi coast. Seawater salinity lower than 10‰ promoted the budding and rooting of B. gymnorrhiza hypocotyls. Relative to those grown in water with salinity levels higher than 20‰ and 30‰ these began rooting about 6 days earlier and mean rooting was 7.1-4.8 days earlier. Rooting rates were 20%-30%. The best seawater salinity condition for R. stylosa hypocotyl rooting was about 20‰ at which the rooting rate and mean rooting rate were 90% and 68% respectively. The rooting rate was only 40% in freshwater. A novel bimodal phenomenon in the continuous rooting rate of B. gymnorrhiza hypocotyles was also observed. Budding of R. stylosa hypocotyls appears to be limited when their base is exposed to light.