Abstract
Coniferous seed orchards require a long period from initial seed harvest to stable seed production. Differential reproductive success and asynchrony are among the main factors for orchard crops year-to-year variation in terms of parental gametic contribution and ultimately the genetic gain. It is fundamental in both making predictions about the genetic composition of the seed crop and decisions about orchard roguing and improved seed orchard establishment. In this paper, a primary Chinese pine seed orchard with 49 clones is investigated for stability, variation and correlation analysis of factors which influence genetic quality of the seed lots from initial seed harvest to the stable seed production over a 12 years span. Results indicated that the reproductive synchrony index of pollen shedding has shown to be higher than that of the strobili receptivity, and both can be drastically influenced by the ambient climate factors. Reproductive synchrony index of the clones has certain relative stability and it could be used as an indication of the seed orchard status during maturity stage; clones in the studied orchard have shown extreme differences in terms of the gametic and genetic contribution to the seed crop at the orchard's early production phase specifically when they severe as either female or male parents. Those differences are closely related to clonal sex tendency at the time of orchard's initial reproduction. Clonal gamete contribution as male and female parent often has a negative correlation. Clone utilization as pollen, seed or both pollen and seed donors should consider the role it would play in the seed crop; due to numerous factors influencing on the mating system in seed orchards, clonal genetic contribution as male parent is uncertain, and it has major influence on the genetic composition in the seed orchard during the initial reproductive and seed production phase.
Highlights
Seed orchards are the most common means of making available a stable supply of genetically improved seed and it constitutes an important component in most coniferous species improvement programs in the world [1]
Differential reproductive success and asynchrony are among the main factors for orchard crops year-to-year variation in terms of parental gametic contribution and the genetic gain [5]
With generated information, genetic thinning, clonal management measures can be adopted to adjust the genetic composition of orchard pool and to improve the level of genetic gain of the resulting seed crops
Summary
Seed orchards are the most common means of making available a stable supply of genetically improved seed and it constitutes an important component in most coniferous species improvement programs in the world [1]. Genetic gain of seed orchards’ crops depends on the section differential between the orchards’ parental populations and that of unselected seed sources as well as orchards’ parental population actual gamete contribution to the harvested seed crops [2]. The attainment of balanced gametic contribution from orchards’ parents is hardly observed due to many factors including differential male and female reproductive success and asynchrony as well as the degree of selfing and pollen introgression from outside unselected sources [3] [4]. The time span from initial seed harvest to stable seed production shows substantial parental gametic contribution instability and is the subject of intense research [6] [7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
