merr., · tissues were determined by the method of quisumbing and thomas (7) after treatment with...

EFFECTS OF IRON ON CHLOROPHYLLOUS PIGMENTS, ASCORBICACID, ACIDITY AND CARBOHYDRATES OF ANANAS

COMOSUS (L.) MERR., SUPPLIED WITHNITRATE OR AMMONIUM SALTS1

C. P. SIDEFRIS AND H. Y. YOUNG

(WITH SIXTEEN FIGURES)

IntroductionIn a former paper (12) data were presented on the effects of iron on

growth, certain physiochemical properties, and ash constituents of Ananascomosus (L.) Merr. The present paper is concerned with data from thesame plants pertaining to the amounts and distribution of chlorophyll,carotenoid pigments, titrable acidity, ascorbic acid, dextrose, levulose,sucrose, starch, the pentosan and hexosan fractions of hemicellulose, celluloseand lignins in different sections of the leaves, stem, and roots.

MethodsSixteen plants were grown for 12 months in constantly aerated solution

cultures supplied with equal amounts of nitrate- or ammonium-nitrogenand either with or without iron (5 mg. per liter of solution). At the end ofthis period 8 were harvested, weighed, sectioned, and analyzed following thetechnique reported in a former paper (10). Methods employed for thechemical analyses of the substances mentioned in this paper were as follows.

The chlorophyllous pigments were determined according to SCHERTZ'Smethods (8, 9). The titrable acidity of the tissues, expressed as percentageof citric acid, was determined with a 0.1 N solution of sodium hydroxideon a 10-ml. aliquot representing 2 grams of fresh tissue. Ascorbic acid wasdetermined with 2, 6-dichlorophenolindophenol in acetic acid according tothe method of BESSEY and KING (3). Sugars in the aqueous extracts of freshtissues were determined by the method of QUISUMBING and THOMAS (7)after treatment with lead acetate and deleading with disodium phosphate.Dextrose was determined by the hypoiodite method of WIDDOWSON (14), andlevulose was calculated from the difference between the values of reducingsugars and dextrose. The colorimetric method of PucHER and VICKERY (6)was employed for the determination of starch. Hemicelluloses were deter-mined after hydrolysis with 0.75 N hydrochloric acid for 2.5 hours on theresidue of the sample employed for the analysis of starch following theremoval of all dissolved substances. The sugars in the above hydrolysate,reported as total hemicelluloses, contained mixtures of pentose and hexosesugars. The furfural content of the total hemicellulose sugars was made thebasis for the separation of the pentose from the hexose sugars. The residue

1 Published with the approval of the Acting Director as Technical Paper no. 149 ofthe Pineapple Research Institute, University of Hawaii.

52

www.plantphysiol.orgon February 9, 2020 - Published by Downloaded from Copyright © 1944 American Society of Plant Biologists. All rights reserved.

http://www.plantphysiol.org

SIDERIS AND YOUNG: EFFECTS OF IRON ON PINEAPPLE PLANTS

of the sample of tissues from the hemicellulose determination was employedfor determining lignin and cellulose. Lignin was determined by the methodof PETERSON, WALDE and HIXON (5). Cellulose was calculated as the differ-ence between the weights of the dried residue (after the extraction ofhemicelluloses) and lignmn.

The significance of the differences between the amounts of the variousitems of the different cultures was calculated, as reported in a former publi-cation (12), from CONRAD'S modification of BESSEL'S formula, and the valuesof z were obtained from Student's Table as modified by LoVE. Table VIIreports the statistical significance of the difference of the amounts of thevarious items mentioned.

ResultsSynoptic expressions have been introduced in the presentation of the

results and in the discussion to replace the longer ones for the appellation of/6

.8' _ AW-Mv5A"0#w

.6 liilaif

4 _ _ 11.11

ORD D#tEVSZ C00sXDezES AC/

OLD MEf'E ACTIVEr YOM* 0LD. MTURE ACTIVEXNAM

LEAVES LEA VESAl / TR A TE A MMON/U MA/

FIG. 1. Chlorophyll in pineapple tissues of plants grown with and without iron, andwith nitrate or ammonium as source of nitrogen.

the various treatments. The series Ammonium-nitrogen will be designatedby A-n and Nitrate-nitrogen by N-n. Also, the cultures "Plus-iron" by Fand Minus-iron" by 0.

CHLOROPHYLLOUS PIGMENTS

Chlorophyll was separated from the carotenoid pigments but no attemptwas made to separate either chlorophyll alpha from chlorophyll beta orcarotene from xanthophyll. The data in table I and in figure 1, showthat the plants of the F cultures contained amounts of chlorophyll consider-ably in excess of those of the 0 cultures regardless of the source of nutrientnitrogen. They show, also, that the plants of the A-n series containedgreater quantities of chlorophyll than those of the N-n series. This rela-tionship has already been discussed (10).

Carotenoids were higher in the plants of the F than 0 cultures of bothseries. They ranged from 10 to 30 per cent. in the A-n and from 70 to 180per cent. in the N-n series., Such comparisons show that the distribution ofcarotenoids paralleled that of chlorophylls. Since the amounts of both types

53



0

-o

0

Q

zC)

004E-0-Cn

0

PLANT PHYSIOLOG Y

=PIC .C110t CCdCC,

o *.

oo rI55 5 55C N oror oO>> o cD L + o o e ~~~X CoC> C H X CD C> r-- r-- C

x¢i cq x x m C> "t x m In C) In C> N lf cl to cl

;~~~~~~c r-- r--

m 4 oioiao

^: > O e ~~m O cl t- m m clt-et

) U- L- t- m to oo (5 CI4 C]6cmt

CCS;CL CtCCD Cw1tCD i *~C5C1

$; 'Itos t- W~m (M sc *0%o C)O C

55o L Es C 4 - 5

Cl r O~ O~ O~ G:1 O~ OR Oq OR 'O O O It OOO

v e e n CO o o t cc in 't m mo inU:q m: to L-in V

$~~~ ~ ~~~~- CA mN - snnNOH t-z O) O Oc :6 c

........... .... ...0¢ QneOOOC :OOOC

-.oC~o~c~5ciSo

A;~~~~~~~~~~I "ItLr- D .1LDC~U: [t- X. I- CANOm n,,~~~~~c ¢ ,C): t-Ol i0C)m M r-l O-i A ) tO r- '5 r- Nc 4 ci cH C;110

___

__ ________

4in ~ -~ C-4l0 0-I

F1~~~~~~~~~~~~4

V-tL c ie e .o1 v O 01t

O

=xbOO 0000 0OC000550000

~_ .

:C:C

: ~:~0:-

:o*s5,s.,.o.,*o

:0

0~ ~

::: ::::

H VQ

~ ~ ~ C O

H

54

CE-z

0 0

0 EQ0 Oz

czo

0

0

0z -0

53 a ;;,-

0 c

Eq4

Z p

'0

0 -

C

0

00

E-'0




.,60

55

J140 MIA'U'/IROAN

.)I~~~~~~~~~~~~~

R, ~ Z / r rEAM #'O'VOI

of~~~~6irosuple _nth nutrient solution, it s probable tha the dereof4f 9

.5A a

0

LEA VE_ S LEA VE -.S

N/ITRA TE A MAlIOA//UM/AFIG. 2. Carotenoid content of pineapple tissues of plants grown with and without

iron, and with nitrate or ammoniuim nitrogen.

of pigments present in a given section were not proportional to the amountsof iron supplied in the nutrient solution, it is probable that the degree ofavailability rather than the total amounts of iron within the plants were thedeterminant factors for the concentrations of chlorophyll and carotenoids.Iron availability was greater in the A-n than N-n series because of more fa-vorable H-ion concentrations in the solution cultures of the former series asshown in an earlier publication (12).

ACIDITYTitrable acidity is reported as milligrams of citric acid per gram of fresh

tissue in tables I and II, and in figure 3. The values differed in differentsections and also varied to some extent in comparable sections of the plantsof the different cultures. They were generally greater in the chlorophyllous

/J0

/60

140

70s60

Cn. . - D

OSP_0t15,l 21 1O Da _-n - aJn S ICr_ n w -

S.f OLDMCAOrJf AC??VS YOS4 OSOMD MATYRAs AC./V J~r*r

STEM LS A V E S STEM ZLA VES

NIRRATE AMMON/I/UMFIG. 3. Citric acid content of pineapple tissues of plants grown with and without

iron, and with nitrate or ammonium nitrogen.



PLANT PHYSIOLOGY

O= CII OO C9c to C\J OO It= 00 t- t- tc t-<-,di "di CA t-16 l0:~ci Ui16 tF etc C> 16 4 cli eC) 0l 16 4Csc> k6 16 k6 i

c2I m* t t- --4 in m 00 g -i t m m g -q O t-C)V l 00° c m too 0e: C)00cooo c>c.o -14 CoCooo

o n . s t- t- c:Ntot o- Dc c o o tC oCo ciN oo It) H t_ ~~ cm re C-t inj 00 to ~c cm t-O 5 to LO CD

E- c-i1 LO]t- OC -4 m "o 0 t_ ci 1; L t-~ °; Cn4 cl cl t]

E-4 0 C. c t-o o 00 000t-OZ 00 00O t X H 1. CA d000 0H 0 0A;O$ O O H H OOc H cO O O.H *)O. O.O .O

X NOs C) *DCUlcl C) OtQC1.l O O 00O'. ol L5 00 C5 Cj m.r L] -0c. cq t- 0. O. OcO

tc 0m- In "tOom m inI' m m CIn-I oiCL O

"li cq* ~ LOt- ec z to ci C) Cl rH M C) C> 01 m C> a)n cici

°V inr-nqczeo Lo L- " 0000

E- r-OH CQt.. OO-c6 t t-OS oi L6 Ln O: Oy O 4 O o cO cO

V~~ ~~~~~r-r-Z.- r-CQOW m¢:cCJO tiP3 Vt- io m 00C t-1S;-O:H t-CvCli t-- to 100

. tC:*01C 555c0:1 5S5c 0000

-zn > ,- 0 IO .C'I lf,et- i0H i-,- 4 Lo i- 01-C'J D

070;~~~~~~~~~~C r-C$O:COCOCH.RC.O~O~ CO.OOOVZ OOO OOOcOO OOOcOOOO)c ) >C C >

* t00oC0 r- r.t-- C: CJ4Is I,-0C0 CCOol lo

0 0o0 lo0-0o0

.-

: t:e-::::0

:c

56

z0

0

0

z

oi0 0

w

ozg.CL

04

CL

'

000

P:zE- -

1-4:; ¢

E-4

~7CZ

C)

0 ox

O 0

E-0z0zfCLo

rk0

.' z

0CL X

QEX ;0;:L

VL E

OCLz00E-4CLEz

0 ..q.4

0 .,.4 z.o $.,U



SIDEL

-4z

Er.

E-4

6s >

.fE

-

E-4

E--

U- ;<

04z E-

54z

ZE

~0

;z

Zkre, O

C

RIS AND YOUNG:

z

0

z

0

rri

z

EFFECTS OF IRON ON PINEAPPLE PLANTS

= t r- C" m m t m t-s ez In 00 00 CI "' m t- m o>Kl. 4 cKi iil.0 iC C C~4 C6 14 14- 61t6

v-I... .

cjI

0~~ ~ ~ ~ ~ 0~

m c,- m -4 -4 4 -4 L. - m 4 ti 6 o6os r-cX o6 c6 4t-- oi

P-- cl NOC, r-. =cs m m (" in --qt 00 0) q -. -1 O) O= ~

-l$ t 6 t-e>: 6 4 c6 6 c; c; 6 c; 4 c

H~ ~ ~ u L6o 6o 4 cy cin H+isoHCD C: Itt 0 m It C) "I 00 to t t-Of C> r-- cl "t t- CD...........toX~

*CU2t1e t- r-- t- r- r

,ClOC t-)10 =sClt- 00: m

co. °°'rn1 tq q C q 45,X.nWm ~ ~ -O0~22 t1I~-~C H OH~OHI~v-IHHHH

I~~~~~~~~~v1 -

E-I:El e

09

-.C

E-C

x

co

pq

> rA

rA 0

p C4E-4

r- CA

Mvv> Vl m 1'0nX m C t mo ]

vr-4 vvv-I4 I C'vi4 o ~4 r0-Ivr-4 .iv t-: CC~

0cli c "=C0 CCCC'vlIqo =- t0 vfI C00CD 0 0)

*. . . . . . . . . . . . . . . . . ...

to m 3to1 toin tO3oD c CD

v-Iv-IQ Cl VCDbe: UO O O Oi Ocm

* . c. -. i. .l .c .- . .' -. .- .c .0 .C .0 . * . . .

~:.1~ ocincir C)1 . Q~C ot- t- In01rC)I v--q t iq tz tIC d CIIa z o 00 c000' I ('i C;v1I]C'1+ccli 0: 1-0t -I

I

z0

0-

z-pH

1- to CY.s ; (o CC]

lf I--qt

4 -4 4 0c _ lr v-

t1- CQ 1I 1- v-I CC

Cli Cl1 v-I~v- v-- v-( -I v-I C ]i

cdP0Pv cv P4

C]CC -31 04CjI+~~~~~~.4l -lcimi qmk

0~~~ ~ ~ ~ ~ ~ ~~~q

0 bICd

57

7-tc. 't C. .R C-.. 't ci 0. k-'.

9. m oc M r--4 km cli .c tc r--ir--i r-. r-i cq CII cq r-I r-i (.-.A

.;, C'R -,i r-! oi iq ". h. cl C.zr r--i r-I r-4 r-I r-i M 01 01 cl

04 M-e.El `40 C)Er' .DrL



PLANT PHYSIOLOGY

90

aO MINUSIRO_1 - ~~~PLU4S

\ 70 .

60

4.0

.30 tAvRA or345 t As /t v4 5 1 3 4 AAvA F/A 3 4v *Z v23 S45 vZ

O w S r f M cS S w-POsvsFsSFsar _sOLD #wrvtfMA ACrIVE Y0 r& S OLD MATURE ACTIVE M74/M&

STEM EEA TEMS LEA VES

NITr&A TE AMMON'IUM

FIG. 4. Active acidity (pH) of sap of pineapple tissues of plants grown with andwithout iron, and with nitrate or ammonium nitrogen.

than non-chlorophyllous sections of the leaves, a fact also reported in aprevious publication (10). The values of titrable acidity fluctuated con-siderably between comparable sections in the plants of the different cultures.They were not consistent with respect to either the amounts of iron or thesource of nitrogen. In the N-n series, however, the cholorphyllous sectionsof the leaves of the F cultures contained significantly greater amountsof titrable acidity than those of the 0 cultures, yet in the A-n the differencesin acidity between the F and 0 plants were not statistically significant.

The pH values of the sap, reported in tables I and II and figure 4, werein relative agreement with those of the acidity for corresponding sectionsalthough the great amounts of buffer substances in certain sections madeperfect agreement between titrable acidity and pH values impossible.

ASCORBIC ACID

The ascorbic acid content of the sap, reported in tables I and II, and infigure 5, was higher in the chlorophyllous than in the non-chlorophylloussections, thus approximately paralleling the distribution of citric acid.The stem and roots either completely lacked ascorbic acid or the amountswere very small and insignificant.

70 = MII/5 /IAON

40

/0 i

Az -f Z 3rv 3 zcr> -00 1 P0 t 5 0' 3 scrz vf41 5 3

H'OLDla ATIAE ACTIVE VOL/MGC OLD AOMArTURE ACTIVE YOUNG1LEA VES LEA VES

A//TRA TE A MMON/VUMFIG. 5. Ascorbic. acid content of pineapple tissues from plants grown with and

without iron, with nitrate or ammonium nitrogen.

58




Ascorbic acid values were considerably greater in the leaves of the 0 thanF eultures of the N-ni series, the differences beingy highly significant, asreported in table VII. In the planits of the A-ii series ascorbic acid wasapparently higher in the "old" (B) and "mature" (C) groups of leavesof the 0 than F cultures, but not in the "active" (D) anid "young" (E)groups. Ascorbic acid showed in many sectionis of the N-n series an inverserelationship to citric acid whereas in the A-n series the relationship wasdirect.

TOTAL SUGARS

The amounts of total sugars, reported in tables III and IV, and in figure6, were, with few exceptions, hieher for the plants of the F than 0 cultures

L4J MI~~~/,V/US IRO//3QO

STE0 PIU A E-7g AV^

K760

240

/60

~/00 K

60li

O/AR FEP R0 / a

T0 A

STEMAr- LEAVE -STELE0A

NI/TRATrE AMMONIUMfFIG. 6. Total sugars in pineapple tissues from plaiits grown witlh or without iron,

anid wvith niitrate or ailmonium nitrogen.

of both series. They were higher in the basal and apical sections of the stemthan in the medial sections. The amounts were greater in the N-n than A-nseries. Contrasts between the amounts of sugars anid chlorophyll in the"mature" (C) and "active" (D) leaves of the F aind 0 cultures of the N-nseries show that mean chlorophyll values were 212 per cent. (F = 0.572 and0 = 0.183) and sugars 16.6 per cenit. (F = 27.5 and 0 = 23.5) higher in the Fthan 0 cultures. Variability in the chlorophyll values was 30.8 per cent.

(cv=w.2) whereas in the sugars it was 57.4 CV=

Accordinoly, sugar values were 1.86 times (57.4 . 30.8 = 1.86) more variable,oni the basis of these calculations, than chlorophyll values. The results sug-gest, therefore, that sugar accumulations in the leaves had been influencedby other factors intimately associated with the metabolic and photosyntheticactivities of the plant besides chlorophyll concentrations.

59



0

PLANT PHYSIOLOGY

It.*.*-...C

X > e CO ~0~00 CQ 0() D t- cO to k: Oc 00 0X) vl: ;lcq U:--I ot4tI

,; -di oo koX noo o

,--0;* .1 m t to r-- (M t- m to kn 00 c C )o C5 )0 -s mU:

to

*

.1 00teCo M rlto 01 00

cs o

cq "I

u:

km t- "t t- m

X0 < te .................. ...n :~ ...........................ctHmemHNNr.. O¢X * tHH0~~c m 00t - im"'4C0>0 mNCKUL- n 00n00mt

OOOI>LI" 0 l M tm 00 U C

E-I/

Go

¢~~~~~~~~~tWJ 0000 00H to.000H - 0 0 00 to0 0Ic

£P:t,o o clo.-, r

+s cyi t6 6 r4c; -4c

: oi 4 t ci

Vq r- r- Cq 11s C C) r- "- = to olC r- LH OtIC C) C) eD C)

>1

w m t O C) Cli i 00 t.- 06 r Ci CD 4 16 (: O; 16 16 t6 Cn t 00 Cl

a~~~~~~'¢-t) tss : (::Cz lf 0: 01 tRC'a cc. ct o

in+qoo coOi to+r; s m lo

cc ..E*b~~~ ~ ~ ~ ~ ~ ~ ~ i...

60

zcj4

o

O °Ci~Z

zo

E-400

lYZ¢

o

EJ:a

p.;~

*Zw

C)

rL90 E-

ZE

u 0

0

EZ

U).:) C. 9 c. v. t-.: .R tR -! tR C. tR C. ci C. C. -. 't t-: C. '-I tR Q. 0. kq11= z C. Cl 00 r--l 01 .O r-I t- M 01 00 L:) .C t- r--i tC C) r--l r--i m t- C> cliw " .:) r-. T-q r--q r--l r-i r-i r--q " r--q r--i r-q r--l r-4 r-i r-iP4 co




5EAl LEA VES

NvI rRA TrEFIG. 7. Reducing sugars in pineapple

iron, and wvithl nitrate or ammonium nitrogen

,srrm LEAVES

A,AMMON/Z/Mtissues from plants grown witlh or without

REDUCING SUGARS

Data for reduciing sugars are presented in figyure 7 anid for dextrose andlevulose in figures 8 and 9, ancd in tables III an-d IV. Dextrose occurred inmuch greater amounts in practieallv all the sections of the leaves, stem, androots than did lev-ulose. In the stem, levulose was either absent or presentin verv small amouints wvhile dextrose imade uip the biilk of the amounts of

17f

.75.

1,

0

a

AMINAUZS IRONPLUS

NIv TRA TE AMMOA/AUAf

FIG. 8. Dextrose in pineapple tissues from plants grown with or witlhout iron, andwith nitrate or ainmonium nitrogen.

61



62 PLANT PHYSIOLOGY

120

/M0 - MM lO/00

970

890

70

60

40

30

0

/0

oDDE~ ~ ~~TA W P 0 ASDP1/Ay7, I 8 C &1 1 a C DS OLD MA rTU/tAcA74VRF ACTIV r 0oMAREACTIVEVOU/N6STEM LEAVES STEM LEA VES

N TR A TE AAlMONI/M

FIG. 9. Levulose in pineapple tissues from plants grown with or without iron,and with nitrate or ammonium nitrogen.

reducing sugars. Dextrose accumulated mostly in the basal and terminalsections of the leaves of the "old" (B), "mature" (C), and "active" (D)groups, whereas levulose accumulations were highest in the basal sections.In the leaves of the "young" (E) group the differences between the amountsof either dextrose or levulose of the basal and terminal sections were not asgreat as in the other groups of leaves. Dextrose occurred in greater amountsin the chlorophyllous (2, 3, 4, 5), while levulose was more abundant in thebasal (1), non-chlorophyllous sections of the leaves. The low amounts oflevulose in the chlorophyllous and the high in the non-chlorophyllous sec-tions might indicate that either the rate of levulose synthesis was consider-

/O Mr lINUS IRON

/00 - PLUSL

9.0

70

60

so

20

/0

O AD-A 0AW#Afn'-1O 5 v|---W9S-nS OLD ArTUR ACTIVE YOVU00 S O ADMATRE ACTVE VA.* SrEM ZEAVES SrEM LEAVES

/ITrA A TE AMM#OWAUMFIG. 10. Sucrose in pineapple tissues from plants grown with or without iron,

and with nitrate or ammonium nitrogen.




ably lower than that of dextrose or that it was utilized more in the synthesesof various types of substances.

SUCROSE

The data in tables III and IV, anld in figure 10 show that sucrose wasmore abundant in the plants of the F than 0 cultures of the N-n series. In theA-n series sucrose did not accumulate in the F cultures and in many sectionsthe 0 cultures had slightly higher sucrose values. There can be no doubt,however, that the greater amounts of sucrose in the plants of the F than 0cultures of the N-ni series resulted from different rates of carbohydrate syln-thesis due to appreciable differences in chlorophyll contenit. The lack of

4'

42

= AVIMdUS IRON

X.. ILz

24

/Z

4-~~~~~~~~~~~~~~~~~~~~~~n

OWAA5/D/ f ff--F O A /15/2

5SMM LM AT ACV STEV OL E A V E S

m/ rRA rE AMMONAI1UMFIG. 11. Starch in pineapple tissues from plants grown with or without iroa, anid

with nitrate or ammonium nitrogen.

appreciable difference in the sucrose content of the F and 0 cultures in theA-n series may be attributed to the small differences in the chlorophyll con-tent and possibly to different rates of utilization of sucrose.

STARCH

Iron availability and the source of nitrogen had affected the amounts ofstarch more than anv other carbohydrates, as reported in tables III and IV,and in figure 11. The plants of the F cultures of both series contained, withfew minor exceptions, more starch than those of the 0 cultures. Also, starchaccumulations were enhaneed more by nitrate- than ammonium-nitrogenunder the same concentrationis of iron.

63



PLANT PHYSIOLOGY

Starch accumulations were restricted mostly to the tissues of the stemand were appreciably greater in the N-n than in the A-n series, whereasreducing sugars and sucrose accumulated mostly in the leaves althoughsome stem sections contained as high amounts of sugars as did leaf sections.The "mature" (C) and "active" (D) leaves contained greater amounts ofstarch than did those of the "old" (B) and "young" (E) groups. Thesmall amounts of starch in the leaves of the "young" (E) group can be ex-plained on the basis of a relatively rapid utilization of carbohydrates for thesynthesis of new tissues, while those in, the leaves of the "old" (B) groupmay be explained by a decreased rate of photosynthetic activity or by apossible hydrolysis of starch resulting from tissue senility.

'C .

MMUSIEWI

OLDrchvaluesfACt/VS b OP DinAhe wr An

MIE1ACELLUOS

-STMFA LEAVE STEM Z AFAVESNITrRATrE A*MbONI41I

FIG. 12. Total hemicellulose sugars in pineapple tissues from plants grown with or

without iron, and with nitrate or ammonium nitrogen.

A synoptic analysis of the effects of iron and nitrogen sources on starchshows that nitrate-nitrogen versus ammonium-nitrogen increased the averagestarch values in the stem 161.6 per cent. for the plus-iron and 295.0 per cent.for the minus-iron cultures. The gains of starch in the stem of the plus-iron versus minus-iron cultures were 33.2 per cent. for the nitrate series and101.3 per cent. for the ammonium series.

HEMICELLULOSES

The amounts of total hemicellulose sugars, reported in tables V and VI,and in figures 12, 13 and 14, were slightly greater in the F than 0 cultures.

64




;Z ~~~~~~~~MIA'U.S IROAI-PLU-/

o

/0 i[~K o~~~~~~~~~~~~~~~~~ I x 5 0 G{ r5D r C Sr 9

OLIAfiArlleE A4Cl/VF YOW/A6& Oz AA Mz/Vc AC 7r1 VF Y041AAS5rEM~~~~/ -F A V e5-5rE" Z EA v S

NI TRAT E AMIOA/IIAMFIG. 13. Pentosanis in pineapple tissues fromi plants growsn w ith or w ithout iron,

and Nvitlh iiitrate or ammonIium Iitrogeii.Peitose sugoars, constitutii ioiiore than three-fourths the amounts of total

hemiieellulose suyars, wsere ogenerallv hioher in most leaf sections of the Fthan O cultures of botlh series. The amounts of hexose suoars showed de-Fided de1Piatiolosfroinpeaptose stgars,beins generallo hither in the leaves

of the sthasF cultores of the N- aseries. TI the A-n series the amounts ofhexose sugars were higher in the "old" (B) and "mature" (C) and lowerin the " active " (D) auid "y-oungio" (E) groups of leaves of the 0 than in theF cultures. The amounits of hexose sug,ars in the stem were higher in the 0than in the F cultures of the N-n series, while in the A-ni series the values

/20

MI//US /IROAI00- -PLUIS -

"j90-

80

60-i.. 4O 1 , I.ll.il llU.,,R/0 i

It 8554 AsILI3 .5 /234 IZs3 52 4SI 55A/-2 s /23 451If 4 5,2S30 D -r C | D -r

Mo-TIP ASF C -"O-47/AIM-e-o

a7£ 0 SD0 a

s OLD MATURE ACrTvE YOU OLDMzrATURE ACrIVE YOUN&STEM LEA VE-5 sTM LEFA VES

NVIT7RA TE AMMON/U4MFIG. 14. Hexosans in pineapple tissues from plants grown with or without iron, and


65



0

-

0

;m4

PLANT PHYSIOLOGY

£~~~~~~~~~~~,-t00,cro -Isemm lzmto0 :nc,m-t o

m oo t- 6 m "1 6v 6C t ;C - 4Cn

L-0 00 r- M r- ~c 00 r- t- to C) in C'O q m m N Cn t1z

i6 4c i4c ;o icii2c icicy 6~ ~e-

E-4 t ct c r- .,I rCi1 tCQ CQ llO R IR IqtSs : IRClics C~rI lls

;A Ch r. .I r- r- r- r- rH rH r- r- r- " " r- rH rH r- C4 r- CA.~qr- .0r-ft m

Ez0 6t:0 ~o ~4C;1 6C ;o : oi ooo-C

Cqr-qcqol-q -I I 1 -q01 -Ir- CA r-qCA c C]r-~

v_ _lato_t__ to__ c__ 0__Lo_ i t- 06 6 0 _r-

r-i r-q r~~~-Ai

w~~~~~~~- 0c >O)C >I o 0 >0 0 c

0

C)E- c11 -qC -~C c0 r~mmt -= mmL o C C0

-:ci44t:~44rH rI ~ -q r- r- r- rqr-qrI rqr- o1~

0I Cl ~C iC ll itl l t Ci ClOKll

Ez ot cO)mr- ct cmt ot -q0 00 -r-

+

E-1 PP~~~~~

z~~~~~~~~~~~~~~~~~~~~~~~P

-4-D~~~ ~ ~ ~ ~ ~ ~ ~~~~I

66

D

Zz

.~0

zI

E- C

00

0

00

ZE$ EP.1< ¢Zr z

E-¢ 4

o o4

O EZoaZ_E-Z

o E- E-

o Z

!I0




zr--q ",di CYD m C) cit m m oc -.14 oc LM m It = = Lel. t- Iliq Cli r-q OC

z0 g oi c; "4 6 L-i t.. o6 t-. c; c6 ti L--. o6 <:. oi t.: o6 (::. c; 4 4 o60-4 r--l r--q r-i r--i r-.

.-q

0 ms e> e CA co cli e cl CA m cq m cli cli tq CIculcS Clc]- rH c

ow

a ~ ~ ~ Cr-0 m*e- II9 -iC1 1Otq C' m c5 m m:.1z It mC: CQ+

E- ll CI IR = 1- t,, (3' nC "t_

V I ot2oH H * 4 m* H H m mS t t o 4 c 6C

2~~~~~~~~~~o0;.'Cr~ I-f t~~-iC -e£lf<'- HQ~C~

z

0- * I01cI201- -.14 (M t L t 0 ~1 --q (M

O RC; o~ "' 00CAs to t c) = t- et r-- In. m:vXt

mr. ooz~6 ~ pvic t0o6oc ;:(.,i mOH4 zyic

H Z 4 -.1/5 0 l t w10 C')Oc kf-1>-r-00X)C11>zO C5

i6v^cymi oi e oi vi c i4 r4 o4 cs c: r- o uicS o i

Vc<:c:ee2eee1o) .0

_V.4

r--q C) -It C) r--l (ZI. 00 m t- m QC It to m CII trz It m r" r-i 1.14 C)zz 4 tz. ti cli C. C. 6 ci 14 cli 4 06 cli oi ci C. L-i cli C. 16 r-4 (Ii 4 C.PQ m rt r--i r--q r-4 r-4 r-4 r-I r-I .4 .4 .l r-4 r-. r-. r-. r--. r--l " r--l r--iP.,

Po

=~~~~~~~~~~~~t¢ mmt- "t<inoc qt- to tc - m(=Oc ''CA1 't

C.)

,i, . . . . . . . . . . . . . . . . ..4O4 Ce P4 CssssX+ ++ 8 n

_Ev , _-~~~~~~~~~~~-....~~~~~~~~~~4..D 4--

E-4~~ ~:::: Co k

E-4*

.d* :

67

z0

z

Ez4

ZI

V 0C Z ¢

~4 Ei2

o1-40

H Ct

04z

E0

0

Z El

0 z E4

r- E-4 O

C t

Ez0A

P:"

E-4



PLANT PHYSIOLOGY

|EOS5M>X g/MU/ S IRON

4O

/5

DADEAW-A A

r z Z It A A

VOID AfAr f ACr'VJ *| OLD Ac7-V& |t

sTEM EA VE-S SrTEW EA VES

IV/ TRA TE AMMONI/UMFIG. 15. Cellulose in pineapple tissues from plants grown with or without iron, and


were reversed. The results indicate that hexosans were more susceptibleto variations by the difference in the amounts of iron anid sources of in-organic nitrogen than pentosans.

CELLULOSE

The amounts of cellulose, reported in tables V and VI, and in figure 15,were affected very little by iron concentrations. The effects of the source ofnitrogen in the solution culture on the amounts of cellulose in the plants of

TABLE VIICALCULATED STATISTICAL SIGNIFICANCE* OF THE DIFFERENCE OF THE MEANS OF THE

SUBSTANCES LISTED BELOW OF COMPARABLE SECTIONS OF THE LEAVES AND

STEM OF PLANTS GROWN EITHER IN PLUS-IRON OR IN MINUS-IRONCULTURES AND SUPPLIED WITH NITRATE OR AMMONIUM

SALTS AS SOURCES OF NITROGEN

NITRATE-N AMMONIUM-N

LEAVES STEM LEAVES STEM

SUBSTANCES IN IN IN INSIGNIFI- FAVOR SIGNIFI- FAVOR SIGNIFI- FAVOR SIGNIFI- FAVORCANCE OF CUL- CANCE OF CUL- CANCE OF CUL- CANCE OF CUL-

TURE TURE TURE TURE

Chlorophyll ... 9999: 1 +Fe .................. 9999: 1 +FeCarotenoids ... 9999: 1 +Fe .................. 9999: 1 +FeAcidity + Fe.................. NoneAscorbic acid 9999: 1 - Fe ................. . NoneTotal sugars 9999: 1 + Fe None 9999: 1 + Fe NoneReducing " None None 9999: 1 + Fe NoneSucrose.. 9999: 1 + Fe None None None.Starch .. 4000: 1 +Fe 9999: 1 +Fe 9999: 1 +Fe 29: 1 +FePentosans 9999: 1 + Fe None ........... 9999: 1 + Fe NoneHexosans 9999: 1 -Fe 45: 1 -Fe None 43: 1 +FeCelluloses None None None NoneLignin.. None None None NoneI ............

* By CONRAD'S formula and from LOVE 'S table.

68




the different treatments were small and lacked statistical significance. Thesesmall differences were in favor of the plants of the N-n series. It is suspectedthat they resulted from differences in the water content of the tissues, asshown in former publications (10, 11). The high cellulose content of thetransitional subehlorophyllous (2) sections of the leaves of the "mature"(C) and "active" (D) groups is of great interest because it conforms withtheir structural requirements. The leaves of these groups require, onaccount of their great length and weight and their outwardly inclinedposition on the stem, greater structural reinforcement than do the leavesof the other groups in order to prevent their downward collapse.

Cellulose, being a structural and not a food or energy-yielding poly-saccharide, did not undergo appreciable changes as a result of changes in the

= $IIAUS IRONV* U-5M#S/>

./2W

- OB

AAO1A Ara4DJ{........Jr.......JrD. C O O S *a

tCj_ w........

JS134 CU4 /245 24rMOl iAn/Aro e ACT/ vSirMW47 AFR 4rlr MO

_SEM L6 A VES STEMM L AVESNIVI TRA 7E AMMONIAI/

FIG. 16. Lignin in pineapple tissues from plants grown with or without iron, andwith nitrate or ammonium nitrogen.

carbohydrate metabolism of the plants induced by the respective amountsof iron of the F and 0 cultures. Except for the smaller weights of the plantsof the 0 than F cultures of the N-n series, no other changes could be observedappreciably affecting the values of cellulose.

LIGNIN

The lignin content of the plants of the different treatments recorded intables V and VI, and in figure 16, ranged from one-half to one-tenth andaveraged about one-fourth that of cellulose. Lignin, like cellulose, being astructural and not a food or energy-yielding substance was affected verylittle by the different amounts of iron in the 0 and F cultures. The datagathered so far indicate that the amounts of lignin, celluloses, and hemicellu-

69



PLANT PHYSIOLOGY

loses were directly related to the quantities of the fibrovascular tissues of therespective plant sections.

DiscussionThe traces of iron contained as impurities in the C. P. nutrient salts were

not sufficient to promote good growth in the plants of the 0 cultures of theN-n series where the initial pH of the solution culture changed in a two-weekperiod from 4.4 to 6.8. Such traces of iron were very effective, however, forpromoting plant growth in the 0 cultures of the A-n series because the orderof pH changes in the solution culture was reversed, shifting in the course oftwo weeks from an initial pH value of 6.6 to a final one of 4.3. Such changesaffected the degree of iron solubility and its availability to plants (12).Where iron was available, as in the F cultures, chlorophyll was produced inample amounts.

The minimum amounts of iron required by A. comosus for optimumchlorophyll development and growth are relatively small. Amounts rangingfrom 0.3 to 0.5 micrograms of iron per gram of fresh tissue have been foundin many green tissues and may be considered adequate provided the rate offlow which maintains such iron concentrations within the plant tissues doesnot diminish appreciably (12).

The most obvious physiological function of iron is its influence on theformation of chlorophyll or more probably of protochlorophyll (4) and otherrelated metalloporphyrins such as cytochrome-c, (2). Following the for-mation of chlorophyll the entire metabolic tempo of the plant is acceleratedwith respect to carbohydrate synthesis, nitrogen assimilation, and nutrientmineral requirements. This indicates that the physiological effects of ironon the general metabolism of the plant are very intimately related to thechlorophyll status of the plant. Hence it will be utterly misleading to placetoo much emphasis on the amounts of iron found in plant tissues or on thosesupplied externally to plants through solution cultures, and too little empha-sis on the chlorophyll content of the leaves inasmuch as experience has shownthat amounts of chlorophyll in the leaves do not always correlate with thoseof iron.

Certain interesting phenomena associated with the distribution of ascorbicacid are the gradients of concentrations of this substance in different sectionsof the leaves of different groups which in most cases were highest in thetermninal and lowest in the basal sections. These gradients might haveresulted from differences in the physiological functions of the different sec-tions. The data also show that ascorbic acid had reached maximum valuesin the leaves of the "active" (D) and minimum values either in the "old"(B) or "young" (E) groups. The differences in the amounts of ascorbicacid between groups of leaves may be explained by the assumption thatascorbic acid, being a by-product of metabolic activity (possibly resulting,like many other acids, from the incomplete oxidation of sugars during respi-ration), is produced in greater amounts in leaves of great vigor and maxi-mum synthetic activity such as the "active" (D) group than in immature

70




leaves such as the "young" (E) group. The relatively small amounts ofascorbic acid in the leaves of the "old" (B), and to a lesser extent of the"mature" (C) group, resulted possibly from catabolic processes caused bytissue senility. The lower values of ascorbic acid in the F than 0 culturessuggest possible oxidation of ascorbic acid by the iron of F cultures in allthe groups of leaves of the N-n series [where average total Fe values, re-ported elsewhere (12), were 19.4 and 47.3 y per gram of fresh leaf tissue forthe 0 and F cultures, respectively]. In the "old" (B) and "mature" (C)leaf groups of the A-n series reduction in ascorbic acid values might havealso been caused by oxidation since iron was 3.14 times more abundant in theF than 0 plants (F =98.5, and 0=31.4 y per gram of tissue). The onlyexceptions were certain sections of the leaves of the "active" (D) and"young" (E) groups of the A-n series, where the amounts of both ascorbicacid and iron were higher in the F than 0 cultures.

The values of titrable acidity, pH, and ascorbic acid indicate that theconditions in the chlorophyllous sections of the leaves were highly favorablefor the solubility and reduction of iron, whereas in the basal sections of theleaves and in the stem they were not as satisfactory. However, chemicalanalyses for iron, reported previously (12), have shown no accumulations ofiron either in the stem or in the basal sections of the leaves.

The plants of the N-n series, although including smaller amounts ofchlorophyll than those of the A-n series of comparable iron cultures, con-tained greater amounts of sugars, suggesting that the conditions which hadaffected the metabolism of nitrogen rather than the amounts of chlorophyllwere responsible for these differences.

The distribution of sugars varied considerably in the different groups ofleaves. Such variations were caused by differences in the physiological func-tions of the sections and by the relative degree of vigor of the differentgroups of leaves. An analysis of such functions shows that the basal sec-tions (1), lacking in chlorophyll, play no part in the photosynthetic proc-esses of the plant in contrast to the chlorophyllous sections (2, 3, 4, 5) whichare intimately associated with this mechanism. Also, the terminal sections(5) become senile and lose a great deal of their vigor and photosyntheticefficiency sooner than the immediately adjoining sections (2, 3, 4). Lossesof vigor and photosynthetic activity are greater in the leaves of the "old"(B) and "mature" (C) than of the "active" (D) and "young" (E)groups. Therefore, accumulations of sugars in any section of the leavesshould be associated either with a decreased rate of utilization as in cases ofretarded growth, with highly favorable conditions for photosynthetic activ-ity, or with a decreased rate of translocation from the leaves to the otherorgans. Low sugar values should be associated with conditions quite oppo-site those favoring accumulation. Thus, the lower values of sugars in thebasal (1) sections of the leaves of the "young" (E) than of the "active"(D) or "mature" (C) groups suggest, on the basis of the above postulations,that a greater rate of sugar utilization for the building of new tissues was in

71



effect in the "young" (E) than in the "active" (D) or "mature" (C) and"old" (B) groups of leaves. Also, the accumulation of sugars in the termi-nal sections (5) of the leaves of all such groups may be attributed, on thebasis of the same postulations, to a retarded rate of translocation or to thesynthesis of much greater amounts than required for the energy-consumingprocesses of the cells and for the synthesis of various substances. However,certain exceptions to the above postulations as, for example, the slightlygreater amounts of sugars in the basal sections of the leaves of the "old"(B) group of the 0 than F cultures of the N-n series cannot be satisfactorilyinterpreted. It is possible, however, that the higher values of sugars in thebasal sections may be attributed either to cessation of the enzymic processesresponsible for starch synthesis or to opposite effects such as hydrolysis ofreserve starches resulting from tissue senility. The low sugar values inthe medial section of the stem may be attributed to the rapid conversion ofsugars into starch by very active enzymatic processes. The preponderanceof dextrose and the relative absence of levulose in the stem might have re-sulted from hydrolyzed maltose which probably could have been releasedfrom starch by hydrolysis.

The amounts of sucrose increased gradually from the basal to the apicalsections of the leaves and stem except in the transitional subehlorophylloussections (2) of the leaves of the "young" (E) group where they decreasedbecause of a high rate of metabolic activity tending to prevent the accumu-lation of this or other sugars in appreciable amounts.

Starch, although a reserve product like sucrose, accumulated in greaterquantities in the stem than in the leaves. The stems of the N-n series con-tained almost twice as much starch as those of the A-n series. It is possiblethat this condition resulted either from differences in the rate of the photo-synthetic activity of the leaves of the two series, or from the energy relationsinvolved in the assimilation of the two forms of nutrient nitrogen. Thereis at present some suspicion, based on evidence from studies on the toxicityof chlorides to A. comosus (13), that chlorides supplied as CaCl2 to nutrientsolutions of the A-n series interfered with the polymerization of sugars intostarches in the stem.

The small differences between the amounts of hemicelluloses in the plantsof the F and 0 cultures indicate that they play a relatively minor role asenergy-yielding substances in the carbohydrate economy of A. comosus. Thedata show that the hemicellulose content of the tissues was increased moreby nitrate-nitrogen than by the amounts of iron in the F and 0 cultures.

The association of high values of hemicellulose sugars with plant organscontaining great amounts of fibrovascular materials [such as the roots andto some extent the basal and terminal sections of the leaves of the "old" (B)and "mature" (C) groups] suggests the possible participation of these sub-stances in the structural formation or cementation processes of fibers.

The amounts of celluloses and lignins were affected very little by thedifferences in the amounts of iron and by the forms of nitrogen. Both cellu-

72 PLANT PHYSIOLOGY




lose and lignin, representing structural units in the plant body, remainedin a static condition and were not susceptible to changes which had affectedsuch energy-yielding carbohydrates as sugars and starches. The effects ofthe different treatments on cellulose and lignin were about the same as thoseon heinicelluloses, but differed considerably from those on starches or sugars.

SummaryThe effects of plus- or minus-iron cultures in association with nitrate- or

ammonium-nitrogen were studied in connection with the distribution ofchlorophyll, carotenoids, ascorbic acid, sugars, starches, hemicelluloses, cellu-loses, and lignin in different sections of the leaves, stem, and roots of A.contosuts and are summarized as follows.

1. Chlorophyll and carotenoid pigments were higher in the leaves of theplus-iron than minus-iron cultures. The plants of the ammoniumii-nitrogenseries contained more pigments than the nitrate-nitrogen series for compara-ble iron cultures which possibly resulted from a greater availability of ironin the former than in the latter series.

2. Titrable acidity gradients reported as citric acid, inereased from thebasal to the terminal sections of the leaves of the plants of all cultures. ThepH values of the sap were approximately inversely proportional to those oftitrable acidity. The stem and roots had low values of titrable acidity andshowed either little or no changes in the different treatments. The highacidity values of the sap from the chlorophyllous sections of the leaves andthe exceedingly small amounts of iron present in the same tissues precludethe possibility of iron precipitation in these tissues of this organ.

3. Ascorbic acid was almost limited to the chlorophyllous sections of theleaves although the amounts present were not directly proportional to thoseof chlorophyll in the plants of the different cultures. The non-chlorophyl-lous sections of the plant, including the basal leaf, the stem, and the roots,contained either none or only mere traces of ascorbic acid. The gradientsof distribution of ascorbic acid in the chlorophyllous sections of the leavessuggest that certain phases of metabolism rather than amounts of chloro-phyll in these tissues were responsible for their ascorbic acid content. Re-duction of the ascorbic acid values in old and senile leaves of plus-iron cul-tures suggests its possible oxidation by iron.

4. Sugars were found in greater amounts in the leaves of the "old,""mature," and "active" groups of the plus-iron than minus-iron cultures.They were higher in the plants of the nitrate- than of the ammonium-nitrogenseries. The source of nitrogen in the nutrient solutions had influenced theamounts of sugars more than the amounts of chlorophyll in the leaves.Accumnulations of sugars were greater in the basal sections of leaves of the"miature" thaii "yvoung" gcroups because the rate of their utilization for newtissue-building processes had decreased in the former. Sugar values in thebasal, medial, and apical sections of the stem were in most cases indirectlyproportional to those of starches, suggesting that the rate of withdrawal ofsugars from the stem is directly proportional to that of starch synthesis.

73



5. The amounts of levulose were slightly higher in the leaves of theminus-iron than plus-iron cultures of the nitrate-nitrogen series. Levulosewas almost absent in the stem. Dextrose, occurring in amounts twice asgreat or more than levulose, was distributed in all organs of the plant.Sucrose was higher in the leaves of the plus-iron than minus-iron plants ofthe nitrate series, but in the ammonium series it was as high or slightlyhigher in the minus-iron than in the plus-iron cultures.

6. Starch was consistently higher in the stem of the plus- than minus-iron cultures, the former containing 101.3 per cent. more starch for theammonium series and 33.2 per cent. more for the nitrate series. The plantsof the nitrate-nitrogen series contained 161.6 per cent. more starch for theplus-iron and 295.0 per cent. for the minus-iron cultures than of the ammo-nium-nitrogen series.

7. The differences in total hemicellulose sugars between the plants of theplus- and minus-iron cultures were slight, with the plants of the former cul-tures containing, in most sections, greater amounts than the latter. Theplants of the nitrate-nitrogen series contained greater amounts of hemicellu-lose sugars than those of the ammonium-nitrogen series. The differencesbetween the amounts of hemicelluloses in the plants of the nitrate- versus theammonium-nitrogen series were greater than those between the plus- versusthe minus-iron cultures. The pentosan fractions of hemicelluloses of thenitrate series were higher in the plus- than in the minus-iron cultures, whilethe hexosan fractions were reversed. In the ammonium series the distribu-tion of hexosans throughout the plant was irregular.

8. The amounts of cellulose were higher in the transitional sections whichbear the strain for the erect position of the young leaves and reclined posi-tion of the mature leaves.

9. Lignin was generally high in those parts of the plant containing greatamounts of fibrovascular tissues such as the roots, basal sections of the stem,and terminal sections of the leaves.

10. The amounts of both celluloses and lignin were affected only slightlyby the different treatments and behaved in this respect like the hemicellu-loses.

PINEAPPLE RESEARCH INSTITUTEUNIVERSITY OF HAWAII

HONOLULU, T. H.

LITERATURE CITED

1. ASSOCIATON OF OFFICIAL AGRICULTURAL CHEMISTS. Methods of analy-sis. 1940.

2. BALLs, ERIC G. Biological oxidations and reductions. Ann. Rev. Bio-chem. 11: 1-25. 1942. Stanford University Press, California.

3. BESSEY, 0. A., and KING5, C. G. The distribution of vitamin C in plantand animal tissues and its determination. Jour. Biol. Chem. 103:687-698. 1933.

74 PLANT PHYSIOLOGY




4. EYSTER, W. H. Protochlorophyll. Science n.s. 68: 569-570. 1928.5. PETERSON, C. J., WALDE, A. W., and HIXON, R. M. Effect of tempera-

ture on sulfuric acid method of lignin. Ind. & Eng. Chem. Anal.Ed. 4: 216-217. 1932.

6. PUCHER, C. W., and VICKERY, H. B. Determination of starch in planttissues. Ind. & Eng. Chem. Anal. Ed. 8: 92-97. 1936.

7. QUISUMBING, F. A., and THOMAS, A. W. Conditions affecting thequantitative determination of reducing sugars by Fehling solution.Elimination of certain errors involved current in methods. Jour.Amer. Chem. Soc. 43: 1503-1526. 1921.

8. SCHERTZ, F. M. The extraction and separation of chlorophyll (a+b)carotin and xanthophyll in fresh leaves preliminary to their quanti-tative determination. Plant Physiol. 3: 211-216. 1928.

9. . The quantitative determination of chlorophyll. PlantPhysiol. 3: 323-334. 1928.

10. SIDERIS, C. P., KRAUSS, B. H., and YOUNG, H. Y. Assimilation of am-monium and nitrate by pineapple plants grown in nutrient solu-tions and its effects on nitrogenous and carbohydrate constituents.Plant Physiol. 13: 489-527. 1938.

11. , , and . Distribution of dif-ferent nitrogen fractions, sugars and other substances in varioussections of the pineapple plant grown in soil cultures and receivingeither ammonium or nitrate salts. Plant Physiol. 14: 227-254.1939.

12. , YOUNG, H. Y., and KRAUSS, B. H. Effects of iron oncertain physiochemical properties and ash constituents of Ananascomosus (L.) Merr., grown in solution cultures supplied either withnitrate or ammonium salts as sources for nitrogen. Plant Physiol.18: 608-632. 1943.

13. , and YOUNG, H. Y. Influence of potassium on chloridetoxicity in Ananas comosuts (L.) Merr. Amer. Jour. Bot. 27: 21s.1941.

14. WIDDOWSON, ELSIE MAY. A method for the determination of smallquantities of mixed reducing sugars and its application to the esti-mation of the products of hydrolysis of starch by taka diastase.Biochem. Jour. 25: 863-879. 1931.

75



merr., · tissues were determined by the method of quisumbing and thomas (7) after treatment with...

Documents