Components of phenotypic variance of seed traits and germination characteristics of 20 ponderosa pine half-sib families

Abstract

A study was conducted to estimate phenotypic variance components of seed traits and seed vigor of 20 ponderosa pine seed lots. A high intraspecific within-group variation in seed germination and seedling growth has been observed in both half-sib and full-sib families of conifers. Some seed traits may influence seed lot quality and seedling survival. Wind-pollinated cones were collected from 20 ponderosa pine maternal trees, 10 cones per tree, in a stand located in Fort Defiance, Arizona. Air-dried seeds were sown under laboratory conditions, by using a completely randomized design to estimate components of phenotypic variance for seed weight (SW), seed coat weight (SCW), seed imbibition (IMB), five germination characteristics, and three Weibull parameters (a, b and c). About 80 % of size classes had a seed weight (SW) e» 41 mg and e» 97 % final germination. The within-plot (within- family) variance component for SW (64.5 %) and IMB (70.4 %) was higher than among-family variation (35.3 and 24.8 %, respectively). The among-family component varied from 35.1 % (Weibull parameter a) to 62.3 % (Peak Value). Results suggest a significant maternal contribution and a high within-family genetic influence on seed quality and germination characteristics. Finally, heavier seeds (SW e» 60 mg), whose time of germination (TOG) occurred at day 3, increased 38.3 % of their seed weight due to water absorption before reaching 50 % germination; on the other hand, seeds whose SW was e» 45 mg and TOG = 7, showed 102.2 % increase in SW before reaching 50 % germination. DOI: https://doi.org/10.54167/tch.v12i3.189