. ] nm:n TH 1'Siu IN PLA.i: . BR~EDING ,,

D~JH.b~.8u AT Tn& VIRGLHA POLY-

TECID IC l ST TlJTE I .~ n PLICATION

FO · HE D~liRbb.. OF MASTER 01!1 SCIENCE.

BY

DUDLEY DICE DIGGES. /II

AP.rtIL 3, 1915.

0 2,'197

COLLAT~RAL READING.

I. The Surviv 1 of the Unlike --------------- Bailey.

2. Species and Varieties ------------------- - De Vries.

3. Pr~nciples of Heredity ------------------- Bateson.

~. Genetics---------------------------------- Walters.

I. Tobacco Breeding in Connecticut ---------Hayes _& East.

2. Correlation and Inheritance in Nicotiana

Tabacum ---~--------------------------- Hayes & East. 3. Repott of Plant Breeder of the Connecticu t

Experiment Station --------------------- H. K. Hayes. 4. The Improvement of Tobacco b y Breeding

and election --------------------------A. D. Sham 1.

OUTLINE.

· I. INTRODUC rION .

2. PP.BVIOUS WORK ON TOBACCO BR~DING.

3. PREVIOUS .ORK OU CORRELATim AND INHERITANCE IN TOBACCO.

4. STATEMENT OE THE PROBLEM.

5. THE MATERIAL USED.

6. DESCHIPTION OF THE VARIETIES.

7. METHODS USED.

8. RESULTS AND DISCUSSION.

9. CONCLUSION.

(I)

INTRODUCTION.

The cultivation of tobacco in Virginia has been of great importance

since the early days of its settlement, and while the crop is not now

cultivated over so large an area as it formerly was , to the present

day it is the chief commercial crop of about one-fourth of the counties

in the State.

In the early ttempte at growing tobacco in Virginia not much

differentiation of type was recognized; however, with greater refine-

ment of t ste better defined ideas of tluani ty were developed and from

the origin-1 types many var ieties we re selected all of wlich fal l,more

or less com..:1 letely, nnoer the main differentiation recot:nized j n tl e

early days ,narnely , the cl ark,heavy,strong types ana the lighter and

milder types.

almost every section and every tobacco market differs somewhat

in regard to the type and 1uali ty of the tobacco for wl ich tliere is

the greatest demand. · .. hile all types are ,more or less, salable the

high cost of produ~tion stimulates the weed.int:· out of the inferior

varieties and necessitates the selection of the ty 1es conforming iost

nearly to the narket requirement s for t~ach particular ,, rade.

,hile this method of continued selection has ~ iven rise to many

good types of tobacco each of "these is still defective in one or more

particular and it remains for t~e plant breeder to re~tify t11ese

6efects by cross breeding followed by selection,in order,to still

en1ance the value of the crop.

:. ith this end in view several of the most popular varieties com-

r.nor1 to this section were crosse and tbe hybrids studied ii. the first and second filial generations in hopes of i11ding- sor:1etl:.ing better

( t:J)

than ei t.r_er of tt e par en types .

_l-JREVIOUS YU K 0N TOBACCO BRL~EDIHG.

ere di 0y and environment a:r e two factors wl.1.ich must be consid-

ered iu any system of breeding •

... he great i ·111 ortance of e:nviro . ental conditions on tobae;co for

both ~uality and _roductivity is plainl~ noticable to any olose

observer 1:vho is well acqu.ainted with the p rodue;tion of tobacco .

Jenkins tI g5) fou.nd tLat on similar land tLer c are laree variations

in quality and yield due to aifferent syste1ns of fertilization .

a..,; el by and Houser 1912) have shown t11a t the tl:ne of 11arvestering ,

after topping , .1.as a great eff ect on b th ,1 1ality and yield . ,limate ,

rainfa.11, <: nd Ht.my 0th.er eonnitions affectinf the environment of the

plant are ~nown to rave a grea influence over tte yield and quality

of the cro • That· these variations i yield and , nality are not tered-

itary but are environ~ental is proven by the fact that in any tobacco

section 'N 1ere a great w111y vari ties are cultivated each year all

tl1ese var i ties are affected in p ractically the sa e r:ianner. .;.hen too ,

under different environmental conditions tLe very same varities f;ive

dif· 'erent results .

Vlhile t11er is no very definite kn owled[' e of the manner of in-

Jrnri tance of tobacco CLa:racters or o the uenefi ts ;v:i1ich nay t;e ob-

tai ied from hybria.iz.ation an subset~.,, ent selection l asselbring I9I2 )

g ives experLnental evidence irom a iu:nber of pure lines of tobacco

which he ~ rew l1oth in uba and in ichigan , which j u stified the eon-clusion tu;:.t "tr,ere is no brea.L{inc up in type aue to 011ange s of en-

vironc1ent , and that whatever cLanges take pla(; e affect all lndivid-

uals of a strain in a sir ilar manner .

v tservc tlons of i ayes and ~as t of the Connecticut }.xperiment

Station on tr.Le appearance of' · several tY})es g rown in tYe onnecticu.t

Valley fro ffi f oreirn seed serve to corroborate Ha 0 selbring's con-

clusion.

ORii.E1.nl'ION Al~D nnm r 1.h. WE r~ · uB.n ·co .

ifobacco being naturally a self pollinatc•d plant whie;h ·per its

c lose inbreedine; for .'1uny years without deteri9'at _!_ on ;and of w1•ich

'tr.ere are many vari ties Tresentinf easily measured quanti ta ti ve dif-

ferences in characters offers special fac iliti es for th stuay of

correlation and inLeritance of plant characters .

Recognizing t1.Lis fact _, . K. ilayes of' the ~onnecticut ~xperiment

Station has made quite an exhaustive stttdy of the correlation and

inheritance of plant characters in several types of tobacco com-

monly cultivated in . onnecticut. ~ n his work he studied the cor -

relation between ;first,the nu~ er of leaves per plant and the hei ·ht

of the plant;second,bet~een the length and the 1readth of the leaf;

third , bet·ae r.n the nuL'lb ·r of leaves an6. the averae e area of the leaves •

. ro r!l the results obtained he came to tne c oncl usi on t1 at: the c or-

rela tion bet\'lreen the number of leaves per plant and the hei r ht of tl1e

plant , and the <.:or.relation tetv1cen t,i.Le numb~r of leaves rJ.:; r plant and

the leaf area "tu.s so small ii each case b.s t o 1e practically ner;li-

g ible. - Owever,he did find a ni[h correlation betwc Jn the l r nfth

and the brearlth of the leaves showing tl1at Loth are very closely

related and that both are dependent on the same cause or causes in

(4)

inheritance .

.dIB PhOB.....i; 1.i..

A careful statistical study or the hybrecls in the first ans

second filial generations;procLwed oy crossing Irnrrow Le Ormnoco /.

with .iliura a S I

and Eureka ~ 1 with Yellow P~yor~,with the object

of determining the amount of variation within these hybr.&d cultures

and the degree of correlation with the parent forms •

.i'hree different varieties of commercial tobacco \Vere nsed for t}ie

studies reported in this paper . These varities had been inbred for

a number of years and v·rnre uniform . to type . Following is a short

description of some 01 1.ihe more important features of the types used

in this experiment .

o . I NARROW LEA:B' ono~moo .

lhe arr ow l.ieaf Oronoco produces long , tapering , drooping leaves ,

averaping 111 len~th a lit~le over twice the breadth . lhe leaves are

thick and of e-ood quality with a slight tendency to p.;rain roufh and

have a trer1eno ous n1ffle • ..:hey have a rned.ium size midrib and an aver-

age intern de of a bout one and one half inches . ~he number of leaves

per plant averages about twenty-two .

Jo . 2 EU.Rf ;AA.

his ts a type wit.h no ruffle havin['' long,narrow , tl'ick leaves

taper_i.ng at bot;h ends • .i.'he leaves are of good quality and ripen up

smooth . l t averages about t .. "enty-tvw leaves per plant , with an inter-

( 5)

node of about one and one ialf inches , and a medinm sized midrib. a

The leaves average in length little over t v. ice the width .

Ho . 3 YEJ.J.LO'.'.' .t1RYOR .

The :Cello" Pryor produces broad ,drooping , mediurn length leaves,

. tapering sli Pntly a t the tip. 2he midrib is of medium size and the

leaves are tii.n averaeing about twenty-one per plant,with an average

length not ~uite twice aa great as the breadth .

1i.h.TH

As far as possible every precaution was taken to prevent experi-

mental errors. uince tobacco ls naturally a close pollinated })lant

all ~hat 1~ neces~ary to keep the seed pure,aftcr a pure strain is

once isolated,is to cover the seed head with a manilla paper bag- be-

fore the blossoms open. This was done in all instances and the se ~d

ot the parental varities were obtained from plants ~rown from seed

which had been self pollinated for several years .

::.'he teclmical work in cros uinf dif:·erent vari ties of tobacco is

very simple. The corolla is split up1one side, before the blossom

opens anu the stamens removed in the p lant intended to be the female

parent . ~ollen is then taken from the sta~ens,of the r lant intended

to be the male -)arent by means of a knife or scalpel , and ap, ,lied to

tLe pistal of the }) lant from which the stamens have been removed.

Usually twenty pods to the plant are enoup11 "LO i'nrnish the quantity

of seed reiuired. fhen all ulossoms not fertilized are removed and

tle seed lead covered with a p aper bag .

rn this ex1Jerirnent the· so d were olJtained from IJr . W. ; • Ureen

of the bowling Green :experiment ~tation . '.rhe time allowed for the work Leing too short to permit one doing the cross ing and gettine

6)

seed for the p1oduction of ) lants of the second filial generation .

These seed were sown in boxes in an open plant bed in iebruary ,

1914, and then transplanted in the field in .:m1e, _ 914. he plants were

qll fertilized alike in the field and in the plant bed and every pre-

caution was taken to ei~e each the same care and attention .

J.he ~Tear was a very unseaeonable one and the plants not only

suffered in the plant bed but had to be watered artificially at the

tL11e of' transplanting . ~hi s naturally resulted in a poor stand and

the J)lants which did live were so lack.inf in uniformity, dne to t-he

adverse conditions, that none of .the results can be acceptecl as au then-

tic. tl ever in ~he recollection of ~he writer ~ ere tne characteristics

of the different tobaccos Jrou ht out to so small a deeree as they

were the :lear this exp erime1J.t ·aas conducted.

J.he difierent vari ties and hybrd.ds :vere p-rown sicle tjy side in the

field in rows of fifty plants each. rhe rows were laid off three

feet four inches wide from center to center and the plants were about

three feet apart in the row;thus ( iving a fair example of what they

woulct do if e rown on a comuercial basis . 1. his tobacco was cultivated

and treatea. in every way as if it were strictly a com'.nercial prop-

ositiun and t11e resilts Lerein recorded are those obtainable under

such conditions •

. L'he :parental types and t.he hybrids were all studien. closely ;Oth

before and at maturity and notes made on all their characteristics •

.J.dUiflL Y ( I X 2 ) l A "{ b~AF OrtOHOCO X }~U11EKA.

The cross between the .l arrow ~.ueaf ,_,rono co as fe!Ilale and the

:..iureka as male was made in 1912 . Then in I9I3 seed for the produc -

7J

tion of 1,he second filial' c eneration were erown. In I9I4 plants

r; rown fro ll the selfed seed of each of the parent t:rr es and frou seed

prooucing both the first and second filial venerations were c11l ti-

- vuted side b-.. side in the field and studied closely.

11s was noted ln "the pr-eceedine oescrip ti ions of the parent types

there is a very little difference intne characteristics,in f eneral ,

of the two. ~ he main dif.i'erence be ing the p resence of a t :remend ous

ruffle at tl1e base of the leaf in the rarrow _ ea.f uronoco wlhich is

aosent in the Eureka .

J.1he ·arrow leaf ronoco .,i s a vari e"ty which is ver~1 l1 opular in

this section giving a product a little above tne average and combin-

ing wo s t of the aesirable qualities with the exception of the ruf -

fle wLich is very objectionable .

rhe Enrelrn is not quite so J:) Opular a variety for wh• ile it ~ ives

a high grade p ro uct ~t is a lighter Brade tobacco and does not , as

a rule ,yield a s much per acre as the 1arrow .ueaf vronoco .

_n making Lhis cross the idea was to obtain a tobacco havine as

good quality and size as the Jarr ow Leaf Oronoco with the elimination

of' the ·uf'fle .

hccord ing to the Mendelian theory in the first f ilial generation

all the plants shoula be nearly uniform in their ap1;earance and. char-

acteristics and in the second filial generation high variability

s11ould occur due to the recombinatlon of the , endelian factors •

.us was to be expected from the above theory , in the first filial

generation the forty-seven eurvivinr plants , of the ori f inal fifty

planted, were decidedly of the Jarrow .Li eaf uronoco typ e in all of

their cLaracteristics showing that the characteristics of the J ar-

row ~e~f r r onoco were redominant over the characteristics of the

l 8)

Eureka. o increase in vi f or,could be seen in the first filial rener-

ation ,over the viror o! the pure bred ~arrow Leaf Oronoco .

In the second f Llial reneration as l1i~h variability as coul0 be

expected , from a hybrid from practically unisexual parents , was ob-

tai1.1.ed. ut of · a total of forty - eight nlants seven plants occurred

with a total absence of the ruffle while forty-on~ plants had a well

defined ruf le. ~hile the proportion of p lants having the ru~fle to

those without ~he ruff le does not exactly accord with ~endel ' s pro-Gt.. ~~M

portion forA uni :1 ·uGiaa' crosse:S this discrepancy can be readily be

accounted for when the large number of seed produced by one plant as

comp areEl 'J i th the small number of r lants studi ed in this experiment

is taken into consideration.

his crOSG '~\ i th .;_,,ureka as female and Yelloy "J.> ryor us male was

also made in _ 9-1..2 and sub~1e .1uently seed t) roduced so as to permit a

study o~ the first and second filial generations in ~~14.

I n this cross the two parent ty1JeS also have many characteristics

in common. he chief diff erbnces between the two being the thin leaves

wi·tll a tendency to c roop in the Yel :;_ ow Pryor as ae-ainst the thick

leaves ·of the l .. ureka f rowinp at ri t_ ht angles with the sto.tk.

The object n~re was ~o get a ~obacco with the size of the Yellow

}ryor but with the leaves . somewhat thickened ~nd t he drooping elimi~ ·-

natea.

In this cross tle first filial generation again was in accordance

with the Mendelian theory. All the plants being of a decided Yel-

low Pryor type. Drooping and thinness of the leaves predominating

over erectr ... ess and thickness of the leaves .

However,in the second filial eeneration the variability in the

different plants was ~reat . The following table gives the co bina-

tions resul ine:

Thin

" Thick

Drooping

Erect

Droo1)ing

Ere:.ct

Leaves------26

" n

n

8

7

5

Here again the proportion is not exactly in accordance with the

Mendelian pro}lortion for j;i ts!Jt;f · but the number of plants "" /"V'-<~ a.Q~ t- ~ 7:/v.. 4~~

.orked with as com ared vith tue number of seed produced per ~~

or hi otJ1er word , U:n compari&on with the posbi ble available corn bi-~

nations ha ~ all the seed been plante·a and grown could be reasonably J----~

expected t rectify this discrepancy .

The above results sho tha in the first filial generations the

ybrids are as 1miform as the parents ;v_i tl the characteristics of

one parent com:pletely prec o.ninating those of the other parent ; that

there is an increase of variability ii the second filial generation

the range of which is practical l y e. ·ual to the combined range of the

parents .

These results can be practically explained ir.. the ?.1endelian

manner , by tl e segregation of potential er aracters in the ger~11 cells

and their lance recombination,therefore,from a lant breedin stand-

point we are justified in believing that quantitative characters are

inherited s well as qualitative .

Due to the very close resemblvnce of the ,., arents in both crosses

no studies in correlation between the parent forms and the hybrids

resulting from the crosses could be made.

(IO)

CONCLUSION.

T•nile this work has not been carried on long enoue'h to draw any

very definite conclusions;especially since the conditions under which

the tobacco was grown were considerably below normal it has been dem-

onstrated y many experiments that the yield and quality of the to-

bacco crop can be im:proved b- breeding followed by selection. And

sinoe,in most sect jons ,the margin of ·projfit on the cx•op is very

small every intelligent tobac co grower should practice these rnethods

for improving the yield and qu.ali ty of his crop, if only on a very

small scale. The :princi le of selection should be carried out from

the selection of the best and t ruest plants to type in the seed bed

to the selection of those giving the best product after curing,for

after the actual crossing is done success oractically depends on at-

tention to even the most minute differences in the plants to be

:propae·ated.

This work is to be continued and advantrage will be taken of any

desirable combinations of the economic attributes which may occur

in the selection and fixation of any new varieties which maJI be

possible.