Set-I: Fertility restoration behavior of minicore genotypes
In set-I, out of 68 hybrids generated by crossing with the first milo based CMS line (104A), 15 crosses exhibited satisfactory (>60 %) seed setting, while 20 hybrids were lacking in seed setting and characterized as perfect maintainers (Table 3). Four genotypes viz., IS 19389, IS 995, IS 28389 and IS 26046 were characterized as strong restorers as they exhibited 97.99 % mean seed set. Nearly 35 per cent of lines were found to be partial restorers and have an average seed set per cent of 23.82. The mean seed set percentage of moderate restorers (9) was 71.22 per cent. Nine lines showed low restoration with the mean seed set per cent of 4.89. Of the 68 hybrids obtained by crossing with the second milo based CMS line (401A), 14 hybrids showed greater than 60 per cent seed set, while 19 hybrids showed no seed set and turned to be perfect maintainers. Only two genotypes, IS 29335 and IS 26046 were recorded as strong restorers and showed a 94.69 % mean seed set. The highest proportion of the lines (31.34%) were found to be partial restorers with an average 24.28 per cent seed set. A total of 11.94 per cent (8) of the total lines evaluated were moderate restorers and revealed 69.47 per cent seeds set. Thirteen lines exhibited low restoration with a mean seed set of 6.81 per cent. Only two hybrids, out of 68, exhibited more than 60 per cent seed setting on selfing on the maldandi male sterile line and only one line IS 19975 was found to be a strong restorer with 100 per cent seed set. The highest proportion of the lines (72.06 %) were turned to be perfect maintainers and were lacking in seed set. Only one line was recorded as the moderate restorer with a 61.54 per cent seed set. Eleven and six genotypes were found to be partial restorers (22.79 %) and low restorers (4.74 %), respectively.
The present study revealed the complex behavior of restoration on maldandi compared to the milo. If we compare all the CMS lines used in the order of complexity for the availability of restorers it would be 104A < 401A < M31-2A, whereas the complexity for the availability of perfect maintainers would be M31-2A<401A<104A.
Set-II: Fertility restoration behavior of derived lines of BRJ-67 and BRJ-198.
Of the 57 hybrids, 104A (milo), a total of 48 lines showed greater than 60 per cent seed set, whereas only one line turned to be perfect maintainers (Table 4). The strong restoration (91.68%) was exhibited by only one genotype, (BRJ 67-8) DSMR-8. Around 54.39 % of lines showed moderate restoration with a 74.05 per cent mean seed set. Partial restorers (8) exhibited mean seed set percentage of 49.13 and none of the lines showed low restoration. A total of 47 hybrids, on the second milo based CMS line (401A), showed more than 60 per cent seed set, whereas none of the lines were recorded as perfect maintainers. The strong restoration was not observed on 401A. The majority (38) of the lines were noticed as moderate restorers and exhibited 69.82 % seed set. The mean seed set percentage of partial restorers (9) was 52.52 %. Only one line showed low restoration with mean seed set per cent of 7.87. The hybrids on maldandi male sterile line (M31-2A), 32 out of 57 hybrids exhibited greater than 60 per cent seed set on selfing. Out of these, five genotypes viz., BRJ-67-4 (DSMR-4), BRJ 67-8 (DSMR-8), BRJ 67-16, BRJ 67-19, BRJ 67-21 were considered as strong restorers as they restored an average 94.29 per cent fertility. The highest proportion of the lines 35.09 % were found to be perfect maintainers with a zero per cent seed set. Fifteen lines were recorded moderate restorers with 70.85 per cent seed set. Two and three lines were turned to be partial and low restorers with 27.18 and 4.66 per cent seed set, respectively.
Across two sets, only one line viz., DSMR-8 restored the fertility on both milo and maldandi male sterile lines. This indicates that the restorers on maldandi may not always restore the fertility on milo. Overall the study indicates that restoration on maldandi male sterile line is complex compared to milo and between two milo lines viz., 104A and 401A, the 401A is more complex compared to 104A. Further from the two sets, 18 lines (Table 5) were selected and repeated testing was made during kharif-2018 and rabi-2018. Across three seasons two lines viz., DSMR-8 and DSMR-4 (Table 6) were found very strong restorers across two cytoplasm and three lines.