Orthogonal test design for optimizing culture medium for in vitro pollen germination of interspecific oil tea hybrids

Abstract Oil Tea (Camellia oleifera) is an important woody edible oil plant in China. Oil Tea suffers from low rate of fruit set during production, which is related to poor pollination and fertilization. Pollen vigor is directly related to pollination and fertilization. Using the interspecific hybrid Y3 (C. grijsii × C. oleifera) as plant material, we studied the effects of sucrose, H3BO3, MgSO4, and IAA on pollen germination using an orthogonal design to determine the best culture medium. Results indicated that pollen germination rates were significantly affected by medium components and ranged from 29.13% to 56.84%. Pollen tube length was the longest in the T5 medium surpassing the control group by 489.36 μm. MgSO4 turned out to be the most important germination medium component having great effect on the pollen germination rate. The optimal culture medium to promote pollen tube growth of Oil Tea Y3 was: 1% agar, 150 g·L-1 sucrose, 0.15 g·L-1 H3BO3, 0.07 g·L-1 MgSO4, and 0.01 g·L-1 IAA. The results of this paper may provide information for foliar application of Mg and IAA, which can improve pollen tube growth of Oil Tea in practice.

摘要 油茶（Camellia oleifera）是我国重要的木本食用油料植物。生产中油茶坐果率偏低，这与授粉受精不良密切相关。花粉活力直接影响授粉受精过程。本研究以种间杂交品系Y3（浙江红山茶（C. grijsii）×油茶（C. oleifera））为试验材料，采用正交设计研究蔗糖、硼酸（H₃BO₃）、硫酸镁（MgSO₄）以及吲哚-3-乙酸（IAA）对花粉萌发的影响，以筛选最优培养基配方。结果表明，培养基组分对花粉萌发率具有极显著影响，萌发率介于29.13%至56.84%之间。T5培养基中的花粉管长度最长，较对照组高出489.36 μm。硫酸镁（MgSO₄）是影响花粉萌发率最关键的培养基组分。促进油茶Y3花粉管生长的最优培养基为：1%琼脂、150 g·L⁻¹蔗糖、0.15 g·L⁻¹硼酸（H₃BO₃）、0.07 g·L⁻¹硫酸镁（MgSO₄）及0.01 g·L⁻¹吲哚-3-乙酸（IAA）。本研究结果可为叶面施用镁肥与吲哚-3-乙酸，以实际提升油茶花粉管生长提供理论依据。