Effect of Temperature on the Time Requirement of Pollen Tubes to Penetrate into the Embryo Sac after Pollination in Cherimoya (Annona cherimola Mill.)
Effect of Temperature on the Time Requirement of Pollen Tubes to Penetrate into the Embryo Sac after Pollination in Cherimoya (Annona cherimola Mill.)
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温度对毛叶番荔枝授粉后花粉管穿入胚囊所需时间的影响
DOI：
10.11248/jsta.55.157
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
T. Ogata
中科院分区：
文献类型：
--
作者：
H. Matsuda;H. Higuchi;N. Kozai;T. Ogata
当发现番荔枝花蕾已经在4周大的叶腋中分化时（Higuchi和宇都宫，1999），这一发现证明了通过修剪和落叶在任何季节人工促进开花的可能性，并导致在西班牙冬季收获成功（Soler和Cuevas，2008）。在这一成功之前的20年，人们尝试通过修剪和落叶沿着在冬季将温室加热到10 ℃的最低温度来生产反季节水果（Yonemoto和Nakao，1993）。在这些条件下，开花发生在早春，但座果率低，收获时果实小。稍低的温度以及高温可能会减少坐果（Higuchi等人，1998; Koura等人，2001）或低湿度（乔治和尼森，1988）。Schroeder（1943）指出，在早春，花朵很难坐果。不成熟的花粉（Saavedra，1977）最初被认为是原因。然而，在日本的温室栽培中，即使天气变得温暖，花粉萌发增加，在开花的早期坐果也不会增加。这一现象不仅与花粉萌发力有关，而且与授粉后夜间温度较低有关。Cherimoya花在晚上开放并散发花粉，并且授粉应在开花后立即进行（例如，Schroeder，1943），因为花粉活力迅速降低（Rosell等人，2006年）。据报道，授粉后，花粉管到达胚珠需要5-9小时（Ikeda et al.，1994年），表明受精发生在午夜到黎明，当温度普遍下降。在典型的日本塑料大棚栽培中，4月下旬（对应于开花初期）的最低温度通常在10 ℃左右。这种低温对雌蕊中花粉管生长的影响尚未研究，尽管温度对花粉生活力的影响已经在体外进行了广泛的研究（Yonemoto等人，1999; Koura等人，2001）和体内（Rosell等人，1999年）。研究不同温度下雌蕊中花粉管的伸长情况，可以提供受精所需时间和受精的最佳温度范围的信息，从而减少人工授粉和管理成本。在本研究中，我们在不同温度下人工授粉后立即培养花朵，以获得足够的时间来完成受精，用荧光显微镜观察子房横切面，确定花粉管到达胚珠前的败育温度范围。然后，我们观察花粉管生长每小时在可达到的温度范围内估计所需的时间为花粉管授粉后到达胚囊。
When cherimoya flower buds were found to be already differentiated in a 4-week-old leaf axil (Higuchi and Utsunomiya, 1999), this finding demonstrated the possibility of artificially promoting flowering in any season by pruning and defoliation, and led to the success of harvesting during winter in Spain (Soler and Cuevas, 2008). Twenty years before this success, an attempt to produce off-season fruit was made through pruning and defoliation along with heating the greenhouse to a minimum temperature of 10 C in winter (Yonemoto and Nakao, 1993). Under these conditions, flowering occurred in early spring, but fruit set was low and the fruits were small at harvest. Fruit set might be reduced by slightly low temperatures, as well as by high temperatures (Higuchi et al., 1998; Koura et al., 2001) or low humidity (George and Nissen, 1988). Schroeder (1943) noted that in early spring, flowers show difficulty in setting fruit. Immature pollen (Saavedra, 1977) was initially considered to be the cause. However, in greenhouse cultivation in Japan, even when the weather becomes warmer and pollen germination increases, fruit set does not increase during the earlier period of flowering. Not only the pollen germinability but also the lower night temperatures after pollination were thought to have been related to this phenomenon. Cherimoya flowers open and shed pollen in the evening, and pollination should be conducted immediately after anthesis (eg, Schroeder, 1943), since pollen viability decreases rapidly (Rosell et al., 2006). After pollination, 5–9 h are reportedly required for the pollen tube to reach the ovule (Ikeda et al., 1994), suggesting that fertilization occurs from midnight to early dawn, when the temperature is generally decreasing. In typical Japanese plastic house cultivation, the minimum temperatures in late April (corresponding to the early flowering period) is often around 10 C. The effect of such a cool temperature on pollen-tube growth in the pistil has not been investigated, although the effect of temperature on pollen viability has been studied extensively both in vitro (Yonemoto et al., 1999; Koura et al., 2001) and in vivo (Rosell et al., 1999). A study on pollen-tube elongation in the pistil at various temperatures would provide information on the time requirement for fertilization and the optimum temperature range for fertilization, leading to a reduction in laborious pollination practices and management costs.In this study, we incubated flowers immediately after hand-pollination at different temperatures for sufficient time to complete fertilization, and observed ovary cross sections by fluorescence microscopy to determine the abortive temperature range for pollen tubes before reaching the ovule. Then, we observed pollen-tube growth hourly within the attainable temperature range to estimate the time requirement for pollen tubes to reach the embryo sac after pollination.