1. 1
August 2001
Introduction and evaluation of leafy vegetables
for summer in Taiwan
Julien V.SANANIKONE
Asian Vegetable Research and Development Center (AVRDC)
Shanhua,Tainan,Taiwan
Supervisor
Dr.George KUO
Abstract
Leafy vegetables are important in Taiwan agriculture. But, although total
vegetable production is high, summer production is relatively low. New accessions
can increase this production. They were evaluated for adaptability in various
seasons. During this summer 2001, some of the selected promising accessions were
further tested in replication trial with the aim to select heat tolerant, high-yielding
and early maturing potential varieties for summer production. Thus, the results
showed that potential in amaranth TOT2353 and TOT2355, in kale LV019, LV20,
LV021 in mustard CN078, in paitsai CN088 and CN098 and for rape TB570, TB473
and TB599. Most of the results confirmed the adaptability of the promising
accessions.

2. 2
Introduction
Leafy vegetables are important components of Taiwanese agriculture and diet.
However the farm and hence the retail prices of leafy vegetables vary a lot within the year.
Generally, the prices are higher during summer than the average of the year. In the year
2000, the July retail price for Chinese kale was 57.78 NT$/kg whereas the average retail
price was 52.88 NT$/kg, similarly the July retail price for leaf mustard was 54.02 NT$/kg
whereas the average retail price was 49.04 NT$/kg and finally the August retail price for
edible amaranth was 57.34 NT$/kg whereas the average retail price was 53.33 NT$/kg that
year (Taiwan Agriculture Prices & Costs Monthly, January 2000, Central Taiwan Office
Council of Agriculture). One of the main reasons for this fact is that the summer climate is
not really favorable for agriculture and then makes the production relatively low. Indeed in
the South of Taiwan, summer is characterized by high temperatures ranging from 25.5 to
31.6ºC, high rainfall (534 mm) and high humidity (82%) (Climatological Data Annual Report
1999, Central Weather Bureau, Taiwan). Further more, gales and typhoons, which are
recorded from May to November, often devastate crops in the fields that become
impossible to harvest. Generally, leafy vegetables were grown in the highlands where the
temperature is cool during summer but because of the lack of soil-water conservation
measures soil and water erosion became a serious problem (AVRDC, 1988a. Vegetable
Research In South-East Asia, AVRDC, Shanhua, Tainan, Taiwan). The lowlands have to supply
the major leafy vegetables for local market demand.
Recently, several species of “new” vegetables have made their appearance in the
Taiwan market. Many of these species are adapted to tropical conditions. These vegetables
can play a role in increasing summer production. But to significantly do so, the
identification of genotypes tolerant to heat, early maturing and high-yielding is necessary.
The objective of this study is to evaluate the potential of some horticultural traits of
leafy vegetables that is to say yield, heat tolerance and growth characteristics. This study
evaluates the potential of five crops namely amaranth, kale, mustard, paitsai and rape. It is
to identify promising crops that will be further tested for the release to the Taiwan national
agriculture research system.

3. 3
Materials and methods
Plant material
Five crops of leafy vegetables, with six accessions each, were tested under net house
condition (Table 1). Among the six accessions, one is a commonly used variety in Taiwan.
The selection of those accessions was based on the results of previous observation trials
that highlighted their good yield potential. This selection also depended on the available
amount of seeds. Since most of them come from foreign countries there was not much
quantity to make use of.
Location and field characteristics
The trial was conducted at the Asian Vegetable Research and Development Center,
Shanhua, Tainan, Taiwan during summer (June-July-August) 2001. All crops were grown in
the same net house (32 mesh, 50m long and 40m wide). The seedlings were planted in the
beds (4 x 0.6 x 0.2 m). Two-row-beds were used with a plot size of 4 m² (1m x 4m) and
spacing 20 cm between plants. The experimental was designed as a randomized complete
block design with 3 replications.
Cultivation management
The seeds were first sown in plug trays in greenhouse on 20 June 2001. Two seeds per
cell were planted 1cm deep. Once the seedlings were strong enough (approximately 20
days after sowing) they were transplanted in the net house, on 9 July 2001 for amaranth,
rape and paitsai, and on 11July 2001 for kale and mustard. Once the seedlings transplanted,
the soil was covered with rice straw.
Compost (Taiwan fertilizer #2; organic matter NPK: 60-5-4) at 1500 kg/ha and chemical
fertilizer (Taiwan fertilizer #43; NPK+Mg: 15-15-15-4) at 400 kg/ha were broadcast one day
before the first transplantation. Nitrogen was also applied 10 to 14 days after transplanting
at 150 kg/ha.
The seedlings were irrigated just after transplanting. Then, if there were no rainfall,
furrow irrigation was practiced once a week during hot-dry periods.
Manual weeding was first realized on the day of nitrogen application. The field was
weeded a second time one day before the first harvest. In case of repeated precipitations,
the times for weeding would be increased.
For pest and disease management, Methomyl (100g/ha, 1500X), Benomyl (1000g/ha,
1000X) and Mancozeb (1500g/ha, 800X) were sprayed when needed and applied uniformly
to all plots.
Several harvests by cutting were done between 15 and 40 days after transplanting
depending on leaf maturity of individual species.(Table 2.)

4. 4
Table 1.List of the leaf vegetable accessions evaluated in summer 2001
Crop Accession number Scientific Name Origin
TOT2263 Ghana,Africa
TOT2265 Ghana,Africa
TOT2327
Amaranthus cruentus L.
Nigeria,Africa
TOT2353 Amaranthus dubius C.Martius ex Thell. India
TOT2355 Amaranthus hypochondriachus L. Unknown
Amaranth
White leaf (check) Amaranthus tricolor L. Known-You Seed (Taiwan)
LV019 Tanzania,Africa
LV020 Tanzania,Africa
LV021 Tanzania,Africa
LV042 Tanzania,Africa
LV043 Tanzania,Africa
Kale
Full White (check)
Brassica oleracea L. cv.Alboglabra
Known-You Seed (Taiwan)
LV008 Malawi,Africa
CN079 CAAS,China
TB574 Indonesia
CN078 CAAS,China
TB559 Philippines
Mustard
Fun Wei (check)
Brassica juncea (L.) Czernjaew
Known-You Seed (Taiwan)
CN088 CAAS,China
CN089 CAAS,China
CN097 CAAS,China (Hunan)
CN098 CAAS,China (Szuchuan)
CN099
Brassica rapa L. cv.pak-choi
CAAS,China (Szuchuan)
Pak-choi
(Paitsai)
Speedy (check) Brassica rapa L.cv.Chinese cabbage Known-You Seed (Taiwan)
TB439 Malaysia
TB570 Indonesia
TB473 Thailand
TB599 Indonesia
TB571 Indonesia
Rape
Local variety (check)
Brassica rapa L.cv.caisin
Known-You Seed (Taiwan)
Data recording
On the transplanting day one plant by plot was sampled to measure leaf area and dry
weight.
Ten and twenty days after transplanting the same samplings were done for kale,

5. 5
mustard, paitsai and rape. For kale and mustard an ultimate sampling was made thirty days
after transplanting. Since amaranth grew really fast, the third sampling was realized fifteen
days after transplanting.
The day before harvesting, the percentage of bolting (plants whose bloom presence
was detectable by sight) was evaluated and the leaf shape, the leaf and stem color were
described.
On the first harvesting day, a sampling to measure leaf area and dry weight was done.
The following data were also recorded: number of days after sowing to harvest; number of
plants transplanted and harvested; leaf width, length and number per plant and yield.
These latter data were evaluated from all remaining plants in the plot except the 1st
and the
20th
ranks which are the borders. At the time of other harvests, only yield was recorded.
(Table 2)
Leaf area was measured by a LICOR-3100 (LICOR, Lincoln, NB., USA). The plants were
dried with a drier at 60ºC for 3 to 7 days depending on plant stage.
Table 2.Numbers of days after transplanting for sampling and harvesting
Sampling 1 Sampling 2 Sampling 3 Sampling 4
Harvest
1
Harvest
2
Harvest
3
Amaranth 2 12 17 - 17 27 38
Kale trspl day 10 20 29 29 35 -
Mustard trspl day 10 20 29 29 35 -
Paitsai 2 12 24 - 24 38 -
Rape 2 12 24 - 24 38 -
trspl day = transplanting day
Data analysis
For the growth analysis the following parameters were determined:
Crop Growth Rate (CGR) expresses the average daily increment of stand total dry weight.
The formula is
( )12
12
ttG
WW
CGR
−
−
= (weight.ground area-1
.time-1
)
Where W1
and W2
are the values of dry weight at two consecutive harvests carried out at
times t1
and t2
, respectively and G is the ground area on which W1
and W2
have been
estimated.
Leaf Area Index is defined as the ratio between leaf area (A) and ground surface (G).
The formula is
G
A
LAI = (area.area-1
)

6. 6
Net Assimilation Rate (NAR) expresses a plant’s capacity to increase dry weight in terms of
its assimilatory surface (leaf area)
The formula is
( )( )
( )( )1212
1212 lnln
ttAA
AAWW
NAR
−−
−−
= (weight. area
-1
.time
-1
) assuming there is a
linear relationship between W and A.
Data were analyzed by SAS Institute’s (Cary, NC, USA) General Linear Models (G.L.M.)
procedure.
Results
The results compiled in Table 3 show that the accessions TOT2353 and TOT2355 of
amaranth have the best yield (15.6 and 15 t/ha respectively). Further more, they also
produce more leaves that were quite long and the widest among the six accessions tested.
Nevertheless, they seem to be heat sensitive since they were the only accessions to flower
before harvest (Figure 1).The local variety White Leaf produced considering yield (12.4 t/ha)
and had not started to bolt on harvesting days.
Amaranth
0 0 0
37
53
0
0
10
20
30
40
50
60
TOT2263 TOT2265 TOT2327 TOT2353 TOT2355 White leaf
Entry
Boltingpercentage
Figure 1.Bolting percentage the day before the first harvest for amaranth
Among kale accessions the results were quite alike for every traits studied. LV019 and
LV021 got the best yield. LV020 produced the most leaves. On the contrary, the local variety
Full White showed really bad results especially for yield,leaf number and leaf length.
The mustard accession CN078 is to be highlighted. Indeed, it had the best yield (9.3
t/ha), and the biggest leaves. It had the fewest leaves but this is not significantly different
from the other accessions. Finally, its heat tolerance is noticeable as it had less than 1% of
bolting the day before the first harvest (Figure 2).

7. 7
Table 3.Evaluation trial of amaranth, kale,mustard,paitsai and rape,summer 2001
Entry
Yield
(t/ha)
Days
for
maturity
Leaf
n
0
Leaf
length
(cm)
Leaf
width
(cm)
Plant
height
(cm)
-Amaranth-
TOT2263 4.7
a
21.8
a
12.3
a
23.0
a
8.1
a
34.6
ab
TOT2265 8.3
a
23.1
ab
13.7
ab
24.7
a
8.0
a
43.8
c
TOT2327 6.2
a
23.8
bc
13.0
ab
23.7
a
8.2
a
42.4
bc
TOT2353 15.6
b
26.0
d
14.8
bc
23.6
a
10.1
b
44.8
c
TOT2355 15.0
b
26.8
d
16.8
cd
22.5
a
9.5
ab
45.5
c
White leaf (check) 12.4
b
25.1
cd
17.5
d
16.0
b
10.9
b
26.9
a
Mean 10.4 24.4 14.7 22.3 9.1 39.7
-Kale-
LV019 5.4
a
30.9
a
6.8
ab
25.2
ab
11.1
ab
33.7
bc
LV020 3.7
ab
30.4
a
9.3
d
25.0
ab
12.4
b
33.9
c
LV021 5.5
a
30.6
a
7.5
bc
26.5
a
11.7
ab
36.0
c
LV042 3.9
ab
30.7
a
8.8
cd
23.8
ab
11.4
ab
33.9
c
LV043 2.2
ab
30.9
a
6.8
ab
22.8
b
10.5
a
28.0
ab
Full White (check) 2.2
b
30.5
a
5.6
a
19.2
c
11.1
ab
24.9
a
Mean 3.9 30.7 7.5 23.7 11.4 31.7
-Mustard-
LV008 5.6
a
29.5
ab
6.6
a
27.9
a
14.0
b
33.4
b
CN079 4.7
a
30.0
ab
6.5
a
22.9
b
12.2
a
28.6
a
TB574 6.4
a
29.6
ab
7.0
a
27.9
a
13.1
ab
32.9
ab
CN078 9.3
b
29.4
a
6.3
a
28.6
a
15.7
c
32.8
ab
TB559 5.7
a
30.3
b
6.8
a
23.8
b
13.2
ab
29.0
ab
Fun Wei (check) 6.3
a
29.6
ab
6.9
a
27.8
a
12.8
ab
32.9
ab
Mean 6.4 29.7 6.7 26.5 13.5 31.6
-Paitsai-
CN088 7.0
cd
27.3
b
8.2
a
30.1
b
12.9
cd
33.7
e
CN089 5.0
bc
27.5
b
8.4
ab
27.5
b
12.0
c
29.4
bc
CN097 0.4
a
24.0
a
8.3
a
11.7
a
7.1
a
14.0
a
CN098 8.0
d
26.3
b
10.0
ab
28.0
b
13.9
d
31.2
cd
CN099 3.6
b
31.6
c
10.5
b
25.8
b
9.1
b
28.0
b
Speedy (check) 7.2
cd
24.6
a
8.8
ab
31.0
b
14.1
d
32.1
de
Mean 5.2 26.9 9.0 25.7 11.5 28.1
-Rape-
TB439 5.1
a
28.3
d
9.5
a
25.4
ab
8.7
a
32.3
a
TB570 8.1
b
27.4
cd
8.4
a
29.0
bc
11.6
b
34.9
a
TB473 7.9
b
25.7
abc
16.2
b
24.9
a
8.6
a
32.1
a
TB599 6.2
ab
26.6
bcd
10.6
a
29.9
c
10.9
b
33.3
a
TB571 5.1
a
25.1
ab
10.7
a
31.7
c
10.9
b
31.7
a
Local variety (check) 5.2
a
24.5
a
11.8
ab
24.1
a
8.2
a
32.1
a
Mean 6.3 26.3 11.2 27.5 9.8 32.7
Means within a column, followed by the same letter are not significantly different by least significant difference (LSD) at 5%

8. 8
Mustard
22 22
49
0,9
18
45
0
10
20
30
40
50
60
LV008 CN079 TB574 CN078 TB559 Fun Wei
Entry
Boltingpercentage
Figure 2.Bolting percentage the day before the first harvest for mustard
For paitsai accessions CN088 and CN098 and local variety Speedy performed the best
yield and the biggest leaves. CN098 could provide an average of 10 leaves per plant and
Speedy was really fast to harvest with only 24.6 days.
Accessions TB570, TB473 and TB599 of rape got the best yield. TB473 had the most
leaves (16.2 per plant) and could be harvested after 25.7 days.TB570 had the biggest leaves
(29 cm long and 11.6 cm wide).
Discussion
In summer 1999, an observational trial identified promising leafy vegetables for
further testing. Unfortunately, the replication trial conducted in summer 2000 led only to
the harvest of kale. Comparing, this latter set of data to the one of this summer shows
nearly the same results,that is to say LV019, LV020 and LV021 appear as the best accessions.
Similarly, Full White got really bad results. Nevertheless, the average yield for summer 2000
was 8.7 t/ha more than the double of this summer yield. This may be explained by the fact
that firstly, the summer 2000 trial last longer with more harvests. Secondly, during this
summer, after the application of the nitrogen fertilizer came a rain that diluted it and
caused the roots to absorb too much nitrogen. The seedlings were burnt and hence
replaced the day after.The lower yield may result of that second transplantation.
Amaranth accession TOT2263, which had been selected in the spring 2000 trial, did
not perform well this summer 2001. Its low yield (4.7 t/ha) can find an explanation in the
low leaf area index (Figure 3.). The leaf area was not sufficient to intercept as much of the
incoming radiation as possible.

9. 9
0,9
1,7 1,8
3,2
2,7
5,6
0,0
1,0
2,0
3,0
4,0
5,0
6,0
TOT2263 TOT2265 TOT2327 TOT2353 TOT2355 White
leaf
entry
LAI(m².m-²)
Figure 3.LAI for amaranth on the first harvest day
Furthermore, since all the TOT2263 seedlings were not vigorous enough to be
transplanted the first time,the first harvest resulted in lower yield (yield was measured with
the total bed area). The beds were completed one week later and then the two last
harvests took more plants into account. Finally, Amaranthus cruentus L. cv Fotètè is widely
cultivated in Africa where it is high-yielding and its growth is fast which was not the case in
this trial.
On the contrary, the accessions TOT2353 and TOT2355 with LAI of respectively 3.2
and 2.7 m².m-
² got the best yield, which is confirmed by Nichiporovich (1960) who
considered that the optimal area range was between 2,5 and 5 m².m-
². White Leaf with a
LAI of 5.2 m².m-
² showed a good heat tolerance as previously mentioned.
Amaranth is characterized by the C4
-cycle photosynthetic pathway, which means a
high photosynthesis at high temperature and radiation. This explains the much higher
average yield for amaranth than for the average yield of the other crops.
For mustard, accession CN078 had the best results whatever the season was. This tends
to confirm this accession to be a heat tolerant, high-yielding and fast growing crop that
would deserve to be introduced in regional trials.
A relatively high level of heterogeneity within each bed of paitsai was noticed. The
purity of the seeds was certainly not acceptable. This makes the results quite not reliable,
though CN088 was selected as in a previous trial.
This summer trial for rape revealed TB570 and TB473 to be promising although
previous trials did not.TB599 continues to appear as a promising crop.

10. 10
Acknowledgements
I would like to thank all AVRDC staff for making my training period really enjoyable. I
really found your pedagogical method instructive as it allowed me to think of the
problems (and the solutions) by myself and to follow every steps of the experiment. A
particular thank goes to Mandy Lin for her great patience in answering my questions!
References
Climatological Data DAnual Report 1999,Central Weather Bureau,Taiwan.
Grubben G.J.H.1976.The cultivation of amaranth as a tropical leaf vegetable.
Communication 67.Royal Tropical Institute, Amsterdam,The Netherlands.207 pp.
Luh,Chi-Lin,1988.Forty years of vegetable research and development in Taiwan.
AVRDC, 1988a.Vegetable research in South-East Asia, AVRDC, Shanhua,Tainan,Taiwan.
p80
Mitchell,L.R.1970.Light utilization by leaf and crop surfaces.Crop growth and
culture.The Iowa State University Press, Ames, Iowa.29-33 pp.
Sienmonsa, J.S.and Kasem Piluek (Eds.) 1994.Plant Resources of South-East Asia.
PROSEA Vegetables.Bogor,Indonesia.pp.82-134
Taiwan Agriculture Prices & Costs Monthly,January 2000, Central Taiwan Office
Council of Agriculture