Influence Of Harvest Method And Schedule On Yield And Spear Size Of Green Asparagus In Indonesia.

Influence of Harvest Method and Schedule on Yield and Spear Size of
Green Asparagus in Indonesia.
Tino Mutiarawati Onggo
Faculty of Agriculture
University of Padjadjaran
Jl. Raya Bandung-Sumedang km 21
Jatinangor, Indonesia.
Keywords: Asparagus officinalis, mother-stalk method, alternate harvest.
Abstract
In tropical climates such as Indonesia, asparagus growth does not have any
dormant period. The high temperature throughout the year maintains high rates of
plant growth and consequently reduced long term plant productivity. The objective
of this experiment was to find the best combination of harvest method and schedule
to maximize spear yield and size of green asparagus during a 20 week harvest
period in the rainy season. The harvest methods tested were : a0 (without mother
stalk (MS)), a1 (with one MS) and a2 (with two MS). The harvest schedules were : p1
(4H – 8R – 8H), i.e. 4 weeks harvesting, 8 weeks rest and 8 weeks harvesting, p2 (6H
– 8R – 6H) and p3 (8H – 8R – 4H). The best harvest schedule depended on the
harvest method. Harvesting without MS increased the number of spears, but spear
size decreased rapidly, so this method produced a lower percentage of marketable
yield. Harvesting with one MS slowed down spear size decrease, so that the

average spear size produced was larger than in harvesting without MS. Combining
this method with the p2 and p3 harvest schedules
produced significantly better
spear size. Harvesting with 2 MS also produced better spear size but fewer spears
and lower yield when combined with harvest schedule p1.
INTRODUCTION
Harvesting of asparagus in temperate zones occurs in spring and is carried out by
cutting off all new spears. During the following summer and autumn, fern growth
produces reserves which are stored in roots and rhizomes; subsequently in the winter/cold
season the crop becomes dormant (Hartman, 1989). In semi-temperate zones such as
Taiwan the crop does not experience dormancy, but growth slows during the hot summer
and cold winter seasons. In these areas high yields can be achieved by adopting the
mother-stalk harvesting method, which is done for 3-4 months in spring and 2-3 months
in fall ( Hung & Huang, 1987; Wang, 1983; Chen, 1983).
In the highland regions of Indonesia which have a hot tropical climate, asparagus does not
have any dormant period, but grows very rapidly and, according to Nonnecke (1989) has
a short productive time. Harvesting is generally done in the rainy season when ambient
temperature is relatively low and humidity and water supply are high. Yield is generally
low, partly because the harvesting method is not suitable for the local climatic
conditions. Applying the harvesting methods used in temperate climates, a high number

of spears are produced, but spear size decreases rapidly and the harvest period also
becomes shorter. On the other hand, when the mother-stalk method is used in Indonesia,

spear number and yield are low. To obtain high yields and good spear quality in
Indonesia, the best combination of method and schedule needs to be determined.
The objectives of this experiment was to find out the best combination between
number of spears left in mother-stalk method and alternating harvest period to produce
good yield and better quality of spears for tropical region.
MATERIAL AND METHODS
The experiment was carried out on a two year old (2nd year harvest) crop of cv.
Mary Washington in Arjasari – Bandung, West- Java, about 800 m above sea level where
the mean daily temperature in the rainy season is 220 – 260C. A double row system of
planting with plant distances (60 cm x 40 cm)(80 cm x 40 cm) and planting depth of 15
cm was employed. The crop was not harvested during the dry season; harvesting
commenced at the beginning of the rainy season (October 2000) by cutting off all stems.
Spears growing in the no-mother-stalk treatments were harvested immediately, while in
the mother-stalk (MS) treatments the first spears were left to grow to become stalks. The
number of stalks left per plant in each plot was adjusted according to the treatments. The
following spears were then harvested. After the first harvest period the crop was left not
harvested for eight weeks, then harvesting commenced again and continued with the same

method until the completion of the harvesting period. A simple randomised block design
with three replicates was used. The complete harvest period was 20 weeks in all
treatments. Plot size was 8.4 m2 (1.4 m x 6.0 m), containing 30 plants. With three
methods of harvesting combined with three harvest schedules, there were a total of nine
treatments as follows:
aop1 :

without MS, harvest schedule (4H – 8R– 8H) = 4 weeks harvesting, 8 weeks
rest (no harvesting), 8 weeks harvesting again
aop2 : without MS, harvest schedule (6H – 8R – 6H)
a0p3 : without MS, harvest schedule (8H – 8R – 4H)
a1p1 : with 1 MS, harvest schedule (4H – 8R – 8H)
a1p2 : with 1 MS, harvest schedule (6H – 8R – 6H)
a1p3 : with 1 MS, harvest schedule (8H – 8R – 4H)
a2p1 : with 2 MS, harvest schedule (4H – 8R – 8H)
a2p2 : with 2 MS, harvest schedule (6H – 8R – 6H)
a2p3 : with 2 MS, harvest schedule (8H – 8R – 4H)
The following yield characteristics were measured:
1. Number of spears per plot during the 20 week
2. Total spear weight per plot

3. Average spear weight / spear size
4. Number and weight of marketable spears per plot
5. Percentage of marketable yield (number and weight of spears)
Harvesting was done between 9.00 – 10.00 a.m. each day by cutting the green spears
at ground level when they had reached 20cm – 25cm. Spears were judged to be
unmarketable if the diameter was less than 0.8 cm, the tip was open, the spear was bent or
damaged, or the length was less than 20 cm.

RESULTS AND DISCUSSION
Number of Spears and Spear Weight
The number of spears and spear weight per plot during the 20 week are presented in
Table 1. The non mother-stalk treatments produced the most spears. Treatment a0p3
(without MS, harvesting schedule (8 – 8 – 4)) produced the largest number of spears, and
it was significantly higher than the treatments with one and two MS and the same harvest
schedule. On the other hand, treatments with 2 MS produced the lowest number of spears
with the p1 harvest schedule (4 – 8 - 8). Beside producing the most spears, treatment a0p3
also gave the highest yield, although statistically it did not differ from the other
combination treatments except for a2p1, which produced the least weight of spears.
The without MS method of harvesting, i.e. cutting off all developing spears,
stimulates budding which continues as long as environmental conditions are conducive

for growth. Rate of spear development and spear size depend greatly on the amount of
reserves stored in the crown. Environmental conditions at the experimental location, such
as ambient temperature during the rainy season, did not inhibit plant growth; in fact they
greatly supported spear growth. Moreover, adequate reserves in the crown were available
due to the no harvest period in the previous dry season. Consequently, the highest number
of spears was found in the without MS treatment (a0) combined with the longest harvest
session at the beginning of the schedule (p3). On the other hand the treatment with two
MS produced the least spears because, as long as the ferns are growing, apical dominance
inhibits spear initiation until fern growth is terminated. (Wilcox – Lee and Drost, 1991 in
Drost, 1997). This apparently requires a sufficient length of time, as shown by the harvest
schedule p3 (4 - 8 - 8); during the first four weeks plant growth was centered on
expansion of the two spears to become stalks; during the following eight weeks the plant
was given rest (not harvested); and finally it was harvested for eight weeks. Consequently
in this combination treatment the real harvest was in fact carried out only in the second
part of the harvesting schedule, and the result was a low yield.
In the treatment with one MS, the plant condition is in between the two extremes
discussed above. Spear number and weight per plot per harvest period did not differ
significantly during the three levels of harvest schedule.
Average Spear Weight
Although the number of spears was high in the without MS treatments, total spear

weight was not significantly differ from the other treatments because mean spear weight
was low. ( Table 2 ). Harvesting over a pro-longed period of time without MS depleted
reserves in the crown, with no new supplies being produced, and, consequently spear size
decreased rapidly. Spear weight is related directly to diameter and length. In this
experiment harvesting was done every day. Spear length was consistent (20 cm – 25 cm)
so the reduction of spear weight was caused by decreasing diameter. Minimum
marketable spear diameter in this study was set at 0.8 cm.
Marketable Number and Weight of Spears
Marketable spear number and weight per plot during the harvest period did not
differ significantly among the treatments, except for a2p1 which had the lowest values
(Table 3). It produce a both the lowest number of spears and the lowest total marketable
spear weight. However, calculated in percentages, all with MS treatments gave higher
marketable spear values than the without MS ones (Table 4). Percentages of marketable

number and weight of spears produced by the one and two MS treatments at all levels of
harvesting did not differ significantly.
CONCLUSIONS
Marketable number and weight of green asparagus spears did not significantly
among the treatments tested in this study, except for treatment a2p1 which produced the
lowest values. However, there was an interdependency between method of harvesting

and harvest schedule. The without MS method of harvesting produced more spears than
the MS methods. The treatment that combined without MS and the (8H – 8R – 4H)
harvest schedule produced the highest yield, but also caused spear size to decrease
rapidly. Consequently, at all levels of harvesting schedule percentages of marketable
spear yield, in both numbers as well as weight, were low.
The one MS method of harvesting reduced spear size decline and produced larger
mean spear size than the without MS harvesting method. The latter method of harvesting
in combination with the harvest schedule of p2 (6H – 8R – 6H) and p3 (8H - 8R – 4H)
produced significantly larger spear size. The two MS method of harvesting also produced
large spears, but spear number was less, causing the overall yield of spears to be low if
this method was combined with the harvesting schedule of p1 (4H – 8R – 8H).
ACKNOWLEDGEMENTS
I wish to thank Mr. Suphendi for technical assistance during the experiment.
Literature Cited
Chen, Y.W. 1983. The Growth of Green Asparagus Spears in Tropical Region (Taiwan).
Taiwan Asparagus Research Report. (3): 388 – 390.
Drost, D.T. 1997. Asparagus. In The Physiology of Vegetable Crops. Wien, H.C.
(Editor). CAB International, Oxon, UK.
Hartmann, H.D. 1989. Spargel – Grundlagen fuer den Anbau. Eugen Ulmer GmbH &
Co, Stuttgart, Germany.

Hung, L. and H. Huang. 1987. Asparagus Breeding in Subtropical Taiwan. Improved
Vegetable Production in Asia. (36) : 128 – 135.
Nonnecke, I.L. !989. Vegetable Production. Van Nostrand Reinhold, USA.
Wang, C.S. 1983. The Mother Stalk Culture of Asparagus in Taiwan. Taiwan
Asparagus Research Report. (3): 384 – 387.

Tables
Table 1 : Number of spears and spear weight of green asparagus per plot during the 20
week harvesting period.
Combination Treatment
Number of Spears/plot
Spear Weight/plot
Method , Schedule
(g)
aop1 : without MS, (4 – 8 – 8)
199.5 ab
1936.4 ab
aop2 : without MS, (6 – 8 – 6)
190.9 ab
1940.9 ab

aop3 : without MS, (8 – 8 – 4)
261.2 a
2710.2 a
a1p1 : with 1 MS, (4 – 8 – 8)
173.4 ab
1901.1 ab
a1p2 : with 1 MS, (6 – 8 – 6)
152.4 b
2182.7 a
a1p3 : with 1 MS, (8 – 8 – 4)
149.3 b
2074.9 a
a2p1 : with 2 MS, (4 – 8 – 8)
98.6
c
1312.2 b
a2p2 : with 2 MS, (6 – 8 – 6)
169.4 ab
2328.1 a
a2p3 : with 2 MS, (8 – 8 – 4)

130.6 bc
2018.4 a
_____________________________________________________________________
* MS = Mother-stalk
** Mean separation in columns by Duncan’s Multiple Range Test, 5% level.

Table 2 : Mean spear weight of green asparagus during the 20 week harvesting period.
Combination Treatment
Mean Spear Weight ( g )
Method ,
Schedule
aop1 : without MS, (4 – 8 – 8)
9.7
d
aop2 : without MS, (6 – 8 – 6)
10.2
cd
aop3 : without MS, (8 – 8 – 4)
10.5
cd

a1p1 : with 1 MS, (4 – 8 – 8)
11.1
bcd
a1p2 : with 1 MS, (6 – 8 – 6)
14.3 ab
a1p3 : with 1 MS, (8 – 8 – 4)
14.0 ab
a2p1 : with 2 MS, (4 – 8 – 8)
13.4 abc
a2p2 : with 2 MS, (6 – 8 – 6)
13.9 ab
a2p3 : with 2 MS, (8 – 8 – 4)
15.5 a
* MS = Mother-stalk
** Mean separation in columns by Duncan’s Multiple Range Test, 5% level.

Table 3 : Number of marketable spear and marketable yield of green asparagus per
Plot during the 20 week Harvesting Period.
____________________________________________________________________
Combination Treatment
Number of Marketable Marketable Spear Weight
Method,
Schedule
Spear per Plot
per Plot ( g)
aop1 : without MS, (4 – 8 – 8)
89.3 ab
1321.3 ab
aop2 : without MS, (6 – 8 – 6)
86.5 ab
1291.2 ab
aop3 : without MS, (8 – 8 – 4)
131.5 a
1936.4 a
a1p1 : with 1 MS, (4 – 8 – 8)
107.2 a
1520.5 ab
a1p2 : with 1 MS, (6 – 8 – 6)
105.7 a
1725.8 a
a1p3 : with 1 MS, (8 – 8 – 4)
105.9 a
1721.8 a
a2p1 : with 2 MS, (4 – 8 – 8)
63.7 b
984.0 b
a2p2 : with 2 MS, (6 – 8 – 6)
118.9 a
2152.7 a
a2p3 : with 2 MS, (8 – 8 – 4)
87.5 ab
1588.5 a
_____________________________________________________________________
* MS = mother-stalk
** Mean separation in columns by Duncan’s Multiple Range Tests, 5% level

Table 4: Percentage marketable spear by number and weight of green asparagus
during the 20 week harvesting period.
_____________________________________________________________________
Combination Treatment
Number of Marketable
Weight of Marketable
Method,
Schedule
Spears (%)
Spears (%)
aop1 : without MS, (4 – 8 – 8)
44.97 d
68.43 b
aop2 : without MS, (6 – 8 – 6)
46.17 cd
67.03 b
aop3 : without MS, (8 – 8 – 4)
51.90 bcd
71.93 ab
a1p1 : with 1 MS, (4 – 8 – 8)
62.10 abc
80.13 ab
a1p2 : with 1 MS, (6 – 8 – 6)
69.73 a
79.37 ab
a1p3 : with 1 MS, (8 – 8 – 4)
71.23 a
83.07 a
a2p1 : with 2 MS, (4 – 8 – 8)
64.63 ab
75.30 ab
a2p2 : with 2 MS, (6 – 8 – 6)
70.13 a
80.43 ab
a2p3 : with 2 MS, (8 – 8 – 4)
67.07 ab
78.70 ab
_____________________________________________________________________
* MS = mother-stalk
** Mean separation in columns by Duncan’s Multiple Range Tests, 5% level.