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|CHARACTERIZATION OF OKRA GENOTYPES FOR HORTICULTURAL TRAITS, POTASSIUM UPTAKE EFFICIENCY AND PERFORMANCE UNDER DEFICIT IRRIGATION
|Saleem, Abdul Manan
Agriculture & related technologies
|UNIVERSITY OF AGRICULTURE, FAISALABAD
|Okra is a promising vegetable crop famous in many countries for its young, green and tender fruits which are used for edible purpose. Diversity exists among okra genotypes for their growth and yield related traits. Moreover, growth and yield of okra is also affected by several factors; availability of nutrients, their uptake and irrigation are important besides the environmental factors. A study was conducted to investigate the variation among local and exotic okra genotypes using morphological markers and heritability studies, potassium uptake and use efficiency under normal and water deficit conditions. For this purpose, three experiments were conducted. In 1st experiment, 24 genotypes were raised till maturity in randomized complete block design (RCBD) with three replications and each replication comprised of fifteen plants. Morphological, yield and quality related traits were noticed and huge variation was observed among genotypes for traits related to yield of okra. Interestingly, heritability parameters including genotypic and phenotypic coefficient of variation (GCV and PCV) as well as broad sense heritability (H2) confirmed that most of the studied characters including plant height, number of leaves, days to flowering, internodal length, fruiting span and fruit number, length, girth and weight as well as fruit yield plant-1 were genetically controlled, which indicated that selection of desired traits can be effective for crop improvement of okra. 2nd experiment was executed with 24 local and exotic okra genotypes with four different levels of potash (0 kg ha-1 MOP, 75 kg ha-1 MOP, 150 kg ha-1 MOP, 225 kg ha-1 MOP) in RCBD factorial arrangement with three replications, to assess the effect of potash on growth indices and potassium uptake as well as potassium use efficiency. Significant differences were noticed for measured growth indices and potassium uptake among okra genotypes at varying levels of applied potassium. All growth related traits were improved by potash application upto 150 Kg ha-1 MOP, but further increase in potash did not result in significant enhancement of growth attributes. GCV, PCV and H2 showed significant variation in genotypes for their potassium uptake and use efficiency. High heritability for studied traits depicted that breeding for potassium use efficiency is possible on the basis of identified promising genotypes (Rama Krishna, Ikra-02 and Line Brand, Ikra-04). In 3rd experiment, 24 okra genotypes were assessed for their genetic potential to tolerate deficit irrigation. Three levels of irrigation including, full irrigation (control), 25% deficit irrigation and 50% deficit irrigation, were provided under field conditions. This experiment was executed in RCBD factorial arrangement with three replications. Significant differences were noticed among different okra genotypes for their tolerance to deficit irrigation. Although, 50% deficit irrigation severely reduced the growth indices, but these reductions were less in tolerant genotypes (Rama Krishna, Ikra-02, Line Brand, Ikra-04 ) as compared to sensitive ones. Leaf relative water contents of tolerant genotypes were high even under 50% deficit irrigation as compared to sensitive okra genotypes. Antioxidant activity, proline and total soluble sugars were increased in genotypes under deficit irrigation treatments but this increase was significantly higher in tolerant genotypes as compared to sensitive ones. Leaf nitrogen, phosphorus and potassium contents were also adversely affected due to deficit irrigation. However, N, P and K concentration was high in tolerant genotypes even at 50% deficit irrigation. High values of GCV and H2 were observed for most of the characters at 50% deficit irrigation level, which showed that selection is effective for desirable traits of okra under severe deficit irrigation to develop high yielding drought tolerant okra genotypes through effective selection and breeding.
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|PhD Thesis of All Public / Private Sector Universities / DAIs.
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