EVALUATION OF OKRA CULTIVARS AND BREEDING LINES FOR AGRONOMIC TRAITS IN UMUDIKE IN SOUTHEASTERN NIGERIA

Six (6) genotypes comprising two (2) cultivars and four (4) breeding lines of Okra (Abelmoschus esculentus (L) Moench) were studied in a randomized complete block design with three (3) replicates to determine their performance under Umudike environmental conditions in 2002 and 2003 cropping seasons. With respect to fresh pod yield, all the genotypes performed very well in both years, although the breeding lines performed better than the two (2) varieties. Breeding lines LD88/1-8-16-2 and LD88/1-8-13-2-4 recorded fresh pod yields of 3.6 and 3.2 t/ha in 2002, 3.5 and 3.3 t/ha in 2003 respectively, which are well above the fresh pod yields recorded for Okra in the tropics. The early maturing Okra genotypes used in the present study with 3 to 4 months duration present a possibility of growing two crops of Okra (early and late croppings) in one year, unlike the indigenous photoperiod sensitive varieties with eight to nine months duration.


INTRODUCTION
Okra (Abelmorchus esculentus (L) Moench) belongs to the family, Malvaceae and is one of the most important vegetable crops cultivated in the tropical and sub-tropical regions of the world, under rainfed or irrigation conditions (Libby, 1968;Agunloye, 1986).Tindall (1983) and Fashakun (1980) reported that Okra contains moderate levels of some essential minerals and vitamins, which are important for metabolic processes that utilize carbohydrates, proteins and fats.
Due to unstable yield which are sometimes low, breeding for high and stable yield in Okra is essentially important (Akoroda, 1986).Replacement of local and indigenous varieties/ species that grow very tall, with high abortion rate and long life cycle of 8-9 months (Kehinde 1999) with high yielding varieties of shorter life cycle (3-4 months) will improve yield.
The indigenous Okra varieties are predominantly cultivated by the local farmers in Umudike.Identification of Okra genotypes which are suitable for southeastern environment will increase the prospect of growing two crops of Okra a year.Thereby enhancing increased Okra production.Therefore, the objective of this study is to determine which of the Okra genotypes would be suitable for the southeastern environmental conditions.

MATERIALS AND METHODS:
Six (6) Okra genotypes (obtained from National Horticultural Research Institute, Ibadan) were used in the study.These include two (2) varieties; NHAe 47-4 and LD88 and four breeding lines: LD88/1-8-13-2-4, LD88/1-8-13-2-5.The experiment was a randomized complete block design (RCBD) with three replications.A total of 18 plots each measuring 1.8 X 1.2m, with a distance of 0.6m separating the plots and 1M separating the blocks was used.Each plot had 3 (three) rows.Each row was 1.8m long.The total experimental area was 13.8X5.6mor 77.28m 2 .In 2002 and 2003, the seeds of the Okra were planted three (3) per hole at a spacing of 0.6X 0.6m between and within rows.Supplying of missing hills, which brought germination count to 100%, was done 10 days after planting.Plants were thinned down to one per stand, three weeks after seedling emergence, giving a total plant population of approximately 27, 778 plants/ ha.
Compound fertilizer, NPK (20: 10: 10) was applied at the rate of 500kg/ha, four weeks after planting, using ring method of application.Weeding was done manually using hoe at three (3) Six (6) and nine (9) weeks after planting.
Karate (Lambda-cyhadrothrin; containing 25g of lambda-cyhadrothrin per litre) brand of insecticide was applied at the rate of 800ml/ha to control insect pest (Podagrica Spp) attack.Data collected were on the following attributes: plant height, number of buds/plant, number of flowers/ plant, number of pods/plant, podlength at maturity, dry pod weight, pod yield/ plant, 100 seed-weight, fresh pod yield/ hectare and rate of flower abortion.The rate of flower abortion was deduced as follows: the total number of flowers and pods per plant were counted from the time of flower production from five tagged plants per plot.
Rate of flower abortion (%) = Total number of flowers -Total number of pods X 100 Total number of flowers 1 Date were subjected to analysis of variance and means were separated using Duncan's New multiple Range Tests.Correlation analysis was also carried out for both years.
The number of leaves/ plant varied from 39 to 55 and from 37 to 56 in 2002 and 2003, respectively. The breeding  lines: LD88/1-8-27-1, LD88/1-8-16-2 and LD88/1-8-13-2-5 produced the largest number of leaves which each year differed significantly (P<0.05) from those produced by the varieties.Number of leaves/ plant associated positively and strongly with fresh pod yield/hectare in both years (Tables 3  and 4).It was observed that these breeding lines also recorded fresh pod yields/ hectare that were significantly higher than those of the varieties (Tables 1 and 2).
Number of lateral branches/ plant varied from 3 to 4 in 2002 and from 1.8 to 2.6 in 2003.The genotypes differed significantly (P<0.05) with respect to lateral branching (Tables 1 and 2).Akoroda (1986), recorded values for lateral branching for genotypes NHAe 47-4, 8p-1-1, and 8p-1-7 as 2.1, 2 and 2 respectively.Positive and strong associations were deduced between number of lateral braches and fresh pod yield/ hectare (Table 3 and 4).Osekita et al., (2000), reported that branching had significant effect on Okra fresh pod yield.The findings from this work also showed that lateral branching significantly (P<0.05)affected the yield of the genotypes under study (Tables 1and 2). Ajibade and Morakinyo (2000), reported that vegetation characters (Plant height, number of leaves / plant and number of lateral branches / plant) determine the amount of photosynthates available for plant growth, fresh pod and seed yield.Tenebe et al., (1985) had reported that vegetative characters are strongly associated with high yields in cow pea.The findings from this work showed that the genotypes with better vegetative growth recorded higher fresh pod yields.(Table 1 and 2).
The results for the number of buds/ plant, number of flowers / plant and number of pods/plant are presented on Tables (1 and 2).The genotypes differed significantly (P<0.05) with respect to each character in 2002.The same trend was observed in 2003.Duncan's New Multiple Range Test was used to separate the means of the characters (number of buds/ plant, number of flowers/ plant and number of pods/ plants) (Tables 1 and 2).Number of flowers and number of pods/plant associated positively and strongly with fresh pod yield / hectare with coefficients of 0.81, 0.91 and 0.70, 0.77 in 2002 and 2003, respectively (Tables 3 and 4).

P. I. OKOCHA and L. N. CHINATU
The results of pod length, dry pod weight and 100 seed weight are presented on Tables (1 and 2).The genotypes differed significantly (P<0.05) with respect to each character (pod length, dry pod weight and 100 seed-weight), in each year.(Tables 1 and 2).The three characters associated weakly with fresh pod yield / hectare, with pod length and dry pod weight having negative coefficients (P>0.05) in both years (Tables 3 and 4).Genotypes with longer pods of higher dry weight bore fewer pods and vice versa.By inferences, increase in number of pods/ plant led to significant (p<0.05)increase in fresh pod yield /hectare.Increase in pod length, dry pod weight and 100 seed weight however, could not lead to increase in fresh pod yield /hectare in both years (Tables 1,2,  3 and 4).Hence, the genotypes (breeding lines) with higher number of pods/ plant, moderate pod length and dry pod weight recorded higher fresh pod yield/ hectare, (Tables 1 and  2).Akoroda et al., (1987) reported that pod length is so significant (distinctive feature) that it could serve as the basis of classification of Okra genotypes.The findings from this work showed that dry pod weight and pod length clearly differentiated (P<0.05) the varieties from the breeding lines (Tables 1 and 2).
The results of the rate of flower abortion are presented on Tables 1 and 2. The genotypes differed significantly (P<0.05) in each year with regards to rate of flower abortion and varied from 19.40 to 35.2% and from 19.40 to 34.01% in 2002 and 2003, respectively (Tables 1 and 2).
Rates of flower abortion also correlated strongly but negatively with number of pods/plant and fresh pod yield/ hectare, (Tables 3 and 4).This means that the higher the rate of flower abortion the lower the fresh pod/ yield.This explains why in both years genotypes with the lowest flower abortion rate (LD88/1-8-16-2) recorded the highest fresh pod yield / hectare, and vice versa (Tables 1, 2, 3 and 4).Tindal (1983), Akoroda (1986), Grubben (1977) and purseglove (1968) reported yields of about 1 to 3 metric tons / hectare (1000 to 3000 kg / hectare) in the tropics.The values obtained from the varieties used in the present study are slightly lower than the highest values reported by these earlier workers, but the yield values of the breeding lines, especially LD 88/1-8-16-2 and LD88/1-8-13-2-4 are higher than the values reported by these earlier workers.These imply that the genotypes performed well in southeastern Nigeria.
Most of the varieties used within Umudike are West African Okra types, A Caillei, which have high yield potentials but are photoperiod sensitive with about 8 months life cycle.Hence they are cropped once in a year.These genotypes used in this study can complete their life cycle in 3 to 4 months, hence can be cropped twice in a year.

CONCLUSION
Within the okra genotypes studied, high performance of the vegetative traits (plant height, number of leaves/ plant and lateral branches) and yield character (number of pods / plant) led to high fresh pod yield.Hence steps should be taken to release the breeding lines LD88/1-8-16-2 and LD88/1-8-13-2-4, as varieties to farmers to increase okra fresh pod production in Southeastern Nigeria.Due to the short life cycle (3 to 4 months) of these genotypes, two seasons okra cropping in a year is highly feasible with the aid of irrigation during dry season.

Table 1 :
Agronomic Characteristics of Okra genotypes in Umudike in 2002