EVALUATION OF POD CHARACTERISTICS AND NUTRITIVE VALUE OF OKRA GENETIC RESOURCES

Numerous okra genotypes of American, African, Indian, European and Turkish origin were examined for their pod properties and nutritive contents. Pod thickness was considerably high in the genetic material from Africa with up to 2.84 cm in diameter in the case of line 1051 from Togo. However, pods of the improved cultivars from the USA and India had a more attractive appearance with diameters varying between 1.15 1.50 cm. The improved cultivars from the USA could also be judged as to have slow fibre development. Dry matter accumulation was higher in the Turkish and African material, varying between 18.15 17.2 % in the better one’s, while this remained between 15.6 13.6 % in the Indian material, and 14.4 11.7 % in the USA material. Three lines from Turkey had top protein levels up to 4.55, 4.43 and 4.41 % in the case of Bati Trakya, Akkoy and Denizli, respectively. Since okra is an important protein source in most developing countries, the material form Turkey might be extensively explored for its nutritive contents. INTRODUCTION Okra (Abelmoschus esculenntus (L.) Moench) is an important vegetable crop commercially grown in most of the tropics and subtropics with an extension to the Mediterranean climate (Duzyaman, 1997). It is an important crop in most developing countries, covering approximately 4 % of the total vegetable consumption (Simonsma, 1982). Fresh tender pods have been reported to be rich of dietary fibre, protein and vitamin C (Grubben, 1977; Candlish et al., 1987). In recent years okra became more and more popular as a new alternative in market diversification in Europe. It is now available as a boiled and fried vegetable in salad bars and restaurants (Qualiotti and Lotito, 1989; Possingham, 1990). Pod composition has been pointed out to be an important quality criterion for the consumer. Ames and Mac Leod, (1990) reported some 148 volatile components of okra. It has mainly been investigated in relation with the age of harvested pods. Pods older than 7 days are considered to be low in quality mainly due to excessive increase in crude fibre and gradual reduction of moisture, both important components of the table quality (Sistrumk et al., 1960). Crude protein and starch contents are also reduced by late harvest, while crude oil content increased (Iremiren et al., 1991). Besides the detailed studies on how composition changes in growing pods, no author has so far turned attention to the genetic background of okra. This study was conducted to investigate the pod characteristics and nutritive value of okra genetic material from diverse eco-geographic regions. The aim was to obtain a comparative view of these characteristics of okra genetic material under study. MATERIAL AND METHOD Forty-eight okra genotypes from different sources (table 1) were included in a field experiment conducted at the University of Ege, Faculty of Agriculture, Department of Horticulture in Bornova, Izmir in sandy  loam soil. Sixteen improved cultivars form the USA, 7 pure lines and 3 commercial cultivars from the African continent, 9 commercial cultivars form India, and 9 recently released cultivars form Turkey, 2 cultivars from Japan Proc. IS on Sust. Use Of Plant Biodiv. Eds. E. Duzyaman Y Iremiren et al., 1991). Some 40  50 pod samples were taken from each plot at the same week, bulked together and evaluated for their morphological characteristics on a metrical basis. After the initial evaluation one third of each pod was cut and dried in the oven at 105°C for further analysis. Basic pod quality analyses such as dry matter, crude fibre, crude protein and crude fat contents (Candlish et al., 1987) were performed on the dried samples and each variable was expressed as a proportion per fresh weight. Crude fibre analysis was performed according to the Lepper method (Naumann ve Bassler, 1993). A Newport Analyser type Nuclear Magnetic Resonance meter (NMR) was used for crude fat analysis (Official Analitical Instrumets, 1982). Prior to this analysis the Newport analyser was calibrated with pure okra oil obtained by extraction of okra seeds in hexane. The Kjeldal method was applied to the dried pod samples for crude protein analysis (Naumann and Bassler, 1993). The resulting data was subjected to the (ANOVA) analysis of variance at the SPSS classificatory program (version 5.0). The subroutine general factorial was run for the randomised block design with 3 replications. Significant differences between groups were determined by applying Duncans multiple range test. RESULTS AND DISCUSSION Sultani, Bato Trakya, Akkoy-41 and Kabaklo genotypes from Turkey are in the Sultani okra group, which are characterised by their thin and small pod types. These genotypes had less then 5.15 g average pod size going down to 3.79 g in the case of Kabaklo, the genotype with the smallest pods in this experiment (mean 7.04 g) (table 2). The same group had also the thinnest pods as shown in the column for pod diameter, which was between 1.22 1.37 cm. Balokesir T-1, Aglasun / Burdur and Denizli local types are characterised as short and thick pear  shaped pods. They had pod diameters close to the grand mean, which was 1.54 cm, and mature pod lengths of 8.8 to 10.8 cm, which is again far below the grand mean of 13.5 cm. African genotypes could be characterised to have short and thick pods, reaching up to 13 g of average pod weight in the case of 1051 Togo and 1159 Togo, the heaviest genotypes in this experiment. Except Congolese (1.44 cm) and 2163 Sudan (1.53 cm), which are close to the grand mean of 1.54 cm, all African genotypes had the thickest pods in the experiment with diameters values above 1.73 cm, reaching 2.84 cm pod diameter in the case of 1051 Togo. They had also the shortest pods, which were all below the grand mean of 5.84 cm and 13.50 cm in the case of edible pod and mature pod sizes respectively. It was earlier reported by Hamon and Charrier (1983) and by Hamon et al. (1986) that genetic material originated from West Africa showed great variability regarding fruit shape. In contrast to the genetic resources from Turkey and Africa, America and India originated genotypes had the longest pods, which made them look more attractive to the consumers. Except of a few genotypes, which remained below the grand average in the edible and mature pod lengths, all genotypes had pod lengths above the grand mean. In the case of edible pod length, Okra Brazil (5.36 cm), Clemson Spineless 80 (5.32 cm) were the commercial cultivars from USA which remained below the grand mean of 5.84 cm. In the case of mature pod length, PSR 1285 (13.40 cm), Annie Oakley II (13.27 cm) were those cultivars from the USA which remained below the grand mean of 13.50 cm.