Understanding how traditional agriculture systems have been maintained would help design sustainable agriculture. In this study, we examined how farmers have used two types of local trees (Torreya grandis) for stable yield and maintaining genetic diversity in the “globally important agricultural heritage torreya tree system”. The two type of torreya trees are grafted torreya (GT) tree and non-grafted-torreya (NGT) tree. The GT tree has only female and was used to produced seed yields. The NGT tree has both male and female and was used to support GT tree by providing pollens and rootstocks. We first tested the ratio of GT tree to NGT tree, their age groups, ratio of female trees (including GT and NGT trees) to male, and the flowering period of GT and NGT trees. We then tested seed yields and genetic diversity of GT and NGT trees. We further tested gene flow among NGT trees, and the relationship of gene flow with exchange rates of pollens and seeds. GT and NGT trees (male and female) were planted in a mosaic pattern with a ratio of 4:1 (GT:NGT). In this planting pattern, one NGT male trees provided pollen for 20 female trees of GT and NGT. The trees were classified into four age groups (I = 100–400 years old; II = 400–700 years old; III = 700–1000 years old; and IV = 1000–1300 years old) based on basal diameter. The entire flowering period was longer for NGT trees than for GT trees that ensured GT trees (which lack of males) being exposed to pollens. GT tree had high and stable seed yield that increased with age groups. High genetic diversity has been maintained in both rootstocks of the GT trees and NGT trees. There was a strong gene flow among NGT trees, which positive correlated with the exchange rates of pollens and seeds. Our results suggest that farmers obtain stable seed yields, and maintain high genetic diversity by ingeniously using the local GT tree as yield producer and NGT tree as supporter. These GT and NGT trees together ensure sustainable torreya production.

中文翻译：

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农业遗产to树系统维持稳定产量和高遗传多样性

了解如何维持传统农业系统将有助于设计可持续农业。在这项研究中，我们研究了农民如何在“具有全球重要性的农业遗产to树系统”中使用两种本地树种（Torreya grandis）来稳定产量和维持遗传多样性。两种类型的to树分别是嫁接的re树（GT）树和非嫁接的re树（NGT）。GT树只有雌性，被用来生产种子。NGT树有雄性和雌性，用于通过提供花粉和砧木来支持GT树。我们首先测试了GT树与NGT树的比例，它们的年龄组，雌树（包括GT和NGT树）与雄树的比例以及GT和NGT树的开花期。然后，我们测试了GT和NGT树的种子产量和遗传多样性。我们进一步测试了NGT树之间的基因流，以及基因流与花粉和种子交换速率的关系。GT和NGT树（雄性和雌性）以4：1（GT：NGT）的镶嵌样式种植。在这种种植方式中，一株NGT雄树为20株GT和NGT雌树提供了花粉。根据基础直径，将树木分为四个年龄组（I = 100–400岁； II = 400–700岁； III = 700–1000岁； IV = 1000–1300岁）。NGT树木的整个开花期要比GT树木要长，这可以确保GT树木（缺少雄性）暴露在花粉中。GT树的种子产量高且稳定，且随年龄增长而增加。GT树和NGT树的砧木都保持了很高的遗传多样性。NGT树之间存在强大的基因流，与花粉和种子的汇率呈正相关。我们的结果表明，农民巧妙地使用当地的GT树作为产量生产者并使用NGT树作为支持者，可以获得稳定的种子产量，并保持较高的遗传多样性。这些GT和NGT树共同确保可持续的香to生产。