Historic, archived document Do not assume content reflects current scientific knowledge, policies, or practices. ecm 7 a ee tN ENE ie a” mii poeta? ioe ‘ Sy GF iS GAA Z Te? PSE SS FOREST SERVICE U.S. DEPARTMENT OF AGRICULTURE INTERMOUNTAIN FOREST AND RANGE EXPERIMENT STATION 507 — 25th Street, Ogden, Utah 84401 USDA Forest Service July 1978 Research Note INT-248 EFFECT OF COLD STORAGE ON DEVELOPMENT OF SUCKERS ON ASPEN ROOT CUTTINGS George A. Schier and Robert B. Campbell! ABSTRACT The effect of cold storage on suckering abtlity of veer exetsed roots was determined for 10 aspen clones Root so euttings were collected in June, August, and October and an stored for from 7 to 42 days at 2°C. In addition; -cuttings ee from dormant trees were stored for 175 days to determine — tf they had cold requirements for suckering. Among clones, ae there were large differences tn capactty to produce root r> ast suckers. Cold storage had a small but stgntficant effect ae on the formation and growth of suckers on root cuttings = collected in June and August. As a rule, clones responded se similarly to cold storage. Sucker production by root seg- — ments from dormant trees was relatively high and was not inereased signtficantly by storage. Inetdence of callus formatton at the ends of root segments tended to increase with time tn cold storage. KEYWORDS: Populus tremulotdes, quaking aspen, aspen root cuttings, sucker development, adventitious shoots, chilling requirements. Aspen (Populus tremuloides Michaux) is vegetatively propagated by rooting cuttings taken from adventitious shoots (suckers) arising on excised roots. Roots are often stored at low temperature before culturing root suckers (Benson and Schwalbach 1970; Sandberg 1951; Starr 1971). However, no information is available as to the effect of cold storage on sucker production. The shoots of physiologically dormant trees generally require a cold period before they resume growth. Under field conditions this requirement is satisfied by natural chilling during the winter months. Roots collected from dormant trees many also have cold requirements that have to be satisfied before they will sucker. 1Plant Physiologist and Biological Technician, respectively, stationed at the Forestry Sciences Laboratory, Logan, Utah. This study was to determine the effect of cold storage on sucker production from root cuttings taken from 10 aspen clones. Roots were collected in spring, summer, and fall and stored for various periods in a cold room. Suckering from stored roots was compared with suckering from roots planted immediately after they were collected. METHODS Root segments were collected from 10 clones in Logan Canyon, east of Logan, Utah, on June 1 (2 weeks after bud break), August 9, and October 12 (after leaf fall), 1976. After the roots were collected they were rinsed, cut into 8 by 1 to 2 cm segments, and soaked for 30 minutes in an aqueous slurry of 0.1 percent benomyl, a systemic fungicide. Segments from each clone were randomly divided into five groups of eight segments each. One group (control) was planted immediately, and the other four groups were wrapped in moist paper toweling, placed in plastic bags, and stored in the dark at 2°C for 7, 14, 28, and 42 days before planting. Segments were planted horizontally 1.5 cm deep in moistened vermiculite in plastic trays (19.5 by 27.5 cm) with adequate drainage. Each group (eight segments from each clone) was subdivided into four lots of two segments. These were distributed among four plant trays so that each tray contained two segments from each clone. The trays were placed in a growth chamber maintained at a 25°/15°C, 12/12 hour temperature regimen and a 12/12 hour photoperiod and were lightly watered each day. When new trays were added to the growth chamber, they were randomly placed among those already present. Six weeks after the root segments were planted, they were lifted and the number of suckers recorded. The height of the tallest sucker per seg- ment was also noted, along with the occurrence of callus at the ends of the segments. The storage periods used may not have been long enough to satisfy chilling re- quirements of root cuttings from dormant trees. Dormant stems generally require more than 2 months of continuous chilling before normal bud break will occur (Barry 1972; Farmer 1968). To make sure that chilling requirements were met, segments from the October collection were also stored for 175 days (October 12 to April 15) and then planted. _- RESULTS The effect of storing aspen roots at low temperatures on subsequent sucker pro- duction is shown in table 1. Storage time had a significant effect on suckering from roots collected in June and August, but not on suckering from those collected in October. Storing June roots for 1 week caused a significant increase (30 percent) in sucker production. Thereafter, increased storage time resulted in only minor changes. Sucker production from August roots significantly decreased (34 percent) during the first 2 weeks of storage and then showed little change with an increase in storage time. Differences among clones were highly significant for all three collection dates. Com- parisons among clones are shown in table 2. A nonsignificant clone-storage interaction indicated that the clones responded similarly to treatments. When the analysis was limited to sucker production by the controls, there were significant differences between dates. However, when data from all treatments were included in a single analysis, differences between dates were not significant. Thus, cold storage generally had an equalizing effect on the number of suckers produced at different seasons, that is, it reduced the seasonal variation in sucker production. Nevertheless, a significant clone-date interaction indicated that some clones showed considerable seasonal varia- tion in sucker production. The effect of cold storage of aspen roots on subsequent height growth of root suckers is shown in table 3. Storage only had a significant effect on sucker growth on roots collected in June and August. Sucker heights on June roots were slightly in- creased by 2 weeks of storage. Longer periods of storage caused approximately 17 per- cent reduction in growth. On August roots, there were no consistent trends. Sucker heights decreased by 15 percent after 1 week of root storage, increased after 2 weeks, 2 Table 1.--Hffect of ttme tn cold storage on mean number of suckers produced from aspen root cuttings (8 by 1 to 2 cm) : Clon Days : ee Onto seer ye TES Parole ror yfh tte Bern Oi 2-91) <2 Mean June Collection 0 Poth US io) 5 II 4.2 as 9.5 a5 2.8 Aled Bie 6.60 b 7 Tbh HY) UW) 4.5 Zor Oa 6.6 4.9 Dos) be/od! S25 5ea 14 OAs 2020) 1026 Toul Al) OF! T58 £75 (0) 2-9) «629 7.87 ab 28 629) 2456 9.5 4.8 2.8 Sez So) 5.15 8298539 8.40 a 42 AAO 224) al OnS Gall 1a Hee i ig Late) 4.6 Sis8 420) Beis 7.39 ab Mean TA05922520 10220 AOU, ee SOMA GToD) (OS008 5590s SaLORGs4Ss 7478 August Collection 0 GR 2769 ew 2 5.9 2A 8.1 1683 Arlee les) 102672! 7 NA SOs ZIG NOGA 3.8 Zo Sim ales 6.5 ae 6.6 6.6 8.84 ab 14 sisly AUsAb IOs G8) TEE Sy el LBS) 4.6 1.4 S10) oo 6.81 b 28 LAE OS GHO 1530 Sad Ile ayd Lilestl Se5 2.6 SOw el LSE 10 42 V322— 1850 9.6 3.9 3.6 7.4 SZ 2.0 6.5. “41 1250 1D Mean E3250 20575) 11/20 A LOMae HOO leo) 4 Sie B55 5015 F6420) SLS October Collection 0 PANS ASS) BL BPA Ds) he 7.8 A<9 Zul: Uses SES 8.80 a i WO) BAS) AlS® 4.4 7 ey Neen | esi 7.0 Dek ela ORS 9.25 a 14 litjat AO géient iijee! Dig) S10 OF: 5.6 4.0 G28) 259 8.84 a 28 Teo. S34 20.2 Sc4 3.9 Haat 5.0 520 ASI ee K0) 8.39 a 42 AarLOM eS 3072256 8.2 Ar 8.8 4.5 4.0 Tats Zo) 9.41 a Mean 16.15 19.05 19.50 AU SLU MItOHIOD) OOD Soe O25) 200) Se98 1 Treatments with no common letter are Significantly different at the 5 percent level. Table 2.--Compartsons among aspen clones tn mean number of suckers per cutting. Clone numbers are tn parentheses. Clones are ranked tn order of de- ereasing sucker production. Underlined means were not stgntftcantly dtfferent (5 percent level) from each other. JUNE (2) (3) (6) (1) (10) (7) (9) (4) (8) (5) pd sos 10.2 9.8 eal 6.4 6.0 Sl 4.8 3.9 223 AUGUST (2) C1) (6) (3) (10) (7) (9) (4) (5) (8) 20.8 £3.05 11.4 il 2 6.2 5.4 5a0 4.1 2.4 1.8 OCTOBER (3) (2) (1) (6) (9) (7) (4) (8) (S) (10) RS) laa 16.2 8.8 6.6 6.0 4.3 516 S57 ZaA0 Table 3.--Effect of time tn cold storage on mean hetght of tallest sucker per aspen root cutting (8 by 1 to 2 em). Days : 1 2 STS Aaa See 6 JUNE COLLECTION 0 US AOn ZeliaO 20) Sm ee 4a 5557 We 27 3Ons Bee lie 329-- 28.0 © 27-60127529me8 7 Wo 1e731 20.2 59m 2534 9 Sl. 08.8 2558 yf Side ei a2 27.0, 26397 a2 14 LAO Io Ey on2 34.5 A hae 24 32 28.2 @ 49.25.37. 29) 04 e29R05mes 28 18.9 16.0 18.8 31.4 ZSES Zia 22 all 28.9) 23,16 27.2, s24iee 42 18.8 S59 LSGe a SOR 32.4 2249 Zoe SL sfey28ao 26.2. 123) 6Siae Mean MRO LEV SAW IESG SIS) | SLO GLOS $0570. ».26..70.3232485) 835255029 .40 G27 95 e274 AUGUST COLLECTION 0 PEE) ZA Dl tee SO a0 4420 @ 3225 2601 54,58) W280 24.4 29.83 a 7 20.4 20.4 LOO, aero a4 38.5 2569 20:56 40.84 24 3 2210) S25 14 24.2 17.89 PINE = ONES Sigs) 5 ZG 31.8 » 4053) 2657) 2558) (238 54Gues 28 21546 19.4 219 Big Ht AS52432 32.0.8 3088 2) 46249729.135)' *27).6 e2o eee 42 24.5 16.5 ZO Baie 51S) 29 Se eZ27.0, SOR Om SZcel 25.5 Z@n(giee Mean 22.75 1905.4 25.15