Subscribe Now Subscribe Today
Research Article
 

Effect of Polybag Size on Growth, Root Morphology and Yield of Chilli (Capsicum annuum L.) Grown in Soilless Culture



Nurul-Idayu Zakaria, Mohd Razi Ismail, Yahya Awang and Puteri Edaroyati Megat Wahab
 
Facebook Twitter Digg Reddit Linkedin StumbleUpon E-mail
ABSTRACT

Background and Objective: In soilless culture, the dimension of polybag affects plant growth and a higher volume of the substrate is related to high production cost. This study was conducted to determine the optimum polybag size for chilli grown in soilless culture. Materials and Methods: The effect of 6 treatments combination consist of two polybag arrangements (horizontal and upright) and three lengths of polybag (17, 19 and 27 cm) were evaluated on growth, dry matter production, root morphology and yield of chilli. This study was performed in a Randomized Complete Block Design (RCBD) with three replications. All the data were analyzed using the two-way analysis of variance (ANOVA) and Least Significant Different (LSD) was used for mean comparison at p<0.05. Results: Chilli plants grown in a horizontal polybag of 17 cm in length showed a reduction of growth, dry matter production, root length and yield. With a similar volume of substrate, chilli grown in a horizontal polybag of 27 cm in length produced higher leaf, root dry matter and yield compared to control treatment. Chilli grown in a horizontal polybag of 17 cm in length and horizontal polybag of 27 cm in length had 32% reduction and 32% increment in fruit fresh weight, respectively compared to control. Chilli grew in an upright polybag of 27 cm in length with a higher volume of substrate produced a similar yield with control. Conclusion: Among the six different polybag sizes, a horizontal polybag of 27 cm in length had shown better growth and yield for chilli grown in soilless culture.

Services
Related Articles in ASCI
Search in Google Scholar
View Citation
Report Citation

 
  How to cite this article:

Nurul-Idayu Zakaria, Mohd Razi Ismail, Yahya Awang and Puteri Edaroyati Megat Wahab, 2021. Effect of Polybag Size on Growth, Root Morphology and Yield of Chilli (Capsicum annuum L.) Grown in Soilless Culture. Asian Journal of Crop Science, 13: 24-35.

DOI: 10.3923/ajcs.2021.24.35

URL: https://scialert.net/abstract/?doi=ajcs.2021.24.35
 
Copyright: © 2021. This is an open access article distributed under the terms of the creative commons attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited.

INTRODUCTION

Chilli (Capsicum annuum L.) is an economically important vegetable crop grown worldwide due to its pungency. It contains a high level of pro-vitamin A, vitamin C and E and carotenoids1,2. In Malaysia, the chilli production area increased from about 2.8 thousand hectares while annual production reached about 32.8 thousand tons3. However, the domestic production of chilli in Malaysia is still below 70% of demand4. The adoption of a soilless culture system for growing chilli is more cost-effective due to efficient and accurate control of water and nutrients which can enhance growth and yield quality5-7.

Container specifications such as length, height, volume and shape affect the size and depth of the root system and also distribution, availability and absorption of water and nutrient in the substrate8. Root growth usually occupies the space of its container and optimal root growth and distribution depends on the physical rooting environment which is the container size9. It has been proved that a larger container size increased root mass in plant10,11. The inadequate container size usually causes root restriction and decrease both shoot and root dry matter and total leaf area12,13. Under ample supply of water and nutrient, root growth is the major factor that controls the shoot growth14.

The optimum container size varies according to many different factors such as plant species, growing density, environmental conditions and duration of growing period15. To select optimum container size for each specific crop, studies have been conducted on different plant types such as fruit vegetables16,17, fruit trees18, ornamental19,20 and forest tree21. Yield response to different container sizes has been reported for sweet pepper22 and cotton23. In general, the yield was enhanced in the larger container compared to the small container. However, Byers et al.24 found that apple trees grown in small containers showed an increase in the number of flowering and fruit set while Ayarna et al.25 showed improvement of dry matter allocation to the fruit of tomato grown in a partial root restriction in Coco wool compared to complete root restriction.

Although container size can affect the growth and development of soilless culture plants such as tomato26, lettuce27, strawberry28 and muskmelon29, yet there was little research have been conducted on the chilli pepper.

Soilless culture depends largely on the use of polybags filled with coconut coir dust as the substrate. Inefficient use of substrate causes wastage of this resource and in the future, it may become a limited resource and expensive due to higher demand and consumption. Therefore, it is important to maximize efficient use of substrate possibly by using less substrate. Therefore, the present study was conducted to determine the effect of polybag size on growth of shoot, root morphology and yield of chilli under soilless culture.

MATERIALS AND METHODS

Experiment site, plant material and cultural conditions: The study was conducted from September-December, 2009 under rain shelter at Field 10, Universiti Putra Malaysia (UPM), Serdang, Selangor. Seeds of chilli pepper (Capsicum annuum var. Kulai) were germinated in peat moss. Four weeks after germination, seedlings that consisted of 4 true leaves were transplanted into a plastic polythene bag containing Coconut Coir Dust (CCD) and Empty Fruit Bunch (EFB) compost (70:30 v/v). The nutrient concentration of 2.5 dS m–1 based on Cooper formulation as stated by Berahim et al.30 was supplied to the plants twice daily via by drip irrigation system. The substrate was flushed with tap water once a week to avoid excessive salt accumulation in the substrate.

Treatments combination and experiment design: The experiment was conducted as a factorial experiment design with 2 different arrangements of polybag (horizontal and upright)×3 lengths of polybag (17, 19 and 27 cm) as presented in Table 1. The experiment was organized in Randomized Complete Block Design (RCBD) with three replications. This experiment was performed with a blocking effect due to the different water pressure along the drip irrigation line. The schematic diagram of seedlings of chilli planted in different polybag sizes is presented in Fig. 1.

Plant growth, total leaf area and plant biomass determination: Plant height was measured from the ground level to the shoot tip using a measuring tape, stem diameter was measured using callipers and total leaf area was obtained using leaf area meter (Li-3000, Li-cor Inc., Lincoln, NE, USA). Measurement was taken from three plants from each treatment during the peak fruiting stage at 84 days after transplant. Plants were harvested and partitioned into leaves, stems and roots before oven-dried at 65°C for 72 hrs for determination of dry weight. The root: shoot ratio was calculated based on dry weights of shoot and root parts as described by Razak et al.31 using the following Eq.:

Image for - Effect of Polybag Size on Growth, Root Morphology and Yield of Chilli (Capsicum annuum L.) Grown in Soilless Culture

Image for - Effect of Polybag Size on Growth, Root Morphology and Yield of Chilli (Capsicum annuum L.) Grown in Soilless Culture
Fig. 1:
Schematic diagram showing seedlings of chilli planted in polybags


Table 1: Treatments combination with the specification of the polybag and quantity of media used in the experiment
Specification of polybag
Polybag arrangement
Polybag length (cm)
Polybag dimension (long×wide×height cm)
Polybag size
Quantity of growing media mixture (kg)
Ratio of CCD: EFB (kg: kg)
17
17×15×11
12×12
0.5
0.35: 0.15
Horizontal
19
19×17×11
16×16
1.0
0.70: 0.30
27
27×23×11
20×20
2.0
1.40: 0.60
17
17×15×22
12×12
1.0
0.70: 0.30
Upright
19
19×17×22
16×16
2.0
1.40: 0.60
27
27×23×22
20×20
4.0
2.80: 1.20
CCD: Coconut coir dust and EFB: Empty fruit bunch

Determination of root morphology: At the 84th Day After Transplantation (DAT), the roots of three plants from each treatment were thoroughly cleaned and were put into acrylic trays of root image analyzer (WinRhizo STD 1600+ Scanner, Regent Instruments Inc., Quebec, Canada) to measured root length and root surface area.

Yield: Mature fruits were harvested from three plants from each treatment at 84th DAT. Total numbers of fruits were calculated and the total fresh weight of fruit was weighed using an electronic balance immediately after harvest. Fruit length was measured from the base to the apex of the fruit without considering the peduncle by using a 30 cm ruler meanwhile fruit diameter was determined at the widest part of the fruit by using a calliper.

Statistical analysis: All the data were analyzed using the two-way analysis of variance (ANOVA) procedure in the statistical analysis system32. The Least Significant Different (LSD) was used to compare differences between the treatments at p<0.05.

RESULTS

Plant growth
Plant height: The effect of polybag arrangement was highly significant (p<0.01) on the height of the chilli plant. Similarly, the length of polybag likewise the interaction effects were highly significant (p<0.01) on the plant height in Fig. 2. The plant height of chilli grown on horizontal polybags showed no significant differences among the three polybags length. However, when grown on an upright polybag, plant on polybag of 19 and 27 cm in length grew taller than polybag of 17 cm.

Stem diameter: The stem diameter of the chilli plant was significantly (p<0.05) affected by polybag arrangement. Moreover, the effect of length of polybag and interaction effect of polybag arrangement and length of polybag was highly (p<0.01) significant for this trait in Fig. 3. The stem diameter of chilli grown on horizontal polybags of 27 cm in length was significantly greater than those grown on 17 and 19 cm. In upright polybags, polybags of length 19 and 27 cm showed greater stem diameter compared to those of length 17 cm.

Total leaf area: The total leaf area of chilli on the 84th day of growing is presented in Table 2. The total leaf area of plants grown in upright polybag was greater (5643.1 cm2) than in horizontal polybag (5089.4 cm2) although the difference was not significant. Chilli plant grown in a polybag of 27 cm in length had the highest total leaf area with the value of 6327.6 cm2 which was about 19% greater than the polybag of 19 cm in length with the value of 5316.6 cm2. Meanwhile, a polybag of 17 cm in length showed a reduction in total leaf area with a value of 4454.6 cm2.

Image for - Effect of Polybag Size on Growth, Root Morphology and Yield of Chilli (Capsicum annuum L.) Grown in Soilless Culture
Fig. 2:
Interaction effect of polybag arrangement and polybag length on plant height of chilli after 84 days of transplanting
Mean values followed by the same letters for each polybag arrangement were not significantly different at p = 0.05 level by the LSD test


Image for - Effect of Polybag Size on Growth, Root Morphology and Yield of Chilli (Capsicum annuum L.) Grown in Soilless Culture
Fig. 3:
Interaction effect of polybag arrangement and polybag length on stem diameter of chilli after 84 days of transplanting
Mean values followed by the same letters for each polybag arrangement were not significantly different at p = 0.05 level by the LSD test

F-test analysis showed that the total leaf area was not significantly (p>0.05) affected by polybag arrangement. However, polybag length had a significant (p<0.05) effect on the total leaf area of the chilli plant whilst their interaction effects were not significantly different (p>0.05).

Biomass partitioning
Total leaf dry weight: Chilli plants grown on horizontal polybags of 27 cm in length have greater total leaf dry weight with the value of 24.84 g plant–1, compared to 17 and 19 cm with the value of 18.32 and 12.09 g plant–1, respectively. However, while grown on an upright polybag, lengths of polybags had no significant effect on total leaf dry weight. F-test analysis showed that the total leaf dry weight was not significantly affected by polybag arrangement (p>0.05). On the other hand, the effect of polybag length was significant (p<0.05) and the interaction effect was highly significant (p<0.01) for the total leaf dry weight of chilli at 84 days after transplant in Table 3.

Total stem dry weight: The total stem dry weight of chilli is presented in Table 4. Polybag arrangement showed no significant effect on total stem dry weight however plants grown in upright polybag have greater (31.6 g plant–1) stem dry weight. The total stem dry weight of chilli was 31.4% greater in polybag of 27 cm in length (37.64 g plant–1) than plant those grown in a polybag of 19 cm in length (28.65 g plant–1). Polybag of 17 cm in length showed a 23.2% reduction in total stem dry weight (21.99 g plant–1) compared to polybag of 19 cm in length (28.65 g plant–1).

Table 2: Mean total leaf area (cm2 plant1) of chilli plant as affected by the arrangement of polybag and length of polybag with their interactions after 84 days of transplanting
Treatment Total leaf area (cm2 plant1)
Polybag arrangement
Horizontal 5089.4a
Upright 5643.1a
LSD (p = 0.05) 913.8
Polybag length (cm)
17 4454.6b
19 5316.6ab
27 6327.6a
LSD (p = 0.05) 1119.2
F-test
Arrangement NS
Length **
Arrangement×length NS
CV 16.21
Mean values followed by the same letters within a column are not significantly different at p<0.05 by LSD test, *: p<0.05, **: p<0.01,***: p<0.001, NS: Non-significant and CV: Coefficient of variation


Table 3: Mean total leaf dry weight (g plant1) of chilli plant affected by the arrangement and length of polybag with their interactions after 84 days of transplanting
Polybag arrangement
Polybag length (cm) Horizontal Upright
17 18.32b 16.50a
19 12.09b 19.69a
27 24.84a 16.17a
LSD (p = 0.05) 6.33 5.26
CV 15.17 13.29
F-test
Arrangement NS
Length *
Arrangement×length ***
Mean values followed by the same letters within a column are not significantly different at p<0.05 by the LSD test, *: p<0.05, **: p<0.01,***: p<0.001, NS: Non-significant and CV: Coefficient of variation


Table 4: Mean total stem dry weight (g plant1) of chilli plant as affected by the arrangement and length of polybag with their interactions after 84 days of transplanting
Treatment Total stem dry weight (g plant1)
Polybag arrangement
Horizontal 27.26a
Upright 31.60a
LSD (p = 0.05) 5.99
Polybag length (cm)
17 21.99b
19 28.65b
27 37.64a
LSD (p = 0.05) 7.34
F-test
Arrangement NS
Length **
Arrangement×length NS
CV 19.39
Mean values followed by the same letters within a column are not significantly different at p<0.05 by the LSD test, *: p<0.05, **: p<0.01, ***: p<0.001, NS: Non-significant and CV: Coefficient of variation


Table 5: Mean total root dry weight (g plant1) of chilli plant as affected by the arrangement and length of polybag with their interactions after 84 days of transplanting
Polybag arrangement
Polybag length (cm) Horizontal
Upright
17 8.49a
7.43a
19 5.37b
8.17a
27 9.37a
7.51a
LSD (p = 0.05) 2.39
1.36
CV 13.62
7.79
F-test
Arrangement NS
Length **
Arrangement×length ***
Mean values followed by the same letters within a column are not significantly different at p<0.05 by the LSD test, *: p<0.05, **: p<0.01,***: p<0.001, NS: Non-significant and CV: Coefficient of variation

This indicated that the more room for the root to grow the higher will be the stem dry weight. Total stem dry weight showed no significant difference (p>0.05) in terms of polybag arrangement. However, the length of the polybag was highly significant (p<0.01) whilst their interaction effects were not significantly different (p>0.05).

Total root dry weight: Chilli plants grown in a horizontal polybag of 17 and 27 cm in length had higher total root dry weight with the value of 8.49 and 9.37 g plant–1, respectively than those grown in 19 cm polybag length (5.37 g plant–1). On the other hand, total root dry weight did not show any differences when grown in upright polybags for the root did not fully occupy the space available since water availability was lower at the upper part than the lower part of the substrate. F-test analysis showed that the total root dry weight was not significantly (p>0.05) affected by polybag arrangement. Nevertheless, polybag length and the interaction effects were highly significant (p<0.01) showed in Table 5.

Total plant dry weight: The total plant dry weight showed no significant (p>0.05) effect due to polybag arrangement. However, it was a highly significant (p<0.01) effect due to polybag length and interaction effect. The total plant dry weight of chilli grown on horizontal and upright polybags was greater in the treatment of longer polybags (27 cm) than those grown on 17 cm in Fig. 4.

Root to shoot ratio: Polybags of 17 cm in length had the highest root to shoot ratio among the three lengths, showing a significant increase by 33.3% higher than those grown in polybags of 19 and 27 cm in Table 6.

Image for - Effect of Polybag Size on Growth, Root Morphology and Yield of Chilli (Capsicum annuum L.) Grown in Soilless Culture
Fig. 4:
Interaction effect of polybag arrangement and polybag length on total plant dry weight of chilli after 84 days of transplanting
Mean values followed by the same letters for each polybag arrangement were not significantly different at p = 0.05 level by the LSD test


Image for - Effect of Polybag Size on Growth, Root Morphology and Yield of Chilli (Capsicum annuum L.) Grown in Soilless Culture
Fig. 5:
Interaction effect of polybag arrangement and polybag length on total root length of chilli after 84 days of transplanting
Mean values followed by the same letters for each polybag arrangement were not significantly different at p = 0.05 level by the LSD test

F-test analysis showed that the root to shoot ratio showed no significant effect (p>0.05) due to polybag arrangement and interaction between the two factors. However, it was highly significant (p<0.01) due to polybag length. Root to shoot ratio was not affected by the arrangement of the polybag.

Root morphological parameters
Root length: The root length of chilli was not significantly affected (p>0.05) by polybag arrangement or polybag length. However, the interaction effect of polybag arrangement and polybag length was highly significant (p<0.01) in Fig. 5. The root length of chilli grown on horizontal polybags of 27 cm in length was significantly higher than those grown on 17 and 19 cm. In upright polybags, polybags of 19 cm in length showed the greatest root length compared to those of 27 cm.

Root surface area: The root surface area of chilli plants was not significantly affected (p>0.05) by polybag arrangement. However, polybag length and the interaction effect were highly significant (p<0.01) in Fig. 6.

Image for - Effect of Polybag Size on Growth, Root Morphology and Yield of Chilli (Capsicum annuum L.) Grown in Soilless Culture
Fig. 6:
Interaction effect of polybag arrangement and polybag length on total root surface area of chilli after 84 days of transplanting
Mean values followed by the same letters for each polybag arrangement were not significantly different at p = 0.05 level by the LSD test


Image for - Effect of Polybag Size on Growth, Root Morphology and Yield of Chilli (Capsicum annuum L.) Grown in Soilless Culture
Fig. 7:
Interaction effect of polybag arrangement and polybag length on fruit fresh weight of chilli after 84 days of transplanting
Mean values followed by the same letters for each polybag arrangement were not significantly different at p = 0.05 level by the LSD test

Chilli plants grown on horizontal polybags of 27 cm in length have higher root surface area compared to 17 and 19 cm. However, upright polybag of 19 cm in length had the highest root surface area than plant those grown on 17 and 27 cm.

Yield production and fruit characteristics: Total fruit fresh weights of chilli were not significantly (p>0.05) influenced by the polybag arrangement. Meanwhile, the effect of polybag length and their interaction were highly significant (p<0.01) for the total fruit fresh weight in Fig. 7. The plant grown on horizontal polybags of 27 cm in length produced the highest total fruit fresh weight compared to 17 and 19 cm. However, the greatest total fruit fresh weight was obtained on upright polybags of 19 cm in length followed by 27 and 17 cm.

The total fruit number per plant of chilli was similar between horizontal (66) and upright (59) polybag. A polybag of 17 cm in length showed the lowest total fruit number per plant (44) which was 33.3% lower compared to a 19 cm polybag (66). Fruit length of chilli was highly significant (p<0.01) affected by polybag arrangement.

Table 6: Root to shoot ratio of chilli plant as affected by the arrangement and length of polybag with their interactions after 84 days of transplanting
Treatment
Root: shoot ratio
Polybag arrangement
Horizontal
0.17a
Upright
0.16a
LSD (p = 0.05)
0.03
Polybag length (cm)
17
0.20a
19
0.15b
27
0.15b
LSD (p = 0.05)
0.03
F-test
Arrangement
NS
Length
**
Arrangement×length
NS
CV
14.72
Mean values followed by the same letters within a column are not significantly different at p<0.05 by LSD test,*: p<0.05, **: p<0.01,***: p<0.001, NS: Non-significant and CV: Coefficient of variation


Table 7: Mean fruit number and fruit characteristics of chilli plant as affected by the arrangement and length of polybag with their interactions after 84 days of transplanting
Treatment
Total fruit number per plant
Fruit length per plant (cm)
Fruit width per plant (cm)
Polybag arrangement
Horizontal
66a
12.8b
1.65a
Upright
59a
15.1a
1.48b
LSD (p = 0.05)
10.59
0.79
0.15
Polybag length (cm)
17
44b
13.6b
1.63a
19
66a
13.7b
1.53a
27
78a
14.7a
1.53a
LSD (p = 0.05)
12.97
0.98
0.18
F-test
Arrangement
NS
***
*
Length
***
*
NS
Arrangement×length
NS
NS
NS
CV
16.10
5.45
8.97
Mean values followed by the same letters within a column are not significantly different at p<0.05 by LSD test, *: p<0.05, **: p<0.01,***: p<0.001, NS: Non-significant and CV: Coefficient of variation.

Similarly, polybag length showed a significant (p<0.05) effect on the fruit length. However, there were no significant interaction effects in Table 7. Fruit of plant grown in horizontal polybag was shorter (12.8 cm) than in upright polybag (15.1 cm). The fruit length of chilli is greater in polybag length of 27 cm (14.7 cm) than those grown in 19 cm polybag length (13.7 cm). Polybag arrangement significantly affected (p<0.05) the fruit width of chilli. But, there was no significant (p>0.05) effect of polybag length and their interaction on fruit width of chilli plants (Table 7). The plant grown in a horizontal polybag had greater fruit width (1.65 cm) than those in an upright polybag (1.48 cm). The fruit width per plant was ranged from 1.53-1.63 cm among the different polybag lengths. F-test analysis showed that the total fruit number of chilli was not significantly (p>0.05) affected by polybag arrangement and interaction of arrangement and polybag length. However, there was a highly significant (p<0.01) effect between polybag lengths (Table 7).

DISCUSSION

Polybag arrangement and length influenced the growth and development of chilli plants grown in soilless culture. Chilli plants grown in restricted root space in a horizontal and upright polybag of 17 cm in length showed similar changes of plant growth and development as observed in other studies which are related to small container volume13,33. The morphological changes in this study include decreased plant height, stem diameter, total leaf area, leaves and root dry matter production. Besides, reducing container size in a horizontal and upright polybag of 17 cm in length affected root length and root surface area of chilli which may lead to limited nutrient availability. Luo et al.34 and Hess and Kroon35 found that varying container sizes affected the root architecture and nutrient acquisition. A small polybag implies a small quantity of substrate thereby reduced the availability of water and nutrients to the plants36.

In this study, it was found that there was an accumulation of root mass at the bottom of the container that may cause by the gravitropism effect. High root density in small container size increased the overlapping zone and barriers to diffusion causing low nutrient acquisition and nutrient deficiency even though nitrogen supply was available in the soil or hydroponic solution37. A partial solution to the restricted supply of water and nutrient in small container sizes is through frequent supply through fertigation38. Accumulation of roots in small container size exposed the plant to oxygen deficiency due to the respiration of dense root mass and existence of a water layer at the bottom of the container39. Oxygen deficiency may partly cause inhibition of root and shoot growth of the plant in small container size40,41.

With increasing container size in horizontal polybags of 27 cm in length, those measured parameters including stem diameter, leaves and root dry matter production were proportionally greater. Similarly, Graham and Wheeler17 and Salisu et al.10 found that growth and dry matter production increased proportionally with container size. Besides, plants grown in this polybag size developed greater root length and root surface area. The shallow root zone about 11 cm depth in the horizontal polybags of 27 cm in length probably allowed water and nutrient to be directly available within the root. A well-developed root system is important because it provides better uptake of water and nutrient followed by increased protein, hormones and other organic substances formation42. Tian et al.43 has reported a similar result that larger containers produced greater root lengths of Cyclocarya paliurus. However, increasing the 22 cm depth of the container in the upright polybag of 27 cm in length with more volume of substrate did not translate into greater dry matter production. This was probably due to irrigation water did not directly available to the plant root since water moves laterally and deeply within the greater depth of this upright polybag. More energy is required by the roots for water uptake in greater substrate volume44. This showed that the shallow root zone of about 11 cm in depth is the suitable rooting size for better growth and development of chilli in soilless culture.

Container size was found to markedly affect the yield of chilli. Fruit fresh weight of the chilli plant was reduced when grown in a horizontal and upright polybag of 17 cm in length. Fruit fresh weight was found to be reduced by 32% when grown in a horizontal polybag of 17 cm in length as compared to the upright polybag of 19 cm in length as the control treatment. Similarly, Bouzo and Favaro45 found a yield reduction of tomato grown in small containers due to the limited water and nutrient absorption by the roots46. Lower dry matter production and yield in small polybag size could be due to lower photosynthesis rate although the limited study has measured photosynthesis rate in plants subjected to varying container size16.

Horizontal polybag of 27 cm in length had 32% greater fruit fresh weight of chilli was in line with the study conducted by Saito et al.47 on the tomato of different pot sizes. Greater fruit fresh weight was more dependent on the increased number of fruit rather than the size of the fruit. The balanced growth of the roots, combined with the readily available water, air and nutrients contribute to the vigorous yield. Large container size allows root to be spread into the new area and developed larger nutrient pool and available water substrate can retained48. Besides, coconut coir dust and EFB compost mixture also had a higher ability to retain water and nutrient46,49. However, greater substrate use in an upright polybag of 27 cm in length showed no increment of yield compared with a horizontal polybag of 27 cm in length. In container culture, an equilibrium point was reached after irrigation and drainage that developed a water table50 and to be absorbed in meaningful quantities, water must be in contact with the roots27. The water table in an upright polybag of 27 cm in length was at the bottom of the container and far from the active developing root zone which restricts water availability to the plant. Therefore, it was not a suitable container size for optimum substrate use in soilless culture.

Several studies to determine suitable container sizes for vegetable crops have been conducted. It is recommended to use a 5-7.5 L volume of substrate for high yield production of tomato38,47. Pot size of 52 L may not be enough for eggplant growth however 36 L was enough for okra. Larger container size of 33 dm3 produced a high fruit yield of sweet pepper when grown and fruits set for a long period22. However, for the past decade, very few studies had been conducted to determine suitable container dimensions for chilli with similar substrate volume. Hence, this study revealed that a horizontal polybag of 27 cm in length was suitable and optimum than an upright polybag of 19 cm in length for chilli in soilless culture.

The selection of polybag size is critically important to saving the cost of production in soilless culture and for efficient use of the substrate. The use of 17 cm polybag length with less substrate resulted in hampered yield because of root restriction while the highest substrate usage in an upright polybag of 27 cm in length did not produce greater yield compared to horizontal polybag of 27 cm in length. Therefore, it is recommended to use the horizontal polybag of 27 cm in length which could be a possible alternative polybag dimension and size for the current commercial chilli cultivation in soilless culture. Since a small polybag can reduce the high cost of substrate and manpower, optimize water and fertilizer use and reduce the problem of substrate disposal, study on the yield improvement of plant in a horizontal polybag of 17 cm in length merit further investigation.

CONCLUSION

Plants grown in horizontal polybags of 17 cm in length had dense and compacted root systems and showed a reduction of growth, root length, dry matter production and fruit fresh weight which was associated with root restriction. Horizontal polybags of 27 cm in length are suitable for chilli in a soilless culture based on greater plant growth, root length and fruit fresh weight. The minimum substrate in a horizontal polybag of 17 cm in length with optimum fertilizer and water use can reduce the high cost of substrate, manpower and problem of substrate disposal however required more explanation on the aspect of plant physiological response.

SIGNIFICANCE STATEMENTS

This study discovers the suitable polybag dimension and size for efficient use of substrate without hampering the growth and yield of chilli in soilless culture. This study reveals the combined effects of polybag dimension and polybag length on plant growth and yield that can be beneficial for researchers in the area of horticulture, crop production and agronomy as well as farmers in managing the substrate volume for vegetable crops production in soilless culture. This study will help the researcher to uncover the critical areas of growth and yield reduction affected in small polybag sizes that many researchers were not able to explore. Thus, a new theory on the selection of polybag dimension and size for chilli in soilless culture for promoting economically feasible and practical soilless substrate management may be arrived at.

ACKNOWLEDGMENT

The authors acknowledge the support of the Ministry of Higher Education, Malaysia under the Malaysia Research University Network (MRUN) Grant (Vot Number: 5539120), entitled “Elucidating Human Exposure to Chemical through Food Chain” and Universiti Putra Malaysia for Graduate Research Fellowship for financial support of this project.

REFERENCES

1:  Perucka, I. and M. Materska, 2007. Antioxidant vitamin contents of Capsicum annuum fruit extracts as affected by processing and varietal factors. Acta Sci. Pol.Technol. Aliment., 6: 67-74.
Direct Link  |  

2:  Olatunji, T.L. and A.J. Afolayan, 2018. The suitability of chili pepper (Capsicum annuum L.) for alleviating human micronutrient dietary deficiencies: A review. Food Sci. Nutr., 6: 2239-2251.
CrossRef  |  Direct Link  |  

3:  Awang, N.A., M.R. Ismail, D. Omar and M.R. Islam, 2015. Comparative study of the application of jasmonic acid and pesticide in chilli: effects on physiological activities, yield and viruses control. Biosci. J., 31: 672-681.
CrossRef  |  Direct Link  |  

4:  Usman, M.G., M.Y. Rafii, M.R. Ismail, M.A. Malek and M.B. Latif, 2014. Heritability and genetic advance among chili pepper genotypes for heat tolerance and morphophysiological characteristics. Sci. World J., Vol. 2014.
CrossRef  |  

5:  Grafiadellis, I., K. Mattas, E. Maloupa, I. Tzouramani and K. Galanopoulos, 2000. An economic analysis of soilless culture in gerbera production. HortScience, 35: 300-303.
CrossRef  |  Direct Link  |  

6:  Nicola, S., J. Hoeberechts and E. Fontana, 2005. Comparison between traditional and soilless culture systems to produce rocket (Eruca sativa) with low nitrate content. Acta Horti., 697: 549-555.
CrossRef  |  Direct Link  |  

7:  Nejad, A.R. and A. Ismaili, 2014. Changes in growth, essential oil yield and composition of geranium (Pelargonium graveolens L.) as affected by growing media. J. Sci. Food Agric., 94: 905-910.
CrossRef  |  Direct Link  |  

8:  Gallegos, J., J.E. Álvaro and M. Urrestarazu, 2020. Container design affects shoot and root growth of vegetable plant. HortScience, 55: 787-794.
CrossRef  |  Direct Link  |  

9:  Judd, L., B. Jackson and W. Fonteno, 2015. Advancements in root growth measurement technologies and observation capabilities for container-grown plants. Plants, 4: 369-392.
CrossRef  |  Direct Link  |  

10:  Salisu, M.A., Z. Sulaiman, M.Y. Abd Samad and O.K. Kolapo, 2018. Effect of various types and size of container on growth and root morphology of rubber (Hevea brasiliensis Mull. Arg.). Int. J. Scient. Technol. Res., 7: 21-27.
Direct Link  |  

11:  Haldankar, P.M., Y.R. Parulekar, M.M. Kulkarni and K.E. Lawande, 2014. Effect of size of polybag on survival and growth of mango grafts. J. Plant Stud., Vol. 3.
CrossRef  |  Direct Link  |  

12:  Zakaria, N.I., M.R. Ismail, Y. Awang, P.E.M. Wahab and Z. Berahim, 2020. Effects of container sizes and nutrient solution concentrations on growth and yield of chilli. Asian J. Crop Sci., 12: 130-140.
CrossRef  |  Direct Link  |  

13:  Zakaria N.I., M.R. Ismail, Y. Awang, P.E.M. Wahab and Z. Berahim, 2020. Effect of root restriction on the growth, photosynthesis rate, and source and sink relationship of chilli (Capsicum annuum L.) grown in soilless culture. Biomed Res. Int., 2020: 1-14.
CrossRef  |  Direct Link  |  

14:  Dodd, I.C., 2005. Root-to-shoot signalling: Assessing the roles of ‘up’ in the up and down world of long-distance signalling In planta. Plant Soil, 274: 251-270.
CrossRef  |  Direct Link  |  

15:  Tsakaldimi, M., T. Zagas, T. Tsitsoni and P. Ganatsas, 2005. Root morphology, stem growth and field performance of seedlings of two mediterranean evergreen oak species raised in different container types. Plant Soil, 278: 85-93.
CrossRef  |  Direct Link  |  

16:  Al-Debei, H.S. and S. Mugnai, 2011. Starch accumulation in the leaves of root-restricted pepper affects plant growth by a feedback-inhibition of the photosynthesis. Adv. Hortic. Sci., 25: 253-259.
CrossRef  |  Direct Link  |  

17:  Graham, T. and R. Wheeler, 2016. Root restriction: A tool for improving volume utilization efficiency in bioregenerative life-support systems. Life Sci. Space Res., 9: 62-68.
CrossRef  |  Direct Link  |  

18:  Boland, A.M., P.H. Jerie, P.D. Mitchell, I. Goodwin and D.J. Connor, 2000. Long-term effects of restricted root volume and regulated deficit irrigation on peach: I. Growth and mineral nutrition. J. Am. Soc. Hortic. Sci., 125: 135-142.
CrossRef  |  Direct Link  |  

19:  Yeh, D.M. and H.H. Chiang, 2001. Growth and flower initiation in hydrangea as affected by root restriction and defoliation. Sci. Hortic., 91: 123-132.
CrossRef  |  Direct Link  |  

20:  Taweesak, V., T.L. Abdullah, S.A. Hassan, N.H. Kamarulzaman and W.A.W. Yusoff, 2014. Growth and flowering responses of cut chrysanthemum grown under restricted root volume to irrigation frequency. Sci. World J., Vol. 2014.
CrossRef  |  Direct Link  |  

21:  Chirino, E., A. Vilagrosa, E.I. Hernández, A. Matos and V.R. Vallejo, 2008. Effects of a deep container on morpho-functional characteristics and root colonization in Quercus suber L. seedlings for reforestation in mediterranean climate. For. Ecol. Manage., 256: 779-785.
CrossRef  |  Direct Link  |  

22:  Xu, G., S. Wolf and U. Kafkafi, 2001. Interactive effect of nutrient concentration and container volume on flowering, fruiting, and nutrient uptake of sweet pepper. J. Plant Nutr., 24: 479-501.
CrossRef  |  Direct Link  |  

23:  Yong, J.W.H., D.S. Letham, S.C. Wong and G.D. Farquhar, 2010. Effects of root restriction on growth and associated cytokinin levels in cotton (Gossypium hirsutum). Funct. Plant Biol., 37: 974-984.
CrossRef  |  Direct Link  |  

24:  Byers, R.E., D.H. Carbaugh and L.D. Combs, 2004. Root restriction, an alternative to rootstocks, for control of flowering, fruiting, tree growth, yield efficiency, and fruit quality of apple. J. Tree Fruit Prod., 3: 11-31.
CrossRef  |  Direct Link  |  

25:  Ayarna, A.W., S. Tsukagoshi and G.O. Nkansah, 2021. Effect of root restriction on the performance of three-truss cultivated tomato in the low-node pinching order at high-density cultivation system. Horticulture, Vol. 7.
CrossRef  |  Direct Link  |  

26:  Oagile, O., P. Gabolemogwe, C. Matsuane and T. Mathowa, 2016. Effect of container size on the growth and development of tomato seedlings. Int. J. Curr. Microbiol. Appl. Sci., 5: 890-896.
CrossRef  |  Direct Link  |  

27:  Heller, H., A. Bar-Tal, S. Assouline, K. Narkis and S. Suryano et al., 2014. The effects of container geometry on water and heat regimes in soilless culture: Lettuce as a case study. Irrig. Sci., 33: 53-65.
CrossRef  |  Direct Link  |  

28:  Sharma, V.K. and A.K. Godara, 2017. Response in strawberry (Fragaria×ananassa duch. ‘sweet charlie’) growth to different substrates and containers under greenhouse. Int. J. Curr. Microbiol. Appl. Sci., 6: 2556-2568.
CrossRef  |  Direct Link  |  

29:  Walters, S.A., H.A. Riddle and M.E. Schmidt, 2005. Container cell volume and transplant age influences muskmelon development and yield. J. Veg. Sci., 11: 47-55.
CrossRef  |  Direct Link  |  

30:  Berahim, Z., S.S. Salamat, N.A. Razak, P.E.M. Wahab and M.R. Ismail, 2016. Efficiency of fertilizer formulation, stock solution volume and media on chili (Capsicum annum kulai F1). J. Plant Nutr., 39: 1570-1577.
CrossRef  |  Direct Link  |  

31:  Razak, A.A., M.R. Ismail, M.F. Karim, P.E.M. Wahab, S.N. Abdullah and H. Kausar, 2013. Changes in leaf gas exchange, biochemical properties, growth and yield of chilli grown under soilless culture subjected to deficit fertigation. Aust. J. Crop Sci., 7: 1582-1589.
Direct Link  |  

32:  SAS., 2004. SAS/INSIGHT 9.1 User`s Guide. Version 9.1. SAS Institute Inc., United States, ISBN-13 978-1580256971, Pages: 824
Direct Link  |  

33:  Ronchi, C.P., F.M. DaMatta, K.D. Batista, G.A.B.K. Moraes, M.E. Loureiro and C. Ducatti, 2006. Growth and photosynthetic down-regulation in Coffea arabica in response to restricted root volume. Funct. Plant Biol., 33: 1013-1023.
CrossRef  |  Direct Link  |  

34:  Luo, H.H., X.P. Tao, Y.Y. Hu, Y.L. Zhang and W.F. Zhang, 2015. Response of cotton root growth and yield to root restriction under various water and nitrogen regimes. J. Plant Nutr. Soil Sci., 178: 384-392.
CrossRef  |  Direct Link  |  

35:  Hess, L. and H. de Kroon, 2007. Effects of rooting volume and nutrient availability as an alternative explanation for root self/non-self discrimination. J. Ecol., 95: 241-251.
CrossRef  |  Direct Link  |  

36:  Poorter, H., J. Buhler, D. van Dusschoten, J. Climent and J.A. Postma, 2012. Pot size matters: A meta-analysis of the effects of rooting volume on plant growth. Funct. Plant Biol., 39: 839-850.
CrossRef  |  Direct Link  |  

37:  Tanyaradzwa, Z.L., M. Tuarira, M. Moses and T. Jefta, 2015. Effects of planting depth and variety on container produced potatoes. J. Global Innovations Agric. Social Sci., 3: 1-7.
CrossRef  |  Direct Link  |  

38:  de Matos Pires, R.C., P.R. Furlani, R.V. Ribeiro, D.B. Junior, E. Sakai, A.L. Lourenção and A.T. Neto, 2011. Irrigation frequency and substrate volume effects in the growth and yield of tomato plants under greenhouse conditions. Sci. Agric., 68: 400-405.
CrossRef  |  Direct Link  |  

39:  Raviv, M., J.H. Lieth, A. Bar-Tal and A. Silber, 2008. Growing Plants in Soilless Culture: Operational Conclusions. In: Growing Plants in Soilless Culture: Operational Conclusions, Raviv, M. and J.H. Lieth (Eds.)., Elsevier B.V., London, UK, pp: 545-571
CrossRef  |  Direct Link  |  

40:  Shi, K., W.H. Hu, D.K. Dong, Y.H. Zhou and J.Q. Yu, 2007. Low O2 supply is involved in the poor growth in root-restricted plants of tomato (Lycopersicon esculentum Mill.). Environ. Exp. Bot., 61: 181-189.
CrossRef  |  Direct Link  |  

41:  Wang, Y., K. Thorup-Kristensen, L.S. Jensen and J. Magid, 2016. Vigorous root growth is a better indicator of early nutrient uptake than root hair traits in spring wheat grown under low fertility. Front. Plant Sci., Vol. 7.
CrossRef  |  Direct Link  |  

42:  Tian, N., S. Fang, W. Yang, X. Shang and X. Fu, 2017. Influence of container type and growth medium on seedling growth and root morphology of Cyclocarya paliurus during nursery culture. Forests, Vol. 8.
CrossRef  |  Direct Link  |  

43:  Ertek, A. and S. Bolat, 2016. Growth and yield of pepper (Capsicum annuum L.) under root zone restriction. Agric. Res. Technol.: Open Access J., Vol. 2.
CrossRef  |  Direct Link  |  

44:  Bouzo, C.A. and J.C. Favaro, 2015. Container size effect on the plant production and precocity in tomato (Solanum lycopersicum L.). Bulg. J. Agric. Sci., 21: 325-332.
Direct Link  |  

45:  Xiong, J., Y. Tian, J. Wang, W. Liu and Q. Chen, 2017. Comparison of coconut coir, rockwool, and peat cultivations for tomato production: Nutrient balance, plant growth and fruit quality. Front. Plant Sci., Vol. 8.
CrossRef  |  Direct Link  |  

46:  Saito, T., N. Fukuda, T. Iikubo, S. Inai, T. Fujii, C. Konishi and H. Ezura, 2008. Effects of root-volume restriction and salinity on the fruit yield and quality of processing tomato. J. Jpn. Soc. Hortic. Sci., 77: 165-172.
CrossRef  |  Direct Link  |  

47:  Chong, C.W. and L.M. Chu, 2007. Growth of vetivergrass for cutslope landscaping: Effects of container size and watering rate. Urban For. Urban Greening, 6: 135-141.
CrossRef  |  Direct Link  |  

48:  Barrett, G.E., P.D. Alexander, J.S. Robinson and N.C. Bragg, 2016. Achieving environmentally sustainable growing media for soilless plant cultivation systems-A review. Sci. Hortic., 212: 220-234.
CrossRef  |  Direct Link  |  

49:  Navindra, B., D. Gianjeet and G.S. Joyce, 2011. Influence of soilless growing media, pot size and sieved media on the production of Hibiscus sabdariffa L. seedlings. Aust. J. Agric. Eng., 2: 147-154.
Direct Link  |  

50:  Kurunç, A. and A. Ünlükara, 2009. Growth, yield, and water use of okra (Abelmoschus esculentus) and eggplant (Solanum melongena) as influenced by rooting volume. N.Z. J. Crop Hortic. Sci., 37: 201-210.
CrossRef  |  Direct Link  |  

©  2022 Science Alert. All Rights Reserved