--P. D. Quang and T. Szundy

The cold tolerance of 18 S2 lines developed from the hybrid Pioneer 3925 and their testcrosses on 2 non-related testers (T1 and T2) were studied at the phytotron in Martonvasar. 10-10 seeds per genotype were planted per replication in 40x60cm wooden boxes at a row and plant distance of 3cm. The experiment was set up in a randomized block design with 4 replications. The temperature of the E 15 chambers was 8 C for 10 days and 13.5 C for 20 days. Soil from a several year maize monoculture and sand at a ratio of 2:1, saturated with water to 70% water capacity,was used for the studies. Until emergence the boxes were covered with plastic. The emergence was observed every day until the 30th day after planting. The number of emerging plants was expressed as a percentage of the seeds planted.

Table 1 presents the emergence percentage of the S2 lines and their testcrosses. The data reveal that the average emergence percentage of the S2 lines was poorer than that of the test hybrids.

The emergence of hybrids developed using the T2 tester was the best in every combination. The behaviour of hybrids developed using T1 tester was not consequent. In 2 cases (7284 and 7303) the emergence percentage of the T1xS2 hybrids was significantly poorer than that of even the S2 lines. Four T1xS2 hybrids (7292, 7304, 7314 and 7315) emerged significantly better than the corresponding S2 lines, whereas in the other cases there was no significant difference between the emergence percentage of the S2 lines and their hybrids developed on T1 testers.

Table 1. Emergence percentage of maize S2 lines and their testcrosses.

No significant relationship was found between the emergence percentage of S2 lines and their hybrids and the hybrids developed on T1 and T2 testers.

Our data support our information so far that the role of the female partner is decisive in the emergence of seeds planted in cold, wet soil. The different behaviour of the hybrids developed on T1 and T2 testers draws attention to the fact that the choice of testers is also important in the study of the cold tolerance of maize hybrids. We are continuing our studies using further different testers.

Return to the MNL 63 On-Line Index
Return to the Maize Newsletter Index
Return to the MaizeGDB Homepage