Significant Progressive Heterobeltiosis in Banana Crossbreeding

Abstract Background: Heterobeltiosis is the phenomenon when the hybrid’s performance is superior to its best performing parent. Banana ( Musa spp. AAA) breeding is a tedious, time-consuming process, taking up to two decades to develop a consumer acceptable hybrid. Exploiting heterobeltiosis in banana breeding will contribute to selecting breeding material with high compatibility, thus increasing banana breeding efficiency. The aim of this study was therefore to determine and document the level of heterobeltiosis of bunch weight and plant stature in the East African highland bananas, in order to identify potential parents that can be used to produce offspring with desired bunch weight and stature after a few crosses. Results: This study found significant progressive heterobeltiosis in cross-bred ‘Matooke’ banana hybrids, also known as NARITAs, when grown together across years with their parents and grandparents in Uganda. All NARITAs exhibited positive heterobeltiosis for bunch weight, whereas half of them had negative heterobeltiosis for stature. NARITA 17 had the highest heterobeltiosis for bunch weight (248.7%), followed by 26666S-1 (229.3%), while the lowest was noted in NARITA 19 (1.2%). Heritability for yield potential and bunch weight were high (0.84 and 0.76 respectively), while that of plant stature was very low (0.0035). There was a positive significant correlation ( P < 0.05) between grandparent heterobeltiosis for bunch weight and genetic distance between NARITAs’ parents (r = 0.39, P = 0.036), bunch weight (r = 0.7, P < 0.001), plant stature (r = 0.38, P = 0.033) and yield potential (r = 0.59, P = 0.0004). Grandparent heterobeltiosis for plant stature was significantly, but negatively, correlated to the genetic distance between NARITA parents (r = -0.6, P = 0.0004). Conclusions: Such significant heterobeltiosis exhibited for bunch weight is to our knowledge the largest among main food crops. Since bananas are vegetatively propagated, the effect of heterobeltiosis is easily fixed in the hybrids and will not be lost over time after the release and further commercialization of these hybrids.