Available via license: CC BY-NC-ND 4.0
Content may be subject to copyright.
/. Amer. Soc. Hort. Sci. 103(3):306 -3 08 . 1978.
Determination of Irrigation and Fertilizer Practices for
Jade Plant [Crassula argentea (L.) ThunbJ1
J. Spooner, L. Daley, G. Ware, and M. Vines
D ep a r tm e n t o f Hor tic u ltu r e, U n iv ers ity o f Georgia, Ath e n s , G A 30 60 2
Additional index words, plant nutrition, succulent plants
Abstract. Daily watering gave increased growth of jade plants over weekly watering if fertilizer was applied. The
optimum fertilizer rate with either weekly or daily watering was calculated as 100 ml of 250 ppm N of a 20N:8.6
P:16.6K fertilizer per 10 cm pot.
Although succulent plants adapt well to drought and limited
water, many growers contend the lack o f care is the secret of
successful succulent culture believing frequent watering and
fertilization are harmful. Accepted practice is to allow the soil
in which these plants grow to dry out between waterings,
particularly since succulents do not show visible signs o f wilting
as do non-succulents.
The frequency of watering is dependent on the physical
characteristics of the growth media. Neither a review of the
literature nor discussions with growers uncovered a “ recom
mended” standard soil mix for succulents, although “well-
drained soil” seemed to be the common denom inator (2 4,
9-12). Since many succulents and cacti are indigenous to the
sandy soils of the desert, well-drained soil has a logical basis.
It is generally accepted that plants under water stress grow
less than plants supplied with adequate water. If this is correct,
commercial growers should be able to produce larger succulents
and in a shorter time by eliminating water stress. This study
was undertaken to investigate the effect of 2 different watering
regimes on plant growth of jade, a popular ornamental succulent.
Since possible nutrient loss could occur through leaching as
a result o f the watering schedule, 5 nutrie nt levels were in
cluded in the study.
Materials and Methods
Plant material and growth conditions. Terminal cuttings
with 2 to 4 leaves were taken from stock jade plants and rooted
in moist sand and potted in 10 cm plastic pots filled with a
standard potting media (Metro Mix 200, W.R. Grace Co.).
At the time o f potting the upper pair of mature leaves was
notched in order to identify all subsequent growth. Plants
were placed in a fiberglass greenhouse on August 23 with temp
ranging from 24° - 30°C (day) and 10° - 21° (night).
Experimental design. The 2 x 5 factorial experiment con
sisted of 10 treatment combination of 2 watering regimes and
5 fertilizer rates with 10 plants per treatment. Treatments
were replicated 4 times and randomized within the greenhouse.
Water was applied at the rate of 100 to 150 ml per pot at
either daily or weekly intervals. The time (0700 hr) and amount
of water applied daily was controlled by a 120 v solenoid value.
Weekly water was applied by hand at the same rate. Five fertil
izer treatments made from distilled water or Peters’ nutrient
20:20 :20 (20 N :8.6 P: 16.6K) containing 0, 50, 100, 200 or 400
ppm N were applied weekly in 100 ml aliquots to designated
pots.
After 6 months when some plants had reached a size that
their top wt caused the pots to overturn, the plants were har
vested. All yield data and samples for assay were taken on
growth occurring above the previously notched leaves.
Protein and chlorophyll. Random samples o f leaves were
taken on Feb. 19 and ground in a m ortar in 0.1 m Tris-phosphate
buffer pH 7.5 (4:1, vol buffer:fresh wt). Protein was assayed
1 Received for publication May 11, 1977.
by the Bradford technique (5) and chlorophyll by the Arnon
method (1).
Titratable acid. Leaf samples were taken at 0600 hr and at
1730 hr when acidity differences were at their greatest (8).
Tissue (10 to 20g fresh w t) was weighed and immersed in
boiling water to kill enzyme activity and to disrupt cell in
tegrity. The tissue was ground in a mortar, transferred along
with all wash-water to a container and steeped in boiling water
for 20 min. Titration to pH 8.5 was with 0.095 n NaOH, and
the results expressed in net titratable acid (difference in titrat
able acid in meq/lOOg fresh wt between samples taken at
0600 hr and samples taken at 1730 hr).
Results and Discussion
The jade plants watered daily grew well and no plants were
lost, contrary to what might be expected based on current
growing recommendations. Jade plants growing in the same
greenhouse under the standard “water and dry-out” practice
did not die but grew very little (data not included).
The relationship among fertilizer rates and water regimes
on fresh wt production of tops is shown in Fig. 1. Daily water
ing produced significantly larger plants (p < 5%) at the higher
fertilizer rates (100, 200, and 400 ppm) than weekly watering.
When no fertilizer was applied, the daily watering probably
leached nutrients out of the soil as significantly smaller plants
were produced. Best plant growth in these experiments was
produced with daily watering at a fertilizer rate calculated to
be 232 ppm N.
The number of leaves per plant was not affected by fertilizer
rate in the weekly treatment but daily water at the 200 ppm
fertilizer rate produced significantly more leaves (Fig. 2) with
the optimum fertilizer rate calculated to be 248 ppm N.
Fig. 1. Fresh wt (g/plant) of jade plants grown 6 months at specified
fertilizer and water regimes. Significance (*) or non-significance
(ns) at 5% level of probability between water regimes at a given rate
of fertilizer application.
306 J. Amer. Soc. Hort. Sci. 103 (3):306 -308. 1978.
6 months at specified fertilizer and water regimes. Significance (*)
Fig. 2. Number of leaves per jade plant grown 6 month s at specified or non-significance (ns) at 5% level of probability between water
fertilizer and water regimes. Significance (*) or non-significance regimes at a given rate of fertilizer application.
(ns) at 5% level of probability between water regimes at a given rate
of fertilizer application.
The growth response measured as the average wt per leaf
versus fertilizer treatm ent for weekly and daily watering sched
ules is given in Fig. 3. A test of homogenity reveals tha t linear
and quadratic effects of fertilizer are significantly different
at the 1% level with optimum fertilizer rate being 200 ppm N.
The response curves between chlorophyll and protein con
ten t and fertilizer are presented in Fig. 4 and 5, respectively.
Content of chlorophyll and protein response to fertilizer rate
when plants are watered weekly gives highly significant (p < 1%)
linear relationships. When plants were watered daily, only
chlorophyll content had a significant (p < 5%) linear response
to fertilizer rate.
The diurnal fluctuation of titratable acidity in Crassulacean
acid metabolism plants is a measure o f the rate of metabolic
activity (8). This difference between high acid in the morning
and low acid in the late afternoon was greatest at the fertilizer
rate of 100 ppm in both watering treatm ents (Fig 6).
Growing jade plants can be improved by changing the gener
ally accepted commercial practice of low fertility and limiting
water, to include weekly applications of fertilizer and adequate
watering. The exact am ount o f fertilizer and the time and
amount o f water to apply for most rapid growth will depend
on the soil type or growth media and pot size used in commer
cial practice. Daily watering in an amount sufficient to com
pletely wet the entire growth media is recommended. Fertilizer
at the rate of 100 ml of 250 ppm N from Peters’ 20:20 :20
Fig. 3. Weight of jade leaves grown 6 months at specified fertilizer and
water regimes.
Fig. 5. Protein content on a fresh wt basis of jade plants grown for
6 months at specified fertilizer and water regimes. Significance (*)
or non-significance (ns) at 5% level of probability between water
regimes at a given rate of fertilizer application.
Fig. 6. Difference in diurnal titratable acid (meq/100 g fresh wt) between
high acid at dawn and low acid at late afternoon among 5 fertilizer
treatm ents and 2 irrigation schedules.
J. Amer. Soc. Hort. Sci. 103 (3):306 -308 . 1978. 307
fertilizer per 10 cm pot per week, is suggested. Commercial
growers benefit by daily watering and fertilizer input to maxi
mize plant size and plant quality per unit of greenhouse space.
The fertilizer rate of 400 ppm N caused salt burn of the stem
at the soil surface. However, caution is needed if one is to
extend these results in areas where phytopathological factors
are not under control, and for species not studied here. It is
also suggested that watering be limited to once a week for a 2
week period prior to sale to increase the plant’s disease resistance.
Literature Cited
1. Arnon, D. 1949. Copper enzymes in isolated chloroplasts. Poly
phenol oxidase in Beta vulgaris. Plant Physiol. 29:1-15.
2. Bailey, L. and E. Bailey. 1941. Hortus second: a concise dictionary
of gardening and general horticulture. MacMillan, New York, p. 713-
715.
3. Baker, J. 1973. Make friends with your house plants. Simon &
Schuster, New York.
4. Boarder, A. 1972. Cultural notes. Cactus & Succ. J. Great Britain
34( 1):5, 6.
5. Bradford, M. 1976. A rapid and sensitive method for the quanti
tation of microgram quantities of protein utilizing the principle of
protein-dye binding. Anal Biochem. 72:248-254.
6. Chidamian, C. 1958. The book of cacti and other succulents. Ameri
can Garden Guild, Doubleday, Garden City, N. Y., p. 68-72, 139-
148,196-205.
7. Crater, D. 1975. Ornamental timely topics. Univ. of Georgia Coop.
Ext. Serv., Athens, Ga.
8. Crews, C. S. Williams, M. Vines, and C. Black. 1975. Changes in the
metabolism and physiology of Crassulacean acid metabolism plants
grown in controlled environments. In Burris and Black (eds.) p. 235-
250. CO2 metabolism and plant prod uctivity. Univ. Press, Baltimore,
Md.
9. Crockett, J. 1972. Foliage house plants. Time Inc., New York,
p. 72-79, 122,293.
10. Doney, V. 1976. Doney do’s and don’ts. Cactus & Succ. J. (U.S.)
48:25-26.
11. Fitch, C. 1972. The complete book of house plants. Hawthorne
Books, New York, p. 33-39, 76, 247-248.
12. Rainbow, A. 1974. The times they are a changing. Cactus & Succ. J.
Great Britain 36(1): 10-11.
J. Amer. Soc. Hort. Sci. 103(3):3 08 -3 10. 1978.
Respiration and Ethylene Production in Mammee Apple
(Mammea americana L.)1
Ernest K. Akamine and Theodore Goo
D ep a r tm e n t o f B o t a n y, Un ive rsit y o f Hawa ii, H o n o lu lu, H I 9 6 8 2 2
A ddi tion al in dex words, bioa ss ay , clim acte ric
Abstra ct. Gas chromatography and bioassays were used to id entify ethylene (C2H4) in fruit emanations o f
mammee apple {M am me a america na L.). C2H4 production probably triggered the respiratory rise in preclimacteric
fruit and its relationship to respiration was typical of that for a climacteric fruit. C2H4 production was however,
independent o f respiration in immature and postclimacteric fruits. C2H4 production increased to a peak and
then declined with deterioration of fruit in spite of nearly constant rates of respiration in immature fruit and
declining rates in postclimacteric fruit. Peak production o f C2H4, 4 08 pi per kg per hr, from preclimacteric
fruit is probably the highest reported among fruits.
An unusually high production of what appeared to be C2H4
was discovered in the emanations of mammee apple in storage
in the course of determining C2H4 p roduction in various species
of fruits. This paper reports the identification of the gas and its
relationship to respiration.
Materials and Methods
Fruits of mammee apple (also known as mamey, apricot o f
Santo Domingo, etc.) were obtained from a single tree on the
grounds of Poamoho Farm, Hawaii Agricultural Experiment
Station.
Immature (about 85% developed), preclimacteric, mature
and postclimacteric (just past ripe stage), fruit were individu
ally sealed in gas-tight 3,250 ml glass containers for 1 hr at
27.5°C for C2H4 identification. One ml samples of the atmos
phere surrounding the fruit were withdrawn with gas-tight
syringe for gas chromatography analyses with a hydrogen flame
ionization unit (Aerograph Hy-Fi 600-D) and alumina column.
Emanations of the fruit were also bubbled into Hg(C 103)2
solution (0.25 m red mercuric oxide in a 2.0 m perchloric acid)
for 1 to 2 hr. The trapped gas after being liberated with 4.0
N LiCl (1 1) was similarly analyzed for C2H4. The gas released
was also scrubbed w ith brominated (23%) activated charcoal
1 Received for publication October 4, 1977. Journal Series No. 2192
of the Hawaii Agricultural Experiment Station.
(4) and crystals of KMn04 (7, 9), materials known to be C2H4
inactivators, and again tested for C2H4. Bioassays were also
utilized to verify the presence of C2H4 in the fruit emanations.
Blossoms of vanda orchid {Vanda Miss Agnes Joaquim) and
carnations {Dianthus caryophyllus L.); young seedlings of
soybean [Glycine max (L.) Merr.] and papaya {Carica papaya
L.); excised terminal shoots of weed species {Amaranthus
spinosus L., Portulaca oleracea L., Euphorbia hirta L. and
Bidens pilosa L.); and green fruit of tangerine {Citrus reticulata
Blanco) were exposed to 50 ml per min streams of air passing
through containers with mammee apples for 1 to 3 days.
Imm ature, preclimacteric, and postclimacteric fruits were
tested within 2 h r after harvest. Four or more fruit o f each
stage of development were used for studies on the relationship
between C2H4 production and respiration. Each fruit was
weighed before sealing in a gas-tight 3,250 ml glass container
for CO2 respiration and C2H4 determinations at 27.5°C.
Separate 1-ml samples of the atmosphere surrounding each
fruit were withdrawn after 1 hr with a gas-tight syringe for
gas chromatographic analyses of CO2 and C2H4. A thermal
conductivity detector unit (Varian Aerograph 90-F) with a
silica gel column was used for CO2 analysis and the hydrogen
flame unit previously described was used for C2H4 determina
tion. Sampling was performed at the time the experiments were
begun and daily thereafter until the fruit deteriorated, i.e.
showed physiological breakdown without decay. Fruit were
aerated between samplings with a continuous flow of air bubbled
308 J. Amer. Soc. Hort. Sci. 103(3):3 08—310. 1978.