白皮松种胚的休眠萌发特性研究

CHARACTERISTICS OF EMBRYO DORMANCY AND GERMINATION OF PINUS BUNGEANA

对经低温层积处理和无预处理的白皮松种子离体胚以及带全胚乳和部分胚乳的胚进行培养试验 ,离体胚分别培养在含不同浓度蔗糖的有或无GA3的琼脂培养基或滤纸上 ;带全胚乳胚和部分胚乳胚培养在滤纸上。结果表明 ,无预处理种子的离体胚培养在滤纸或低浓度的蔗糖琼脂培养基上均不能萌发出胚根 ;当蔗糖浓度为 3 0 %时 ,2 0 %的胚可萌发出胚根 ;在 3 0 %～5 5 %范围内 ,随着蔗糖浓度的增加 ,胚根萌发率及萌发速度呈上升趋势 ,萌发率可达 40 % ,发芽指数可达 6 5 %·d- 1 ;继续增加蔗糖浓度不能使其余 60 %的胚萌发。无预处理在滤纸上培养的带全胚乳胚 92 0 %可萌发 ,带 1 2或 2 3胚乳的胚 74 7%可萌发 ,带 1 3胚乳胚仅下胚轴伸长 ,胚根不萌发 ,去除内外种皮及胚乳包被的胚 (裸胚 )没有解除休眠 ,而下胚轴在任何培养基质上都能迅速伸长。低温层积处理 3 6d和GA3处理种子离体胚在低浓度蔗糖 (分别为 0 2 %与 0 4% )琼脂培养基上可萌发 ,低温层积胚在蔗糖浓度为 3 0 %时萌发率 90 % ,发芽指数为 2 6 3 %·d- 1 ,GA3处理胚在蔗糖浓度4 0 %～ 5 0 %时萌发率 60 % ,发芽指数为个 7 5 %·d- 1 。经低温层积处理的种子离体胚在 3 0 %蔗糖琼脂培养基上 70 %胚第 3天萌发出胚根 。

The characteristics of seed dormancy and germination of Pinus bungeana were studied with naked embryos (seed capsule and endosperm were excised off) and embryos with whole or partial endosperm of the seeds either non-pretreated or low temperature stratified. Naked embryos were cultured separately on agar-solidified media containing different concentrations of sucrose or on filter-paper bridge. Embryos with whole or partial endosperm were cultured on filter-paper bridge. For naked embryos of the seeds without pretreatment, radicles could emerge on culture system of neither filter-paper bridge nor agar media supplemented with low concentrations of sucrose; 20% of the radicles could germinated on media containing 3.0% of sucrose, the germination rate tended to rise when sucrose concentration in range of 3%～5.5%, the highest germination proportion (Gp) could reach 40% and the germination index (Gi) were 6.5%·d -1. The remainder 60% of embryos could not germinate even when sucrose concentration of the media was higher than 6%. For the non-pretreatment seeds cultured on filter-paper bridge, 92% or 74.7% Gp was obtained as embryos with whole or two-third to half of endosperm. No growth of radicle except hypocotyl elongation was found of embryos with 1/3 part of endosperm, and naked embryos still in dormancy except the rapid hypocotyl elongation, which could culture on either one matrix experimented. For embryos pretreated by cold stratification for 36 days or GA 3 immersion, naked embryos could germinate on agar media containing lower concentrations of sucrose (0.2% or 0.4% respectively),and 90% of Gp was obtained on media supplemented with 3.0% of sucrose after stratification, 60% of Gp was got on media with 4.0%～5.0% sugar after GA 3 treatment, and Gi was 26.3%·d -1 or 7.5%·d -1 respectively. 70% of naked embryos germinated at the third day, but embryos with intact endosperm germinated at 40%, 10%, 10%, 10%, 0% and 30% separately from the fourth to ninth day. From these results we inferred that the embryo was of property of dormancy, but its hypocotyls were not. The testa permeability was not the main factor to inhibit embryo germination, embryo germination did need enough sucrose supply and was regulated by its endosperm.