The potential of breeding okra (Abelmoschus esculentus L.) for water stress tolerance

Abstract

Okra plant grows well but produces a few pods under water limited conditions. A linear relationship between okra production and the amount of water supplied is known to exist. Review of previous literature has shown that drought cause damage to okra plant of varying degree during its ontogeny, the reproductive phase being the most prone to the detrimental effects of drought. More specifically, the highest effect on yield was recorded when drought was found to occur during flowering and pod formation. Existence of genetic variability among genotypes is the most important component for the success of a breeding programme for increased drought resistance. Previous reports show the existence of a substantial amount of variability among okra genotypes. However, most of the traits related to drought tolerance are quantitative in nature. Therefore, estimation of type and amount of total genetic variability associated with the target traits is equally important. Determination of the type of genetic variability may help in the formulation of comprehensive breeding programme regarding the further improvement of the target trait. It is also important to find out the target trait that is related to drought tolerance and also shows good relationship with yield. Many traits are measured with complex and time-consuming techniques that are unsuitable for screening large numbers of progeny in breeding programmes. As a result, breeders tend to measure them in small populations. In addition, the stage at which trait allows the evaluation of a plant would also predict its suitability. A trait, which is evaluated earlier in the plant growth and shows freedom of its interaction with growth stages, will speed up the breeding programme. Breeding efforts at molecular level are usually intense for finding drought related molecular markers which helped us in the screening of large population without actually been exposed to drought stress. Furthermore, development in the reverse genetics has led us to isolation of novel drought tolerant genes synthesized by cDNA obtained form mRNA expressed in drought stress and non stress plants. An integrated approach has been presented here for the development of drought tolerance in okra. The increasing strengths in genomics, proteomics and molecular marker systems should be made use of to facilitate breeding of okra genotypes for water stress tolerance.