Exploitation of heterosis for yield and yield related traits in okra (Abelmoschus esculentus (L.) Moench)

The present study was conducted in okra to estimate the magnitude of heterosis and to identify superior cross combinations for yield and its component traits. Thirty six F1s were developed by crossing 6 lines viz., Pusa Sawani (L1), Parbhani Kranti (L2), Arka Abhay (L3), Arka Anamika (L4), AE 65 (L5) and 14/11 (L6) and 6 testers viz., AE 64 (T1), AE 66 (T2), AE 17 (T3),14/4 (T4), 14/5 (T5) and 14/10 (T6) of okra in line x tester design during summer of 2018. All the 36 F1s along with their 12 parents (6 lines and 6 testers) and one standard check (Bhendi Hybrid CO 4) were evaluated in a randomized complete block design with two replications at Department of Vegetable Crops, Tamil Nadu Agricultural University, Coimbatore. Significance of mean squares due to treatments revealed the presence of considerable amount of genetic variability among the parents and cross combinations for all yield and yield attributing traits. The relative heterosis recorded the highest of 39.71 per cent in L3 x T2 (Arka Abhay x AE 66) in which twenty one cross combinations were positive and significant. Heterobeltiosis (dii) registered the highest of 28.65 per cent in Pusa Sawani x 14/4 (L1 x T4) in which eighteen cross combinations were significant and positive. The standard heterosis (diii) over check hybrid Bhendi Hybrid CO 4 recorded the highest of 37.12 per cent in Arka Anamika x 14/10 (L4 x T6) and twenty hybrids are positive and significant. Based on the results of the heterosis studies, it is clear that none of the 36 F1 hybrids of okra exhibited any consistency in terms of the direction and degree of heterosis over three bases viz., relative heterosis, heterobeltiosis and standard heterosis for all the characters studied. In the present study, the magnitude of standard heterosis was found to be highly variable in direction and magnitude for all the characters under study. Negative heterosis was desirable for the traits viz., days to first flowering, days to 50 per cent flowering, internodal length and per cent disease incidence in respect to yield while positive heterosis was considered to be desirable for the remaining traits viz., plant height, number of branches per plant, fruit length, fruit girth, fruit weight, number of fruits per plant and yield per plant. Arka Anamika x AE 17 (L4 x T3) expressed significant and positive standard heterosis over the standard parent Bhendi Hybrid CO 4 for eleven traits. The same cross combination Arka Anamika x AE 17 (L4 x T3) recorded significant and negative standard heterosis over the standard check for days to first flowering, days to 50 per cent flowering and per cent disease incidence. Similarly, the cross combination Arka Anamika x 14/10 (L4 x T6) recorded significant standard heterosis over the standard parent Bhendi Hybrid CO 4 for eleven characters. The cross combination of 14/11 x 14/4 (L6 x T4) also noted significant standard heterotic effect over the standard parent for ten traits. AE 65 x 14/4 (L5 x T4) is another best hybrid in terms of heterotic effect over the standard check in which it revealed significant values for nine traits. Considering the above facts, the above mentioned hybrids i.e., Arka Anamika x AE 17 (L4 x T3), Arka Anamika x 14/10 (L4 x T6), 14/11 x 14/4 (L6 x T4) and AE 65 x 14/4 (L5 x T4) could be selected for further improvement in yield and yield attributing components.