Paclobutrazol Rate and Time of Application for Potato Minituber Production on Aeroponics System

12 Pages·2014·0.09 MB·English

Paclobutrazol Rate and Time of Application for Potato Minituber Production on Aeroponics System
is a portion of a dissertation submitted by first author in fulfilling a degree requirement.

Meksy Dianawati1, Satriyas Ilyas2, G.A. Wattimena2, Anas D. Susila2

Assessment Institute of Agriculture Technology of West Java, Jalan Kayuambon 80, Lembang, West
Bandung, West Java, Indonesia, 40391.

I thank Indonesian Agency for Agricultural Research and Development for funding in doing this
research and Center for Tropical Horticulture Studies, Bogor Agrcultural University for funding in
publishing this manuscript.

1To whom reprint requests should be addressed. Email address: [email protected]
2Departement of Agronomy and Horticulture, Bogor Agriculture University, Jalan Raya Darmaga,
Bogor, Indonesia. 16680
1
Subject Category : Vegetable Crop

Paclobutrazol Rate and Time of Application for Potato Minituer Production on Aeroponics System

Additional index words. Solanum tuberosum L. induction, tuberization, stolon, seed, retardan

Abstract. Percentage of tuber formation from stolon on potato minituber production aeroponically is
only 5-10%. Therefore it still can be increased by tuberization induction. The research was conducted
to increase tuberization by using several rates and times of application of paclobutrazol (PBZ) on
aeroponics system. This experiment was conducted in a plastic house in Lembang, West Java,
Indonesia, at an altitude of about 1,200 m above sea level and in the tropical belt of South East Asia at
107 o 36’ E, 6o 49’ S, from April until October 2012. Two factors of rates and application times of PBZ
were arranged in Randomized Completely Block Design in three replications. The first factor was
rates of PBZ i.e. 5, 10, 20, and 40 mg L-1. The second factor was application times of PBZ i.e. 4 weeks
after transplanting (WAT); 5 WAT; 6 WAT; 4 and 5 WAT; 5 and 6 WAT; 4, 5, and 6 WAT. Check
was no PBZ application. The results showed that PBZ could induce tuberization of potato plants
significantly by 59% from 11.44 to 28.09% on aeroponics system. The application of 20.92 mg L-1
PBZ at 6 WAT could increase number of tubers significantly by 65% from 12.33 to 30.5 per plant.
The number of total-tubers positively correlated with number of moderate-tubers (87%), percentage of
effective stolon (86%), number of large-tubers (52%), and negatively correlated with weight per tuber
(85%)

Indonesia potatoes production is low availability of high quality seed (Wattimena 2000). Increasing in
demand for potato seed G0, G1, G2, G3, and G4 as well as for consumption will have impacted on
increasing of total production. The availibility of nationally certified potato seed in Indonesia is only
15% from total 103,582 thousand tons of seed per year (Rosalina, 2011). Meanwhile, the production
cost of potato seed is quite high, around 40-50% from total cost of potato production, so farmers often
use a portion of harvested tuber to produce seed for the next planting season.
Increasing potato seed quality can be made from tissue culture technique. This technique can provide
micro tuber and cutting which are pathogen-free, uniform, and not depending on the season.
Furthermore, microtuber and micro cutting can produce minituber. Minituber production by spraying
nutrient to plant roots as aeroponics system, began to be developed in Indonesia. Minituber produced
in convensional production system are about 3-5 tubers per plant, while on aeroponics system are
approximately 16-29 tubers per plant (Muhibuddin et al., 2009). The higher production on aeroponics
system mainly due to the high efficiency of nutrient absorption, can be harvested many times, high
stolon growth, relatively free from patogen, and easy to control the plant system (Ritter et al., 2001;
Nugalliyadde et al., 2005; Farran and Castel, 2006).
The absence of a barrier in the roots on aeroponics system made stolon number could grow more than
10 (Nugalliyadde et al., 2005) by the number of secondary stolon branches ranged from 10-15.
However, the percentage of tuber formation from stolon estimated that only 5-10% of stolon 100-150
per plant. Therefore, it is still a potency to increase the number of tubers by tuberization induction in
various ways. The use of anti giberilin has been investigated to induce tuberization on aeroponics
system such as the CCC, methyl jasmonat, and uniconazole. Tuberization induction with paclobutrazol
(PBZ) on aeroponics system and proper application timing information has not been known yet.
According to Chang et al., (2008), improper treatment induction could reduce tuber yield.
PBZ [(2R, 3R + 2S, 3S)-1-(4-chlorophenyl) 4,4-dimethyl-2-(1,2,4-triazol-1-yl)-pentan-
3-ol] (PBZ) is a triazole plant growth regulator that inhibit giberilin (GA) biosynthesis and abscisic
acid catabolism so stunted vegetative growth and tuber growth turns into (Verma et al, 2010). The
research of Gunawan (1998) showed that PBZ could increase the number of minitubers at a rate of 15
mg L-1, while the best PBZ rate of research of Hutabarat (1994) was 30 mg L-1. However Sitepu
(2007) reported that using of PBZ at 45 days after planting was late to increase the number of tubers as
tubers have formed. Therefore it needed to find the proper rate and time application of PBZ to increase
the number of minitubers of potato plant on aeroponics system. The objective of this study is to induce
tuberization of potato on aeroponics system using various rates and application times of PBZ.

Materials and Methods
The experiment was conducted in a plastic house in Lembang, West Java, Indonesia, at an altitude of
about 1,200 m above sea level from April to October 2012. The site was located in the tropical belt of
South East Asia at 107 o 36’ E, 6o 49’ S. Monthly temperature and humadity were 20,06 oC and 85,78
%, respectively. The size of greenhouse was 13 m width, 20 m length and 6 m height. The greenhouse
was covered with 15% UV plastic and its wall was covered with nylon insect screen with 30 mesh.
Experimental design
Two factors experiment was arranged in Randomized Completely Block Design (RCBD) in three
replications. The first factor was rates of PBZ i.e. 5, 10, 20, and 40 mg L-1. The second factor was
application times of PBZ i.e. 4 WAT; 5 WAT; 6 WAT; 4 and 5 WAT; 5 and 6 WAT; 4, 5, and 6
WAT. Check was no PBZ application. PBZ was applied as foliar spray using Cultar formulation (250
g L-1active ingredient PBZ).
Multiplication of potato seed
Plantlet was one month age of Granola variety (from Indonesia Vegetable Research of Institute).
Plantlet was planted in sterile growing media (charcoal husk: horse manure = v/v = 1/1) with a spacing
of 5 cm x 5 cm. Growing media sterilized by steaming until 100 OC for 5 minutes to make it sterile.
Planlet was protected by paranet (65%) from direct sunlight.
The first propagation by cuttings was done first after plantlet age of 3-4 weeks in the nursery. The
following cuttings were made after 5-7 leaves, strong stems, and healthy roots. After 2 weeks, the
cutting transplants were transplanted on aeroponics system.
Mini tuber production on aeroponics system
A wooden aeroponics box measured 1 m height, 0.80 m width, and 11 m length. The surface of the
box made from Styrofoam of 2.5 cm thickness was wrapped in silver black plastic mulch. The
circulation of nutrient solution used PVC pipes of 13 mm driven by Grundfoss water pumps with the
pressure of 1.5 to 2.0 atm (840 watt, 220 volt).
The cuttings were planted in the plant spacing of 15 cm x 15 cm on aeroponics system and then
covered with rockwool to hold stem of plant. The cuttings were protected by paranet (65%) from
direct sunlight during the first week. Mixed AB nutrient solution was contained 225 ppm NO -, 25
3
ppm NH +, 75 ppm P, 400 ppm K, 175 ppm Ca, 75 ppm Mg, 136 ppm S, 3 ppm Fe, 2 ppm Mn, 0.2
4
ppm Cu, 0.3 ppm Zn, 0.7 ppm B, and 0.05 ppm Mo (Muhibuddin et al., 2009). Nutrient solution was
passed automatically through sprinklers of 1.6 mm length and the distance among each sprinkler was
60 cm. The electrolyte conductivity (EC) and acidity (pH) of nutrient solution were maintained at each
value, 1.5 to 2.0 mS m-1 and 5.8-6.0, respectively. EC of nutrient solution was adjusted to suit
addition of nutrient solution, while the acidity was adjusted to suit H SO or NaOH solution.
2 4
The maintenances of plant included temperature and humidity checks using thermohygrometer,
sprinkler checks in order that sprayed nutrient solution runs smoothly, and checks concerning the rate
of nutrient solution using EC and pH meters (Ezodo 7200). Five days before harvest, nutrient spraying
using sprinklers was stopped. Harvesting was done at the age of 112 days after transplanting (16
WAT) when the leaves were dry.
Observations and analysis methods
Plant growth was observed at 8 WAT covering plant height (cm), leaf area (cm2), number of stolons,
number of tuber initiation, number of tubers, weight of tuber per plant (g), and percentage of effective
stolons (%). Observation of the final harvest at 16 WAT included number of stolons, number of tuber
initiation, number of total tubers, and number of tubers by standard of weight per tuber, tuber weight
per plant (g), weight per tuber (g), percentage of effective stolons (%), rate of bulking tuber (g day-1)
and harvest index.
The height of plants was measured from the base of stem to the last growing point. Leaf area (cm2)
was observed by using gravimetric methods (Sitompul and Guritno, 1995). The number of stolons
began calculated if their length was up to 10 cm. Tuber initiation occurred when the tip of stolons was
twice longer than diameter of the stolons or stolon swelled about 0.5 cm (Adisarwanto, 1993). The
percentage of effective stolons was generated by dividing the number of total tubers with the number
of stolons and then multiplying the result by 100%. All tubers were calculated in accordance with the
weight standard for large-tubers (> 10 g), medium-tubers (1-10 g), and small-tubers (<1 g). The tuber
weight per plant (g) was the weight of a tuber that has been dried for five days per plant. The weight
per tuber (g) was resulted from the weight of tubers per plant divided by the number of total tubers.
The rate of tuber bulking was generated by dividing the tuber weight per plant with the harvest age.
The harvest index was resulted from dividing the weight of tuber per plant by weight of plant and then
multiplying the result by 100%.
The data were analyzed by employing analysis of variance, and if there was a significant difference, it
would be followed by the orthogonal polynomial test for treatment of PBZ rate and the orthogonal
contrast test for treatment of PBZ application time with the confidence level of 0.05. If there was
interaction between two treatments, the orthogonal polynomial test concerning rate of PBZ would be
conducted for each treatment of PBZ application time. The test of correlation was conducted between
number of total tubers and other variables at 16 WAT.

Results and Discussion
There was no interaction between treatments concerning rate and time application of PBZ at 18 WAT,
therefore the effects of each treatment were discussed separately (Table 1 and 3). The interaction of
two treatments affected the variables of number of total tubers and percentage of effective stolons in
the final harvest (Table 5), while the effects of each treatment towards the other variables were
discussed separately (Table 2 and 4).
Effect of rate of PBZ
The application of PBZ rate was used to decrease plant height, leaf area, and number of stolons at 8
WAT (Table 1). Decreases in plant height resulted from this PBZ application ranged between 12-21%
(Table 1). Although leaf area decreased to 29% (Table 1), the leaves looked dark green, small, and
thick after 3 days of application. This was consistent with the research by Balamani and Poovaiah
(1985) showing that plants with PBZ were 3.5-fold shorter than the check ones, while the research by
Tekalign and Hammes (2004) indicated that PBZ reduced leaf area by 50%, however the chlorophyll
content in leaves increased. According to Sumiati (2000), the decline in leaf area due to retardants
helps repair the geometry of the plant stand and therefore avoided mutual shading and competition
among lower leaves so that the penetration of solar radiation in the canopy can be improved. Wang et
al., (2009) state that the use of retardants can inhibit the growth of stolons. According to Verma et al.,
(2010), the inhibition of GA by PBZ caused cell division to keep occurring, however new cells did not
extend themselves.
The optimum rate of PBZ for number of total tubers, weight of tubers per plant, and percentage of
effective stolons ranged from 23.16 to 24.2 mg L-1 (Table 1). The optimum rate of this study was
higher than the findings of the research by Gunawan (1998) on the ground of 15 mg L-1 and was lower
than the findings of the research by Hutabarat (1994) using compost media of 30 mg L-1. The lower
rate of PBZ compared to optimum rate of PBZ has a low percentage of effective stolons, therefore,
even though number of stolons and tuber initiation are high, number of tubers formed is only slightly
(Table 1). This indicates that the rate remains too low to inhibit the formation of GA. The PBZ rate
which was higher than optimum rate had a lower value of observation variables than the other PBZ
treatments (Table 1). This indicates that the rate of PBZ was so high that lower tuberization.
According to Simko (1994), the too high rate of PBZ could accelerate the initial time of tuberization,
but tuber formation stopped faster than the check did.
The weight of tubers per plant, number of total tubers and number of tuber initiation at 8 WAT in the
low check treatment (Table 1) indicated that the study was on non-induced conditions. This was
presumably due to the availability of sufficient and continuous nutrients and high temperatures at the
time the study was conducted (monthly midday temperature average on plastic house was 32.29 oC).
According Tekalign and Hammes (2005), potato plants in non-induced conditions such as high
temperature which was above 29oC did not immediately form tubers because of its GA-high content.
Ritter et al. (2001) state sufficient and continuous nutrient availability on aeroponics system
encourages excessive vegetative growth.
The number of total tubers and the percentage of effective stolons at the 8 WAT in every single PBZ
treatment were higher than the check (Table 1). This showed that all types of treatments concerning
the rate of PBZ could induce tuberization in non-induced conditions. Although the growth of stolons
got slower due to the presence of PBZ treatment, stolons immediately initialed forming tubers due to
the application of PBZ, so that number of tubers increased. Tekalign and Hammes (2005) report PBZ
supplying could induce tuberization in non-induction conditions at high temperatures since stolons
immediately started to initiate.
The optimum rate of PBZ at final harvest for tuber initiation, the number of large-tubers, number of
medium-tubers, weight of tubers per plant, weight per tuber, and rate of bulking tuber ranged from
18.19 to 22.17 mg L-1 (Table 2). The number of total tubers from the best rate treatment was
dominated by the number of large- and medium-tubers (Table 2).
The application of PBZ could increase harvest index (Table 2). This suggests that PBZ encourages
efficient food allocation to tubers than it did to stover. This indicates that tubers were a dominant sink.
Balami and Poovaiah (1985) state that the application of PBZ immediately after tuberization induction
could reduce canopy growth and increase tuber growth by increasing the mobilization of food and
nutrients to the tubers. The results of the research by Tekalign and Hammes (2005) showed two weeks
after PBZ treatment, the food division for the tubers increased from 23 to 26% compared to the check
that had not encountered any initiation yet.
Sessile tubers occupied in this study were found in treatment of 40 mg L-1 PBZ. According to Jackson
(1990), sessile tubers were formed by strong induction. The tubers did not grow from the tip of
stolons, but they grew straightly from the nodes of the stems. The research findings by Simko (1994)
showed that sessile tubers were formed by the high-rate PBZ application at the top of the stem, while
for the moderate-rate of PBZ, sessile tubers were formed at the bottom of the stem. In low-rate PBZ,
sessile tubers were formed at the end of a long stolon.
Effect of paclobutrazol application time
In addition to the rate of retardants, according to Wang et al., (2009), the influence of retardants
depended on the age of plants and the physiological stage of the plants. The application of PBZ three
times (W6) could inhibit the growth of plant height and number of stolons at 8 WAT compared to
application of PBZ twice (W4 and W5) (Table 3). This was because PBZ could serve as retardants
inhibiting the vegetative growth of plants (Tekalign and Hammes, 2005), therefore, the application of
PBZ with more frequency could lead to a decrease in vegetative growth. The repeated application of
PBZ (W4, W5, and W6) resulted in the lower plant height and less number of stolons, but number of
total tubers, percentage of effective stolons, and tuber weight per plant were higher at 8 WAT than
ones of single PBZ (W1, W2, and W3) ( Table 3). In the final harvest, the repeated application of PBZ
(W4, W5, and W6) could decrease number of stolons, increase number of large-tubers, weight of
tubers per plant, rate of tuber bulking, and harvest index (Table 4).
Interaction of rates and application times of PBZ
The increase in number of total tubers using the treatment of PBZ was compared to the check by 47%
(Table 5). The optimum rate to produce maximum number of total tubers ranged from 17.9 to 21.3 mg
L-1. The maximum number of total tubers, i.e. 35.24, was obtained when PBZ was given at 6 WAT of
20.92 mg L-1. On the contrary, the application of PBZ which was too early at 4 WAT with the rate of
20.29 mg L-1 caused the maximum number of total tubers obtained low, which were 24.78.
The use of PBZ could increase tuberization induction indicated by the increase in the percentage of
effective stolons by 59% from 11.44 to 28.09%.
The percentage of maximum effective stolons was 42.7, obtained when application of PBZ was at
24.98 mg L-1 at 4 WAT (Table 5). This suggested that the early application of PBZ at 4 WAT could
increase percentage of effective stolons. However, because number of stolons was not enough to
support the growth of tubers (Table 4), number of total tubers produced was also less (Table 5).
Therefore, the application of PBZ must also consider number of stolons that has been developed in
order that the tuberization induction by PBZ can effectively increase number of total tubers. This was
in line with the statement of Tekalign and Hammes (2004) stating that the low number of total tubers
was often associated with the low number of stolons. This study did not come to an agreement with
Bandara and Tanino (1995) and Sitepu (2007) which state that PBZ should be given in the early stages
of plant growth. The findings of the research by Sembiring and Simatupang (1994) showed that the
application of triacontanol retardants at the 3, 5, and 7 WAT produced more tubers than the
application of both at the 2, 4, and 6 WAT or 4, 6, and 8 WAT did. Chang et al., (2008) report that
growth disturbance should be done 35-42 days after planting to induce tuberization, because if it has
done at the 21 days after planting, it may disturb the growth of tubers. Bandara et al., (1998) report
that the application of PBZ in the early maturing cultivars was given at the 21 days after planting, thus
increasing tuber yield by 67%, whereas the application of PBZ on the late maturating cultivars was
given at the 38 days after planting, thus increasing tuber yield by 30%. Late maturating cultivars took
longer time in relation to the vegetative growth than early maturing cultivars did for eventually
converted into tubers using PBZ application.
The repeated application of PBZ at 4, 5, 6 WAT had to use a lower rate of 17.9 mg L-1 (Table 5). This
was because repeated application might increase the rate of PBZ received by the plants. The findings
of the research by Sumiati (2000) using retardants mepiquat chloride showed that the time application
done twice at the 35 and 42 days after planting resulted in the higher number of tubers than the ones of
the application done once at the 42 days after planting. However, if the application of mepiquat
chloride was done once at the 42 days after planting, the rate of mepiquat chloride used should be
higher.
The number of total tubers positively correlated with the variable of number of moderate-tubers
(87%), percentage of effective stolons (86%), number of large-tubers (52%), and negatively correlated
with weight per tubers (85%) (Table 6). This indicated that the high number of total tubers was
dominated by medium- and large-sized tubers. PBZ could increase number of total tubers due to the
increased percentage of effective stolons. The increase in the number of total tubers caused weight per
tuber to decrease. Tekalign and Hammes (2005) report a negative relationship existing between
number of total tubers and weight per tubers by the application of PBZ. This contrasted with the
research by Bandara and Tanino (1995) reporting that the application of PBZ could increase the
number of total tubers up to 100% without affecting weight per tubers.

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Table 1. The effect of PBZ rates on observation variables at 8 WAT
Rates of PBZ Plant No. Percentage of
(mg L-1) height Leaf area Stolons Total effective Tuber wt
(cm) (cm2) Initiations tubers stolon (%) per plant (g)
0 59,24 523,1 91,33 9,33 0,67 0,78 0,35
5 52,03 509,93 86,00 16,67 12,55 14,92 20,5
10 50,25 511,31 78,44 14,11 17,33 22,67 22,83
20 47,00 420,13 71,44 10,56 17,05 24,59 21,5
40 47,73 370,15 68,39 4,94 11,33 16,89 17,94
Respons L* L* L* L*Q* L*Q* L*Q* L*Q*
R2 13,3 21,4 18,7 40,6 53,3 52,1 52,1
Optimum rate - - - 10,31 23,16 24,20 24,11
L: linier, Q : quadratic, ns, * : no significant or significant on polynomial orthogonal test at P<0.05

Table 2. The effect of PBZ rates on observation variables at16 WAT
Rates of PBZ No. tubers Tuber wt Wt Harvest Rate of
(mg L-1) per plant per index tuber
No. Initiatio Mediu (g) tuber bulking
stolons n Large m Small (g) (g day-1)
0 111,00 15,00 0,67 7,67 4,00 83,00 6,73 81,38 0,74
5 94,50 20,67 4,39 14,50 3,11 124,31 5,89 92,37 1,11
10 89,61 20,28 6,89 21,17 1,61 128,06 4,45 92,27 1,14
20 78,89 20,50 7,72 15,44 3,61 122,50 4,71 91,77 1,09
40 73,50 16,11 2,61 7,50 5,28 109,72 7,33 93,44 0,98
Respons L* Q* Q* Q* L*Q* L*Q* L*Q* L*Q* L*Q*
R2 34,8 15,8 43,1 34 22,5 31 43 53,6 30,7
Optimum rate - 19,79 20,9 18,26 14,84 22,17 18,19 28,69 22,13
L: linier, Q : quadratic, ns, * : no significant or significant on polynomial orthogonal test at P<0.05

Table 3. The effect of PBZ application time on observation variables at 8 WAT
Application times of Plant height
PBZ (cm) Leaf area (cm2) No. stolon
4 WAT (W1) 48,45 482,49 69,25
5 WAT (W2) 52,43 476,32 75,67
6 WAT (W3) 54,10 458,76 90,92
4, 5 WAT (W4) 43,94 436,37 74,67
5, 6 WAT (W5) 50,46 436,31 74,58
4, 5, 6 WAT (W6) 46,15 427,53 71,33
Single vs Repeated 51,66 vs 46,85* 472,5 vs 433,4ns 78,6 vs 73,5*
W1,W2 vs W3 50,44 vs 54,10ns 479,4 vs 458,8ns 72,46 vs 90,9 *
W1 vs W2 48,45 vs 52,43* 482,5 vs 476,3ns 69,2 vs 75,7ns
Twice vs three times 47,20 vs 46,15* 436,3 vs 427,5ns 74,6 vs 71,3*
W4 vs W5 43,94 vs 50,46* 436,4 vs 436,3ns 74,7 vs 74, 6ns
ns, * : no significant or significant on orthogonal contrast test at P<0.05
Continuing Table 3. The effect of PBZ application time at observation variables 8 WAT
Application times of No. total Percentage of Tuber wt per
PBZ No. initiations tubers effective stolon (%) plant(g)
4 WAT (W1) 11,25 12,25 18,27 20,04
5 WAT (W2) 13,42 13,92 18,59 19,62
6 WAT (W3) 12,5 14,58 16,67 21,08
4, 5 WAT (W4) 11,75 15,33 20,75 21,46
5, 6 WAT (W5) 22,18
10,42 15,92 20,54
4, 5, 6 WAT (W6) 10,08 15,42 22,17 21,42
Single vs Repeated 12,4 vs 10,8ns 13,6 vs 15,6* 17,8 vs 21,7* 20,3 vs 21,1*
W1,W2 vs W3 12,3 vs 12,5ns 13,1 vs 14,6ns 18,4 vs 16,7ns 19,8 vs 21,1ns
W1 vs W2 11,3 vs 13,4ns 12,3 vs 13,9ns 18,3 vs 18,6ns 20,0 vs 19,6ns
Twice vs three times 11,1 vs 10,1ns 15,6 vs 15,4ns 21,5 vs 22,2ns 21,0 vs 21,4ns
W4 vs W5 11,8 vs 10,4ns 15,3 vs 15,9ns 20,8 vs 22,2ns 21,5 vs 20,5ns
ns, * : no significant or significant on orthogonal contrast test at P<0.05

Table 4. The effect of PBZ application time on observation variables at 16 WAT
Application times of Tuber wt per Wt per tuber Rate of tuber Harvest Index
PBZ plant (g) (g) bulking
(g day-1)
4 WAT (W1) 116,54 6,16 1,04 92,06
5 WAT (W2) 118,75 5,72 1,06 92,44
6 WAT (W3) 125,29 5,15 1,12 92,56
4, 5 WAT (W4) 117,87 5,33 1,05 92,31
5, 6 WAT (W5) 122,38 5,38 1,09 92,42
4, 5, 6 WAT (W6) 126,04 5,86 1,13 92,99
Single vs Repeated 120,2 vs 122,1* 5,7 vs 5,5ns 1,07 vs 1,09* 92,4 vs 92,6*
W1,W2 vs W3 117,6 vs 125,3ns 5,9 vs 5,2ns 1,05 vs 1,12ns 92,3 vs 92,6ns
W1 vs W2 116,5 vs 118,7ns 6,2 vs 5,7ns 1,04 vs 1,06ns 92,1 vs 92,4ns
Twice vs three times 120,1 vs 126,0ns 5,4 vs 5,9ns 1,07 vs 1,12ns 92,4 vs 92,9ns
W4 vs W5 117,9 vs 122,4ns 5,3 vs 5,4ns 1,05 vs 1,09ns 92,3 vs 92,4ns
ns, * : no significant or significant on orthogonal contrast test at P<0.05