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SOME FACTORS AFFECTIIW !lA.GNESIUH
UPTAKE BY CITRUS LEAVES
A thasi s pr e;scnte:~ in l)r.;rtial fulfilment of
the r oquircments for tho Deer oc of
Master of Horticultural Science at Massey University
Palmerston North New Zoalan0.
by
Shnli0re .. m Ku1:1ar Thapa
1971
A B S T ,h A C T
Pineap~le sweet oran~e seedlings and rooted leaf bud cuttings of Meyer lo~ons were used to investigate the effects of some cf the factors affecting mac:;nesium u1.:;take by leaves.
Magnesiun was cteterrnined by thiazol e yellow nethot of Drosdoff and Nearpass ( 1948) anc1 u:,take was usually m0asured 24 hours after spray treat• ent.
It was shown that the addi t ion of wetting a5ents to
nacnesiuD nitr2.te sprays si t;nificant1.y increased the u1)tako of mac;nesiun '.)y l eaves. The nonionic wetter (Terrie GN9) at the very l ow (0.01% a.i.) anr~ high (0.08 - 0.1% a.i.) concentratio.ns di e~ not affect nc1.c;nesiu,:1 uptake, whereas at interi11ediate con- centrations, ma5nesium uptake was increased.
Use of the humectant clycerine at 1 or 2 percent sienif- icantly increase,, the uptake of nagnesiu1a by leaves, compared with sprays to which no: slycerine was added, but had no bene- ficial effect o,ver sprays which contained a nonionic wetter (Te·rric GN9).
Magnosium uptake by leaves grown in 100% relative humidity for two weeks was greater than the uptake by leaves grown in averaGe relative humidity of 71%
Both morning ar.d tho evening sprays resulted in great er uptake of magnesium by :!_oavos, compared with afternoon sprays.
A significant increase in l eaf magnesium concentration occurred after 2 hours of a magnosiur:1 nitrate spray applica- tion. Loaf magnesium concentration rose steeply for 24 hours after spraying, thereafter remaining constant. (Becaus;) it was not possible to measure the degr ee of magnesium transport out of the l eaf, it i s not cl ear whether m&gnesium uptake, in fact, stopped after 24 hours).
Of the three magnesium salts used, magnesium nitrate and magnof;ium c hloridG sprays rGsll.ll t ed in groa tor magnesium upta.i..:e by l 0aves, compar ed with magnesium sulphate sprays.
Uptake varied wi th tho cone entra.tion of magnesium in. the l eaves. The lower the concentration of ~agnesium in the leaves, the l oss the uptake of magnesiur:;i by loaves, and tho hie;hcr the cone entration o.f magnesium, the higher tho uptake of magnesium.
Leaf nitrogen also affected uptake of magnesium by l eaves.
High l eaf nitrogen (2. 92~~ of dry weight) resulted in greater uptake of magnesium than the loVT l oaf nitrogen
(2 .08%
af dry wei ght). Tho avera6 e increase in the c.oncentrati.on of magnesium in the l oaves o,f low nitrogen plants v1as0. 09%
o,f dry weight, while in l eavos of high nitrosen plants tho increase was0.19%.
Thus the incroo.w in the % l eaf cone ontration · of i:lai:)1Gsium
in the high nitros2n ; lants waE dcubl o that of tho low nitrogen pl ants. This may to a direct effect of the low l oaf nitroccn or an inc1.irec t one .h1c to tho in•:uc cc'. low lce.f ;-1ac;nosim1 in those plants.
- - -- - -* - -- - --
A C K N O W L E D G E M E N T S
I gratefully ecknc~lotl~G tho continuous assistanc0 ant guidance of Hr D.A. Slaie of the Dopartucnt of Horticulture, Massey University in conplotinc this project. My sincere thanks also go to Professor J.A. Veale of the Department of Horticurlture for his nsGful sugiestions and ac1.vico.
This stutly was made possibl e by financial assistance from t~e Ne~ Zoal anJ Department of
External Affairs under the Colonbo Plan. I ac very [rateful having bacn given this opportunity.
1 •
2.
INTRODUCTION
.'f'ABLE OF CONTENTS CHAFER 1
CHAPTER 2
FOLIAR APPLICATION OF NUTRIENTS
· CHAPTER 3 LITERATURE REVIEW
3.1. Pathways of ponetrc..tion of nutrients, her:Jie.i.dos and other substances into the leaf.
3. 1. 1.
3. 1. 2.
3.1.3.
3. 1.5.
Entry through stomata Structure of tho cuticle 3.1.2.1.
3.1.2.2.
3.1.2.3.
St:r-ucturo wa.11
Structure Mechanisms
3.1.5.1.
3.1.5.2.
3.1.5.3.
Physical nature of tho pl:mt cuticle
Chemical nature of tho plant cuticle
Tho role of the cuticle anc1.. na.ture of the. col l
of the plasma-mem :Jr ane of foliar penetra.tion Mechanism.s of ponetra-
tio.n in tho cuticle Mech2..nism.s· o,f penetra-
tion in the cell wall Mechanisms of penetra-
tion in the plasma- membrane
1
3
7
7 7 8
8
12 15
16 21 22
22
26
26
3.2 .. Fae tors .3.f f cc tinr 11011otr.:-, ti •_,n an'.l 3.2. 1. Pl.s.nt factors
3.2.1.1.
l.il.0Vornont 30 30
of tho ~lant cuticle 30 3.2. 1.2. AGO C• f the l oaf
3 . 2.1. 3 .
Leaf surfaces and rJorpholocy3.2.1.4. Mineral status of tho lc:i.f
3.2.2 .. External factors
3 . 2 . 2.1.
3 . 2. 2. 2.
3 . 2. 2. 3 .
3.2.2.4.3 . 2. 2. 5.
3.2.2.6.
3 . 2 . 2.7.
The citrus leaf U12tak.e of ma.c;nesium anr_~, other crops 3.4. 1. Glasshouse
3.4.1.1.
3. 4 .1. 2 .
Licht
Temperature Humidity
pH of the s~r~y solu- tions
Surfactants Humectants
Solute characteristics
b;:t: 1-oaves of citrus
and luborator;:t: studios Tho effect of different magnesium s.:1.l ts on magnesium absorption The effect of differ- ant spreaders and hygroscopic aeonts on
ma.gnes ium abs ori)tion
32
32
33
34 34
35
37
39 41
43
44
49 49
49
51
ThG r~to of O~OGiULl
ahaorption
Tho effect of sprc.l.ying at different hours of the d~y
Tho effect of nitrogen lovol
The effect of macncsiun 53
55
57
level 60
Plant responses to fi 81.d concU t ions 62
3 . 4. 2 . 1.
3.4.2 . 2.
3 . 4 . 2 . 3 .
Responses to citrus Miscellaneous responses The effect of nitrogen level
Tho effect of magnesium lovel
M~rne.sium nobility studies Literature review Summary
62 66
69
7174
CHAPTER 4
MATERIALS AND KCTH0DS
4. 1 • 'rhe experi1:1ents
4,2. Con11Josition an~l ;,reraration of concentratecl nutrient stock solution for experiments
4 . 3 . .
Techniques usorl_ in crowinc pinea;;ple sweet oranee seedlings4 . 6 .
4 . 7.
Sowin5 of seeds Planting out
Fcojin3 the ~lents
0rowi n,:; ?_!__!'1_eyer l oaon l eaf bud. cuttine;s Exeerimontal ncthods
4.5,1.
4.5.2.
Spraying techniques Ex1Jerimental desi gn Leaf sampl es and analysis 4.6.1.
4. 6 . 2 . 4 . 6 . 3 .
4.6.4,Sampling techniques Cloaning-
Ashing
Techniques of leaf magnesium analysis
Statistics
76
76
77
78 78 78
79 7980 80
81
88 88
89 91
91 92
CHAPTER
5
5. 1. Ex~eriment I
Tho effect of different wetting a~ents on the uptako of m~~nosiuw by l eaves.
5.2. Ex~erirnont II
Tho effect of :iiffercmt concentrations of a noni onic wetter (Terrie GN9) on tho uptake of magnesium by leaves.
5. 3. Ex]'cffirirnnt III
93
93
96
Tho eff0ct of different concentrations of
cl ycorine on tho uptake of rna~nesius by l eaves. 101
5. 4.
Ex?erinont IVThe effect of hm-:1.idi ty on tho uptake o-f magncsiu• by l eaves.
5 . ~.
~xp~riment VThe effect of srraying at different times of the d~y on the uptake of magnosiun by l eaves.
5 . 6.
Exuerinent VI103
105
The rat e of uptake of ma[';nesium by l eaves. 107 5. 7. ~ _periment_~II
The effect of different 3aGnesium salts on tho uptake o-f mac;nosiun by leaves.
5 . 8 .
Experiment VIIIThe effect of l eaf magnesium l evel on the uptake of magnesium by leaves
110
112
6.
7.
5.9.
Expcrirucnt IXTho ofL:c t of l eaf ni troGon l.evel on the
CHAFER 6
DISCUSSION OF THE DATA
CONCLUSION APPENDICES BIBLIOGRAPHY
CHAPTER
7.
115
117
131
TABLE
LIST OF TABLES
Sto~atal pore si zes of citrus l oaves (Turrell, 1947).
2 Th8 effect of tlifforent raacnosium salts on na5nesium absorption
(Fi.sher anc Walker, 1955).
3 Th~ effect of three spreaders an magnesium atsorption from a 5 per cent Mgso
4.7H2o spray applic~tion (Fisher and Walker, 1955)
4 The effect of glycerine, carbowax and m2thyl cel losolve on cagnesium atsorption fro• a 5 per cent Msso
4.?H
2o spro.y applicati on (Fisher end Walker, (1955)
5 The rat o of e1acnosi.um al:sorpti.on over a 12 day period (Fi.sher and Walkeri 1955)
6 Tho effect of Mgso
4.?H2o solution applied at different hours 6urinB the day
(OlGnd and Opiand, 1956).
7 Moan concentration of elements(% dry weight) in l oaves (Ford, 196?).
8 Effects o-f mat;nesium treahi.ents on the
concentration of magnesiun in the l eaves of
PAGE
48
50
52
53
55
57
62
Valoncict orange (Embl eton anc1 Jones, 1959) 65
9 Magnesium concentration in grape leaves as affected :.)y spray and soi l application of Mgso
4.?H20 (Scott and Scott, 1951) 68
Ti1.:3LE
(ForE:hey, 195.9). 70
1 1 ~-~0 an con contra t ion of clo:-:ieot:__: (% dYIY Jo• •-,;,,1L ' . . J . · .',hD t) in l eovcs, stc1.TIE.i :--:nrJ root::. (Fora, 1966) . 7.3
t M ( ..,-,, ) ~r O 1 · t ·
cen . g ~u
3 2.b~
2
•
pray •pp 1ca 10n. 9~- 12a Tho effect of different ~ctting agents usca~t 80~ wettability of th~ loaf area.
13 The effect of rJifferent concontro.t iono of D
nonionic wettorr (Torrie GN9) on the upta}:o of i:nar;nosi um by l eaves from a 2.5 per cont
13a The visual nsscfJ;::iii1ent of the ,,ottine of tho upper surface of the citrus leaves by
To rric GN9.
14
The effect of different concentrations of97
99
gl ycerine on ths uptako of ma~nasium by l eaves from a
2 . 5
per centhlg(No
3 )
2
. 6E
2
0
spray application.15
The effect of humidity on the uptcko of mari:nosium by leaves from n2 . 5
per cent102
1 OL+
TABLE
1 6 The effect of s::raying at ,1iffcrent tiri1os of the day on the u11take 0f ::1a1:.,nesiw,1 by leaves frorn a 2.5 percent Mg(No
3) 2.6H
2o spray
PAGE
a~plication. 106
17 The rate of uptake of ~asnesiu• by l eaves from a 2.5 percent Mc,(~m
3) 2.6H
20 srray
a~plication. 108
18 The effect of different TiaGnesiug salts on the uptake of • aGnesium by l oavos.
19 Th(: effect of leaf ;:1aGnesiu::1 l ovel on the uptake of ua~nesiuc by leavos frora a 2.5 por- cent Mc(No
3) 2.6H
2o sprny application. 20 The effect of leaf nitroeen level on tho
uptake of nacnesium by leaves from a 2.5 per-
1 1 1
113
11 6
LIS'I' OF FIGURES AND PLA'I1ES ...
-~----
..FIGURE
rrjpothotical structure of tho functional
asject s nf the rlant cuticle (Foy et al; 1967) , 10 1 a A c1.i asrai7! showin:.c, the su~stances th2.t r1ny
compose tho cell wall (Miller,
1938) .
2 Tho level of P32 activity found in the ;otiol e fol lowinc, a 4-hour l}ericc' of trn.nslocation fron tho blac'l,) as a function of pH of tho an-'lie,~
solutisn (Sv.r-.:i_nson am1. \'/hitney,
1953 )
3 The rate of a~sorJt ion of nitrocen, ;hosfborus
4
and macnosiu• from s}rays applieC to tho l ower
sur fac '..: ,:: f McIntosh a~:_;_-·le leaves
(Fisher an~ Valker,
1955 ) ,
Standard wettins chart for citrus l oav0s
5
The standarf curve of wettability of tho upper surface of the citrus l eaves fer different vret tin~: at~onts .6 The effect 8f different concontruticns of a nonionic wetter (Torrie GN9) on ~ho uptake of uagnesiura by l eaves.
6a The effect of different concentrations of a nonionic wetter (Terrie GN9) on the wettinG 0£
the uprer surface of the citrus l e&ves. 7 The rate of uptake of macnesium by l eaves. 8 Tho effect of l oaf magnesium 1cvol on the
uptake of m,:1,.enesiu1.1 by l oaves. PLATE
Pinoappi o sweot orange seodlinG supflied with hich and low lGvel of nitrocen.
18
38
54
83
84
98
100
1 09
114
88
( fac:i.ng p.agQ)
APPENDIX
LIST OF APPENDICES
Comi)ositio:n cf concentrated. nutric,nt stock solution for exJerirnonts I, II, III, V, VI,
VII -?tlllt VIII.
2 Couposi tio,n of cone ontrated nutrient stock solution for experiment IX.
3 Quan ti tati ve r.iicro c.~eterminntion o,f ;nacnesium in plant tissue and soil extracts.
4 5
A rapid colorimetric method. Nitr'Jge:n analysis.
Analysis of vnriance of the eff0ct of diffor- ont '!lotting agents on the uptake of magnosiur.1
by leaves.
6
Analysis of variance of the effect of differ- ent wettinc agents used on the uptake ofmagnesium by l eaves, at
80%
wettability of tho l eaf area.7 Analysis of variance of tho effect of differ- ent concentrations of a n,.,nionic (Terrie GN9) on the uptake of magnesium by leaves.
7a Analysis of variance o·f the visual assessment of the wettins of the upper surface of the citrus loaves hy Terrie GN9.
8 Analysis of variance of the effect of differ- ent concentrations of vlycerino on the uptake
of magnesium by leaves.
PAGE
134 .
135
136 139
142
142
143
143
144
APPENDIX
9 Analysis of variance of tho effect of humid- i ty on tho uptake ,::,f m?.cnesium ty l oaves.
10 Analysis cf varianc0 of the effect 0f spray- ins at differunt times of the day.
11 Analysi s of varianc o of the r:1 te of uptake of
JQ[uosium by leaves.
12 Analysis 0f variance of th& effect of differ- ent mnEnesium. salts on the uptake of me.cnesium ty leaves.
13 Analysi s of variance of the effect of l eaf rnagnosiu• lovol on the uptake of magnesium l,y l0aves.
14
Analysis of variance of the effect of l oaf nitrogen Level on the uptclrn of ma6nosium cy leaves.PAGE
146
146
147
148
149
CHAPTER 1
1. INTRODUCTION
Nutrient sprays, these days, are becoming increasingly important to supplement the mineral requirements o:f the crops to increase crop production.··
Nutrient sprays may be important in two directions.
(i) Where soil application of fertilizers is not responsive or very slow.
(ii) To prevent the development of a deficiency symptom vary sonn before the trouble is expected or immediately it has app€ared.
1
But the responses of nutrient sprays are influenced by environmental factors (both physical and chemical) and plant
!actors. Magnesium absorption is not an exception to these factors. Leaves of same plant species do not sho,w responses to magnesium sal.t sprays, while o.thers do • . Soil application of magnesium salts on the other hand, has been slow. in action or has not been effective or partially effective. Foliage application of magnesium sal.ts appears to be superior to soil application in increasing the concentration of magnesium in the leaves and in reducing deficiency syptoms. But the respoilS'es are not consistent.
The present study, therefore, was undertaken to deter-
mine the degree to which a number of likely factors might
2
affect the magnesium absorption by citrus leaves. The
literature review, description of the methods and the discuss- ion of the results have been presented with the aim of provid- ing as much background information as possible in order to facilitate further detailed studies of magnesium absorption. For this reason, the literature review has been made more extensive than otherwise would have been required. The discussion of the results includes some hypotheses and spec- ulations which lack evidence to support them, but they may be of value for future work.
