GENETIC STUDIES IN OKRA (Abelmoschus esculentus (L.) Moench)
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Date
2008-06-04
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MAHATMA PHULE KRISHI VIDYAPEETH RAHURI-413 722, DIST. AHMEDNAGAR Maharashtra State (India)
Abstract
In the present investigation entitled "Genetic studies in okra (Abelmoschus esculentus (L.) Moench)," an attempt has been made to estimate the gene effects, operative for control of important quantitative and qualitative characters by using generation mean analysis in six intervarietial crosses of okra. The genotypes for present study comprised of five YVMV resistant cultivars (parents), two moderately registrant and two susceptible cultivars to YVMV, F1, F2, B1 and B2 population. The material was grown in Randamised Block Design with three replications at Div. No. 16, ZARS, RFRS, Ganeshkhind, Pune, during summer and kharif 2006. Five random competitive plants in P1, P2, Fi while 20 in F2 generations and ten in B1 and B2 generations in each replication were selected for recording the observations on plant height, number of branches per plant, number of nodes per plant, inter nodal length and first fruiting node. Observation on flowering, fruit characters, yield and incidence of YVMV were recorded from whole plot of each treatment. Significant heterotic effects over mid-parent in favorable direction for 12 characters, over better parent for all characters except incidence of YVMV and over top parent for eight character were observed. The highest value of heterosis was observed for yield over better parent in hybrid C5 : GK-IV-2-2-3 x GK-Sel.-l followed by hybrid c1 : Phule Utkasha x HRB-142 and hybrid C3 : GK-II-4-1-2 x GK-IV-1-2-14; in the both the seasons. Highest and significant positive heterosis for yield over top parent was observed in hybrid C5 followed by hybrid C3 and C1 in both the seasons. Highest value of mean performance for yield was observed in hybrid C5, hybrid C1 and hybrid C3 in both the seasons. Considerable amount of inbreeding depression was also observed for most of the traits studied in hybrid C5, C1 and C3 alongwith good quality fruit attributes required for consumers acceptance. Selection in advanced generations and exploitation for hybrid vigour will be advantageous from above mention hybrids. Parameters of variability were high for incidence of YVMV, plant height, branches per plant, internodal length, first fruiting node and yield per plant. Heritability estimates in particular cross combination varied from season to season and highest values were recorded for number of branches per plant in the hybrid Cj (99.48%) in summer and plant height (97.59%) in hybrid C2 in kharif season. These estimates were small for the characters fruit weight and fruit diameter in hybrid C3, incidence of YVMV in hybrid C2, yield per plant in hybrid C4 in summer and C2 in kharif season and days to 50 % flowering in hybrid C6. Genetic advance was highest for three characters viz., incidence of YVMV, branches per plant and plant height in most of the hybrids under study. Correlation co-efficient was high for yield per plant and had significant and positive genotypic and phenotypic correlation with number of fruits per plant and negative correlation with YVMV incidence. The yield showed positive genotypic correlation with plant height, branches per plant, fruit weight, nodes per plant and negative genotypic correlation with days to 50% flowering and first fruiting node. Nature and magnitude of gene effect for quantitative characters showed presence of additive gene action for fruit diameter; additive and non-additive gene action for plant height, days to 50 % flowering, fruit length and incidence of YVMV. While, non additive gene action observed in nodes per plant, length of internode, first fruiting node, fruit weight, fruits per plant and yield per plant. For the majority of the characters, duplicate type of gene action was observed. From the overall performance, it may be concluded that, hybrids C5, C1, and C3 can be used for exploiting hybrid vigour as well as for selecting desirable segregating population in future. Similarly B1 and B2 generations of cross C1 and C5 having high mean performance for yield, low incidence of YVMV and having good quality fruit attributes showed promise for further improvement programme in the okra.
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