Validation of predicted type of breeding population (F2/backcross), and prediction and validation of the performance of F2 and backcross derived testcross hybrids in maize (Zea mays L.)

Improvement of popular single cross hybrids (SCHs) by improving one of their parents is a fast-track means to enhance the genetic potential of maize hybrids. Determination of the type of breeding population (BP) (F2/BC) to be developed is one of the keys to the successful improvement of elite SCHs. We predicted that BC BP would be better than F2 BP in developing improved versions of the identified parents of two SCHs-Hema and Nithyashree, while F2 BP would be better than BC BP in developing improved versions of another SCH - MAH 14-5 in our recently published article. In this article, we provide empirical evidence to validate the predicted type of BP. For this purpose, we compared the testcross (TC) hybrids' (144) performance (for grain yield) of random plants of F2 and BC BPs derived from three crosses across two locations. True to our prediction from our previous study, in terms of high TC hybrid mean, BC BP was highly significantly better than F2 for developing improved versions of identified parents of Nithyashree; while F2 was numerically better than BC BP for developing improved versions of identified parents of MAH 14-5. On the other hand, BC BP was numerically better than F2 for developing improved versions of identified parents of Hema. A fairly good correspondence between predicted (based on their parental TC performance) and observed grain yield potential of F2 and backcross-derived TC hybrids (except those derived from backcross BPs of two crosses) suggested that mean parental TC performance as a good predictor of TC performance the BPs derived from them. Based on the results of the current study, we opine that reliable prediction of the TC hybrid performance of BPs based on their parental TC performance helps enhance the pace and efficiency of hybrid maize breeding programmes.