Department of Plant Breeding and Seed Technology, University of Agriculture, Abeokuta 110101, Nigeria

2. Department of Plant Breeding and Seed Technology, University of Agriculture, Abeokuta 110101, Nigeria

Received: April 27, 2011 / Accepted: May 26, 2011 / Published: November 30, 2011.

Abstract: Stability among 50 accessions of West African okra (Abelmoschus caillei) was assessed under three diverse ecological environments at Abeokuta, Ibadan and Mokwa in Nigeria during 2005 and 2006 cropping season. The accessions were grown in a Randomized Complete Block Design with three replications; data were collected on 5-10 randomly selected plants from each plot. Only 20 accessions were subjected to stability analysis on the basis of yield across the three environments. The joint regression analysis, deviation means square were computed using Eberhart and Russell method and complemented with Francis and Kannenberg method. The regression coefficients of accessions mean yields on the environmental index resulted in regression coefficients ranging in values from 0.5549 to 1.6667. OAA/96/175-5328, NGAE-96-011 and NGAE-96-0060 were among the superior genotypes with high yield performance. The large variation in regression values indicated large differences in genotype response to different environments. It suggests that stability concept of Ebelhart and Russell could be modified to use any yield components that has strong correlation with yield for stability analysis. The two promising accessions of A. caillei (NGAE-96-011 and NGAE-96-0060) needed to be further tested on farmers’ field to obtain on-farm data, after which it should be recommended for official registration and released by the National Committee on Naming, Registration and Release of Crop varieties in Nigeria.

Key words: Stability assessment, environmental index, genotype, West African okra.

1. Introduction kinds of genotype × environment (GE) interaction, is useful for explaining adaptation patterns, as only this

Okra is an important vegetable crop in Nigeria. It is interaction can be exploited by selecting for specific usually grown by small scale farmers as cash crop to adaptation or by growing specifically adapted obtain regular income during planting season. The genotypes. For public institutions, the breeding of West African genotypes are very common within the diversified, specifically adapted germplasm can be a household gardens due to its late maturity and major element of a research policy for sustainable prolonged harvesting period even after the rainy season. agriculture. Safeguarding crop biodiversity by Okra is also an important vegetable crop in India, USA, increasing the number of varieties under cultivation Brazil, Australia and Turkey. Nigeria is the second will have positive implications for the stability of largest producer of okra in the world with an estimated production at the national level [3]. The phenomenon

0.72 million ton produced annually, this represent 15% of genotype-environment interaction is a common of total world annual production [1]. problem in plant breeding program and has long been a It has been widely acknowledged [2] that only challenge to plant breeder. A variety developed by a genotype × location (GL) interaction, rather than all plant breeder is usually grown at different locations for

many years of different conditions. Assessing any Corresponding author: Aladele Sunday Ezekiel, Ph.D., assistant director, research field: plant breeding. E-mail:

genotype without including its interaction is sundayaladele@yahoo.com.

Stability Assessment of Some West African Okra (Abelmoschus caillei)

Genotypes in Nigerian Genebank

incomplete and thus limits the accuracy of yield replications of 2 rows per plot at 4.2 m long and with estimates [4].

between rows interval of 1.0 m and within row interval It is usually preferable to estimate yield stability and

of 0.6 m was followed. The experiment was conducted reliability values with reference to all GE interaction

for two years during 2005 and 2006 rainy season. All effects. The objective of this study is to investigate the

the necessary cultural practices such as thinning, genetic stability of some accessions of West African

weeding, fertilizer applications and spraying of okra using different statistical methods.

insecticides were applied as at when due. Thinning was done to reduce the trial to one plant per stand at the