摘 要

本实验以南京林业大学校园内紫玉兰和镇江扬子江林业苗圃内的美国玉兰为亲本，进行了正交杂交授粉试验，初步探讨了美国玉兰与紫玉兰杂交生物学基础，主要结论如下：

1.美国玉兰和紫玉兰开花物候期观察

美国玉兰和紫玉兰均为虫媒两性花植物，雌雄异熟。开花过程可分为初花期、盛花始期、盛花期、末花期、谢花期5个阶段。美国玉兰花期从4月底至5月中旬，初花期1~2d，盛花始期2~3d，盛花期一般10d左右，5月中下旬进入末花期和谢花期。紫玉兰一般3月开花，花期持续20d左右，且花期集中。初花期1~2d，盛花始期和盛花期一般均为4d，末花期和谢花期时间短，通常1~2d。

2.紫玉兰开花动态及柱头可授期的确定

紫玉兰的开花动态可分为4个阶段：花苞阶段、微开阶段、半开阶段、全开阶段。柱头上分泌的粘液先增多再减少，微开阶段时柱头的粘液分泌量达到最大值，此时是和紫玉兰的最佳可授期；随后柱头开始萎蔫褐化，直至全开阶段，玉兰柱头丧失可授性。

3. 花粉在柱头上的萌发生长与坐果率

美国玉兰花粉在授粉后8h后才能见到大量萌发，授粉16h后花粉管在花柱组织中极度伸长，集结成束，20h后花粉管进一步伸长，可以到达花柱1/2处，45h后美国玉兰花粉束到达紫玉兰柱头底部，60h后进入子房室。紫玉兰（♀）×美国玉兰（♂）组合坐果率很低，没有收获到杂交果实, 其原因可能是受精不成功或胚败育。

关键词：紫玉兰 美国玉兰 杂交组合 花粉管生长

First exploration of the sterility reason in M. liliiflora (♀) × M. acuminata (♂)

Abstract

Taking Magnolia acuminata from Nanjing Forest Uniersity and Magnolia liliiflora form Zhenjiang Yangzi River as experimental materials,we carried out the reciprocal cross pollination test.The eproductive biology of Magnolia acuminata×M.liliiflora was investigated. The results were shown as follows:

1. Flowering phenophase of M. acuminata and M.liliiflora:

M. acuminate and M. liliiflora was insect-borne hermaphroditic plants. Stamens and pistils were not mature at the same time. There were 5 stages in the flowering process of M. acuminate and M. liliiflora, that was, the early flowering stage, the early-full blooming stage, the end-full blooming stage, the end flowering stage, the withering flowering stage. Flowering time of M. acuminata was from late April to mid-May. The early flowering stage maintains 1 or 2 days and the early-full blooming stage was about 2-3 days. The full blooming stage was about 10 days. In the mid-May, M. acuminata changed into the ending flowering stage and the withering flowering stage. M. liliiflora began the flowering period in March. The flowering time was concentrate and the stage was about 20 days. The early flowering stage was nearly 1-2 days and time of the early-full blooming stage and the end-full blooming stage was about 4 days. The end flowering stage and the withering flowering stage was not very long, almost 1-2 days.

2. Flowering dynamics and stigma receptivity of M. liliiflora

Flowering dynamics could be divided into four stages: the bud stage, the micro-open stage, half-open stage, full-open stage. The stigma secreted much mucus first and then reduced. At the micro-opening stage, the secretion of mucus reached to a maximum. It’s the best time for pollination. Then stigma began to wilt browning.

1. Germination and growth of pollen and fruiting rate of hybrid

After 8h pollination, a large number of M. acuminata pollen germinated. 16h later, the pollen tube in style organization extreme elongation, assembled into bundles.20h later, the pollen tube elongation could reach the 1/2 style of M. liliiflora. Pollen tube beam could arrive at the bottom of the M. liliiflora stigma after 45h, and 60h entered the ovary locule. The cross combinations had low fruiting rate. The M. liliiflora (♀) × M. acuminata (♂) group didn’t gain hybrid fruit. And the reason could be unfecudation or embryo abortion.

key words: M. acuminate ， M. liliiflora, Hybrid combination, Pollen tube growth

目录

1 前言 6

2 试验材料与方法 7

2.1试验材料 7

2.2试验方法 7

2.2.1美国玉兰和紫玉兰开花物候期观察......................................................7

2.2.2紫玉兰柱头形态及可授期的确定..........................................................7

2.2.3花粉的采集和杂交授粉.........................................................................7

2.2.4花粉活体萌发率测定..............................................................................8

2.2.5花粉管生长的荧光显微观察..................................................................8

2.2.6杂交果实发育情况调查..........................................................................8

3 结果与分析 8

3.1美国玉兰和紫玉兰开花物候期及花部特征 8

3.1.1美国玉兰开花物候期及花部特征 9

3.1.2紫玉兰开花物候期及花部特征 9

3.2美国玉兰和紫玉兰开花动态观察 10

3.2.1美国玉兰开花动态观察.....................................................................10

3.2.2紫玉兰开花动态观察.........................................................................10

3.3紫玉兰柱头形态及可授期的确定................................................................11

3.4美国玉兰花粉活体萌发率测定....................................................................11