裙带菜3n、4n孢子体的人工育苗和海区栽培

Artificial seeding and cultivation on 3n and 4n sporophytes of Undaria pinnatifida

使用室内保存培养的裙带菜2n♀♂配子体自交及与正常n♀♂配子体杂交,培育出裙带菜2n♀×n♂、n♀×2n♂两个组合3n幼孢子体和2n♀×2n♂组合的4n幼孢子体。经过40d海区暂养后测定,3n幼孢子体两个组合平均长度分别为1.2cm和1.1cm,大于对照组合2n幼孢子体的0.9cm和4n幼孢子体组合的0.7cm。使用从短滨螺中提取的粗酶和R-10纤维素酶的混合酶液将2n、3n幼孢子体酶解为原生质团,经Giemsa染色后观察到的染色体数分别为2n=60,3n=90。分苗后的海区栽培期间,在藻体的长度和重量方面,2n♀×n♂、n♀×2n♂两个3n孢子体组合间差异不显著(P>0.05),与对照组合2n孢子体之间的差异极显著(P<0.01)。在裙带菜进入繁殖期的5月上中旬,3n孢子体仍保持较快的生长速度,在5月20日测定两个组合的藻体长度和重量分别达到4.2m、2.3kg和4.0m、2.2kg,而对照组合2n孢子体仅达到2.3m和1.3kg。4n孢子体生长明显地慢于对照的2n孢子体(P<0.01),藻体生长最大值的时间为3月中旬,最大藻体长度和重量仅为1.6m和1.1kg。试验结果表明,3n孢子体不发育,在繁殖期内无孢子叶形成,表现出不育的特性;4n孢子体形成孢子叶,但孢子叶很薄,孢子囊形成的数量少,发育水平也很低,经阴干刺激仅有极少量的孢子放出,显示出低育的特性。

3n sporophytes of Undaria pinnatifwla were the hybrids developed by crossing gametophytes of 2n♀ with n♂ and crossing gametophytes of n♀ with 2n♂ . 4n sporophytes of Undaria pinnatifuta were the hybrids developed by crossing gametophytes of 2n♀ with 2n♂ . All the gametophytes used above were obtained formerly and conserved indoor. After 40 days＇ temporary cultivation, juvenile sporophytes＇ lengths of 2n♀×n♂ and n♀×2n♂ grew up to 1.2 cm and 1.1 cm, respectively, which were both longer than 0.9 cm of 2n and 0.7 cm of 4n. Protoplasts were isolated from 2n, 3n juvenile spomphytes by the mixed liquid of crude enzyme extracted from Littorina breviula and cellulase R-10 and then were stained by Giemsa. The results showed that chromosome number of sporophytes were 2n = 60 and 3n = 90. There was very significant difference in length and weight of sporophytes between 3n and 2n （ P 〈 0.01 ） while there being insignificant difference in those between 2n♀×no♂ and n♀× 2n♂ during the period of sea cultivation after seed separation. 3n sporophytes kept a rapid growth in the first and second ten days of May as 2n sporophytes entering reproductive period. On 20th Marc, 2n♀×no♂ and n♀×2n♂ sporophytes reached 4.2 m and 2.3 kg, 4.0 m and 2.2 kg in length and weight, respectively, which were much better than 2.3 m and 1.8 kg of 2n sporophytes. Compared with 2n sporophytes, 4n sporophytes grew slowly （ P 〈 0.01 ）. 4n sporophytes reached the maximal length and weight of 1.6 m and 1.1 kg during the middle ten days of March. The hybridization experiments indicated that 3n sporophytes were of sterility and the sporophylls were not formed. 4n sporophytes were of low-fertility with thimbleful spores released from sporophylls, which were flaky and could produce little sporangia, after drying in the shade.