Post date: Dec 24, 2014 5:23:3 PM
The Open4st - 2014 Bell Nursery season was busy with lots of progress in our goal to produce vigorous, good rooting, well formed and diverse aspens. Below is a summary of the year's progress:
We planted 1854 total aspens representing a variety of stock types with 1173 aspens surviving in the 2014 nursery. Final tallies include 980 seedlings from 24 families, 820 rooted cuttings, 24 rooted stock, 184 ortet rooted cuttings and 145 cuttings propagated via WASP.
24 aspen families were grown at Rakers Greenhouse with a 38% mean germination rate, resulting in 1173 seedlings. Each family was measured for the tallest and median height tree within about 3' of the tallest tree (about 20 trees). The overall tallest tree was 156 cm (15xb), the mean tallest was 126 cm and 88 cm for the mean median height. Six families had germination rates at 10% or less. Four of these families had the female parent Plaza AG. The other 2 families involved an AAG trihybrid and a bisexual AG 9AG105. It will be interesting to see if these low germinating families will continue to have progeny with low germination rates that could be leveraged to produce effectively sterile materials.
A general observation was made that bigtooth parents are more difficult to breed than other aspens. The flowers have waxy coating that requires soaking the branch in warm water for about 30 minutes. Female bigtooth aspens are difficult to work with but eventually produce viable seed. Therefore female CAG clones may be more valuable.
Family seedling leaf/stem variability was subjectively scored on a 1-5 scale with 1 being low and 5 being high variability within the family. The mean score was 3.54. The 4 families with a 5 score were 9xbr, 5xrb, 4xrr and 1xbar. Three of these were mated with an AG parent but 2 were the bisexual 9AG105. 5xRB had a 35% seed germination rate, the others were less than 7%. It was interesting to note that 1xBAR failed to germinate at Rakers but McGovern produced 4 seedlings likely because they were planted immediately after collection. It will be interesting to see if there will be any good rooting and or vigorous selections from these families. 5 families scored a 2 for variability, 3 were of CAG and bigtooth parentage (8xbg, 18xbg, 19xgb).
2014 Family comparisons: While I think there is no seedling to long term field growth correlation, it is interesting to note family seedling growth patterns. Six families consisted of CAG male (CAG177) or female (CAG204) mated to 6 bigtooth aspens and one smalltooth (P. tremuloides). The mean of their tallest trees was 131 cm, exceeding the mean of 126 for all families and the best AxA family (107xAA) with 138 and the best GA F1 from 4xgw with 123 cm. The tallest tree of these families was a 7xbt which was the 4th tallest tree for all families. Four of these 6 families had median heights above the mean value of 89. It will be interesting to see how these CAG x aspen families compare to F1 AGs and the CAG F2 crosses to show if hybrid vigor can exist apart from an F1 cross. These types of crosses hold a lot of potential if they are productive because they employ a wild and diverse parent with potential for good rooting and selection possibilities from recombination.
Parental Sibling Observations: Two sibling male/female bigtooth aspens (gg102 and gg101) with Lower Penninsula parents were mated to 2 sibling male/female Canadian CAG clones (CAG204 and CAG177). The families 18xBG and 19xGB had both bigtooth parents G5 and G6 were growing about 300' apart from Michigan's Upper Peninsula in an area known for its figured aspen wood. There were interesting 1 year seedling differences between these families. Both crosses had similar Rakers germination rates (38% for 18xBG vs 33% 19xGB) but 18xBG had 1 Rakers flat seeded vs 1/2 flat for 19xGB. 18xBG ranked 3rd in median height (107cm), behind 15xB and 14xB CAG families while 19xGB ranked 13th (83cm) the shorter than all other CAG x native aspen families. Note that the 6th ranked family 13xGB (102cm) with Lower Peninsula parents had a female bigtooth mated to the male CAG177. It was interesting that G5 and G6 performed so differently and that G5 outperformed all others despite its Northern source in this one year study. If the 18xBG to 19xGB vigor differences continue to later stages, then perhaps there is significant selection potential for aspen parents from any given region.
The family with the tallest trees (tallest and median) is the CAG family, 15xB (c173 x 9ag105). Note that 2xB (c173 x AG15) from 2012 had a clonal selection, 2B25 that was the tallest in the 2014 nursery at 320 cm. Both families differ only by the P. alba female parent on the AG side (A10 vs. PCA2). It was observed that the 15xB had high stem variation in terms of diameter, form and bud patterns relative to the 2xB family. It will be interesting to track the performance of all 4 CAG crosses, compare them to F1 AGs and CAG204/CAG177 and breed them with native aspens.
The top 3 families for median diameter were 15xb, 14xb and 18xbg. The top 3 families for tallest single tree height were 15xb, 20xbs and 14xb. The top 3 families for the greatest range (variation) from tallest tree to the median were 20xbs, 5xrb and 107xaa. It will be interesting to see if there are any correlations to be made from future field performance results back to these nursery seedling results.
The "Plaza" wild AG performed poorly from a breeding perspective. It was found in NE Grand Rapids in a fertile lowland area with many hybrids. It is likely a wild AG clone but I can never be sure of its parentage. There were 4 crosses with Plaza all had Rakers germination rates lower than 11%. These female flower branches were taken from the lower branches of a huge tree so it would be interesting to do crosses with better quality branches to investigate if the issue is branch or compatibility.
Conducted a Leaf Study: Compared leaf shapes/margins to overall phenotypes and family types. In general, families with more than 50% alba parentage had more lobed shaped leaves with a cordate to ovate pattern (alba like). Families with less than 50% alba tend to have more intermediate cordate shaped leaves somewhat typical of F1 AG hybrids. While typical F1 AG and CAG familes are 50% alba the AGs have intermediate leaves, but the CAG families tend to have more alba lobing and tomentose with intermediate outliers. Perhaps this can be attributed to the recombination of a double hybrid and that the CAG parents tend to have more alba than intermediate leaf traits. The CAG (B) families mated with AG crosses and 11xAB tended to have the most leaf variation (mixtures of lobed and intermediate). Most alba types had dentate to sinuate leaf margins. Only 12xRB and 7xBT were scored to have doubly serrate margins. Other families had variable margin patterns. See: Open4st Aspen Clonal/Family Leaf Shape Photos
The 20xbs family did not appear to have the expected aspen traits (too much alba) of a CAG x P. smithii. We observed that the male parent 4xBT has alba like leaves (like AGA or canescens) and is likely the mistake causing this issue.
9AG105 is bisexual and was mated to C173 (15xB median=128), CAG177 (5xRB median=60), Plaza AG (3xRR median=78), CAG204 (9xBR median=80). It was interesting that 15xB was the best family over all and with intermediate variability. 9xBR ranked 15th for median height, while its sibling reciprocal 5xRB ranked 19th for median height and had the second highest height range.
The family 7xBT was the only CAG backcross to employ the native P. tremuloides. It ranked 8th in median height rank (100cm) but had the tallest seedlings from Rakers (6"). It will be interesting to compare this family to the other CAG x B families.
The clone 101AA11 (30AA5MF x NFA) had 98% rooting over 2 years with 59 cuttings survived. It is the best aspen rooter and should be used in future crosses.
Figured Wood: Observed consistent undulating grain patterns in 13-17mm radially split sections of 1 year lightly figured AGRR1 stems. This split wood process will be used as part of the early clonal selection. Also, collected four bigtooth clones from an area known for figured aspen.
Converted the Competition Indexer Program to the Postresql database and integrated with the online r4st database program.
Nursery Context: Most of the Bell Nursery cutting material was planted on 4/20/14 in a 672 square foot nursery (22' x 15 and 19 x 18). The ramet cuttings were 6" long with diameters ranging from 7mm to ~13mm. Mini-stools were planted that consisted of a 1-0 stock plant that is 6" long with a 1-2" root length. The cutting material was planted in rows planted on 30" centers and seedlings on 36" centers with dual rows of cuttings 4" apart and cuttings planted about 2" apart in each row. The internal 4" between the rows was covered with Miracle Gro Sphagnum Peat Moss, which had some plant food and absorbed water easily. The area between the double rows was covered with green grass clipping mulch. These materials helped to reduce weed growth and prevented hardening of the top soil layer that is typical on this site after repeated watering. The nursery was irrigated as needed with a 5' tall sprinkler. The last seedlings were planted on 7/2/14 and most materials had bud set by 9/22/14.