Genetic and morphologic characters affecting the popping expansion of popcorn

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T m POFMHS EUMSSIC* OF POFCGRH

by P aul ju n io r ly o rly

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DOCfQfi OF MXXjQCOBir l& j o r S u ib jeo t C rop B ro o d in g

Iowa S t a t e C o lle g e IM S

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U M I N um ber: D P 1 3 3 5 0

IN F O R M A T IO N T O U S E R S

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H a la tio n Betw een th e P o p p in g E x p a n sio n o f S in g le C ro s se s a d T h e ir p a r e n t a l I n b r e d L i n e s ................... .... . ............................. C re a s e s b etw een f e l l o w P e a r l in b r e d l i n e s

. . . . . . .

C ro s s e s b etw een J a p a n e s e H u lle s s in b r e d l i n e s

.......................

I n t e r t y p e o r o s s e s b e tw e e n Y ello w P e a r l an d J a p a n e s e H u lle s s in b r e d l i n e s .........................................

19 19 26

32

Ufepopped K e rn e ls i n C ro s s e s o f fflg h an d 1pm E x p an sio n in b r e d l i n e s . . . . . . . . . . . . . . . . . . . . . . . .

35

E f f e c t o f X en ia on p o p p in g E x p a n sio n

. . . . . . . . . . . .

38

S e l e e t i o n W ith in a n O p e n - P o llin a te d V a r i e t y . . . . . . . . .

42

G e n e ra l V s. S p e c i f i c Com bining A b i l i t y f o r P o p p in g Ex­ p a n s io n . . . . . . . . . . . . . . . . . . . . . . . . . . .

45

H a la tio n B etw een P o p p in g E x p a n sio n an d C e r ta in Mor­ p h o lo g ic a l an d A gronom ic C h a r a c te r s . . . . . . . . ...................

49

DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . .

53

. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

56

SUMMARY

REFERENCES . . . . . . . . . . . . . . . . . . . . . . ACKHOWUSDOEMEBTS

................... .

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APPENDIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T T 4 - 4 - S

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68 62 63

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IKESODUCflOH

t h e r e a r e fe w o r o p s w h io h v a r y mor© in q u a l i t y th an , p o p o o ra .

S e v e ra l

f a c t o r s a r e r e s p o n s ib le f o r t h e p r e s e n t s i t u a t i o n i n c l u d i n g im p ro p e r m o is­ t u r e , p o o r v a r i e t i e s w ith h e a v y , c o a r s e hall an d low p o p p in g e x p a n s io n ,., m ix tu r e w i t h d e n t ©ora, and laproper storage, r e s u l t i n g i n d i r t y , m o ld y ,

mouse riddled o r o th e r w is e Inferior ©ora. gome o f t h e s e c a u s e s earn h e rem e d ied by h a t t e r m ethods o f s t o r a g e an d ear© i n g e t t i n g t h e © rep fro m t h e p r o d u c e r t o t h e co n su m er.

O th e rs ©an h e rem ed ied o n ly hy im provem ent

in v a r i e t y o r t y p e . P o pping e x p a n s io n , or p o p p in g volum e, m easu red hy t h e u n i t s o f volum e ©f popped e o r n o b ta in e d from a n original wit o f s h e l l e d c o r n , i s u s e d a s t h e primary c r i t e r i o n of q u a l i t y of a p o p o o m v a r i e t y .

She im p o r­

ta n c e o f t h i s measure t o o p e r a t o r s o f ©ommeroial e s ta b l is h m e n t s i s o b v io u s s i n c e h ig h e x p a n s io n i n c r e a s e s t h e i r profits ©Aon t h e i r p r o d u o t i s s o l d

on t h e basis of volum e r a t t i e r than weight* A h ig h e x p a n s io n i s a l s o asaooiated w ith p a l a t a b i l i t y b e c a u s e the larger, l i g h t e r a n d f l u f f i e r k e r n e l s a r e u s u a l l y t h e m ore t e n d e r .

been made i n t h e im provem ent o f a few v a r i e ­ ties by c a r e f u l s e e d s e l e c t i o n .

Much greater im provem ent i s now p o s s i b l e ,

h o w ev er, b y u s in g t h e m odem m ethod o f h y b r i d i s a t i o n o f in b r e d l i n e s w h ic h h a s been s o s u c c e s s f u l with f i e l d © ora. E x c e p t f o r e v id e n c e o b ta in e d fro m s t u d i e s to im p ro v e popping expansion b y m ass s e l e c t i o n , l i t t l e i s known o f the i n h e r i t a n c e o f popping quality.

I t is r e a s o n a b le t o assu m e t h a t

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e x p a n s io n o f p o p o o ra I s c o n d itio n e d b y c e r t a i n p r o p e r t i e s o f t h o endosperm a n d p e r i o a r p an d t h a t th o mode o f i n h e r i t a n c e i s u n d o u b te d ly v e r y com p lex. Any in f o r m a tio n on t i e r e l a t i o n b e tw e e n th o p o p p in g e x p a n s io n o f in b r e d l i n o s a n d t h o i r h y b r id s an d on th o r e l a t i o n o f k e r n e l oha r a o t e r o an d pop* p in g e x p a n s io n s h o u ld b o o f v a l u e l a o u t l i n i n g an d c o n d u c tin g a w e ll ’piKaSPd Oi^rOk-OikWkaaat'

w e pTt?gTHm i>*tMin i*misotwi Iw &tn »"■ PrBOuaSg

jm.

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K n i f f OP LIYEMYORE l i t e r a t u r e b e a r i n g d i r e c t l y upon t h i s p ro b lem i s v e r y U n i t e d . R i s t o r i e & l l y , p o p o o rn m s known an d u s e d hy the n a t i v e s o f t h e W e s te rn H em isphere b e f o r e th e coating of th e white n a n ( 8 7 ) .

An o ld C h in e se

hook i n th o l i b r a r y o f C o n g re s s , w r i t t e n i n 1 5 9 0 , d e s c r i b e s a ty p e o f

miss, the kernels of w h ich hurst o p en when h e a te d ( 5 3 ) .

The e a r l y

settlers knew an d u s e d p o p o o rn freely b u t o n ly i n th e l a s t t h i r t y o r f o r t y y e a r s has i t d e v e lo p e d as. a n im p o r ta n t a r t i c l e o f e o s m s re e . Many v ie w p o in ts h av e b e e n e x p r e s s e d t o a c c o u n t f o r t h e p o p p in g a b i l i t y o f popoom . p in g q u a l i t y ,

An o ld idea m s t h a t o i l i n s m s m y was a s s o c i a t e d w i t h pop­ t h e 1890 e d i t i o n o f t h e C e n tu ry D ic tio n a r y s t a t e s t h a t

" p o p c o rn ab o u n d s i n ell, th e e x p a n s io n o f which c a u s e s a n e x p l o s i o n , i n w h ich t h e c o n t e n ts o f th e k e r n e l become p u f f e d o u t , n e a r l y h id i n g t h e

seed c o s t an d assu m in g a p u re w h ite c o l o r .* T h is b e l i e f was s h o rn t o b e e r r o n e o u s b y S t o r e r (3 1 ) who s u c c e s s f u l l y popped kernels fro ® w h ich th o oil had b e e n rem oved.

He a l s o fo u n d t h a t

a lth o u g h p ie o e s o f kernels would pop, a t te m p t s w ere u n s u c c e s s f u l when t h e p e r i c a r p m s e n t i r e l y rem oved.

Several studies h av e b e e n reported on t h e f a c t o r s t h a t i n f l u e n c e p o p p in g e x p a n s io n p a r t i c u l a r l y ©a t h e m o is tu r e c o n t e n t o f t h e k e r n e l . e x a c t m echanism of p o p p in g , h o w ev er, has n o t been f u l l y e s t a b l i s h e d .

The Ac

e a r l y a s 1 8 9 4 , S tu rte w a n b ( 8 8 ) stated " t h e a p p l i c a t i o n o f h o t w a te r t o s t a r c h muses i t t o become plastic.

T h is f a c t seem s t o u n d e r l i e t h e e x -

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p la n a t i o a of t h e p o p p in g of o o r a ,

P opoorn o o n ta in s s t a r c h g r a n u le s a r ­

ra n g e d w i t h i n a to u g h en d o sp erm .

When h e a t i s a p p l i e d t h e s t a r c h becom es

p l & s t i o , an d t h e w a te r f u r n i s h e s t h e ste a m w h ic h s e e n e x p lo d e s th e k e r n e l , a n d , tu r n i n g i t inside o u t an d e x p a n d in g ' t h e s t a r c h , fo rm s a l a r g e f l u f f y sn o w -w h ite mass.** I n 1903 W i lb e r t (3 6 ) s t a t e d t h a t " e a c h i n d i v i d u a l c e l l i s a m i n ia t u r e

sealed c o n t a i n e r , t h e anils of w h ic h a r e s u f f i c i e n t l y d e n s e t o r e t a i n th e c o n f in e d m o i s t u r e , u n t i l th e same h a s b e e n c o n v e r te d i n t o s te a m u n d e r

pressure* ...... If t h e c o m i s old and d r y i t w i l l a t h o s t o n ly s p l i t open from a num ber of cells n e a r th e centre of t h e c o m k e r n e l.* .

B o th

W i lb e r t ( 3 6 ) an d X raem sr ( 2 0 ) , whoa© h i s t o l o g i c a l s t u d i e s l e a d him t o b e­

lieve t h a t p o p p in g o f c o m m s due t o 'the- m in u te s t r u c t u r a l c h a r a c t e r i s ­ tic# of the s t a r c h g r a i n s , w ere able to im p ro v e t h e p o p p in g o f o ld a n d d r y c o m by so a k in g an d partially d r y in g t h e g r a i n . W e a th e im x (3 4 ) after a review o f l i t e r a t u r e , c o n c lu d e d t h a t t h e pop­ p in g of a g r a i n o f o o r a was an e x p l o s i o n , . u n d e r p r e s s u r e , o f m o is tu r e con­ ta in e d in th e s ta r c h g r a in s .

O h t l l t h e i n s t a n t of t h e e x p l o s i o n , t h e

p r e s s u r e i s c o n f in e d b y t h e colloidal matrix i n w h ich t h e s t a n d i g r a i n s a r e em bedded.

He concluded t h a t neither air n o r an y v o l a t i l e o i l m s i n

a n y m y c o n c e rn e d w ith th® p r o c e s s a s t h e e x p lo s iv e medium an d t h a t t h e d i f f e r e n c e b e tw e e n p o p p in g and a q n -p a p p in g ty p e s w as e n t i r e l y o n e o f h a r d n e s s of en d o sp erm . Prom a s tu d y o f sam p les fro ® d i f f e r e n t s o u r c e s an d fro m a s e r i e s o f m o is tu r e level# of th© same m m . Carr an d l i p l e y (4), u s in g p e r c e n t p o p

as an in d e x of q u a l i t y , concluded t h a t p o p p in g m s q u i t e in d e p e n d e n t of t h e w a t e r c o n t e n t e x c e p t b etw ee n very w id e l i m i t s .

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Stewart (29) m s th e f i r s t t o u s e t h e v o lu m e tr ic ateth o d f o r a e a s u r l a g t h e p o p p in g q u a l i t y , a n d showed t h a t p o p p in g q u a l i t y o o u ld n o t h e a c c u r a t e l y d e te rm in e d l a t e r n s o f p e r c e n t p o p .

i s fo u n d a a o i s t u r e o f

13 t o IS p e r c e n t to b e the m oat f a v o r a b l e for m ad a m p e p p in g v o lu m e, f h e p o p p in g t l a e m s s h o r te n e d b y t h e u s e o f .lard l a t h e p o p p e r,

p o p c o rn

w hioh had l o s t its p o p p in g q u a l i t y th r o u g h e x p o s u re t o d r y h e a t m s i a » p ro v e d by t h e a d d i t i o n o f w a te r .

He fo u n d t h a t o u t s i d e s t o r a g e u n d e r

lew f o r k o o n d itio n e u s u a l l y gave a a o i s t u r e c o n t e n t a p p r o a c h in g optimum f o r p o p p in g , e x c e p t during t h e d r i e r summer m o n th s.

S te w a r t r e p o r te d

l a t e r (30) t h a t popoom stored e» t h e e a r u n d e r o u ts id e c o n d i t i o n s h a d

not lost its p o p p in g q u a l i t y after 14 y e a rn an d h ad d e t e r i o r a t e d b u t l i t t l e when shelled before s t o r a g e . H a r tle y an d WilMsr (9) s u g g e s te d t h a t a m o is tu r e c o n t e n t o f a b o u t 12 p e r c e n t g av e the optimal e x p a n s io n ,

they fo u n d t h a t t h i s m o is tu r e

level was usually attained u n d e r n a t u r a l a tm o s p h e r ic c o n d itio n s *

A ccord­

i n g t o s t u d i e s b y T e a g e r ( 4 1 ) t h e optimum m o is tu r e w as fo u n d t o b e b etw ee n 11 a n d 15^ p e r c e n t . l y e r l y ( 2 1 ) studied tbs e x t e n t t o w h ic h v a r io u s f o o t e r s a f f e c t e d pop­ p in g e x p a n s io n ,

f h e optimum m o i s t u r e w as fo u n d t o b e b e tw e e n 12 a n d 14

p e r c e n t , v a r y in g s l i g h t l y , p e rh a p s w i t h v a r i e t y an d l o t .

th e use o f o il

i n t h e popper in c r e a s e d the p o p p in g e x p a n s io n s l i g h t l y a n d m a t e r i a l l y de­ c r e a s e d the p o p p in g tim e .

p r e s s i n g im m ature p o p c o rn m a rk e d ly re d u c e d i t s

p o p p in g q u a l i t y . Share w as n o a p p a r e n t l o s s i n p o p p in g e x p a n s io n o f c o m s t o r e d f o r five y e a r s w hen it w as b r o u g h t t o a n optimum m o is tu r e l e v e l . D a ta were g iv e n w h ich s u g g e s te d a n e g a t iv e c o r r e l a t i o n b o th b etw een v i g o r

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o f p l a n t s a n a p o p p in g e x p a n s io n a n d y i e l d a n d p o p p in g e x p a n s io n .

F a la -

i a b i l i t y tests., i n w h ich v a r io u s v a r i e t i e s w ere r a t e d f o r f l a v o r , t e n d e m e s s , a n d a b s e n c e o f h u l l showed c o n s id e r a b le u n if o r m ity a l th o u g h t h e ra n g e in ratings m s wide.

Certain i n d i v i d u a l s showed a p r e f e r e n c e f o r

a p a r t i c u l a r ty p e w h ile o t h e r s preferred a n e n t i r e l y d i f f e r a a t t y p e , s o t h a t n o on© variety o r hybrid could b e d e s ig n a te d a s p r e f e r a b l e t o a l l in d iv id u a ls .

S e v e r a l s t u d i e s i n d i c a t e d t h a t t h e tim e r e q u ir e d t o b r i n g

p o p c o rn t o good p o p p in g c o n d i t i o n f o llo w in g h a r v e s t c o u ld b e s h o r te n e d b y t h e u s e of a r t i f i c i a l driers, a lth o u g h a l a p s e of tw o t o f o u r w eeks a f t e r rem o v al from t h e d r i e r m e n e c e s s a r y for th e m o is tu r e t o become e q u a l l y d i s t r i b u t e d among t h e e a r s . W i l l i e r an d B ru n so n (3 8 ) fo u n d 12 p e r c e n t m o is tu r e optimum t o o b t a i n

the g r e a t e s t am ount of popped c o m .

A r a t h e r d e t a i l e d s tu d y v a s made o f

t h e assQ G dahion o f c e r t a i n m o rp h o lo g ic a l k e r n e l c h a r a c t e r s a n d p o p p in g e x ­ p a n s io n .

Within a p a r t i c u l a r v a r i e t y t h e s m a l l e r k e r n e l s a n d th o s e w ith

l e a s t soft, starch w e re found t o give a l a r g e r p o p p in g e x p a n s io n on t h e a v e r a g e th a n th o l a r g e r an d m ore s ta r o h y k e r m i s ,

l e n g t h , b r e a d t h an d

t h i c k n e s s of the k e r n e l w ere negatively c o r r e l a t e d w ith p o p p in g e x p a n s io n . Buncaa ( 8 ) fo u n d & h ig h p o s i t i v e c o r r e l a t i o n b etw ee n p o p p in g ex p an ­ s i o n a n d o r is p n e e s o f p o p c o rn a s m easu red b y t h e d o o r c a s e i n volum e o f pepped c o m white p r e s s e d . B runson ( 1 ) d is c u s s e d th e m eth o d s u s e d an d t h e p r o g r e s s made i n pop­ c o r n b r e e d in g ,

f h e v a r i e t y S u p e r g o ld , o r i g i n a l l y in t r o d u c e d b y t h e

K ansas S t a t i o n a s S u n b u r s t, was d e v e lo p e d b y e a r - t o - r o w s e le c tio n , f o r h ig h e x p a n s io n ,

f h e e x p a n s io n w as I n c r e a s e d fro m 13 t o 26 volum es b y

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s e le c tio n .

B ru n so n s t a t e d t h a t t h e o r o a s in g o f in b r e d l i n e s o f f e r e d t h e

w o g t a rs B is t& a m ethod o f im 'oraviiiir DODcom. l a * s e r i e s o f a r t i c l e s i n t h e S eed t r a d e le w * (1 2 ) a h i s t o r y i s g iv e n o f t h e p o p c o rn i n d u s t r y i n t h e U n ite d S t a t e s , e i t h p a r t i c u l a r r e f e r e n c e t o t h e d ev elo p m en t an d d i s t r i b u t i o n o f v a r io u s v a r i e t i e s .

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AMD

METHC© OP FEQCBDOHB

f h e in b r e d l i n o s u s e d i n t h i s i n v e s t i g a t i o n w ore f u r n i s h e d b y Dr* J . C* E ldredg© of t b s Iowa A g r i e u l t u r a l E x p e rim e n t s t a t i o n .

T w en ty -n in e

l i n e s c l a s s i f i e d from p r e v io u s w ork a s h ig h o r le n t i n p o p p in g e x p a n s io n

were s e l e c t e d from t h e v a r i e t i e s J a p a n e s e H u lle s a an d f e l l o w P e a r l .

The

n a n s l e l l a w P e a r l , also applied t o a d i s t i n c t v a r i e t y , i s u s e d h e r e a s a ty p e n a a e f o r a l l y e llo w v a r i e t i e s h a v in g p e a r l ty p e k e r n e l s .

The perm an­

e n t c u l t u r e nu m b er, varietal origin, g e n e r a tio n s s o l f e d , t h e a v e r a g e pop­ p in g e x p a n s io n o b ta in e d i n 1 9 5 9 , 1 9 4 0 , a n d 1941 an d t h e a v e r a g e num ber o f uapopped k e r n e l s p e r 100 o o . of unpopped o o r a t o 1941 a r e p r e s e n te d t o

table 1 .

T h ese t o b r s d l i n e s were divided i n t o six . g ro u p s on t h e b a s i s o f

varietal o r i g i n , © ndospem color, a n d p o p p in g e x p a n s io n a s shown b elo w t ja p » » e s e Hjullsss I n b r e d s

Group

I*

Group I I . Group III. Group m .

H igh P o p p in g , W h ite J a p . 7 in b r e d s

J - l to J -7

U g h P o p p in g , fellow J a p . 2 in b r e d s

f J - 1 4 and f J - 1 5

low p o p p in g . W h ite Jap. § in b r e d s

J -8 t o J-1 2

I P * F o p p to g , fellow Jap. 1 in b r e d

fJ-1 8

f e l l o w p e a r l In b r e d s Group

V.

'Group V I .

H ig h P o p p in g , fellow p e a r l 8 in b r e d s low P o p p in g , f e l l o w P e a r l 6 in b r e d s

IP -1 7 t o IP -2 4 D-25 a n d D-28 fP -2 7 t o f f - 2 9 an d YP-31

R eproduced with perm ission of the copyright owner. Further reproduction prohibited without permission.

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11 -

f a b l e j . ' f h e p erm a n en t S t t l t u r e num ber, p e d i g r s o , v a r i e t a l o r i ­ g i n , ' g e n e r a tio n s s e l f e d i n 1 9 4 0 , th o a v e r a g e p o p p in g e x p a n s io n f o r 1 9 3 9 , ’ 1940 a n d 1 9 4 1 , an d t h e a v e r a g e num­ b e r o f uapopped k e r n e l s p e r 100 e o . o f o o ra i n 1941 o f 29 in b r e d s in e lu d e d i n c r o s s e s o f h ig h an d low e x p a n s io n in b r e d s . f m o , P .O . t SO. ,

1989 F e d ig r e e

{ | | , T « r l . t . l , 0« M r - , * > « * * « t O r ig in * a t i o a s t , t i tS elfed :* 1939 * 1940 * 1941

« jfu a b e r , l^ C T t tg e rn e ls * 1941

d -1 J-2 j-s J-4 J-8 j-6 J-7

J a p .H u ll . 8 h 8 - 8 « 7 - 1 0 - 2 € - 2 3 - l- l *» C 1 1 9 -1 9 -1 6 -2 1 -S 6 -4 2 -2 -2 a * 1 2 5 -2 4 -2 1 -2 3 -4 4 -4 8 -2 -1 K 8 0 4 7 -2 8 -3 5 -5 4 -4 7 -8 0 -2 -1 » 0 1 -3 -4 -7 -2 0 -1 1 -1 6 -2 fJ 8 9 -0 -S 6 -9 l-2 2 -4 -l ftrto ftd *

9 9 9 9 9 9 8

2 7 ,0 2 3 ,9 2 5 .6 2 5 .5 3 8 .3 2 5 .0 2 8 .0

2 8 .7 « 3 3 .1 2 6 .9 2 7 .4 2 5 .9 2 5 .9

2 7 .8 2 6 .6 2 6 .0 2 5 .4 2 6 .4 2 7 .0 2 9 .6

23 37 22 21 26 21 20

J-8 J-8 J-1 0 J -ll J-1 2

fJS 3 -3 -2 -4 s a e -4 5 -iv -i-i T J 6 -M -1 7 -3 6 -3 -1 B a 5 - 6 7 - 4 6 - 2 - l~ l E a 2 -6 4 -4 0 -lw -1 -1

J n p .H a l l . « • * «

8 6 7 7 7

2 0 .8 1 8 .6 1 4 .1 1 4 .6 1 9 .2

2 1 .6 1 9 .0 1 3 .2 1 1 .9 1 6 .6

1 8 .9 2 0 .5 1 7 .7 1 8 .0 2 3 .4

51 68 110 158 26

fJ-1 4 fj-lfi

f f 3 8 - 8 8 -4 9 -6 9 -3 -1 -1 8 h 6 -0 -8 9 —5 8 -7 8 -8 4 -1 -1

torn S M ^ b rtd *

A 7

3 8 .9 2 7 .1

2 6 .6 2 5 .8

2 6 .6 3 0 .5

46 12

T J-1 6

fJ l-2 9 -1

fe l* J a p .

4

1 8 .4

1 9 .6

45

S u n b u rst « » *

ff* 2 3 Wh~m

S b l- 8 8 - 2 9 - 3 - 2 - 1 S b lO -5 8 -1 -1 -1 -1 § 5 6 -5 4 -1 -1 -1 -1 S b 5 - 8 4 - 4 5 - 2 - l- l S b S -9 0 -3 2 -1 -1 -1 S M -5 2 - 1 - 3 - 1 - 1 B e Q O 2 ~ 6 0 -l-l-l B e Q S 3 - 1 0 0 - « 8 - 4 9 -l- l- l

7 7 7 7 7 7 8 8

2 7 .3 2 8 .2 2 7 .1 2 7 .6 2 7 .8 2 7 ,8 3 8 .8 2 6 .0

2 8 .6 2 8 .8 2 8 .4 2 8 .2 2 8 .4 2 8 .8 2 8 .5 2 9 .6

2 8 .5 2 9 .4 2 9 .2 2 9 .7 3 0 .0 3 1 .1 » 2 6 .0

46 18 18 12 28 17 *, 28

D -25 9 -2 6 7 P -2 ? fP -2 8 fP -2 9 tt-tt

8 S D 4 -4 0 -4 -1 -1 -1 7 0 4 -4 7 - 3 - 2 - 1 - 1 E rQ S 3 -7 G -3 -? -l-l B rQ G 2 -8 9 -3 -2 -l-l B eQ 0 3 -7 O ~ l-l-l P .O .( l a d S a r ) 4 - 5 - 2

D ynam ite a Q u.G old. » M

7 7 7 7 6 4

1 7 .7 1 8 .7 1 2 .8 1 0 .8 1 0 .0 1 5 .8

1 8 .5 1 5 .4 1 7 .8 1 7 .2 1 3 .8 1 6 .2

1 8 .8 2 1 .8 1 7 .1 1 7 .5 1 7 .6 1 5 .8

39 31 71 76 67 72

IP -1 « w m fp -to fp -ti

IN I

h

« $ * .0 » ld . a

t

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J a p a n e s e H u lle sis x f o l l o w P e a r l v a r i e t a l h y b r id .

Reproduced with perm ission of the copyright owner. Further reproduction prohibited without permission.

-

12 -

fh.9 in b r e d s s e l e c t e d f o r h ig h p o p p in g e x p a n s io n h a d b e e n s e l f e d s i x o r m ore gen® r a t i an a an d m ere q u i t e s t a b l e *

U n f o r tu n a te ly , n o s t o f t h e low

p o p p in g in b r e d s w e re d is c a r d e d d u r in g t h e sours® o f in b r e e d in g e x c e p t o n es p o s s e s s in g u n u s u a l o r o u ts ta n d in g p l a n t c h a r a c t e r s .

S e v e ra l o f th e in ­

b r e d s w ith lo w e x p a n s io n s c o n s e q u e n tly w e re m ore v ig o r o u s t h e n a s s t o f t h e l i n e s w i t h h ig h e x p a n s io n ,

i l l o f t h e in b r e d s s e l e c t e d f o r leer pop­

p in g e x p a n s io n , h o w ev er, t e d beam s e l f e d a t l e a s t f o u r g e n e r a t i o n s , fy p io & l k e r n e l c h a r a c t e r i s t i c s o f t h e in b r e d s a r e shown i n f i g u r e s 1 an d

2

. E x p a n sio n s w ere d e te rm in e d fro®, d u p l i c a t e p o p p in g t e s t s m e a e h o f

fiv e re p lic a te d p lo ts .

I n many o a s e s .t h e p o p p in g volum es o b ta in e d i n

1941 w ere c o n s id e r a b ly h ig h e r t h a n those o b ta in e d d u r in g t h e p r e v io u s tw o y ears*

T h is w as p a r t i c u l a r l y t r u e f o r t h e in b r e d s w ith lo w e x p a n s io n ,

f h e h ig h e r volum e i n 1941 r e s u l t s fro ® t e t t e r p e p p in g te c h n iq u e and. p o s­ s i b l y i n s a n e e a s e s fro m t e t t e r s e e d c o n d i tio n an d more o p b in u a m o is tu r e c o n te n t.

Ho p o p p in g e x p a n s io n m s o b ta in e d i n 1941 on TP-23 b e c a u s e o f 1939 an d 1940 e x p a n s io n s m s u s e d

f o r t h i s In b re d . I n o r d e r t o d e te rm in e t h e p o p p in g e x p a n s io n o f P j c r o s s e s b etw ee n h ig h a t e lo w p o p p in g i n b r e d s , l i f t s i n g l e c r e s s e s w ere p ro d u c e d i n 1 9 4 0 , f h e c r o s s e s b etw ee n a n d w i t h i n th e tw o v a r i e t y g ro u p s a r e a s f o ll o w s *

R eproduced with perm ission of the copyright owner. Further reproduction prohibited without permission.

-

F ig . 1.

Fig* 2 .

13 -

Kernel c h a r a c t e r i s t i c s o f f o l l o w Pearl inbreds*

Kernel c h a r a c t e r is tic s o f J a p a n e s e H u l l e s s in b red s.

Reproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission.

P o p p in g VolUBU* Of

parental Mass

Humber o f C ro s s e s

C r o s s e s b etw ee n f e l l o w P e a r l in b r e d l i n e * H igh x H igh H igh x Low Lew *..Lew T o ta l

26 27 16 “ TST

C ro s s e s b etw een J a p a n e s e S u l l a a s in b r e d l i n e s S ig h x H ig h U g h x Low **»*&*» T o ta l

22 41 16 I f "

C r e s s e s b etw ee n f e l l o w p e a r l a n d J a p a n e s e H o llo a s in b r e d l i n e s H igh x H ig h H ig h x Low Low x Lew fe ta l

18 IS 12 T0T

f i » f l « t to o g ro u p s o f r , o ro a o e s t o g . t t . r - 1 t h t o ™ . . t u t o r * , f o r c o m p a riso n w ere p la n te d at dates in

§ x t l a t t i c e s q u a r e d e s ig n s w ith

f i t s r e p l i c a t i o n s an d the t h i r d g ro u p with six. s ta n d a r d s f o r c o m p ariso n w as a r r a n g e d in ran d o m ised c o m p le te b lo c k s with fits r e p l i c a t i o n s ,

in

'the test, o f h y b r id s th e plot s i s e was. 2 x 6 h i l l s * , th i n n e d t o t h r e e plants per Mil*

The inbred material was s p a c e p la n te d I n f i r e r e p l i c a t e d

3 0 - f o o t ro w s, a p p r o x im a te ly 10 in c h e s b etw ee n p l a n t s .

A l l M i l s o f th e

h y b r id s w ere h a r v e s te d and c o r r e c t i o n s made f o r m is s in g h i l l s .

M a ts o f

t h e in b r e d l i m e were h a r v e s te d for p o p p in g sam p les o n ly . O r d i n a r i l y p o p co rn harvested and s t o r e d u n d e r a tm o s p h e r ic c o n d i tio n s

at Mmm does net r e a e h p o p p in g c o n d i t i o n u n t i l t h e f o llo w in g s p r i n g ,

p re­

v io u s remits ( 2 1 ) had shown t h a t t h e tim e r e q u ir e d t o b r i n g p o p c o rn t o

R eproduced with perm ission of the copyright owner. Further reproduction prohibited without permission.

« 15 -

good p o p p in g c o n d i tio n n i g h t t o s h o r te n e d by th o u s e o f a r t i f i c i a l d r i e r s . I n n# e a s e , h o w ev er, had popoorn. ta k e n d i r o o t l y fro m t h e d r i e r g iv e n a s a t i s f a c t o r y e x p a n s io n .

M o is tu re t e s t s sh o o ed t h a t o v en th o u g h t h e a v e r ­

age a o i s t u r e m s o p t i a m there m s variation in a o i s t u r e c o n t e n t b etw ee n i n d i v i d u a l ears, s o n s b e in g too w e t an d 'e t h e r s to o d r y .

A la p s e o f

s e v e r a l w eeks a f t e r d r y in g m s n e c e s s a r y f o r a o i s t u r e t o bacomo e q u a l l y d is trib u te d . The in b r e d s an d h y b r id s c o n ta in e d frost 15 t o 21 p e r c e n t m o is tu r e when h a r v e s te d i n late S ep te m b er an d e a r l y O c to b e r.

F i f t e e n e a r s from

e a c h hybrid plot and the entire l o t o f o a r s fro m th e in b r e d p l o t s w e re s a v e d for popping tests.

T hese were p la c e d i n 15 pound lo o s e m esh

p o t a t o b a g s an d p la c e d i n one o f th e c o m d r i e r s .

H a y w e re d r i e d t o

a p p ro x im a te ly 1© p e r c e n t aoisture i n order t h a t t h e d i f f e r e n t h y b r id s w ould become m ore nearly equal i n moisture,

t h e d r i e d e a r s w e re ta k e n

from t h e drier an d hung i n a n o p en shed until t h e n i d d l e o f K ovem tor a t w h ich tins th e y were still c o n s id e r a b ly b elo w optimum m o i s t u r e . e a r s ware s h e l l e d an d a p p r o x im a te ly one

The

p i n t o f t h e b u lk e d g r a i n fro m

e a c h p l o t w as p la c e d i n a s m a ll c l o t h t o g an d s t o r e d i n a c o n d i tio n i n g room ,

fhe te m p e r a tu r e o f toe c o n d i tio n i n g ro a n v a r i e d b e tw e e n 65 a n d 7©

d e g r e e s P. a n d the r e l a t i v e h u m id ity could b e m a in ta in e d f a i r l y c o n s t a n t

at a n y p o i n t between 6© an d 90 p e r c e n t b y h a n g in g c l o t h s o f v a r y in g w id th s from a b u c k e t o f w a t e r . t i o n o f air.

An electric f a n g av e a c o n s t a n t c i r c u l a ­

A f t e r about t h r e e weeks tim e i n t o e c o n d i tio n i n g roam t h e

d n p a n e s* H u lle s s sam p les c o n ta in e d a p p r o x im a te ly 12 p e r c e n t an d t h e

fellow F e a r l ty p e s a p p r o x im a te ly lf§ p e r c e n t m o i s t u r e .

The s a m p le s w ere

R eproduced with perm ission of the copyright owner. Further reproduction prohibited without permission.

** 1 6 *»

th e n p la c e d in iaoi stu r© p r o o f c a n s an d s t o r e d until p o p p ed .

The M a te r i a l and p ro c e d u re u se d i n a s tu d y of t h e a f f e c t o f x e n l a on p o p p in g e x p a n s io n wad i n a study of the e f f e c t i v e n e s s of s e l e c t i o n i n a n o p e n - p o ll in a t e d v a r i e t y will be d is c u s s e d later.

R eproduced with perm ission of the copyright owner. Further reproduction prohibited without permission.

17 -

p o e p im m c m m m

Unfortunately, a standard procedure for testing popping e x p a n saio n lias never been established.

Consequently comparisons of p o p p in g d a t a

obtained by different investigators must be -made w ith c a u t i o n . fhe popping eq u ip m en t u se d i n th e p o p co rn b r e e d in g I n v e s t i g a t i o n s at Iowa State College m s u s e d i n th o s e s t u d i e s ,

f h e p o p p e r was o f t h e

asm! e l e c t r i c o o n aaero ial t y p e , with a bow l c a p a c i t y o f a b o u t 3 l i t e r s . A sam ple o f 100 e e . o f un p o p p ed , c le a n e d o o r a m easured i n a s m a ll b r a s s c y l i n d e r m s used f o r all t e s t s e x c e p t those on s i n g l e e a r t e s t s w h ich w i l l be d is c u s s e d l a t e r ,

f h e beating u n i t m s r e g u la te d s o t h a t t h e

corn began t o pop in from 48 t o §0 seconds. T ea o c . o f M asola o o r a o i l and o n e - h a l f te a s p o o n of salt w ere p o u re d i n t h e p o p p e r w ith e a c h s a m p le . After popping* the c o r n m s t r a n s f e r r e d t o a m e ta l c y l i n d e r an d t h e ex* p e n s io n r e a d directly to the tenth's o f a volum e from a g ra d u a te d p lu n g e r .

The unpopped k e r n e l s were -then s c r e e n e d o u t and c o u n te d o r e s ti m a t e d by c o u n tin g < m e -fo u rth to o n e - h a l f o f t h e sample i f t h e num ber was v e r y la rg e .

B u p li e a t e popping t e s t s w ere made on e a c h p l o t .

The se c o n d

sam ple w as popped after t h e entire first aeries h ad b e e n c o m p le te d , u s u a l l y

several d ay s o r a week later, fhe p o p p e r a n d m e a su rin g g r a d u a te s a r e shewn i n ■figures 3 an d 4 .

R eproduced with perm ission of the copyright owner. Further reproduction prohibited without permission.

of the copyright owner. Further reproduction prohibited without permission.

Fig» 3 .

G raduates f o r m easuring unpepped slid popped s o m . Sm all t r a s s g r a d u a te h o ld s 100 c e .

F ig . 4 .

Popper u sed in th e popping expan­ s io n s t u d i e s .

19 -

mtvmiTummii}, HBSBLfS

fhe d a t a fro m t h i s i n v e s t i g a t i o n m i l l bo p r e s e n te d under s i x m a jo r d i v i s i o n s * ( 1 ) S o la tiu m b etw een t h e p o p p in g e x p a n s io n o f s i n g l e c r o s s e s a n d t h e i r p a r e n t a l i n b r e d s , ( 2 ) Cnpopped k e r n e l s i n c r o s s e s b e tw e e n h ig h

and l e v e x p a n s io n in b r e d l i n e s , (3) I f f e o t o f x e n i a on p o p p in g e x p a n s io n , ( 4 ) S e l e c t i o n w i t h i n a n o p e n - p o ll in a t e d v a r i e t y , ( 5 ) G e n e ra l v s . s p e c i f i o cara b in in g a b i l i t y f o r p o p p in g expR na|oyit &nA ( 6 ) R e l a ti o n b etw ee n popp in g e x p a n s io n an d c e r t a i n m o rp h o lo g ic a l and ag ro n o m ic o h a m o to r s .

H a la t io n B etw een t h e p o p p in g E x p a n sio n o f S in g le C ro s s e s an d f b e i r P a r e n t a l S ab red l i n e s As p r e v io u s l y i n d i c a t e d , t h r e e g ro u p s o f s i n g l e c r o s s e s m ere in c lu d e d i n t h i s stu d y * c r o s s e s among in b r e d l i n e s o f f e l l o w p e a r l , among J a p a n e s e B a i l e e s , a n d I n t e r t y p e c r o s s e s b etw ee n f e l l o w P e a r l a n d J a p a n e s e B a i l e e s , t h e d a t e f rom e a c h .group a r e p r e s e n te d s e p a r a t e l y b e lo w .

C ro sa c e b etw een Y ello w p e a r l in b r e d l i n e s f h e y i e l d i n pounds p e r a c r e , p o p p in g e x p a n s io n , p e r c e n t lo d g in g an d o t h e r ag ro n o m ic d a t e an d t h e a n a l y s i s o f v a r ia n c e f o r y i e l d o f t h e 78 ex­ p e r im e n ta l f e l l o w P e a r l s i n g l e c r o s s e s a n d one s i n g l e c r o s s an d tw o o p e n p o l l i n a t e d v a r i e t i e s , f e l l o w P e a r l an d S u p erb S o u th A m erican , a s s ta n d a r d s f o r e o a p a r is a n a m p r e s e n te d i n t a b l e 1 o f t h e a p p e n d ix .

R eproduced with perm ission of the copyright owner. Further reproduction prohibited without permission.

-

20 -

X le ld d a t a were a n a ly s e d b y th e I n t e r b l o c k m ethod g iv e n b y T a te s (4 1 ) for l a t t i c e s q u a r e d e s i g n s ,

with t h i s m ethod bh e row a n d colum n

sums o f s q u a r e s a r e c o r r e c t e d for blook affects bat t h e v a r i e t a l sum o f s q u a r e s i s o b ta in e d fro m t h e unadjusted v a r i e t a l m e sa s.

S in e s t h i s s tu d y

is p r i m a r i l y c o n c e rn e d w i t h pepping e x p a n s io n e x t e n s i v e r e f e r e n c e m i l l n o t b e made to t h i s ag ro n o m ic d a t a .

D u p lic a te p o p p in g t e s t s m ere made o a

e a o h o f t h e f i v e replications an d t h e data a n a ly s e d a s a ran d o m ised com­ p l e t e block. ta b le I I .

She a n a l y s i s o f variance f o r e x p a n s io n i s p r e s e n te d i n

A t the foot o f t h e a n a l y s i s o f v a r i a n c e t a b l e s a num ber o f

single d e g re e of freed o m co m p a riso n s o f i n t e r e s t have b e e n l i s t e d , fhsas comparisons, o b ta in e d from t h e sum o f s q u a r e s b etw ee n g r o u p s , a r e n o a - o r th o g o n a l an d f o r tint r e a s o n have n o t bm m in c lu d e d i n t i e r e g u l a r

analysis. f h e swan square w i t h i n plots Is t h e s a m p lin g v a r ia n c e w h ich may b e

attributed primarily t o v a r i a t i o n s is popping, f h e c o e f f i c i e n t o f v a r i ­ ability b a s e d os t h e w i t h i n p l o t mean s q u a r e w as 3 .2 p e r c e n t f o r t h i s g ro u p of crosses an d i s a p p r o x im a te ly t h e same a s t h a t f o r t h e o t h e r g ro u p s to this i n v e s t i g a t i o n ,

f h e sa m p lin g error a t t r i b u t e d t o p o p p in g

m y be c o n s id e r e d v e r y lew particularly t o v ie w o f t h e f a c t t h a t d u p l i ­ c a t e sa m p le s were popped several days o r w eeks a p a r t an d i n seme o a s e s

by d i f f e r e n t w o r k e r s .

T h ese r e s u l t s would indicate t h a t tw o sam p les

per p l o t a r e p ro b a b ly s u f f i c i e n t t o accurately m easu re v o lu m e.

The

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error.

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A n a ly s is o f v a r ia n c e o f p e p p in g e x p a n s io n o f 78 f o ll o w p e a r l s i n g l e c r o s s e s and one s i n g l e c r o s s wad tw o o p e n - p o ll in a t e d v a r i e t i e s a s s ta n d a r d s f o r c o m p ariso n grown a t Awes, Iow a, l a 1141.

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• s i g n i f i c a n t ( p r o b a b i l i t y lo o s th a n . 9 5 ) . I n a l l s u c o o o d in g t a b l e s t h e same cu sto m o f u s in g a s t e r i s k s i n t h e P o o lia m w i l l b e u s e d . * * H ig h ly a i p i i f i e a n t ( p r o b a b i l i t y le e * th a n . 0 1 ) . '" 'T h e g ro u p co m p a riso n s l i s t e d h e r e an d i n s u b s e q u e n t t a b l e s a r e o e r t a i n c o m p a riso n s w h ic h a r e o f i n t e r e s t an d h av e b e e n o b ta in e d from t h e b e tw e e n g ro u p sim o f s q u a re s * t h e s e s e t s o f g ro u p com­ p a r is o n s a r e in a i- o r th o jp io l an d f o r t h a t r e a s o n a r e n o t in e lu d e d in th e re g u la r a n a ly s is above.

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-

22 -

th e v a r ie ty x r e p li c a t io n v a r ia n c e , e r r o r b , m s s ig n i f i c a n t l y h i g h e r than bh» sam pling v a r i a n c e .

The h i g h e r v a r i a b i l i t y b etw ee n v a r ­

i e t i e s in d i f f e r e n t r e p l i c a t i o n # than b etw ee n d u p l i c a t e s o f t h e same

plot was p r o b a b ly d m is p a r t to slight d i f f e r e n c e s b e tw e e n r e p l i e a t e s is m o is tu r e c o n t e s t of the s a m p le s .

D if f e r e n c e s in v i g o r o f p l a n t s

fro m plot t o plot a s in f l u e n c e d b y soil f e r t i l i t y m y a c c o u n t f o r some v a r i a b i l i t y a lth o u g h the am ount in d u c e d i n t h i s m y w as u n d o u b te d ly v e r y s l i g h t i n t h i s e x p e rim e n t s i n c e t h e m a n s q u a r e f o r r e p l i c a t i o n s w as s m a l l,

t h e c o e f f i c i e n t o f v a r i a b i l i t y f o r p o p p in g e x p a n s io n b a s e d

on th o v a r i e t y x r e p l i c a t i a u I n t e r a c t i o n i n t h e e x p e rim e n ts o o n d u o te d i n t h i s I n v e s t i g a t i o n ranged from 6.? f o r the Y ellow P e a r l c r o s s e s t o 1 0 .1 for' th e J a p a n e s e H u lle s s crosses.

were f u r t h e r divided i n t o t h r e e g ro u p s a c c o r d in g t o t h e e x p a n s io n o f t h e p a r e n t a l in b r e d s j H ig h x h ig h , h ig h x

low, and lo w x lo w .

A h ig h l y s i g n i f i c a n t d i f f e r e n c e i n p o p p in g expan­

s i o n m s o b ta in e d b e tw e e n t h e hybrids within e a c h g ro u p an d a l s o b e tw e e n t h e m eans o f e a o h g ro u p .

A fre q u e n c y d i s t r i b u t i o n o f t h e h ig h an d low

p a r e n t a l in b r e d s and th e s i n g l e crosses o f e a o h g ro u p i s p r e s e n te d i n

table HI*

f h e d i s t r i b u t i o n s o f high x h ig h an d o f lo w x low g ro u p s o f

single c r o s s e s b o th extended somewhat bey o n d t h e i r p a r e n t s .

The mean

o f b o th g ro u p s differed fro m the mean o f t h e i r r e s p e c t i v e p a r e n t s , how­ e v e r , b y less th a n o n e v o lu m e,

fhe high x low s i n g l e c r e s s e s w e re i n t e r ­

m e d ia te e n d their rang© included t h a t o f b o t h p a r e n t s .

The mean o f t h i s

g ro u p , 2 3 .4 , w as a lm o s t I d e n t i c a l w i t h t h e mean o f t h e h ig h an d low i n -

bred p a r e n t s , 2 3 .6 .

f h e e x p a n s io n s fro m t h e h ig h x h ig h an d t h e lo w x

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28 -

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24 -

low c r e a s e s showed & v e r y good a g re e m e n t w i t h t h e p a r e n t a l i n b r e d s , b u t i n t h e high x law g ro u p c e r t a i n com bination© w e re e q u a l t o c r o s s e s o f

Mgh p o p p in g .parent# suggesting that some low p e p p in g in b r e d l i n e s may be of v a lu e in c r o s s e s far co m m ercial use*

O th e r c r o s s e s , h o w ev er,

were no better than th o s e fro® low popping p a r e n t s i n d i c a t i n g a d i f f e r e n ­ t i a l re s p o n s e of t h e Inbred l i n e s ,

%£» .popping expansion fer a l l fellow P e a r l s i n g l e o r o s s e c i s g iv e n i n table If.

T h ere w as i n s u f f i c i e n t s e e d o f t h r e e s i n g l e e r o s s e s t o i n ­

c lu d e then is th e regular yield trial*

these were grow n o n ly i n s i n g l e

p l o t s an d the p o p p in g e x p a n s io n s as d eterm in ed . fro ® t h e s e s i n g l e p l o t #

are in c lu d e d i n t h e table. Jfo seed m s obtained of t h r e e s i n g l e c r o s s e s . T h e i r p o p p in g e x p a n s io n was e s tim a te d fro® t h e a v e r a g e o f t h e p a r e n t a l

inbred# in s i m i l a r e r o s s e s ,

for ex am p le, th e p o p p in g volum e o f D-26

x T P-23 was e s tim a te d a s t h e mean of t h e a v e r a g e e x p a n s io n o f D -25 x h ig h e x p a n s io n inbred# p l u s t h e average e x p a n s io n o f TP-23 x low e x p a n ­ s i o n Inbred l i n o s . |h e lowest average p o p p in g volum e o f t h e s i n g l e e r o s s e s b etw ee n h ig h e x p a n s io n inbred l i n e # w as above t h a t o f t h e h i g h e s t e o a a b in a tio n o f lew e x p a n s io n in b r e d lines*

F o r example, tbs tw o lo w e s t volum es o b ta in e d

fro ® c r o s s e s among t h e high e x p a n s io n p a r e n t s , 2 4 .1 e n d 2 6 .6 , w ere h i g h e r th a n t h e two h i g h e s t v o lu m e s, 2 4 .0 an d 2 3 .3 , o b ta in e d fro m lo w x lo w com­ b in a tio n s .

T hese result# i n d i c a t e t h a t one c a n b e r e a s o n a b ly s u r e o f

s e c u r in g h ig h e x p a n s io n h y b r id s when h ig h e x p a n s io n In b ro d e a r e c r o s s e d an d li k e w is e the h y b r id s of lo w e x p a n s io n in b red © w i l l i n a l l p r o b a b i l i t y bo lo w .

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« 26 -

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re la tio n s h ip ,

The mean. y i e l d o f th e s e e r o s s e s was a p p r o x im a te ly e q u a l

t o th e f e l l o w P e a r l e r o s s e s an d c o n s id e r a b ly above t h a t f o r t h e J a p a n ­ e s e B a ile e s c o m b in a tio n s .

The -ear®' o f t h e s e c o m b in a tio n s w e re i n t e r -

m e d ia te b etw ee n t h e tw o p a r e n t a l ty p e s i n s h a p e , th e k e r n e l s te n d in g t o be. lo n g an d f l a t , re s e m b lin g d e n t c o r n k e r n e ls *

D ata t o b e p r e s e n te d

l a t e r w i l l show t h a t e x p a n s io n i s n e g a t i v e l y c o r r e l a t e d w ith k e r n e l s o f t h i s sh a p e an d p o s s i b l y a l s o n e g a t i v e l y c o r r e l a t e d w i t h y i e l d .

T y p ic a l

e a r s o f f e l l o w p e a r l * J a p a n e s e H u l l e s , an d t h e i a t e r t y p e e r o s s e s a r e s h o rn i n f i g u r e 5 . H i g e n e r a l , h o w ev er, t h e a g re e m e n t b etw ee n t h s r e s u l t s from i n t e r a n d i n t r a t y p e c r o s s e s w as good*

The a v e r a g e f o r t h e h ig h x h ig h c r o s s e s ,

a lth o u g h lo w e r th a n t h e p a r e n t a l i n b r e d s , w as ab o v e t h e v a l u e f o r t h e h ig h x low an d lo w x low c o m b in a tio n s .

The a v e r a g e e x p a n s i o n s .f o r t h e

. l a s t tw o g ro u p s ran k ed i n th e o r d e r g iv e n .

S e v e r a l c r o s s e s i n t h e low

x low g ro u p w are c o n s id e r a b ly lo w e r t h a n t h e p a r e n t a l I n b r e d s , p r o b a b ly d u e t o k e r n e l sh a p e a s s u g g e s te d abwve*

These in te r ty p © hybrids may o f f e r p ro m ise p a r t i c u l a r l y f o r home use r a t h e r th a n co m m ercial p r o d u c ti o n .

Suoh c r o s s e s t e n d t o com bine

th e higher y i e l d o f t h e fellow p e a r l ty p e w ith t h e d e s i r a b l e te n d e r n e s s a n d a b s e n c e of halls o f the J a p a n e s e S u l l e s s t y p e .

yapopped Israels in Crosse# of Sigh and Low Expansion I n b r e d L in e s

S he a v e r a g e a a s to e r o f u apopped k e r n e l s fro m e a c h 100 o o . o f un­ popped o o rn i n t h e t h r e e g ro u p s o f v a r i e t a l G ro sse s a n d f o r t h e p a r e n t a l

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35 -

in b r e d l i n e s i s sum m arised i n t a b l e X .

I n g e n e r a l tbs r e s u l t s w ere

s i m i l a r t o th o s e f rom tbs s tu d y o f p o p p in g e x p a n s io n .

S h a re mas a

n e g a tiv e r e l a t i o n s h i p b etw ee n the p o p p in g e x p a n s io n an d t h e num ber o f unpopped kernels ( s e a t a b l e M U I f o r c o r r e l a t i o n s ) ,

t h e c r o s s e s in v o lv ­

in g h ig h volum e in b r e d s had a » u o h mealier num ber o f unpopped k e r n e l s th a n e i t h e r the- high x low or low x lam c o m b in a tio n s i n ea o h of t h e t h r e e g ro u p s .

The a v e ra g e number o f unpopped k e r n e l s f o r t h e o r o s s e s

ap p ro a c h e d the a v e r a g e o f the p a r e n t a l in b r e d l i n e s a l th o u g h i t w as

somewhat leas. These r e s u l t s suggest t h a t low p o p p in g volum e o f in b r e d s an d h y b r id s was due i n p a r t t o t h e f a i l u r e o f p o p p in g .

f a b l e X.

A v erag e num ber of unpopped k e r n e l s p e r 100 o o . o f unpopped c o m for v a r io u s g ro u p s o f o r o s s e s an d f o r t h e p a r e n t a l I n b r e d s

^panese' ' * & l . jpea. * H ttlle s s t x d a p . B u ll. P e a rl t t j is , of i t Mo, o f t He* o f t i a Ho. i Ufcpoppedi Mo, *®apopped * llwS I j K e r n e ls j * K e r n e ls t K e r n e l* j *

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erosses w as t y p i c a l f o r t h a t o f t h e o t h e r g ro u p s and i s p r e s e n te d i n t a b l e X I,

D if f e r e n c e s w i t h i n g ro u p s o f e r o s s e s b a s e d m e x p a n s io n o f

p a r e n t a l l i n e s were h i g h l y s i g n i f i c a n t an d f e e d i f f e r e n c e s b etw ee n g ro u p s w e re li k e w is e h i g h l y s i g n i f i c a n t .

The c o e f f i c i e n t s o f v a r i a b i l i t y t o t h e v a r i -

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(C o a tia u e 4 )

-

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