Disese Detection nd Losses Effect of Potto Virus Y on Cultivrs nd Hyrids of Burley Toco R. C. Sievert Reserch Plnt Pthologist, Agriculturl Reserch Service, U.S. Deprtment of Agriculture, Toco Experiment Sttion, Greeneville, TN 37743. Present Address: Toco Reserch Lortory, Route 2, Box 16G, Oxford, NC 27565. Coopertive investigtion of the Agriculturl Reserch Service, U.S. Deprtment of Agriculture nd the Tennessee Agriculturl Experiment Sttion. Accepted for puliction 10 Ferury 1978. ABSTRACT SIEVERT, R. C. 1978. Effect of potto virus Y on cultivrs nd hyrids of urley toco. Phytopthology 68: 974-978. involving L8 prentge. Cured l from disesed plnts generlly hd significntly higher levels of totl, cid-insolule, nd nitrte, nd produced solution with higher ph. Solule, totl lkloids, phenols, nd wter-solule cids were generlly significntly lower in infected mteril. Infected plnts generlly were shorter, nd hd fewer nd smller leves thn helthy plnts. Eleven urley toco cultivrs nd hyrids infected with potto virus Y hd lower yields, gr nd crop indices, nd mrket vlues. Tolernce to the virus ws exhiited y some cultivrs ecuse its fect rnged from mild to severe. The vlue per hectre of toco from infected plnts ws reduced y I to 83%. The most tolernt cultivrs were Kentucky (Ky) 10, Ky 12, nd Ky 14; the lest tolernt were hyrids Additionl key words: Nicotin tum, veinnding. The occurrence of potto virus Y (PVY) in toco, Nicotin tum L., hs incresed in recent yers nd in some loclities is mjor disese. In toco, the disese is clled veinnding, with urley toco displying generl yellowing nd often premture th of lower leves. In flue-cured toco, the symptoms re similr except tht one strin of the virus cuses necrosis in cultivrs resistnt to root knot nd nother strin cuses necrosis on ll flue-cured cultivrs (3). Potto cultivrs vry in susceptiility to PVY (1, 4) ut little is known out how toco cultivrs rect other thn tht they re ll susceptile (8). The ojectives of this experiment were to termine: (i) whether ny of the currently grown commercil urley toco cultivrs nd hyrids re tolernt to PVY; (ii) the fect of PVY on yield nd qulity of urley toco; nd (iii) the fect of PVY on selected chemicl constituents of cured urley toco. MATERIALS AND METHODS Eleven cultivrs nd hyrids of urley toco were used in this study (Tle 1). A split-plot sign ws used with inocultion tretments consired s the whole plots nd cultivrs s the suplots. Ech suplot consisted of 27 plnts of one cultivr or hyrid with the end plnt not hrvested; thus ech suplot constituted 0.00 10 h (1 / 400 of n cre). Within the whole plots, ech cultivr or hyrid ws rndomly replicted three times. The plnts in one lock were inoculted with PVY on 23 June 1970 nd 29 June 1971, 32 nd 28 dys, respectively, fter trnsplnting, using the method previously scried (7). The plnts in the other lock were not inoculted nd 00032-949X/78/000 170$03.00/0 Copyright 1978 The Americn Phytopthologicl Society, 3340 Pilot Kno Rod, St. Pul, MN 55121. All rights reserved, served s checks. The toco ws grown, hrvested, nd hndled fter hrvesting in the mnner norml for commercilly grown urley toco. The cured toco ws weighed nd ssigned gr y Ferl toco inspectors. The gr inx, mesure of l qulity, ws clculted from the ssigned grs; the crop inx ws termined y multiplying the yield (in l/a) y the gr inx. L numer, length nd width, nd plnt height for 10 plnts in ech plot were scertined on 6 August 1970 nd 12 July 1971. The numer of plnts flowering were counted on 24 nd 28 July 1970. Smples of the cured toco were dried, ground, nd nlyzed for selected chemicl constituents. Ech smple ws composite smple, tht is, the smple for ech plot consisted of l tissue from ech stlk position in the sme porportion tht the l tissue from ech stlk position contriuted to the totl weight for tht plot. Chemicl nlyses were performed t the Toco Reserch Lortory, Oxford, North Crolin nd the Reserch Lortory of Liggett nd Meyers Toco Compny using the procedures scried previously (9). The dt were sttisticlly nlyzed y nlysis of vrince. RESULTS All inoculted plnts veloped PVY symptoms nd the checks remined free of PVY symptoms. Tle 1gives the yield, qulity, nd vlues of the crop; Tle 2 presents the results of the chemicl nlyses;nd Tle 3 indictes how the virus ffected severl physicl chrcteristics of the plnt. Yield, qulity, nd vlue.-the yield of ll cultivrs nd hyrids ws reduced y PVY ut the reductions were significnt only for (Bu 37), Bu 49,, nd. Yields of PVY-infected entries rnged 974
July 1978] SIEVERT: PVY ON BURLEY TOBACCO from 555 to 2,730 kg/h (verge 2,007 kg/h). Helthy plnts produced 2,705 to 3,339 kg/h (verge 2,932 kg/h). The disese significntly reduced the gr inx of ll cultivrs nd hyrids. Nondisesed plnts produced cured l toco with gr indices from 0.491 to0.617, verging 0.552; cured l produced y toco plnts infected with PVY hd indices from 0.201 to 0.367 (verge 0.309). The crop inx, mesure of oth yield nd qulity, ws lowered significntly y PVY. It vried from 1,192 to 1,780 for helthy toco nd from 99 to 904 for disesed toco. The verge for the toco from ll helthy cultivrs nd hyrids ws 1,45 1, wheres the verge for ll disesed cultivrs nd hyrids ws 602. The vlue/ kg for inoculted toco lso ws reduced significntly y the virus. In noninoculted toco, the vlues rnged from 1.689 to 1.748 (men 1.710). The men for toco infected with PVY ws 1.571 nd rnged from 1.470 to 1.624. The vlue per hectre of noninoculted cultivrs nd hyrids ws significntly higher thn for PVY-infected mteril for ll entries. Vlues for helthy toco rnged from $4,593 to $5,837 (men $5,015). Plnts infected with PVY produced cured toco with vlue tht rnged from $816 to $4,421 (men $3,183). Chemicl constituents.-the mount of in toco from plnts infected with PVY ws significntly greter thn tht in toco from helthy plnts. Totl in cured toco from disesed plnts rnged from 4.50 to 5.06% y weight, wheres the rnge in helthy toco ws 3.73 to 4.27%. The verge for ll 975 disesed cultivrs nd hyrids ws 4.77% nd the men for ll helthy cultivrs nd hyrids ws 3.96%. Acid insolule lso ws significntly higher in PVY-infected toco thn in helthy toco, verging 2.12% in the former nd 1.32% in the ltter. The rnge in disesed toco ws 1.77 to 2.50% nd 1.21 to 1.49% in helthy toco. Toco from plnts infected with PVY hd significntly lower percentge of tht ws solule, rnging from 46.5 to 62.4% (men 55.6%). The toco from helthy plnts hd n verge of 66.6% of the present s solule, nd the mount rnged from 65.2 to 69.6%. The fect of PVY on the mount of -mino ws vrile. Bu 49 hd significntly less when infected with PVY, ut there ws no pttern for the other cultivrs nd hyrids - some hd more when infected ut others hd less. Nitrte generlly ws higher in PVY-infected toco, ut the differences were not significnt for four cultivrs: Ky 12, Ky 14,, nd. Noninoculted toco hd levels of nitrte from 0.40 to 0.55% (men 0.48%). Nitrte in disesed toco from the 11 cultivrs nd hyrids rnged from 0.42 to 0.73% (men 0.62%). Generlly, there ws reduction in the mount of phenols present in PVY-infected toco lthough the reductions were not significnt for Bu 49, Ky 12, Bu 21 X L8, nd. The rnge in disesed toco ws 0.29 to 0.74% (verge 0.47%) nd the rnge in helthy toco ws 0.50 to 1.04% (men 0.77%). Disesed toco hd less lkloids thn helthy TABLE 1. Effect of potto virus Y on yield, qulity, nd vlue of 11 cultivrs nd hyrids of urley tocoy Cultivrz Not inoculted Virgini 509 Yield (kg/h) 2,719 d 2,705 d 2,720 d 3,122 2,934 3,339 3,061 2,957 3,014 2,719 d 2,959 Gr inx.527.563.498.578.563.597.617.569.541.491.533 d d Crop inx 1,280 1,359 1,215 1,619 1,485 1,780 1,679 1,499 1,447 1,192 1,410 c f Vlue ($/kg) 1.699 1.716 1.692 1.716 1.715 1.748 1.719 1.712 1.703 1.689 1.696 Vlue ($/h) 4,620 4,640 4,603 5,358 5,032 5,837 5,262 5,062 5,134 4,593 5,019 d d Inoculted 2,084.303 gh 569jk 1.616 c 3,366 i 1,715 e.283 h 464 k 1.557 e 2,670 j 1,766 e.315 gh 552jk 1.571 2,775 j 2,578 d.362 852 gh 1.603 4,131 fg 2,716 d.361 888 g 1.624 c 4,411 2,730 d.367 e 904 g 1.619 c 4,421 Virgini 509 2,298.323 gh 679 hij 1.586 3,643 hi 2,470 d.344 g 772 ghi 1.586 3,917 gh 2,504 d.312 703 hij 1.545 e 3,868 gh 664 f.228 i 1401 1.501 f 996 k 555 f.201 i 991 1.470 f 816 k YTwo-yr mens sed on three replictions per yer; mens in the sme column followed y the sme letter re not significntly different (P = 0.05) ccording to Duncn's multiple rnge test. ZArevitions: Bu = Burley; Ky = Kentucky.
[Vol. 68 PHYTOPATHOLOGY 976 toco ut the mountws significntly less in only 10of the 11 entries. The mount rnged from 2.63 to 4.21% when PVY ws present nd from 3.90 to 4.80% in the sence of the virus. The mens were 3.48 nd 4.40% for disesed nd helthy plnts, respectively, Less wter-solule cids were present in PVY-infected toco thn in helthy toco, rnging from 1.92 to 3.27% (men 2.58%). In virus-free toco it rnged from 2.86 to 3.33% (men 3.18%). Although 10 of the 11 cultivrs nd hyrids hd reduced wter solule cids when infected with PVY, the reductions were significnt for only three cultivrs nd three hyrids. The ph of solution prepred from ground cured l ws higher for ll disesed toco except Ky 14, ut the increses were significnt only for Bu 49,, nd. The verge ph for ll helthy entries ws 5.90 nd rnged from 5.83 to 5.95. The verge for PVYinfected toco ws 6.06 nd rnged from 5.83 to 6.35. Physicl chrcteristics.--plnts contining PVY were shorter thn helthy plnts, with the exception of inoculted Ky 10 which ws 3.3 cm tller thn noninoculted plnts of the sme cultivr. The reductions in plnt height were significnt only for Bu 37, Bu 49, Ky 14, nd the two L8 hyrids, Generlly there were fewer hrvestle leves on plnts inoculted with PVY thn on noninoculted plnts lthough the differences usully were not significnt. Only three entries hd significntly fewer leves. These were Bu 37,, nd which hd 15,31, nd 43%, respectively, less leves per plnt. Leves on plnts infected with PVY were significntly shorter nd nrrower thn leves on helthy plnts. L length of infected plnts cresed from 6 to 41%; the width ws reduced y 11 to 44%. The percentge of plnts flowering generlly ws higher mong plnts inoculted with PVY thn mong helthy plnts. Only Bu 49 nd the hyrid verged fewer plnts flowering when infected with PVY ut the differences were not significnt. Cultivrs Bu 21, Bu 37, Ky 10, Virgini 509, nd, infected with PVY, hd significntly greter numer of plnts flowering thn helthy plntings of the sme cultivrs. DISCUSSION Infection y PVY hd leterious, nd in some instnces, severe fects on the quntity nd qulity of cured toco produced y 11 urley toco cultivrs nd hyrids. The reductions in vlue per hectre verged 36%, ut rnged from 11% for Ky 12 to over 80% for the hyrid. The reduced per-hectre vlues were due to oth lowered yields nd toco of lower qulity. The yield reduction rnged from 7 to 81%, verging 32% less, nd the gr inx ws lowered from 36 to 62%, verging 44% less thn toco from comprle helthy cultivrs nd hyrids. The reduction in yield ws TABLE 2. Effect of potto virus Y on selected chemicl constituents of ir-cured l from 11 cultivrs nd hyrids of urley tocow Totl Acidinsolule Solule -Amino Nitrte Totl Totl ' phenols lkloids 1.30 1.41 1.49 1.24 f 1.33 65.8 65.3 65.2 69.6 67.2.453.429.510.551.589 3.88 Virgini 509 4.01 fg 3.88 1.21 f 1.32 1.25 f 68.4 67.1 67.5.532.444 gh.466 g.49 g.88.55 c.66 g.50 g.83 3.91 3.73 h 1.34 1.28 f 65.7 65.4.524 d.447 g.46 g.40 g 3.86 1.31 65.9.428.42 g Cultivrx Not inoculted 3.81 4.27 4.09 gh e g.51.43.52.50.50 g.80.75 d fg g.50 gh g 1.04 g.73 4.80 4.45 4.77 3.90 Wtersolule cidsz ph (ml) 2.86 3.26 3.20 3.33 3.09 5.91 5.95 5.87 5.89 5.83 c c f 4.17 4.78 4.64 3.22 5.87 5.84 3.32 3.18 5.90.90.72 3.95 4.35 d 3.09 5.93 c 3.24 5.95 c.66 g 4.63 3.20 Inoculted 3.56 gh.42 gh.70.452 g 2.11 55.5 fg 4.74 c 3.52 gh.29 h.70.451 g 4.98 2.23 55.3 fg 2.94 i.34 h.71.421 52.6 gh 4.83 2.31 4.21.46 g.64.542 59.9 4.86 1.96 3.41 h.61 d.52 cgh.546 1.90 d 59.6 4.70 4.03.58.54 cgh.579 1.77 62.4 4.68 4.07.33 h.73.497 2.16 57.6 Virgini 509 5.06 3.81 fg.38 h.67.496 4.80 2.18 55.1 fg 3.33 h.46 gh.64.486 c 2.03 56.3 e 4.63 2.76 ij.74.45 fg.411 gh 2.22 50.8 h 4.50 d 2.63 j.71.42 g.381 h 46.5 i 2.50 4.65 WTwo-yer mens sed on three replictions per yer; mens in the sme column followed y the sme different (P = 0.05) ccording to Duncn's multiple rnge test. XBu = Burley; Ky = Kentucky. YPercent of totl tht is solule in wter. zmilliliters of 0.1 N NOH required to neutrlize 1.0 g of oven-dried nd ground toco. 5.93 c 6.05 2.47 fg 6.08 2.63 6.29 2.09 hi 3.10 5.96 c 2.95 d 5.83 f 3.27 5.83 f 3.02 d 5.88 2.87 6.02 2.75 5.94 c 6.22 2.23 gh 6.35 1.92 i letter re not significntly
July 1978] SIEVERT: PVY ON BURLEY TOBACCO cused y comintion of fewer hrvestle leves nd lso smller leves; there ws reduction in oth length nd width of leves on plnts infected with PVY. The reduction in hrvestle leves resulted from tenncy of leves on infected plnts to yellow premturely. Thomson nd Wright (10) lso found tht PVY reduced plnt height, l re, nd l weight of flue-cured toco in New Zelnd. The presence of the virus ffected the mounts of severl chemicl constituents in the cured l. Totl ws higher in PVY-infected toco nd ws due lrgely to n increse in cid insolule. Nitrte lso ws higher, ut the increses were not significnt for four cultivrs. Smples from PVY-infected plnts hd higher ph's, ut the increses generlly were not significnt. Totl lkloids were lower in PVYinfected toco lthough the reduction ws -not significnt for Ky 14. Totl phenols nd wter solule cids were lso lowered y the virus, ut the reductions were not lwys significnt. The chnges in the chemicl constituents cused y PVY in this study gree closely with those reported in nother type of study (9) nd follow the sme pttern reported for toco vein mottling virus (TVMV) (5). There were inite differences in the mgnitu of the fect of PVY on the yield nd vlue per h of the cultivrs nd hyrids includ in this study. A numer of ville cultivrs re tolernt of the virus nd will produce good yields even when infected with PVY erly in the seson, Ky 12 ws the lest ffected cultivr in this test. The 977 percent crese in yield, gr inx, vlue per kg, nd vlue per h due to PVY ws less for Ky 12 then for ny of the other cultivrs or hyrids tested. Although the yield ws reduced when Ky 12 ws inoculted with PVY, the reduction ws not significnt. There ws, however, significnt reduction in the qulity s mesured y the gr inx, nd consequently significnt reductions in the crop inx s well s the vlues per kg nd h. Cultivrs Ky 10, Ky 14,, nd lso were tolernt to PVY. The lowest yields were produced y Bu 37, Bu 49, nd the two L8 hyrids. Generlly, the fect of PVY on the yield of urley cultivrs is similr to the fects of toco etch virus (TEV) nd TVMV on urley toco (2, 6). Two exceptions re Virgini 509, which ws severely ffected y TVMV ut only mortely ffected y PVY nd TEV, nd Ky 12, which hd significnt reduction in yield due to TEV, ut ws tolernt to PVY nd TVMV. Cution should e exercised in selecting cultivr tolernt to the potyvirus complex to insure tht it is not t the expense of resistnce to nother disese. Those cultivrs nd hyrids with resistnce to lck shnk generlly were ffected more y PVY, TEV, nd TVMV thn cultivrs nd hyrids tht do not hve lck shnk resistnce. The two hyrids involving L8 s one prent were severely ffected nd proly could not e profitly grown in n re where the potyviruses re enmic. Further studies re need to termine whether lck shnk resistnce is geneticlly linked with resistnce to the PVY group. TABLE 3. Effect of potto virus Y on physicl chrcteristics of 11 urley toco cultivrs nd hyrids' CultivrZ Not inoculted Virgini 509 Plnt height Leves (no.) 127.7 124.6 d 118.1 114.0 g 124.6 d 127.3 125.6 127.0 131.6 119.4 118.4 19.8 ghi 20.8 cg 21.4 20.7 cgh 23.0 21.5 21.0 cg 19.5 ghi 23.4 17.7j 19.0 hij L length 58.2 57.7 56.6 62.9 59.9 61.8 62.3 60.9 60.1 61.1 60.4 c d d L width 25.4 26.1 26.4 27.5 27.0 28.3 28.0 27.2 26.9 25.3 27.4 d d Flowering 13.0 36.3 18.7 13.0 2.7 11.5 11.0 17.5 11.7 47.8 60.8 gh c g gh h gh g Inoculted 121.8 18.9 ij 53.0 gh 22.2 hi 28.8 108.4 fg 17.6 j 49.0 i 21.0 i 55.7 104.0 g 19.8 ghi 50.7 hi 22.8 gh 18.2 g 117.3 21.0 cg 57.3 c 24.1 fg 27.2 119.9 22.0 d 55.2 g 24.0 fg 12.8 gh 112.9 g 19.5 ghi 57.5 c 25.0 24.2 c Virgini 509 115.1 c 20.4 ghi 54.6 fg 22.9 gh 26.0 117.0 19.7 i 57.1 23.7 30.5 121.9 22.4 54.7 fg 23.9 25.7 77.5 h 12.1 k 39.2j 16.0j 50.8 73.2 h 10.9 k 35.7 k 15.3 j 55.2 'Ech figure is the men of six replictions (three in ech of 2 yr, 1970 nd 1971) except for percent flowering which is the men of counts m on 24 nd 28 July 1970. Mens in the sme column followed y the sme letter re not significntly different (P= 0.05) ccording to Duncn's multiple rnge test. 'Arevitions: Bu = Burley; Ky = Kentucky.
978 PHYTOPATHOLOGY [Vol. 68 LITERATURE CITED the chemicl composition of urley toco y infection with toco vein mottling virus. To. Sci. 21:83-84. 6. PIRONE, T. P., nd G. V. GOODING, JR. 1973. Effect of I. BAWDEN, F. C., nd B. KASSANIS. 1946. Vrietl toco vein mottling virus on field-grown urley differences in susceptiility to potto virus Y. Ann. Appl. toco vrieties. Plnt Dis. Rep. 57:845-847. Biol. 33:46-50. 7. SIEVERT, R. C. 1971. Effect of time of inocultion with 2. GOODING, G. V., JR., nd M. ROSS. 1970. Effect of potto virus Y on yield nd qulity of urley toco. toco etch virus on yield nd mrket vlue of Phytopthology 61:588-589. commercil cultivrs of urley toco in North 8. SIEVERT, R. C. 1972. Sources of resistnce to potto virus Crolin. To. Sci. 14:55-57. Y in the genus Nicotin. To. Sci. 16:92-94. 3. GOODING, G. V., JR., nd S. A. TOLIN. 1973. Strins of 9. SIEVERT, R. C. 1978. Effect of erly hrvest of urley potto virus Y ffecting flue-cured toco in the toco infected with potto virus Y on yield, qulity nd southestern United Sttes. Plnt Dis. Rep. 57:200-204. chemicl constituents. To. Sci. 22:51-53. 4. JONES, L. K. 1937. The susceptiility of pottoes to the 10. THOMSON, A. D., nd D. S. C. WRIGHT. 1966. Incince vein-nding virus. J. Agric. Res. 55:69-79. nd some fects of potto virus Y on New Zelnd flue- 5. PIRONE, T. P., nd D. L. DAVIS. 1977. Modifiction of cured toco. N. Z. J. Agric. Res. 9:886-893.