COMPARISON OF NORTH CAROLINA DESIGNS IN OKRA (Abelmoschus esculentus (L.) Moench)
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Date
2010-12
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Abstract
The present investigation entitled “Comparison of North Carolina Designs in Okra (Abelmoschus esculentus (L.) Moench)” was undertaken at the Vegetable Research Station, Junagadh Agricultural University, Juanagdh. F2 generation was obtained by selfing the Fl generation at the same place during kharif 2006. The plants of F2 generation of the crosses were used to generate the experimental materials for NCD I, II and III during summer 2007. The experimental progenies developed in
NCD I, II and III were evaluated alongwith their selfed progenies of parent plants in a compact family block design with two replications for designs I & II and three replications for design III at the Instructional Farm, College of Agriculture, Junagadh Agricultural University, Junagadh during kharif 2007.
The progenies developed through NCD I, II and III in F2 populations of two cross viz., HRB-55 x Kamini and BO-13 x Parbhani Kranti of okra were used to study the genetic variances. The mean performance of the progenies of all the NCDs and their selfed progenies were studied. The major findings are as under.
Mean performance of NC designs.
The highest mean values for fruit yield, plant height, number of nods per plant, fruit girth and number of fruits per plant in different NC designs were obtained in NCD II for both the crosses.
The mean value of middle inter-nodal length of plant was the highest in NCD III followed by NCD II and NCD I for both the crosses.
Higher mean fruit length was observed in NCD II for the cross 1 and in NCD I for the cross 2.
The mean fruit weight was found more in NCD I for the cross 1 and NCD III for the cross 2.
Early flowering was observed in NCD II for the cross 1 and it was significant with NCD I, while in cross 2, early flowering was observed in NCD III and it was significant over NCD I and NCD II.
Mean performance in selfed progenies (F3)
Higher values for fruit yield, plant height and average fruit girth were obtained in selfed progenies of NCD III for cross 1.
The average number of nodes per plant was observed to be higher in NCD II for both the crosses.
The mean value of middle inter-nodal length of plant was the highest in NCD III for both the crosses.
The mean values for fruit length and weight were more in NCD I for both the crosses.
The average number of fruits per plant was higher in NCD III for both the crosses.
The mean value for days to flowering was less in NCD I for the cross 1 and in NCD III for the cross 2.
Comparison of means
The fruit yield, number of nodes per plant and number of fruits per plant were significantly higher in all the NCD I, II and III, when compared with their F3s in both the crosses.
Genetic variances
None of the additive variances was significant in NCD I in both the crosses.
Additive gene action was observed for plant height, number of nodes/plant, inter-nodal length, fruit length, number of fruits/plant and average fruit weight in NCD II for both the crosses.
Plant height and inter-nodal length for both the crosses and fruit length and average fruit weight for cross 1 in NCD III exhibited additive gene action.
None of the dominance variances was significant in NCD I and NCD III in two cross.
Dominance gene action was important for fruit girth in both the crosses for fruit yield in cross 1 and for fruit length in cross 2 on NCD II.
Dominance ratio
The dominance ratio for fruit yield and number of fruits per plant in cross 1 and plant height in cross 2 in NCD I suggested partial dominance. Over dominance was observed for fruit length in both the crosses and fruit girth, number of fruits/plant and average fruit weight in cross 2 in NCD I.
Reliability of designs
The highest percentage of significant additive variance was observed in NCD II and III. The highest percentage of significant dominance variance was observed in NCD II followed by NCD III.
The highest percentage of significant genetic variances were observed in NCD II followed by NCD III.
The highest percentage of genetic variances with positive sign were observed in NCD I.
The highest percentage of variance with SE lower than the estimates of variance was observed in NCD II.
Considering the significance, signs and SE of the genetic variances, it can be concluded that NCD II got the maximum score value and hence found to be the most suitable mating design for the field study of genetic variances.
The results of present study suggested that NCD II is comparatively better for estimation of additive and dominance variances among all the NC designs studied.
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crossing over, planting, fruits, genetics, additives, yields, beverages, developmental stages, biological phenomena, breeding methods