Journal of Tropical Forest Science 16(3): 369-372 (2004) 369 RELATIONSHIP BETWEEN LEAF FLUSHING TIME AND INITIATION OF LEAF RUST IN POPLAR S. Sharma Sharm. C . R *a& Department of Mycology Plantand Pathology, University of Horticulture Forestry,and Nauni, Solan (H.P.)- India230 173 The indigenous species of poplar (Populus ciliata) is widely distributed in the temperate Himalayas from Kashmi Arunachao rt l Pradesh between 130 350o 0t abov0m levea ese l (Sharma 2000). Apart from indigenous species, exotic hybrids and species of Populus, namely, P. nigra, deltoides,. P euramericana,x . P tremula. P alba . d P beine an ar g grow Indin i a (Khosla & Khurana 1982). Melampsora ciliata, an indigenous, heteroecious and microcyclic rust having only uredinia d teliaan l l stages, attack . ciliata,sP . alba,P . deltoides,P . nigra,P x . P euramericana, yunnanensis. P trichocarpa. P d an (Anonymous 1979, Sharm Sharma& a 2000). This rust specie alss oswa reporte occuo dt Nepaln i r , attackin ris s ciliata,. it gf P k o d an introduction into Europe has also been indicated (Vannini et al. 1996). This pathogen is widely distribute Himachan di l Pradesh (western Himalayaso s t bu l 313o )as t fro 0 0m m70 far no pathotypes have been reported. Studies of effects of leaf maturity and shoot age of clone f Populuso s spp n susceptibilito . larici-populinaM yo t s showha n that leavef so intermediate age have the greatest susceptibility to infection (Sharma et al. 1980). The variation in leaf flushing time of poplar genotypes (Mohanty 1997) and disease initiation (Khan 1994) have been observe thesd dan e findings for basie m doinr th sfo presen e gth t work. This observation was collectively studied to see the relationship between these aspects which may be utilised for future research. Cutting tese th t f clonesso , hybrid speciesd san , with length 18-2f wer, so cm 3e planted at 45 x 45 cm spacing in a randomised block design in the nursery beds at 30° 52' N latitude and 77° 11' E longitude and 1350 m above sea level on 7 February 1999. All cuttings were obtained from vigourously growing plants maintaine propagatior dfo n purposee .Th clones, hybrids and species planted were Theog, Narkanda, Diyar, Chamoli-2, Chhatrari, Madhoni, Delcant, Nagni-2 (P. ciliata clones); P. ciliata hybrids (P. ciliata x P. maximowiczii), namely, 37M1, 53M1, 64M1, 84M1, 87M1, 96M1, 112M1, 2M2, 30M2, 53M2, CM2-5-20/91, CM2-10-7/91, CM2-4-15/91, CM2-13, CM2-39, CM2-46, CM2-84 Populusd ;an spp., namely, P. yunnanensis, deltoides. P Hyb-3d '19an ' . These cuttings were plante nursere th n di y beds surrounde hillocks/mountainy db therd san e wer semi-evergreeo en n poplar e treeth n si vicinity, which could otherwis sourcs a t inoculumf eac eo . phenologicae Th l observations wer phenophaseseo madtw n eo , namely, leaf emergence and fully expanded leaf. A particular phenophase starts when about 10% of individuals are observed in that phase and is complete when a maximum of 10% individuals have not entered that particular phase (Semalt Sharmy& a 1996) observatione .Th s were recorded thrice weekly. Leaf emergenc defines emergence ewa th y db f foldeeo d leaves froe mth whild bu e fully expanded markeleas fwa d wit emergence hth completf eo e leaf. Initiation of disease was recorded with the first appearance of urediniopustules on the leaf. Data on days to reach leaf emergence, fully expanded leaf and disease initiation were recorded after planting of cuttings. Received August 2001 *E mail: [email protected] 370 Journal of Tropical Forest Science 16(3): 369-372 (2004) date aTh were subjecte statisticae th do t l analyses using standard procedure describes sa d by Panse & Sukhatme (1985). The correlation between leaf flushing time and disease initiatio alss onwa determined. The time taken after planting to reach the stages of leaf emergence, fully expanded leaf and disease initiation in clones and hybrids of P. ciliata and Populus spp. is presented in AmonTable. ciliata3 . P o t e s1 g th clone s Theog, Narkanda, Diya Madhond ran i tooe kth least time of 40 days to reach leaf emergence while clone Nagni-2 took the longest time of days 9 lease 4 Th . tday 7 timemergencr 5 sf fo e o fullf eo y expanded recordeleas fwa n di Diyar and Madhoni clones while the longest time of 74 days was recorded in Nagni-2 clone. Other clones took 58 to 61 days for the emergence of fully expanded leaves. Rust appeared Jun5 2 en o 1999 day8 13 ,s after plantin Theogn i g clone whil appearet ei Jul7 yn d o 1999 , day2 15 s after plantin Delcangn i t clone (Tabl. e1) Leaf emerged 51 days after planting in P. yunnanensis and 59 days after planting in P. deltoides '19' and Hyb-3 (Table 2). The first fully expanded leaf took 74 days to appear in P. deltoides '19Hyb-3d an ' , whil yunnanensis. P n ei toot i days5 k7 . Rust appeare deltoides. P dn i Jun7 1 '19 en 1999o ' ,day 0 i.e13 .s after planting whilyunnanensis,. P n ei appearet i d after 160 days. Among the hybrids, CM2-39 and CM2-84 took the least time of 49 days for the emergence of leaves while 53M2 took the longest period of 56 days (Table 3). The first appearanc fullf eo y expanded recordeleas fwa CM2-39n di day6 6 , s after planting whil laste daye4 th 7 , s after plantin 53Mgn i CM2-84d 2an . Hybrid 53M1 too lease kth t time of 138 days for the initiation of rust while CM2-46 took 165 days, i.e. the longest time. Correlations between leaf flushing time (leaf emergenc fulld ean y expanded leaf) diseasd an e initiatio thesn ni e poplar genotype givee . Diseassar 5 Tablen ni d an e s4 initiatio positivels nwa y correlated with leaf emergence (0.4775 fulld an )y expanded leaf (0.2485 ciliata. P n )i clones while negatively correlate ciliata. P dn i hybrids. Disease initiation in Populus species was negatively correlated with leaf emergence (- 0.6547) but positively correlated with fully expanded leaf (0.6547). Pooled correlation coefficients showed that Tabl e1 Numbe dayf ro reaco st h leaf flushin initiatiod gan leaf no f rus clonen ti f so Populus ciliata Clone Day reaco st h leaf Day reaco st h fully Days to reach emergence expanded leaf disease initiation Theog Marc9 (1 0 h4 1999) Apri9 ( 1 l6 1999) 138 (25 June 1999) Narkanda 40 (19 March 1999) Apri9 ( 1 l6 1999) Jun148 1(2 e 1999) Diyar 40 (19 March 1999) Apri55 7( l 1999) 142 (29 June 1999) Madhoni Marc9 40(1 h 1999) 5Apri5 7( l 1999) 151 (8 July 1999) Chamoli-2 42 "(21 March 1999' ) Apri6 ( 8 l5 1999) 143 (30 June 1999) Chhatrari 44 (23 March 1999) 59 (7 April 1999) Jun8 (2 e 1 199914 ) Delcant Marc3 (2 4 h4 1999) 59 (7 April 1999) Jul9 ( y2 199915 ) Nagni-2 Marc8 49(2 h 1999) 74 (22 April 1999) 150 (7July 1999) Table 2 Number of days to reach leaf flushing and initiation of leaf rust in Populus spp. Populus species Days to reach leaf Day reaco st h fully Day reaco st h emergence expanded leaf disease initiation P.yunnanensis Marc0 (3 1 h5 1999) 75 (23 April 1999) (17Jul0 16 y 1999) P. deltoides 'Lux' Apri7 ( 9 l5 1999) Apri2 74(2 l 1999) 154 (11 July 1999) P. deltoides '19' Apri7 ( 9 l5 1999) 74 (22 April 1999) Jul7 y(1 19990 13 ) Journal of Tropical Forest Science 16(3): 369-372 (2004) 371 disease initiatio positivelys nwa , though poorly, correlated with leaf emergenc fulld ean y expanded leaf. Partial correlation coefficients between disease initiation and leaf flushing time in the poplar studie presentee dar Tabln di . Disease5 e initiatio positivels nwa y correlated with leaf emergence in P. ciliata clones and hybrids while the opposite was observed between fully expanded leaf and disease initiation. Pooled partial correlation coefficients showed that disease initiatio positivels nwa y correlated with leaf emergence (0.0948 negativelt )bu y correlated with fully expanded leaf. Multiple regressions between disease initiation and flushing time indicated that a unit chang lean ei f emergenc fulld ean y expanded leaf could influence disease initiatioo t p nu 0.036 and 0.842 units respectively (Table 6). The coefficient of multiple determinations (r) revealed that 76.32% variation in disease initiation was contributed by leaf flushing time2 . Tabl e3 Numbe f dayo r leao st f flushin initiatiod gan f leano f rus hybridn i t f so Populus ciliata Hybrid Days to leaf Day fullo st y Days to disease emergence expanded leaf initiation CM2-84 49 (28 March 1999) 74 (22 April 1999) (6Jul9 14 y 1999) CM2-39 49 (28 March 1999) Apri4 (1 l6 6 1999) Jul1 ( y4 199915 ) 53M1 51 (30 March 1999) 68 (16 April 1999) 138 (25 June 1999) 2M2 Marc0 (3 1 h5 1999) 68 (16 April 1999) 142 (29 June 1999) 30M2 51 (30 March 1999) 68 (16 April 1999) Jun0 (3 e3 199914 ) 64M1 51 (30 March 1999) 68 (16 April 1999) 149 (6 July 1999) 84M1 51 (30 March 1999) 68 (16 April 1999) (7Jul0 15 y 1999) CM2-5-20/91 51 (30 March 1999) Apri6 (1 l8 19996 ) (7Jul0 15 y 1999) CM2-10-7/91 51 (30 March 1999) 68 (16 April 1999) 151 (8 July 1999) 87M1 51 (30 March 1999) Apri6 (1 l8 6 1999) Jul8 ( y1 199915 ) CM2-4-15/91 51 (30 March 1999) 68 (16 April 1999) 154 (11 July 1999) 37M1 51 (30 March 1999) Apri6 68(1 l 1999) 161 (18 July 1999) CM2-46 Marc0 (3 1 h5 1999) 68 (16 April 1999) 165 (22 July 1999) 112M1 Apri1 ( 3 l5 1999) Apri9 71(1 l 1999) 152 (9 July 1999) CM2-13 53 (1 April 1999) Apri9 71(1 l 1999) Jul0 y(1 19993 15 ) 53M2 Apri4 ( 6 l5 1999) Apri2 74(2 l 1999) Jul8 ( y1 199915 ) Tabl e4 Simple correlation coefficient (r) between disease initiatio lead nan f flushing tim Populusn ei species/clones/hybrid2 s Flushing time P.