Post date: Sep 27, 2016 4:23:58 PM
The Open4st team made significant progress in the 2016 Bell Nursery season towards our goal to produce vigorous, good rooting, and diverse aspens. The primary 2016 focus was to propagate, test and select clones derived from earlier breeding and nursery selection efforts. Below are highlights of the season:
2016 Nursery Stock Types
The following stock types were used in the 2016 nursery:
8" Dormant Cuttings (DC): Dormant cutting lengths were increased from 6" to 8" in 2016 to make final nursery selections that were closer to the standard 10" field grade cutting length.
Mini-Stools (MS): 1-0 stock cut to 10" length with roots pruned to 1" laterals and having a 3" top stem.
Family Dormant Cuttings: (FDC): A single family 8" dormant cutting taken from the ortet at about 2" from the root collar.
Other minor materials planted include Seedlings (SEL), 1-1 stock, and WASP stock.
2016 Nursery Summary
The 2016 Bell Nursery was irrigated, mulched, fertilized and located on about 1000 square feet with 17 rows, most planted on 30" centers. See: 2016-Bell-Nursery spreadsheet and 2016 Nursery photos.
The 2016 nursery had 2802 trees of various stock types planted with 2127 live trees surviving (76%).
The 8" Dormant cuttings (DC) were planted in rows 30" apart with cuttings spaced 2" within the row and separated by 4" double rows and MiracleGro Peat moss applied between the cuttings. All clones were represented with 5 cuttings in one or more replications.
Mini-Stools (MS) were planted in rows 30" apart with trees spaced 5" within the row. Most clones were represented by 3 mini-stools in one replication.
The mean rooted cutting collar median diameter was 7 mm. The mean rooted median Mini-Stool collar diameter was 13.2 mm.
There were 178 Mini-Stool clones planted spread across 468 trees and ending the season with a 94% survival rate and an average median stool collar diameter of 13 mm.
There were 174 dormant cutting clones planted spread across 1500 cuttings with a 74% survival rate and an average median collar diameter of 8.2 mm.
For more details see the r4st database and the 2016 Nursery Stock Summary
2016 Clonal Selection Process
It is important to note that most of the McGovern Breeding Program (MBP) materials in the 2016 nursery have not been field tested. Therefore the nursery selection process focuses on the primary objectives of promoting vigorous, good rooting clones from a collection of diverse aspen families. Future clonal field trials are needed to select durable regional clones, investigate any nursery to field trial correlations and leverage future breeding opportunities with the elite performers.
Each 2016 MS and DC replication was scored for median lower collar diameter, survival rate, a subjective "Plus Tree" score of "Y" (Yes) and the estimated number of 12" field grade cuttings with a top diameter at least 9 mm termed, "field_grade_ft".
In previous years the dormant cuttings were 6" long to select clones that can root at a shorter length and for easier storage/handling/lifting. They were previously ranked using a "Vigor Survival Plus Tree" formula represented by: (median collar diameter * survival rate) + sum of Plus Trees). Vigor Survival is the product of (median collar diameter * survival rate). Plus trees are a subjective "Yes" score for a given replication that were observed to have outstanding performance in its environment. It is handy for cross checking performance across replications but its subjective nature makes it variable.
The primary 2016 selection criteria was based on dormant cutting vigor survival and the number of 12" field grade cuttings with a top diameter at least 9 mm termed, "field_grade_ft". The mini-stool data was not used for selection since they only had one replication and had variable mini-stool stem sizes.
The formula for ranking dormant cutting performance was termed, "cut_fcut_rep" represented by: average(vigor_survival) + average(field_cuttings_ft) * (count(replication_nbr) *.1). This metric is objective (doesn't use the Plus Tree values) and factors in the variable number of replications since each clone may have 1 to 11 replications (eg. 100AA12).
The above formula provided the primary 2016 selection rank criteria. However, the final sets were manually adjusted to ensure diverse family and species representation while maintaining adequate vigor and survival (propagation) metrics.
2016 Selection Types
The 2016 selections are subject to change before or during the Spring 2017 processing date. See the vw_2016_6_nursery_field_summary view details for current selection details. See the 2016 Nursery Stock Types for aggregate selection type details. Below are details for the 2016 Selection Types:
Primary - Elite selections: These selections will represent about 30 clones that are recommended for field trials. It includes 4 FDC clones that require additional nursery testing. These clones are represented by 18 different families and 5 selection types (A, AH, H, ASH, C). The primary DC selections had 91% survival rate with 384 trees and 771 feet of field grade cuttings available for the 2017 season.
Secondary - Archive selections: These selections represent about 30 clones that will be archived for later use, since most have siblings in the primary group. These DC selections had a 91% survival rate with 246 trees and 412 feet of field grade cuttings available for the 2017 season.
Tertiary - Parent selections: These represents parents of previous MBP crosses. These DC materials are represented by 11 clones and a 65% survival rate with 55 available trees and 11 field grade cuttings. Most simply do not propagate as well as their progeny.
Families - Re-test selections: These represent 2 2016 families 25xR and 6xGG that will have some trees planted in a 2017 field and all others tested as FDC 8" ortet stock in 2017 nursery that will also preserve each Mini-stool. It will be very interesting to see if any of the native bigtooth 6xGG aspen FDC cuttings can grow roots.
Discarded Clones: About 100 clones are expected to be discarded. They have a 64% survival rate.
Family Classification System
A classification system was developed to help categorize these aspen materials. Below is a listing of these classes which are also included in the "rank_class" field of the vw_2016_2_nursery_key_summary table. The final selections and counts are subject to change.
A = Alba x Alba - More or less 100% AxA materials (eg. 83xAA04, 107xAA). 3 Primary selections
AH = Alba Hybrid - Have more than 50% P. alba (eg. 2xBA, 22xAR). 8 Primary selections
ASH = Aspen Hybrid - Have less than 50% P. alba (eg. 22xBG, 7xBT). 8 Primary selections
H = Hybrid - Have 50% P. alba (2xB, 25xR, 5xCAGR). 13 Primary selections
C = Control - 1 clone (DN34)
N = Native (eg. gg12)
Miscellaneous Notes
There were 644 aspen seedlings planted that used the GG12 figured aspen as the male parent. In September 2016, 375 seedlings survived with a 75% survival rate and an average median collar diameter of 6 mm. See: 2016 MBP Aspen Crosses. In 2017 8" cuttings of these materials will be tested for rooting and about 10% will be planted in field trials.
The female AxAG hybrid AAG2002 was mated to the native bigtooth clone, GG12 (1xARG) with 5% germination and open pollinated (2xARW) with 6% germination. These similar germination rates help validate comparisons between artificial crosses and open pollinated matings. See: Selecting for Effectively Sterile Clones.
The open4st team hopes to ramp up, test and distribute the new selections to cooperators seeking to participate in open Aspen research. The final selections will need to be carefully reviewed and consider archiving other lesser rooting clones that may have phytoremediation potential. There are 144 total clones with rooting over 49% (see:
vw_2016_7_dc_rooting_over_49percent). These may need to be screened separately.
The selections should also consider future breeding opportunities, while avoiding inbreeding. For example many MBP families use similar parents such as A10 and NFA. CAG Families like 14xB may require more selections, since it can be mated with more promising clones like 100xAA11.
112 MBP 5' 1-0 aspen trees were planted as archive clones. See Photos.
Two WASP experiments were conducted using the JRM Endophyte mycorrhizal product. See 2016 WASP Tests.
2017 Stock and Nursery Projections
Below are the 2017 projections to distribute and plant the 2016 aspen stock:
For each primary selection, plant 2 "deer-proof" 6' sized trees at an archive MBP DOT site and plant 14, 8" cuttings or mini-stools in the MBP nursery. This material could be used for a 2018 field trial.
For each secondary selection, plant 1 deer-proof" 6' sized tree at an archive MBP DOT site and plant 4, 8" cuttings or mini-stools in the MBP nursery.
Distribute 4 or 8, 10" cuttings of primary, secondary clones and 8, 6xGG and 25xR seedlings to Purdue for a 2017 field trial.
Distribute 10 clones for a potential MSU Pytorediation clonal lab test.
Plant selected FDC and Family (6xGG, 25xR) cuttings and mini-stools in the 2017 nursery, select top clones and check cuttings for figure. There are about 1300 cuttings that will be planted in the 2017 Bell nursery with about 380 available linear foot of growing area. If cuttings were planted in double rows at 4" apart (6 cuttings/foot) then 2280 cuttings could be planted (380 feet x 6/foot). If cuttings were planted in double rows at 5" apart (4.8 cuttings/foot) then 1340 cuttings could be planted (380 feet x 4.8/foot). I will plant at 4" spacing.
Change all references of the "Primary Elite" selections to just "Primary". The "elite" designation should be reserved for final selections, not nursery selections.