Improvement of Selected Okra (Abelmoschus Spp.) Varieties for Fruit Yield and Productivity
CHAPTER ONE
Objectives of the study
- To improve the photoperiodic response, especially in local or late maturing varieties of Okra
- To estimate heterosis and heritability for improved yield and productivity
- To determine combining ability
- To estimate gene effects of quantitative traits
- To determine inheritance pattern of qualitative traits for improved fruit production
CHAPTER TWO
MATERIALS AND METHOD
Experimental Site:
The experiment was conducted at the Teaching and Research Farm, Department of Crop Science, University of Nigeria, Nsukka located in the Derived Savanna Zone at Latitude 6052’N, and Longitude 07024’E, with an altitude of 447.26 m above sea level (Uguru et al., 2011).
Experimental Materials:
The experimental materials used for the study comprised of seeds of 13 varieties of Okra (Abelmoschus spp). The varieties were: 3 Local varieties (Ele Ndu, Ele Ogwu and Ele Uhie) as well as 10 improved varieties (Ludu V Dwarf, Esculentus V, Jokoso, Agwu Early, TAE 38 dwarf, Clemson spineless, V-21 Ivra, V.35, LD-88 and NHE 47.4 (Table 1).
Land Preparation and Sowing
The experimental field were ploughed and harrowed with tractor and marked out into blocks and plots. The okra seeds were soaked in water, the day before sowing. The seeds were sown at a depth of 1-2 cm at two seeds per hole with a spacing of 0.5 m within and 0.6 m between rows. The seedlings were thinned down to one at two weeks after sowing to give a population of 33 333 plants/hectare.
Sources of Planting Materials
The local varieties were sourced from local farmers in Nsukka and Obukpa communities both in Nsukka LGA of Enugu State; while the improved varieties were sourced from the National Horticultural Research Institute (NIHORT), Okigwe, Imo State
CHAPTER THREE
RESULTS
Evaluation of the Parental Accessions
The parents evaluated varied considerably in performance and yield components (Table 3). ‘Ele Uhie’ parent showed significantly (p < 0.05) higher branch length, number of fruits/branch, number of fruits/plant, number of flowers/plant, plant height at maturity and total fruit yield/ hectare (123.7 cm, 8.31, 29.76, 9.03, 237.66 cm and 32.56 t/ha, respectively); though, it was statistically similar to the parent, ‘Ele Ndu’ in number of fruits/branch, number of fruits/plant and total fruit yield (7.67, 26.67 and 30.59 t/ha). ‘Jokoso’ parent had significantly (p < 0.05) lower branch length, number of fruits/branch, number of fruits/plant, number of flowers/plant and total fruit yield (0.00, 0.00, 6.17, 2.15 and 4.02 t/ha, respectively). ‘Ele Ogwu’ parent had significantly (p < 0.05) higher days to 50% germination, days to flower bud initiation, days to anthesis, days to 50% flowering, days to first fruiting and days to fruit maturity (8.33, 58.99, 91.25, 94.37, 92.25 and 100.63). On the other hand, ‘Agwu early’ parent, had lower days to 50% germination, days to flower bud initiation, days to anthesis, days to 50% flowering, days to first fruiting, days to fruit maturity and plant height at maturity (4.00, 22.21, 47.13, 49.11, 48.13,
52.28 and 57.80 cm) respectively; though, it was statistically similar to the parent ‘Clemson spineless’ in days to 50% flowering, days to first fruiting and days to fruit maturity (49.25, 48.31 and 54.83, respectively). ‘Ele Ndu’ had significantly (p < 0.05) higher stem girth (9.12 cm), while ‘V-21 Ivra’ had lower stem girth (4.28 cm) than the other parental accessions evaluated.
The results of the fruit traits of the parental lines evaluated indicated that the accession, ‘Ele Uhie’ showed significantly (p < 0.05) higher 100 seed weight, dry fruit weight, fruit girth, fruit weight, number of ridges/pod and number of seeds/pod (5.19 g, 11.46 g, 11.10 cm, 34.50 g,
11.33 and 120.57, respectively) compared to the other parental accessions, but statistically similar to ‘Ele Ndu’ in 100 seed weight and fruit weight (5.05 g and 33.39 g). ‘V-21 Ivra’ parent had lower 100 seed weight, dry fruit weight, fruit girth, fruit weight, number of ridges/pod and number of seeds/pod (3.91 g, 5.90 g, 5.56 cm, 17.14 g, 6.00 and 56.25 respectively). ‘Clemson spineless’ had higher fruit length (14.35 cm), though statistically similar to ‘Ele Uhie’ (12.09 cm). The parent, ‘Ele Ogwu’, had significantly lower fruit length (4.08 cm) compared to all the parents (Table 4).
CHAPTER FOUR
DISCUSSION
The significant differences that occurred in all the parental accessions and the hybrids for the traits of interest studied showed that appreciable diversity existed in the parents and their related hybrids. The occurrence of significant genotypic differences among the parents and their hybrids is in line with the views of Rao (1972), Kuleung et al. (2006), Moncada et al. (2007), Shengbin et al. (2007) and Abdel-Moneam (2009), who posited that the success of any plant breeding programme is dependent to a very large degree on the genetic diversity of the available germplasm. Similarly, Eshiet and Brisibe (2015), were of the opinion that significant differences in some of the traits is an indication that genetic diversity exists among the varieties, thereby providing a basis for selection. Joshi (1979) and Lee et al. (2008) opined that involving genetically diverse parents in crossing could be advantageous in the sense that it would provide an opportunity for bringing together gene constellations of divergent origin. ‘Agwu early’ parent that initiated flower buds, flowered and fruited earlier than all the parental accessions indicated earlier maturity. The results agreed with the report of Reddy et al. (2012) that days to 50% flowering, first flowering node, and first fruiting node are indicators of earliness in okra. Early flowering not only gives early pickings and better returns but also widens fruiting period of the plant. On the other hand, the late maturing parents, ‘Ele Uhie’, ‘Ele Ndu’ and ‘Ele Ogwu’ had higher total fruit yield of 32.56 t/ha, 30.59 t/ha and 11.51 t/ha, respectively, though they matured later than the other parents. The results agreed with the report of Udengwu (2008) that, late maturing okra vareties, with longer critical day length (CDL) as influenced by high photoperiodic sensitivity had enlongated vegetative and reproductive growth, especially when early planting is made. This subsequently results in increased fruit size, fruit length, fruit girth, number of fruits/plant as well as increased fruit yield. Agwu early with lower plant height at maturity, had the smallest fruit size. It indicated that plant height at maturity is a good indicator of fruit size of okra plants. The F1 hybrids which comprised of mostly crosses between local parents and improved parents were intermediate in days to flower bud initiation, days to anthesis, days to 50% flowering, days to first fruit appearance, days to maturity, plant height at maturity and number of fruits/plant. These suggest an occurrence of incomplete dominance as the local parents were mostly favoured. The results agreed with the report of Adiger et al. (2013), that hybrids obtained from crosses between local and exotic varieties were intermediate in productivity to their related parents.
CHAPTER FIVE
Inheritance Pattern of the Traits
The inheritance pattern of fruit colour showed that all the F1s were green with pink patches in the hybrids involving OGW (dark green) x UHIE (green with pink patches); UHIE (green with pink patches) x AGW (light green) and UHIE (green with pink patches) x CLM (yellow green). The green with pink patched colour had complete dominant effect over the other fruit colours in the crosses. It agreed with the report of Nath and Dutta (1970) which revealed that fruit skin colour was controlled digenically by more dominant light green and pink colours that were dominant over the green colour. Though the reports of Kalia and Padda (1962) differed in this regard.
For fruit pubescence, crosses involving ‘Ele Ogwu’, which had very spiny fruits, resulted in F1s with fruit pubescence ranging from intermediate smooth, intermediate spiny to slightly spiny fruits. It implied that, the character of spiny pods was partially dominant over the other traits.
SUMMARY AND CONCLUSION
Significant variation occurred among the parents and the F1 hybrids of okra. The cross ‘UHIE x LD88’ recorded significantly (p < 0.05) higher total fruit yield (38.25 t/Ha), number of branches/plant (7.00), number of fruits/branch (8.64), number of fruits/plant (35.63) and number of flowers/plant (10.16). ‘Agwu early’ parent, had lower days to 50% germination, days to flower bud initiation, days to anthesis, days to 50% flowering, days to first fruiting, days to fruit maturity and plant height at maturity (4.00, 22.21, 47.13, 49.11, 48.13, 52.28 and 57.80 cm, respectively); though, it was statistically similar to the parent. The cross, ‘UHIE x LD88’ had significantly (p < 0.05) higher 100 seed weight (4.66 g), dry fruit weight (11.51 g), fruit girth (8.50 cm), fruit weight (32.56 g) and number of ridges/pod (10.67). It was statistically similar to Ele Uhie in number of ridges/pod.
Heterosis, which indicates the better performance of the hybrids over their related parents, showed that the cross, ‘OGW x AGW’ had higher negative MPH values for days to flower bud initiation (-40.04), days to anthesis (-27.96), days to 50% flowering (-26.21), days to first fruiting (-27.64) and days to edible fruit maturity (-30.24) while the cross ‘OGW x AGW’ gave higher negative MPH value for days to 50% germination (-40.39). The cross ‘OGW x LD88’ had higher positive BPH value in total fruit yield/hectare (161.26).
Segregations among the F2 hybrids and their parents showed that the cross, ‘UHIE x LD88’ recorded significantly (p < 0.05) higher number of branches/plant, number of fruits/branch and number of fruits/plant and total fruit yield (5.38, 8.13, 35.66 and 37.51 t/Ha respectively). Ele Uhie was statistically similar in total fruit yield/hectare (35.51 t/Ha). Ele Uhie had significantly higher plant height at maturity (237.02 cm). It was statistically similar to ‘OGW x UHIE’ (219.42 cm) and Ogwu (203.61 cm).
The generational means of the agronomic, yield and yield component traits of selected parents and crosses showed that the parent Clemson had significantly (p < 0.05) lower days to first fruiting, days to flower bud initiation, number of fruits/plant and number of flowers/plant and total fruit yield/hectare,. The cross ‘UHIE x LD88’ of BC1 recorded significantly higher fruit yield/hectare, number of branches/plant, number of fruits/branch, number of fruits/plant and number of flowers/plant.
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