Abstract
Multipurpose utilization, including as rope, pulp, and filtration media, is what makes kenaf (Hibiscus cannabinus L.) special. This experiment was conducted to select elite pedigrees with high biomass production through backcrosses. The agronomic performance, fuel characteristics, and histological analysis of the elite lines were investigated at the BC1F2 generation in comparison with the Control. Significant differences were observed in 12 evaluations of variety and pedigrees. Five plants, including the two Controls (Jangdae and Hongma300) and three pedigrees, showed a large difference in the number of flowering days from July 5 to September 30. The plant height of BC100-10 (447 cm) was the highest among the genotypes. Regarding branch number, BC100-15 showed the best performance with 29 branches. Stem dry weight was found to be the lowest in Jangdea at 792 g, whereas BC100-17 showed the highest dry weight. Hongma did not set seeds owing to late flowering. However, with 34 g/plant on average, three elite lines had more seeds than Jangdae (16 g/plant), which are vulnerable to decay owing to viviparous germination. In the fuel characteristics analysis, the heating value of the three elite lines ranged from 4,510 to 4,930 kcal/kg, which was much higher than that of the two Controls (4,320 kcal/kg). The ash content analysis indicated the lowest value at 3.2% for the line BC100-10, which was similar to Korea’s 3rd-grade. Based on the histological analysis of the stem, the pedigrees were close to Hongma. Taken together, these three elite lines would be useful as genetic resources for high biomass production.
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Key words: kenaf, pedigree, fuel characteristics, histological analysis
Introduction
Kenaf (
Hibiscus cannabinus L.), which belongs to the family of Malvaceae, is an annual C3 and a common warm season fiber plant native to India and Africa (
Yazan et al. 2011). It is one of the most important fibre crops in the world. It has been cultivated and used twine, rope, gunny bag, sackcloth, pulping and paper making, oil absorption, potting media, board making, filtration media and animal feed (Dempsey 1975,
Sellers & Reichert 1999,
Cheng 2001,
Charles 2002). Also, the seeds are good source of low cholesterol vegetable oil and for biodiesel production (
Webber & Bledsoe 1993). Although kenaf is a tropical plant, its cultivars are now well adapted to a wide geographical and climatic range (
Danalatos & Archontoulis 2010). Its height reaches 4-6 m in about 4-5 months and a yield is 6-10 tonnes of dry mass per acre each year, which is 3-5 times greater than the yield for the southern pine tree taking 7-40 years to be used (
LeMahieu et al. 2003). The ‘green tag’ is further associated with kenaf because of its promising growth, and scavenges extensive amounts of Carbon dioxide (CO
2) from the atmosphere. It is the most abundant gas which could give severe effects to the global warming. So, kenaf is the best suitable resource to go green.
The Renewable Energy Portfolio Standard (RPS) has been operated in 44 countries including USA, Japan, and so forth. Since 2012, it has been implemented in Korea. The policy’s aim is to increase expansion of a new renewable energy to decrease the CO
2 of an atmosphere. So, a lot of wood pellet have been imported in Korea to be used in a thermoelectric power plant from 2013 year. To my surprise, its amount of income was 540 billion Won in 2018 (
Kim et al. 2020). More seriously, the harmful insects such as red imported fire ant (
Solenopsis invicta) and Fire Blight (
Erwinia amylovora) have been coming in with the imported pellets, causing a severe social problem.
Kenaf is commercially cultivated in more than 20 countries, particularly in India, China, Thailand and Vietnam (
Olasoji et al. 2014). This plant was introduced in Korea in the 60’s. However, it has limited use in the country. In recent years, its value in Korea has been increasing as it has been used as forage, and for biomass and fuel production. Researches on kenaf have been done by the different research institutions in Korea since 2003 which focus on the development of new varieties, agronomic practices, and downstream application development studies such as animal feed (
Kang et al. 2018,
Lee et al. 2018). To successfully cultivate kenaf in Korea, the development of its new varieties producing high biomass is essential. Unfortunately, the yield of an early maturing kenaf variety in Korea is still very low. The highest yield achieved for early maturing varieties were 14.8 and 16.1 ton per hectare only in Jeokbong and Jangdae, respectively, thus becoming a major limitation for commercial use (
Ryu et al. 2018). Of all the available early maturing kenaf varieties, only a few were suitable to be planted in Korean climate. The late flowering kenaf plant variety has been identified as the most essential trait required for growing in Korea to increase biomass production. However, this variety was not able to bear seeds in Korean climate. Thus, in order to overcome the problem on the lack of varieties, the development of a new kenaf variety with selected target traits is imperative.
Thus, the main objective of this study was to generate new kenaf varieties with high biomass through backcross breeding. Also, it aimed to describe pedigrees in regards to their morphological, genetic and histological traits in comparison to the Control varieties, Jangdae and Hongma, in BC1F2 generation.
Materials and Methods
Location, experimental design, treatments, and agronomic practices
A field study was conducted for 4 years, from 2017 to 2020, at Iksan, Korea (35.9 N, 127 W) on a fine sandy loam, 1~2% slope. The field was cleaned and treated with 3 kg Pendimethalin herbicide 10a-1. Before planting, fertilizer was applied at a rate of 15 kg 10a−1 N, 10 kg 10a−1 P and 10 kg a−1 K. A field cultivator was used to incorporate the fertilizer and to prepare the seedbed for planting. Planting was done at 80×40 cm distance on 1st May. The primary weeds in the field were tumble pigweed (Amaranthus albus L.), purslane (Portulaca oleracea, Purslane), and removed throughout the growing season by herbicide and handweeding.
Climate conditions during the experimental period
During the experimental period, from 2017 to 2020, the average minimum temperature in the area was 17.7℃ and average maximum temperature was 26.7℃, with a total of 580~1,525 mm rainfall (
Table 1). The optimum temperature for kenaf to grow ranges from 20-27℃ (Koester et al. 2014) and rainfall of 500-1,200 mm (
Banerjee et al. 1988,
Bañuelos et al. 2002). Thus, the climatic conditions in Iksan City is very suitable to raise kenaf.
A selection step of the elite lines was done (
Fig. 1). Two varieties, Jangdae and Hongma300, were used as parental lines for crossing. F
1 lines were established in 2017 using Jangdae as female and Hongma300 as male resource. In 2018, backcross was implemented with Jangdae used as recurrent parent and harvested BC
1F
1 seeds. The seeds of previous year were planted, harvested BC
1F
2 seeds, and since then assigned numbers for 22 lines in 2019. 20 seedlings per each pedigree of BC
1F
2 generation were grown to maturity in an upland field in 2020. The elite lines showing normal seed fertility were investigated on individual plants. The stem color, leaf shape, 1
st flowering date, capsule shape, plant height, stem diameter of 15 cm above soil surface, branch number, dry weight, and seed weight were recorded for three elite lines and compared to the Control plants (Jangdae and Hongma300) evaluated in 10 replications. All genotypes were evaluated for the anthracnose incidence, using a five-point scale method (0 point = Disease free, 1 point = 1~20% incidence, 2 point = 20.1~30% incidence, 3 point = 30.1~40% incidence, 4 = point over 40.1% incidence). The fuel characteristics was evaluated from KTR (Korea Testing & Research Institute), which is a national accredited agency, according to Ministry of Environment Notice 2020-219 in 2020 (
Seo et al. 2015).
The stems were air-dried for 48 hours at 30℃. Each stem was then fastened using a nipper before cutting vertically to avoid mechanical injury for the vertical section filming. The specimens were air-dried for 20 hours at 80℃ to shoot, then placed on an aluminum stub, and plated with gold using a gold ion sputtering device (Jeol, JFC-1100E, Fine Coat, Tokyo, Japan) at 10 mA for 400 seconds. A mutant stem plated with gold was observed using a scanning electron microscope (Jeol, JSM-5410LV, Tokyo, Japan) at 15 kV condition (
Bednorz et al. 2008).
Results were analyzed for analysis of variance (ANOVA) using SAS Enterprise Guide 4.2 (Statistical Analysis System, 2009, SAS Institute Inc., Cary, NC, USA). Also, comparison of means was done at 5% level of significance using Duncan’s Multiple Range Test (DMRT).
Results and Discussion
Characteristics of donors
The elite pedigrees were developed from a cross between ‘Jangdae’בHongma300’. The female parent released from KAERI (Korea Atomic Energy Research Institite) is of Korean origin. The cultivar divided into mid-late flowering group has been flowering for three months from early-July to late-September, when planted on May 1. As a result, it can be harvested up to 16.1 ton per hectare at 100 days after seeding that is a relatively low yield (
Kang et al. 2016). However, the male parent introduced from China has been designated as late-flowering, since the first flower blossoms in late-September. In the end, it has a high biomass production of 17.9 ton per hectare at the same harvest time with Jangdae (
Kang et al. 2016). Accordingly, growers have been preferring Hongma300 to Jangdae for an aerial-part biomass.
To develop new superior genotypes compared to its parent, backcross method has been used in a lot of crops (
Ali et al. 2006,
Behmaram et al. 2014,
Noori et al. 2016). Screening and selection of desired lines were the most critical step in early generation. Assessment of important morphological traits in BC
1F
2 progeny is common. 440 BC
1F
2 populations were planted and primarily selected for the flowering date, anthracnose and biomass amount of aerial part through at least twenty observations. Finally, the progenies showing transgressive performance of the target traits over the parental lines were obtained. The selection intensity showed 0.68% with three elite lines picked out. This suggests the presence of gene for improved biomass amount in the donors, which in some cases were not expressed in the donor phenotype.
Ali et al. (2006) reported a result in agreement with ours.
Through single-crossing, it was impossible to select an elite line satisfying a flowering date we want. So, backcross program was implemented. Results on stem color, leaf shape, 1
st flowering date, and capsule shape of the Controls and pedigrees were presented (
Table 2). The stem color among the three pedigrees was significantly different from Hongma300, being similar to Jangdae in green. The leaf shape of all the genotypes was palmate. The 3 lines (BC100-10, BC100-15, BC100-17) came into blossom at a period of August 12 and 31, which were a big difference in the number of flowering days of Jangade on July 5 and Hongma300 on September 30. The capsule shape of all genotypes was same as ovoid. The incidence of anthracnose for the 3 pedigrees was classified as 1 point with Hongma300 compared to Jangdae of 3 point in the range of 30.1~40%. Anthracnose is perhaps the most serious potential disease problem. So, the anthracnose-resistant varieties were bred in a heavily disease field (
Li & Huang 2013). Similarly, the useful lines through the backcross program was obtained by other studies for rice and kenaf (
Ali et al. 2006,
Behmaram1 2014).
Fig. 2 shows the varying plant height by the genotypes. The range of plant height was the highest in the line BC100-10 with 447 cm among the genotypes. However, no statistical difference was noted when comparing the two Controls and the average of the three genotypes be marked with the slashes. No statistical analysis for the three mutants was carried out because there was only one lines in BC
1F
2 generation. The result was same to another study which showed that the kenaf, sweet sorghum and okra pedigrees of backcross breeding program gave a significantly morphological difference in comparison to Controls (
Behmaram1 2014,
Bunphan et al. 2014,
Chavan et al. 2019).
Fig. 3 shows the results on the diameter of the test plants. Individual comparison of the two Controls and the three lines indicated only one line (BC100-17) having a wide gap with the Control and other lines.
Behmaram1 et al. (2014) revealed that a significant difference was not observed in the diameter between the two Controls and BC
1F
2 populations. One distinctive feature showing a big difference between our finding and previous author’s result is a difference of parental lines. We used the mid-late and late flowering varieties with a difference of 85 days in flowering. On the other hand, the early flowering varieties were utilized by
Behmaram1 et al. (2014), showing the maximum difference of 20 days in flowering.
Result from
Fig. 4 indicated that the range of branch number of the pedigrees was different with the two Controls. The means of branch number for the Controls were from 10 (HM) to 13 (JD), while the pedigrees ranged from 15 to 29. There was a highly significant genotypic variation among the genotypes. Based on the results, line BC100-15 had the most number of branches that is, 29, followed by line BC100-17 with 19, and the lowest in line BC100-10 with 15. This conformed that a high level of genetic diversity for this trait was generated through crossing. It was indicated that this trait would respond very well to continuous selection (
Panse 1957).
Akinrotimi & Okocha (2018) revealed that the wide variation in the agro-morphological characteristics of the crop proves there is a wide genetic diversity among the genotypes. Also, number of branches per plant exhibited higher percentage of genetic advance (
Malek et al. 2014).
As to a leaf dry weight range per plant, the pedigrees showed approximately a middle value between HM and JD (
Fig. 5). The means of dry weight for the HM and JD were 317 and 153 g/plant respectively, while pedigrees ranged from 227 to 262 g/plant. Notably, the highest leaf dry weight among pedigrees is line BC100-10, followed by line BC100-15, and the lowest was line BC100-17. There was something unusual about the relationship between the branch and leaf for line BC100-15. This line had the largest number of branches of 29 (
Fig. 4), but the weight of the leaves was similar to that of other pedigrees (
Fig. 5). The genotype’s branches mainly occurred on the upper part of plant from early September, producing short branches with fewer leaves. It was thought that because of such growth property, the branch number increase didn’t lead to the leaf dry weight increase. So, we are going to precisely investigate whether this phenomenon will be emerged in the next generation. Some authors likewise noted significant difference on leaf dry weight when compared to the genotypes (
Hossain et al. 2011,
Noori et al. 2016). Previous two authors reported that an increase of leaf dry weight didn’t raise the increase in stem dry weight.
The stem dry matter accumulation at harvest differed significantly among the genotypes (
Fig. 6). Of the pedigrees, the highest dry matter of stem (1,519 g) was produced in line BC100-17 which was followed by the stem dry matter (1,219 g) of line BC100-15 and BC100-10 had the lowest (1,072 g) stem dry matter. Overall, the breeding lines have more stem dry weight than the two Controls. These findings are in agreement with the results of
Al-Amier et al. 2008,
Joshi et al. 2016 who reported the segregating lines with the highest stem dry matter in kenaf and pennyroyal. And, other authors showed that the stem dry weight of the BC
1F
2 genotypes was a big difference depending on the recurrent line (
Behmaram1 et al. 2014,
Noori et al. 2016). Also, high heterosis for yields related traits was reported on kenaf (
Liu 2005).
Fig. 7 shows the analysis of seed weight per plant between the Controls and pedigrees. The Control (HM) did flower on September 30. So, the seeds weren’t developed enough to germinate due to a low temperature. Individual comparison of the Control (JD) and the pedigrees showed that all lines had significant variation. The means of seed weight for the Control (JD) were 16 g/plant, while pedigrees ranged from 26 to 45 g/plant. Among the pedigrees, the line BC100-10 with weight of 45 g had the highest value and the line BC100-17 with 26 g weight had the lowest value. Results indicated that most of the new pedigrees showed better performance than the Control (JD) with the significant variations in weight of seeds per plant, with these results confirming other studies (
Banerjee et al. 1988,
Osman et al. 2011). The seed yield range of three lines is considered to be 200-375 kg/1,000 m
2. Literature reported a seed yield in a range of 100-150 kg/1,000 m
2 in US for ‘SF-459’ and Mexico for ‘Everglades 41’, however, a seed yield for 20 varieties (2QC etc.) in Nigeria is lower than 100 kg/1,000 m
2 (
Olasoji et al. 2014). Kenaf has an indefinite inflorescence trait. The viviparity occurred at the seeds that have been bloomed early due to much rainfall in Korea, lowering a germination. So, the seed yields in kenaf are a top-priority breeding goal to come over the problem. Three lines with high seed yield and biomass yield potential were identified for the promising performance in Korea. These genotypes showed promising results as dual purpose kenaf lines; seed and biomass production.
Fuel characteristics
The pellets appearance showed a bright color with a high gloss and there were no bad features of making pellets. So, we concluded that a pellet’s formability was very good in appearance. Fuel characteristics was done with those pellets (
Table 3). As for the heating value, the three lines ranged from 4,510 to 4,930 kcal/kg which was much higher than two Control varieties with 4,320 kcal/kg. It is excellent enough to satisfy the quality standards of Korea’s 1
st-grade. This result demonstrates that it is higher than that of reed which belongs to an herbaceous plant (
Kim & Han 2016). To my surprise, the results of the elite lines was consistent with previous studies (
Kim & Han 2016,
Kim et al. 2020) which used wood such as larch and acacia. The ash content analysis produced the line BC100-10 showed the lowest value with 3.2% which was approximate to the Korea’s 3
rd-grade. Based on the result, the kenaf’s ash quantity was a lot lower than that of reed (
Kim and Han 2016). So, the kenaf has an advantage to use as a raw material for biomass pellets.
Histological difference was detected using scanning electron microscope (SEM) image (
Fig. 8). The SEM image of stem tissue between Jangdae and Hongma300 differed significantly. The lumens (L) in core fiber of all elite lines were similar to the Hongma300, which was smaller than the Jangdae (
Fig. 8). It was thought that this dense connective tissue can increase the density of the pellet. High-density materials showed a higher mass in relation to volume and thereby they have a higher combustion yield. It was reported that high density affected the fuel value index of biomass for energy generation (
Hersztek et al. 2019). It has been the first report to reveal a tissue difference between the Control and backcross pedigree in kenaf.
From all the experimental results, the selection for isolating the elite pedigrees was highly probable for high biomass production. Finally, the selection in BC1F2 generation would increase the probability of identifying superior lines, while the three pedigrees can be useful as a resource for high biomass production in Korea.
Acknowledgements
This work is supported by a fund of project designated as No. PJ014779012020, Rural Development Administration (RDA), Republic of Korea.
Fig. 1Selection steps of kenaf elite lines.
Fig. 2Difference of plant height for HM, JD (Control) and BC1F2 three pedigrees in 170 days after planting. Result of two Controls is shown as mean ± standard deviation, obtained from ten replications. Av. (BC) indicates the mean of the three pedigrees (BC-100-10, BC-100-15, and BC-100-17). A statistical analysis for the three pedigrees cannot be carried out because each line is only one in BC1F2 generation. HM and JD indicate Hongma300 and Jangdae, respectively.
Fig. 3Difference of stem diameter for HM, JD (Control) and BC1F2 three pedigrees in 170 days after planting. Result of two Controls is shown as mean ± standard deviation, obtained from ten replications. Av. (BC) indicates the mean of the three pedigrees (BC-100-10, BC-100 15, and BC-100-17). A statistical analysis for the three pedigrees cannot be carried out because each line is only one in BC1F2 generation. HM and JD indicate Hongma300 and Jangdae, respectively.
Fig. 4Difference of branch numbers for HM, JD (Control) and BC1F2 three pedigrees in 170 days after planting. Result of two Controls is shown as mean ± standard deviation, obtained from ten replications. Av. (BC) indicates the mean of the three pedigrees (BC-100-10, BC-100 15, and BC-100-17). A statistical analysis for the three pedigrees cannot be carried out because each line is only one in BC1F2 generation. HM and JD indicate Hongma300 and Jangdae, respectively.
Fig. 5Difference of leaf dry weight for HM, JD (Control) and BC1F2 three pedigrees in 170 days after planting. Result of two Controls is shown as mean ± standard deviation, obtained from ten replications. Av. (BC) indicates the mean of the three pedigrees (BC-100-10, BC-100 15, and BC-100-17). A statistical analysis for the three pedigrees cannot be carried out because each line is only one in BC1F2 generation. HM and JD indicate Hongma300 and Jangdae, respectively.
Fig. 6Difference of stem dry weight for HM, JD (Control) and BC1F2 three pedigrees in 170 days after planting. Result of two Controls is shown as mean ± standard deviation, obtained from ten replications. Av. (BC) indicates the mean of the three pedigrees (BC-100-10, BC-100 15, and BC-100-17). A statistical analysis for the three pedigrees cannot be carried out because each line is only one in BC1F2 generation. HM and JD indicate Hongma300 and Jangdae, respectively.
Fig. 7Difference of seed weight for HM, JD (Control) and BC1F2 three pedigrees in 170 days after planting. Result of two Controls is shown as mean ± standard deviation, obtained from ten replications. Av. (BC) indicates the mean of the three pedigrees (BC-100-10, BC-100 15, and BC-100-17). A statistical analysis for the three pedigrees cannot be carried out because each line is only one in BC1F2 generation. HM and JD indicate Hongma300 and Jangdae, respectively.
Fig. 8Histological analysis of Jangdae (JD), Hongma300 (HM) and line BC100-10, BC100-15 and BC100-17 by scanning election microscope (SEM) image. The lumen (L) in the three lines was similar to HM being used as donor. Bar = 100 ㎛.
Table 1Climatic conditions of field during the experimental period, from May 2017 to October 2020.
Table 1
|
Region |
Temperature (℃) |
Rainfall (mm) |
|
Av. minimum |
Av. maximum |
Av. |
|
2017 |
17.3 |
25.3 |
22.5 |
580 |
|
2018 |
17.9 |
27.7 |
22.3 |
1,022 |
|
2019 |
17.9 |
27.3 |
22.1 |
696 |
|
2020 |
17.6 |
26.6 |
21.4 |
1,525 |
|
Av. |
17.7 |
26.7 |
22.1 |
956 |
Table 2The Different characteristics among BC1F2 generation kenaf elite lines from vegetative to reproductive growth period.
Table 2
|
Genotypes |
Stem color |
Leaf shape |
Flowering period |
Capsule shape |
Anthracnosez
|
|
Hongma300 |
Light red |
Palmate |
After Sep. 30 |
Ovoid |
1 |
|
Jangdae |
Green |
Palmate |
Jy. 5~Sep. 30 |
Ovoid |
3 |
|
BC100-10 |
Green |
Palmate |
Aug. 12~Sep. 30 |
Ovoid |
1 |
|
BC100-15 |
Green |
Palmate |
Aug. 16~Sep. 30 |
Ovoid |
1 |
|
BC100-17 |
Green |
Palmate |
Aug. 31~Sep. 30 |
Ovoid |
1 |
Table 3Fuel characteristics of kenaf pellets.
Table 3
|
Items |
Hongma300 |
Jangdae |
BC100-10 |
BC100-15 |
BC100-17 |
|
Heating value (kcal/kg) |
4,320±75a
|
4,300±65a
|
4,510±90b
|
4,680±70c
|
4,930±110d
|
|
Ash (%) |
3.4±0.1ab
|
3.3±0.05b
|
3.2±0.15b
|
3.6±0.15a
|
3.4±0.1ab
|
References
- Akinrotimi CA, Okocha PI. 2018. Evaluations of genetic divergence in kenaf (Hibiscus Cannabinus L.) genotypes using agro-morphological characteristics. Journal of Plant Sciences and Agricultural Research 5: 654-659.
- Al-Amier H, Toaima N, Mansour BMM, El Hela AA, Sastry KS, Craker L. 2008. Use of mutations to improve essential oil yield and constituency in pennyroyal. J Herbs Spices Med Plants 11: 91-101.
- Ali AJ, Xu JL, Ismail AM, Fu BY, Vijaykumar CHM, Gao YM, Domingo J, Maghirang R, Yu SB, Gregorio G, Yanaghihara S, Cohen M, Carmen B, Mackill D, Li ZK. 2006. Hidden diversity for abiotic and biotic stress tolerances in the primary gene pool of rice revealed by a large backcross breeding program. Field Crops Res 97: 66-76.
- Banerjee R, Sinha MK, Roy MKG. 1988. Correlation and path coefficient analysis of yield components in Hibiscus sabdariffa L. Jute Development J 8: 643-645.
- Bañuelos GS, Bryla DR, Cook CG. 2002. Vegetative production of kenaf and canola under irrigation in central California. Industrial Crops and Products 15: 237-245.
- Bednorz L, Czarna A. 2008. SEM and stereoscope microscope observations on the seeds of some Ornithogalum (Hyacinthaceae) species. Biologia 63: 642-646.
- Behmaram R, Saleh G, Foroughi M, Noori Z, Panandam JM, Harun J. 2014. Genetic control of fiber yield and quality in kenaf (Hibiscus cannabinus L.). Iran J Genet Plant Breed 3: 31-41.
- Bunphan D, Jaisil P, Sanitchon J. 2014. LW7 marker application for sweet sorghum breeding in BC3F2. Khon Kaen Agr J 42: 93-104.
- Charles L. In: Janick J, Janick A. 2002. (Eds). Trends in New Crops and New Uses. ASHS Press, Alexandria, VA: pp. 321-357.
- Chavan TA, Wadikar PB, Chavan BR, Naik GH. 2019. Genetic variability study in segregating generations of okra (Abelmoschus esculentus L.). Int J Curr Microbiol App Sci 8: 2270-2275.
- Cheng Z. 2001. Kenaf research, products and applications in Japan (in Chinese). Plant Fibersand Products 23: 16-24.
- Dampsey JM. In: Dampsey JM 1975. Hemp. (Ed). Fiber crops. The University Presses of Florida, Gainesville, Florida: pp. 46-89.
- Danalatos NG, Archontoulis SV. 2010. Growth and biomass productivity of kenaf (Hibiscus cannabinus L.) under different agricultural inputs and management practices in central Greece. Ind Crop Prod 32: 231-240.
- Hersztek MM, Gondek K, Jewiarz M, Dziedzic K. 2019. Assessment of energy parameters of biomass and biochars, leachability of heavy metals and phytotoxicity of their ashes. J Mater Cycles Waste Manag 21: 786-800.
- Hossain MD, Hanafi MM, Jol H, Jamal T. 2011. Dry matter and nutrient partitioning of kenaf (Hibiscus cannabinus L.) varieties grown on sandy bris soil. Journal of Plant Sciences and Agricultural Research 5: 654-659.
- Joshi R, Prashat GR, Sharma PC, Singla-Pareek SL. 2016. Physiological characterization of gamma-ray induced mutant population of rice to facilitate biomass and yield improvement under salinity stress. Indian J Plant Physiol 21: 545-555.
- Kang SY, Kwon SJ, Jeong SW, Kim JB, Kim SH, Ryu JH. 2016. An improved kenaf cultivar 'Jangdae' with seed harvesting in Korea. Korean J Breed Sci 48: 349-354.
- Kang CH, Lee IS, Go DY, Kim HJ, Na YE. 2018. The growth and yield differences in kenaf (Hibiscus cannabinus L.) in reclaimed land based on the physical types of organic materials. Korean J Crop Sci 63: 64-71.
- Kim SH, Han GS. 2016. Fuel characteristics of biomass pellets fabricated with reed stalk. J of Korea TAPPI 48: 99-106.
- Kim SH, Jeon HM, Han GS. 2020. Fuel characteristics of wood pellets fabricated with tropical acacia wood. J of Korea TAPPI 52: 103-109.
- Lee IS, Kang CH, Kwon SJ, Na YE. 2018. Effects of PEG priming and treatment on kenaf (Hibiscus cannabinus L.) seed germination. J Agric Sci Technol B 8: 278-289.
- LeMahieu PJ, Oplinger ES, Putnam DH. 2003. Kenaf. In: Alternative field crops manual. http://www.corn.agronomy.wisc.edu/FISC/Alternatives/Kenaf.htm
- Li D, Huang S. In: Monti A, Alexopoulou . 2013. The breeding of kenaf. (Eds). Kenaf: A multi-propose crop for several industrial applications. Springer, Cham, Switzerland: pp. 45-58.
- Liu Y. 2005. Diallel and stability analysis of kenaf (Hibiscus cannabinus L.) in South Africa. Master's Thesis University of the Free State.
- Malek MA, Rafii MY, Afroz MSS, Nath UK, Mondal MMA. 2014. Morphological characterization and assessment of genetic variability, character association, and divergence in soybean mutants. Sci World J 2014: 1-12.
- Noori Z, Saleh G, Foroughi M, Behmaram R, Kashiani P, Zare M, Halim RA, Alimon R, Siraj SS. 2016. Generation mean analysis for forage yield and quality in Kenaf. Iran J Genet Plant Breed 5: 23-31.
- Olasoji JO, Aluko OA, Agbaje GO, Adeniyan ON, Kareem KO, Olanipekun SO. 2014. Studies on seed yield potential of some selected kenaf (Hibiscus cannabinus L.) genotypes. Afr J Biotechnol 13: 2420-2424.
- Osman M, Golam F, Saberi S, Majid NA, Nagoor NH, Zulqarnain M. 2011. Morpho agronomic analysis of three roselle (Hibiscus sabdariffa L.) mutants in tropical malaysia. Aust J Crop Sci 5: 1150-1156.
- Panse VG. 1957. Genetics of quantitative characters in relation to plant breeding. Indian J Genet Plant Breed 17: 318-328.
- Ryu JH, Kwon SJ, Ahn JW, Kim SH, Lee SY, Kim JB, Jo YD, Ha BK, Kang SY. 2018. Development of a stem-color mutant kenaf (Hibiscus cannabinus L.) cultivar, 'Jeokbong', and analysis of its functional compounds. Hortic Sci Technol 36: 77-84.
- Sellers T, Reichert NA. 1999. Kenaf properties, processing and products. Master's Thesis Mississippi State University.
- Seo JW, Lee ES, Kang CY, Kim SB, Yoon YH, Park H. 2015. Comparison of quality characteristics of woodpellet manufactured from Pinus densiflora S. et Z. and Pinus rigida Mill1. J Korean Wood Sci Technol 43: 374-380.
- Webber CL, Bledsoe RE. In: Janick J, Simon JE. 1993. Kenaf: Production, harvesting, and products. (Eds). New crops. Wiley & Sons, New York, USA: pp. 416-421.
- Yazan LS, Foo JB, Ghafar SAA, Chan KW, Tahir PM, Ismail M. 2011. Effect of kenaf keed oil from different ways of extraction towards ovarian cancer cells. Food Bioprod Process 89: 328-332.
