Roeder Stefan, Serra Sara, Musacchi Stefano
Tree Fruit Research and Extension Center, Department of Horticulture, Washington State University, Wenatchee, WA 98801, USA.
Department of Horticulture, Washington State University, Pullman, WA 99164, USA.
Plants (Basel). 2021 Jul 16;10(7):1460. doi: 10.3390/plants10071460.
In vitro germination assays are frequently used in screening trials to evaluate the pollen viability of pollinizers. To be effective, screening trials must have defined threshold criteria, from which individuals can then be assessed. However, despite decades of research on pollen viability, no established threshold is available to categorize apple cultivars based on their in vitro pollen tube lengths. This study aimed to identify and characterize the subgroups of cultivars based on their pollen tube growth performance. In vitro pollen tube lengths of 41 individuals were determined by incubating samples on artificial germination media at 15 and 25 °C. A six-number summary statistic was calculated, and hierarchical clustering on principal component (HCPC) analysis was used to determine and characterize subgroups. Furthermore, a decision tree model was used to predict class membership for future datasets. HCPC analysis partitioned the 41 individuals into three subgroups with different performances. The decision tree quickly predicted the cluster membership based on the second quartile at 15 °C and the third quartile at 25 °C. The thresholds from the decision tree can be used to characterize new observations. The use of the methods will be demonstrated using a case study with 29 apple accessions.
体外萌发试验常用于筛选试验，以评估授粉品种的花粉活力。为确保有效性，筛选试验必须有明确的阈值标准，据此对个体进行评估。然而，尽管对花粉活力进行了数十年研究，但尚无既定阈值可用于根据苹果品种的体外花粉管长度对其进行分类。本研究旨在根据品种的花粉管生长性能确定并描述其亚组特征。通过在15℃和25℃的人工萌发培养基上孵育样品，测定了41个个体的体外花粉管长度。计算了六数汇总统计量，并使用主成分分层聚类分析（HCPC）来确定和描述亚组。此外，使用决策树模型预测未来数据集的类别归属。HCPC分析将41个个体分为具有不同表现的三个亚组。决策树根据15℃时的第二四分位数和25℃时的第三四分位数快速预测聚类归属。决策树的阈值可用于描述新的观察结果。将通过一个包含29个苹果种质的案例研究来展示这些方法的应用。
