Key message

In arboriculture, the number and diversity of pollen donors can have a major impact on fruit production. We studied pollination insurance in hybrid chestnut orchards (C. sativa × C. crenata) provided by nearby wild European chestnuts (C. sativa) in southwestern France. Most fruits were sired by hybrid pollenizers rather than by wild chestnuts. When these hybrid pollenizers were too scarce, a frequent situation, pollen produced by wild chestnut trees did not compensate for the lack of compatible pollen and fertilization rates and fruit production collapsed.

Context

The demand for chestnuts has been increasing in recent years in many European countries, but fruit production is not sufficient to meet this demand. Improving pollination service in chestnut orchards could increase fruit production.

Aims

Investigate pollination service in chestnut orchards. Evaluate the contribution to pollination of trees growing in chestnut woods and forests.

Methods

We investigated five orchards planted with hybrid chestnuts (C. sativa × C. crenata) cultivars in southwestern France. We combined fruit set data, which provide information about pollination rate, with genetic data, which provide information about pollen origin. We used this information to estimate the contribution of nearby C. sativa forest stands to the pollination of each orchard.

Results

Pollination rates vary considerably, being fivefold higher in orchards comprising numerous pollen donors than in monovarietal orchards. Because of asymmetric hybridization barriers between hybrid and purebred cultivars, the surrounding chestnut forests provide very limited pollination insurance: less than 14% of the flowers in these monovarietal orchards had been pollinated by forest trees.

Conclusion

Because chestnut orchards are now increasingly relying on hybrid cultivars, surrounding wild European chestnut trees are no longer a reliable pollen source. To achieve maximal fruit set, efforts must therefore concentrate on orchard design, which should include enough cultivar diversity.

中文翻译：

---

尽管靠近板栗林，但遗传一致的杂交板栗园中的花粉受到强烈限制

关键信息

在树木栽培中，花粉供体的数量和多样性会对水果生产产生重大影响。我们研究了法国西南部附近野生欧洲栗子 ( C. sativa ) 提供的杂交栗子园 ( C. sativa  ×  C. crenata ) 的授粉保险。大多数水果都是由杂交授粉者而不是野生栗子培育的。当这些杂交花粉媒介过于稀缺时（这种情况很常见），野生板栗树产生的花粉无法弥补相容花粉的缺乏，受精率和果实生产崩溃。

语境

近年来，许多欧洲国家对板栗的需求不断增加，但水果产量不足以满足这一需求。改善板栗园的授粉服务可以增加水果产量。

目标

调查板栗园的授粉服务。评估栗树林和森林中生长的树木对授粉的贡献。

方法

我们调查了法国西南部五个种植杂交栗子（C. sativa  ×  C.  crenata ）品种的果园。我们将提供授粉率信息的果实集数据与提供花粉起源信息的遗传数据结合起来。我们利用这些信息来估计附近苜蓿林对每个果园授粉的贡献。

结果

授粉率差异很大，有大量花粉供体的果园比单一品种果园高五倍。由于杂交品种和纯种品种之间的不对称杂交障碍，周围的板栗林提供的授粉保障非常有限：这些单一品种果园中只有不到 14% 的花朵经过林木授粉。

结论

由于板栗园现在越来越依赖杂交品种，周围的野生欧洲板栗树不再是可靠的花粉来源。因此，为了获得最大的坐果率，必须集中精力进行果园设计，其中应包括足够的品种多样性。