Crowns (vegetative organs produced at the apical end of fruits)

23 Pages·2005·3.03 MB·English

GROWTH OF ANANAS COMOSUS (L.) MERR. AT DIFFERENT
LEVELS OF MINERAL NUTRITION UNDER GREENHOUSE AND
FIELD CONDITIONS. I. PLANT AND FRUIT WEIGHTS
AND ABSORPTION OF NITRATE AND POTASSIUM
AT DIFFERENT GROWTH INTERVALS'
0. P. SIDERIS AND H. Y. YOUNG
(WITH EIGHT FIGURES)
Received February 24, 1950
Introduction
Pineapple plants, fertilized under field conditions with ammonium sul-
phate, may absorb from the soil ammonium or nitrate or both simultane-
ously due to the oxidation and conversion of the former to the latter by
micro-biological activity. Following absorption by the roots, ammonium is
converted to amide, amino, or protein compounds, but nitrate is translo-
cated per se via the stem to the leaves, where in the chlorophyllous but not
in the non-chlorophyllous tissues it is assimilated by conversion to proteins
and other related compounds (12).
Available data (12) indicate that ammonium is absorbed by pineapple
roots at much greater rates than nitrate. However, because of the conver-
sion of NH4 to NOs in the soil within a few weeks after the time of applica-
tion under favorable conditions, the absorption of nitrogen by the roots as
nitrate may be greater than as ammonium, due to longer periods of con-
tact of the former with the roots.
The assimilation of nitrate in the chlorophyllous but not in the
non-chlorophyllous basal sections of the leaves makes possible chemical
determinations of the nitrate concentrations in the latter sections which
may be made the basis, as to amounts and time, for future applications of
nitrogenous fertilizers.
The results reported below furnish information, at different growth
intervals, on the weights of the plants, leaves, stems, peduncle and fruit,
and concentrations of nitrate in the same organs of cultures grown in nu-
trient solutions in the greenhouse and in the soil in the field, with different
amounts of nitrogen, potassium and calcium.
Methods
CULTURAL
Crowns (vegetative organs produced at the apical end of fruits) from
a single clone of uniform weight, length of leaves and thickness of stem,
were selected and suspended, for approximately four weeks, through a
1Published with the approval of the Director as Technical Paper No. 192 of the
Pineapple Research Institute, University of Hawaii.
594
595
SIDERIS AND YOUNG: ANANAS COMOSUS (L.)
3-inch hole in a board 12"x 12"x1" over a 4-gallon porcelain crock filled
with tap water for root initiation and development. At the end of this
period, the plants with uniformly developed root systems were selected and
grown subsequently in nutrient solutions of different concentrations of
nitrate, potassium and calcium, while all other nutrient elements were kept
at relatively constant levels, as in table I.
TABLE I
MOLAL CONCENTRATION OF DIFFERENT SALTS IN THE VARIOUS CULTURES
CULTURES
SALTS
A B CORH D E F G I J
Ca(NO.)2 ... *0005 .001 .002 .004 .005 .0005 .001 .002 .002
CaSO42H,O ...0016 .0011
.............. .
KO,S . ....001 .001 ..001 .001 .001 .00025 .0005 ...............
KNOS .. . .. .. .............. .. ......... ............. .004 .006
MgSO4 .001 .001 .001 .001 .001 .001 .001 .001 .001
....
NaH2PO4 ...... .00025 .00025 .00025 .00025 .00025 .00025 .00025 .00025 .00025
Fe S04 .0005 .00005 .00005 .00005 .00005 .00005 .00005 .00005 .00005 .00005
ZnSO4.00001 .00001 .00001 .00001 .00001 .00001 .00001 .00001 .00001 .00001
Na2B407 .00001 .00001 .00001 .00001 .00001 .00001 .00001 .00001 .00001 .00001
Concentrations in milligrams per liter of solution of NO3 and Ca for
cultures A, B, C, D, and E were, respectively, 14 and 20, 28 and 40, 56
and 80, 112 and 160, and 140 and 195, with K constant at 78 y. Similar
concentrations of NO3 and K for cultures F, G, H, I, and J were respec-
tively 14 and 19, 28 and 39, 56 and 78, 112 and 156, and 140 and 234, with
Ca constant at 80 y.
All sets, each comprising 16 plants with one plant per crock, were con-
stantly aerated and the nutrient solutions changed at 3-week intervals.
At the time of changing the nutrient solutions, aliquot samples were taken
of the old solutions before discarding and of the new ones before trans-
ferring the plants thereto, and measurements were made for nitrate, potas-
sium and calcium. Also, volume measurements of these solutions at the
beginning and end of intervals of change were made and adjusted to the
original volume for correction of the residual concentrations of NO3, K
and Ca.
All plants were initially suspended in their respective nutrient solu-
tions on June 21, 1942, and analyses for NO3, K and Ca were made on
July 14, 1942, at the end of the first interval of absorption of nutrient ele-
ments. Similar analyses were repeated at 6-week intervals until July
1943.
Plants grown in soil, reported in figure 6, were treated with liquid fer-
tilizers, i.e., the fertilizer salts dissolved in water, applied to the leaves in-
stead of dry fertilizer salts to the soil. Approximately 100 ml. of 0.05 M.
KNOI and 0.05 M. Ca(NO3)2 per plant was applied to the center, or re-
gion of new leaves, different amounts of fertilizers in various treatments
adjusted by different frequencies of application.
596 PLANT PHYSIOLOGY
ANALYTICAL
-In addition to the analysis of the nutrient solutions for NO3, K and Ca,
plant tissues were also analyzed for the same elements.
The plants were sectioned according to techniques previously reported
(11). The leaves and stems were segregated into groups of different
chronological and physiological age, as old, mature, active, and young.
The individual leaves of each group were cut at variable lengths, segregat-
ing chlorophyllous from non-chlorophyllous areas and terminal from in-
termediate or basal sections. The basal sections of all pineapple leaves are
free from chorophyll, the length of such sections decreasing with advanc-
ing age. The tissues of the basal sections, in o1d and mature leaves, are
tough and highly fibrous. Similar tissues in active and young leaves, of
meristematic status, are tender and brittle. All other secttionhs of'
leaves contain chlorophyll, the terminal sections more than others (11).
For the analyses of plant tissues conducted at the intervals designated
in the various figures and tables, two plants were taken from each set, sec-
tioned, and the tissues were either ashed or their sap extracted according.
to the requirements for the measurements of various substances. Sap ex-
tractions were made after mixing 20 grams of the tissues with 80 ml. of
water, macerating in a Waring Blenidor, and extracting the liquid frac-
tion by straining through canton flannel with the application of manual
pressure. For sugar determinations, aliquots of these extracts were
treated with lead acetate and subsequently deleaded with Na2H P04.
Similar aliquots, for the determination of nitrates, were treated with
CuS04, and the excess copper removed with Ca(OH)2. For determina-
tions of potassium, calcium or magnesium, the tissues were ashed, the ash
dissolved in 10 ml. of 0.5 N. HCl and then diluted to 100 ml. For total
nitrogen, the tissues were processed according to the Kjeldahl method,
with selenium oxychloride as catalyst.
Nitrates were determined colorimetrically with phenol disulfonic acid
(1), potassium with nitroso-R-salt (14), and calcium titrimetrically with
K MnO4 after precipitation with ammonium oxalate (1).
Results
WEIGHTS OF PLANTS AND COMPONENT ORGANS
Determination of the weights of greenhouse plants were begun 80 days
after planting, and repeated at approximately 6-week intervals, i.e., Oc-
tober 21, December 1, 1942, January 12, February 22, April 6, May 18,
July 1 and August 24, 1943.
The results, in figure 1, show that plant and stem weights increased
more than root weights with greater amounts of nitrate in association with
equiionic concentrations of calcium in cultures A to E, or of potassium in
F to J. Under similar conditions, root weights did not increase in propor-
tion to leaf or stem weights.
SIDERIS AND YOUNG: ANANAS COMOSUS (L.) 597
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C U L T U R E S
FIG. 1. Plant (P), stem (S) and root (R) weights for cultures A, B, 0, D, E, F,
G, H, I and J, in September (9), October (10), December (12), 1942, January (1),
February (2), April (4), May (5) and July (7), 1943.
Root weights, as per cent. of total plant weights, in figure 2, showed
ascending gradients at successive growth intervals from September to
April and May in the low-N cultures A, F, G and B, C, or H, respectively,
but descending gradients thereafter. In the high-N cultures D and E,
9
G, , 9 10
February(2), A l 4), May(5)andJuly(7),9 74 4 1
6. 7
4
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ek
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FIG. 2. Root weights as per cent. of plant weights for cultures A, B, 0, D, El F.,
0, H, I and J, in September (9), October (10), December (12), 1942, January (1),
February (2), April (4), May (5) and July (7), 1943.
598 PLANT PHYSIOLOGY
except for minor deviations, the gradients were of a descending order from
September 1942 to August 1943. In cultures I and J, failing to undergo
floral differentiation, and with equally high-N as D and E, descending
gradients developed from September 1942 to January and February 1943
for I and J, respectively, changing thence to ascending gradients until
August 1943.
The results, presumably associated with the availability of carbohy-
drates in the roots at different growth stages for cultures of different levels
of nitrogen, might suggest that root growth was influenced by the amounts
of translocationable carbohydrates from the leaves to the roots. Such
carbohydrates, according to information to be presented in a future publi-
cation, were more plentiful in plants with small than great supplies of
nitrates, presumably resulting from differences in the rate of utilization
accompanying the assimilation of NO3. The significance of translocation
of carbohydrates at different rates to roots from leaves is reflected on the
growth of the former, in the histograms for May, June and August, 1943,
FIG. 3. Photographs of representative plants of cultures E (5) and J (10) taken
in May 1943.
in figure 2. These periods, corresponding with stages of rapid fruit
growth, show that root growth in all cultures, except in I and J, which
failed to produce fruits, did not increase due to the diversion of the main
stream of sugars to fruits instead of to roots. In cultures I and J the
inflection of the curve of the histograms, beginning with January and Feb-
ruary, the season for floral differentiation, and ending in July, the season
for fruit harvest, in figure 2, was directed upward instead of downward
due to the translocation of sugars to roots instead of fruits, the latter fail-
ing to develop.
Figure 3, depicting representative plants of cultures E and J, shows
the latter failing to produce fruits, but leaves with brittle sclerotic tissues.
The failure of cultures I and J to produce fruits but undergo abnormal
morphological leaf changes may be attributed to high potassium in-com-
bination with high nitrogen, rather than to high nitrogen alone, because
similar concentrations of nitrogen in combination with calcium in cultures
D ad E did not interfere either with the periodicity of floral differentia-
tions or cause abnormal morphological changes in the leaves or stem. It is
zL o ~~Ii.
599
SIDERIS AND YOUNG: ANANAS COMOSUS (L.)
possible to assume that high concentrations of potassium, antagonizing the
absorption of calcium, might have reduced the latter to deficiency levels in
the tissues or interfered with its physiological functioning, with the re-
sultant histological changes mentioned above.
In addition to the morphological changes in the leaves of cultures I
and J, the stem increased in length, diameter and weight. Such changes,
indicated by the ratios of stem to total plant weights for cultures with
equal amounts of nitrogen but with different amounts of potassium in the
nutrient solution, were, respectively, 0.088 and 0.066 for A and F; 0.095
and 0.077 for B and G; 0.104 for C and H; 0.109 and 0.174 for D and I,
and 0.107 and 0.160 for E and J. Therefore, cultures A, B, I and J, with
greater amounts of potassium, had higher ratios of stem to total plant
weights than cultures F, G, D, and E, with less potassium.
The data suggest that different concentrations of potassium had pre-
sumably modified variously the carbohydrate-nitrogen metabolism, allow-
ing in the cultures I and J of high potassium-high nitrogen-intermediate-
calcium vegetativeness, and in cultures A, B, C, D, and E of low to high
calcium-high nitrogen-intermediate potassium, floral differentiation.
PLANT GROWTH AND WATER REQUIREMENTS
The curves in figure 4, depicting plant growth as measured by the
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FIG. 4. Weights (grams) of fresh tissue produced per day and of water absorbed
for the same period at different growth intervals for culture C, obtained as the quotient
of the cumulative plant or water weights by cumulative time. 4-A. Water (ml.) re-
quired per gram of fresh tissue for the various intervals. 4-B. Water absorption by
roots of different chronological and physiological ages.
600 PLANT PHYSIOLOGY
weight of tissues produced per day, and water requirements by that uti-
lized per day for different growth intervals from the time of planting to
the floral differentiation period, were calculated by dividing plant and
water weights by the cumulative time in days. The quotients resulting
therefrom, indicative of the weight of the plant tissues produced or of the
water absorbed per day, showed progressive increments with time. Re-
sults obtained previously (10) suggested that the growth curve of pine-
apple plants conforms closely to that of autocatalytic reactions.These
curves, in figure 4, typical of cultures C or H, indicate that between the
fifth and 52nd week after planting, the recorded mean fresh weight per
plant was approximately 4287 grams and the volume of water absorbed
was 60864 grams; the latter equivalent to 14.2 grams per gram of fresh
tissue. Of the 14.2 grams of water, 93%, i.e., 60864-4287÷ 60864x100,
was transpired, the remainder, 7%, becoming constituent of the plant
tissues.
The values reported for plant weights and volumes of water are ap-
proximations, due to the death of senile leaves and some water losses from
the containers through evaporation, although proper care reduced the
latter to a minimum.
Inpineapple plants, where all growth except root growth emanates from
meristematic regions of the apicaltissues of the stem and ofthe basaltissues
of the leaves, the increased plant growth rates with the passing of time
result from the ever expanding areas of meristematic tissues in the organs
mentioned. Maximal growth rates attained on the 40th week after planting
culminated in a plateau lasting approximately 16 weeks, which preceded
floral differentiation and completion of the ontogenic cycle. With the
initiation offlowering, vegetativeness in the mother plant completely ceased,
and all subsequent growth was characteristic of the developing fruit, shoots
or ground suckers and slips (10, 11).
The data infigure 4-A, depicting amounts of water required per gram oI
fresh tissue for each successive growth interval, were calculated on the basis
of the water absorbed and the fresh tissues produced per interval.
The data in figure 4-A are strictly concerned with the weights of the
tissues and of water utilized during each interval exclusive of the cumu-
lative weights of tissues, water and length of time of preceding intervals.
They differ from those in figure 4 in that the latter are based on the
cumulative weights of tissues, water and length of time of all preceding
intervals. Thusthe results infigure 4-A show that the rate of water utiliza-
tion per gram of new tissue was much greater in the earlier (14th to 31st
week) than in the later stages of growth and that the factors contributing
thereto, although not carefully ascertained, were presumably higher rates
of transpiration, due to greater tissue succulence, lower suberization of
epidermal tissues and less shading from superimposed leaves-conditions
associated more often with young and small plants in the early growth
stages than with- mature and large plants in the late stages.
SIDERIS AND YOUNG: ANANXAS COMOSUS (L.) 601
Figure 4-B, depicting water absorption by individual roots of different
chronological and physiological ages, obtained by a method reported previ-
ously (7), shows that young roots absorbed more water from nutrient
solutions than those of more advanced chronological and physiological
status. Young roots exposed a much greater surface area of meristematic,
non-lignified, white tissues at the tip than old roots; similar tissue areas in
much older roots were considerably smaller. Water absorption by dead
roots, although extremely small, resulted presumably from inbibitional
forces.
The results in figure 4-B, revealing absorption of great volumes of water
by young roots, suggest that under conditions of ample water and oxygen
supplies in the soil and without interference from pathogenic organisms,
a small number of young roots might suffice for the partial procurement
of water and mineral nutrients to the plant. Actually, under field condi-
tions, plants having lost all the subterranean roots from pathological causes
in wet areas, are often found to continue growth by the development of
white, functional tips in the leaf axillary roots above the level of the soil,
which absorb water and mineral nutrients applied in solution as sprays.
This condition develops more often in plants with mature stem tissues, more
characteristic of the post-fruiting and fruiting than pre-fruiting stages.
ABSORPTION OF NITRATE AND POTASSIUM
Cumulative absorption curves ofNO3 and K for the various solution cul-
tures, in figure 5-A, showed, for the entire life of the experiment, approxi-
mately twice as great absorption of K, in grams per plant, as of NO3. The
amounts of NO3 and K supplied to the nutrient solutions correlated posi-
tively with those absorbed by the roots with coefficients of correlation:
r=0.95 and r= 0.92 for the NO and K, respectively, both statistically sig-
nificant at P =.01.
Also of interest in the quadrangular enclosure of figure 5-A are the
equivalent ratios of absorbed K to NO3, which were, for the different cul-
tures, as follows: A, 2.63; B, 1.43; C, or H, 0.92; D, 0.81; E, 0.79; F, 0.73;
G. 0.84; I, 1.13 and J, 1.17.
The results show that in cultures A and B, with low Ca and NO3 but
with intermediate K, the ratios of absorbed K to NO3 were higher than 1.0.
Likewise, in cultures I and J, with high K and NO3 but with intermediate
Ca, ratios ofK to NO3 greater than 1.0 were obtained. In all other cultures
similar ratios were lower than 1.0. The mean ratio of K to NO3 for the
combined cultures C or H, D, E, F, and G was 0.82 + 0.10, suggesting
that cations other than K, presumably Ca and Mg, were absorbed, approxi-
mately to an extent of 18 ±- 10% of the cations required to equalize the
negative electrostatic charges of NO3 in excess of K, assuming that cations
and anions were absorbed at equivalent amounts.
The data, for the cultures A, B, I and J, with K to NO3 ratios greater
6;02-0PLAN-T PHI-YSIOLOGY
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FIG. 5. A. Cumulative absorption curves ofnitrate andpotassium for cultures A,B,
C, D, E, F, G, H, I and J. Above, in quadrangle, equiionic ratios of absorbed K to
NO3 for the same cultures. B. Weights of supplied and absorbed K and NO. per plant
SIDERIS AND YOUNG: ANANAS COMOSUS (L.) 603
than 1.0, suggest that anions other than NO3 were absorbed to equalize the
positive electrostatic charges of the cations absorbed in excess of NO3.
In figure 5-B, the histograms depicting total amounts of NO3 and K,
supplied to and absorbed by the plants, reveal that potassium absorption as
per cent of total supply for the various cultures was as follows: A, 87; B,
89; C, or H, 89; D, 87; E, 85; F, 87; G-, 90; I, 80; J, 42. In the same
figure, the columns for nitrate indicate that absorption of NO3 as per cent
oftotalsupply for thevarious cultures was as follows: A, 99; B, 89; C or H,
67; D, 37; E, 21; F, 94; G, 76; I, 44 and J, 26. The results show that
potassium absorption was 87 ± 3%o of the total supply in all cultures except
J. Similar data for nitrate show that in cultures A, B, F, G, with low
nitrate content, per cent, absorption ranged from 76 to 99 of total supply.
In cultures D, E, I, and J, with high nitrate content, similar values ranged
from 21 to 44% of total supply.
The results show that pineapple roots absorbed more K than NO3, sug-
gesting differential rates for cations and anions. It is possible that the
negative electrostatic charges of the root tissues might be responsible for
greater attraction of K than of NO3.
In figure 5-C, results from field-grown plants with different levels of
potassium but with equal nitrogen show that high potassium applications
increased plant weights progressively. Also, the ratios of stem to plant
weights increased with greater amounts of added potassium as K30 per
acre, as follows: 0.1035, at zero pounds, 0.1215, at 200 pounds; 0.1230 at
400 pounds; 0.1400 at 800 pounds; 0.1450 at 1600 pounds and 0.1700 at
3200 pounds. Stem and plant weights correlated with a coefficient r= 0.96,
statistically significant at P = 01. Likewise, fruit and plant weights corre-
lated with a coefficient r= 0.98, statistically significant at P=.01.
According to the data in figure 5-C, total slip weights per plant, i.e., the
product of mean weight multiplied by the number of slips, increased in the
same order as the amounts of potassium supplied to the plants.
The data in figure 5-B, depicting K and NO3 levels in the basal meri-
stematic tissues of the active D leaves (9) of the plants reported in figure
5-C, for the growth intervals of August (A), October (0), November (N)
and February (F), showed descending gradients in the K concentrations
for the treatments of 0, 200, 400 and 800, but ascending gradients for those
of 1600 and 3200 pounds of K,O per acre.
The K content per plant in grams calculated from the product of the
plant weights, in figure 5-C, by the potassium content in the tissues of the
plants harvested in February (F), in figure 5-D, was for the various treat-
ments of K20 per acre, as follows: 8.8 at 0 pounds; 12.0 at 200; 12.9 at400;
15.6 at 800; 24.5 at 1600 and 31.2 at 3200.
from June 1942 to July 1943 for cultures A-J. C. Weights of plants, fruits, stems and
slips of cultures grown in the field with 500 lbs. of N and K20O,0 200, 400, 800, 1600
and 3200 lbs. per acre. D. Nitrate and K content of the tissues of the cultures, in
5-C, in August (A), October (0), November (N) and February (F).