Propgtion of citrus rootstocks in greenhouses by seed, stem cuttings nd tissue culture to ccelerte budded tree production for out plnting. Richrd C. Beeson Jr. Assoc. Professor Mid-Florid Reserch nd Eduction Center - Apopk University of Florid
Bckground Seed sources of trditionl rootstocks re shrinking. Seed of new vrieties of rootstocks very low or non existent. Options re stem cutting of tissue culture
Rooting cutting I hve history of propgting woody plnt cutting beginning 1973. Strting with zle nd rhododendron cuttings F Lter Live ok, Americn Elm nd numerous other species First cuttings of trifolites in 2013
First propgtion of citrus cuttings reported in lte 1800 s First use of uxins ws in 1935. Bck then, citrus stems were rooted in glss enclosed rooting boxes in Stuck in snd nd hnd wtered frequently. IAA t 2000 to 3000 ppm ws the stndrd In the mid-1950 intermittent mist cme into fvor using 120VAC vlves NAA ws lso used, but t ½ the concentrtion
Stem mturity For growing shoots, higher success nd greter root growth occurred with cutting tken from below the first 12 inches Auxin Use of thickening gent (Cell-u-wett) incresed rooting success to over 90% compred to using wter s the solvent
In 2014 strted experimenting with rooting of stem cuttings Tble 1. Description of types of cuttings Clss Description 1 1 node, with 1 lef cut between nodes t the bottom of stem 2. 2 nodes, with 2 leves, cut between nodes t the bottom 3 3 nodes, with 3 leves, cut between nodes t the bottom 4 2 nodes, with 2 leves, cut just below the bottom node 5 3 nodes, with 3 leves, cut just below the bottom node 6 4 nodes, with 4 leves, cut just below the bottom node
Stem cuttings Shoot mturity Mture hrdwood cuttings were superior to softwood cuttings. For ornge rootstocks, single node (l lef nd 1 bud) generlly rooted within 6 weeks under overhed mist from mid-mrch to mid-november. Except sour ornge, 20 other trifolite generlly rooted >90 during this period. From lte November to lte Februry, rooting ws less thn 20% with poor root growth. However heting the substrte to 80F incresed rooting,but only to < 40%
Tretment Auxin conc. Root dry mss (g) New shoot length (mm) Number of shoots 1 node cut t stem 0 0.166 gh 23.8 lm 0.21 h 1 node cut t stem 2500 0.174 fgh 70.8 efgh 0.89 def 1 node cut t stem 5000 0.182 fgh 12.6 m 0.21 h 1 node cut t stem 7500 0.140 gh 30.2 klm 0.53 g 2 node cut t stem 0 0.150 gh 38.9 jklm 0.58 g 2 node cut t stem 2500 0.288 d 61.6 fghij 0.79 efg 2 node cut t stem 5000 0252 de 86.3 cdef 0.95 def 2 node cut t stem 7500 0.262 de 80.9 cdefg 1.03 cde 3 node cut t stem 0 0.295 cd 100.6 bc 1.52 3 node cut t stem 2500 0.374 b 68.6 efgh 1.16 bcd 3 node cut t stem 5000 0.373 b 109.6 b 1.5 The more nodes (leves) the greter the shoot growth. However, more nodes, more sprouts I use single lef/single node cutting for trifolites
Tble 1: Rooting percentge, root nd shoot dry msses of single node cuttings treted with 4000 or 7500 ppm uxin (Dip&Gro) concentrtions Dte 4000 ppm uxin 7500 ppm uxin Percent Percentge rooted rooted Root Dry mss (mg) Shoot elongtion (mm) Root Dry mss (mg) Shoot elongtion (mm) 6 My 94 110.7 11.4 100 113.9 15.5 15 My 92 181.6 12.6 94.7 139.8 b 30.3 6 August 100 129.1 b 19.1 100 173.1 11.1 2 September 100 73.7 b 0.5 100 102.1 3.5 15 100 45.6 b 0 100 63.0 0 September 14 October 100 102.0 0.8 100 29.9 0 3 November 100 43.9 0 56.7 29.1 0 1 December 63.3 40.3 0 86.7 67.2 0 4 Jnury 10 1.0 b 0 40 10.0 0 12 Jnury 30 4.8 0 33.3 5.3 0 5 Februry 6.7 0.9 0 23.3 3.0 0 23 Februry 83.3 27.8 0.6 80 25.2 0 18 Mrch 76.7 54.7 0 93 83.8 0 5 April 100 120.2 3.1 100 117.5 4.5 28 April 97 79.8 b 9.8 b 100 100.2 33.7 20 My 97 80.7 17.2 100 76.9 12.5 10 June 97 69.4 b 8.4 100 93.4 3.5
Effect of bottom het on root dry mss during the winter for Huhrski Kuhrski 90.0 Root dw (mg) 80.0 70.0 60.0 50.0 b b b 40.0 30.0 20.0 10.0 0.0 b b b b b 1/12-2/23 2/5-3/17 2/23-4-5 3/18-4/27 4000 Amb Temp 4000 Bottom Het 7500 Amb Temp 7500 Bottom Het
Tissue culture hrdening Tissue cultured plnt were obtined 5 times over the course of yer. Initited 6 July, 28 September, December 14, Mrch 9, My 17 Rootstocks were : C35 C-54 Sour Ornge US0812 Swingle -13 Kuhrsek-13
Tissue Culture Plntlets were removed from tissue culture boxes Roots were cut off nd stems cut into 2 cuttings No dditionl uxin ws pplied Plntlets were stuck in 60% pet:40% perlite nd plced in tents hevily shded Reltive humidity ws grdully reduced from >90% to 50%, then shding ws Removed one t time. Tretments consisted of lowering conditions every 2, 3, 4 nd 5 dys
Conclusions 2 dys lwys nd 3 dy for some rootstock produced the best rooted cuttings Cutting hrdened from Mrch to September were most successful > 90% Cutting initited in mid-novenber through the end of Mrch were mostly filure Use of bottom het from mid-october through Mrch ws successful with 80 degree tempertures