Efficiency of artificial hybridization in soybean during the summer depending on temperature and relative humidity

Hybridization is an important improvement method used in the soybean culture. However, there is little information on the recommended relative moisture and air temperature degree for artificial pollination. Therefore, this study aimed to determine the efficiency of artificial hybridization between soybean parents according to different periods of the day. Artificial pollination of 14 hybrid combinations occurred in greenhouse in three periods of the day. The parents were: TMG 801, TMG 803, BRSGO 7560, BRS Valiosa RR, Agua-Marinha RR and NK 7059 RR. The studied variables were: relative moisture, air temperature, number of days to flowering, performed artificial pollination, pods without sepal, produced seeds, germinated seeds, hybrid plants and percentage of pods without sepals. Data were submitted to normality and homogeneity of variance test, analysis of variance, Tukey, Scheffé and χ2 tests, and correlation analysis. Six hundred ans seventy-two artificial pollinations were performed. From which were obteined 436 pods without sepals and approximately 90% of produced seeds was hybrid. The results indicated that artificial pollinations performed in January, with parent used in this study, were more efficient in the period from 10:00 a.m. to 12:00 a.m., with mean relative moisture of 34.1% and mean temperature of 38.5 ºC and 2:00 a.m. to 4:00 p.m. with 30.7% and 41.6 ºC respectively for relative moisture and means of temperature.