Registration of Maize Inbred Line Bo23 with High Cold Tolerance and Agronomic Performance for Early Sowing

Bo23 (Reg. No. GP-599, PI 677346) is a maize (Zea mays L.) inbred line developed at the Department of Agricultural Sciences, University of Bologna (Bologna, Italy), using as source the F-2 of the cross B73 x IABO78. B73 is a well-known inbred from a US Corn Belt germplasm, and IABO78 is an inbred from Italian germplasm not previously used in breeding. Bo23 was released in 2016 due to its high cold tolerance and agronomic performance when sown early. The breeding procedure leading to Bo23 consisted of four cycles of full-sib recurrent selection and three cycles of selection in inbreeding for germination at low temperature. In the evaluation of selection responses, a line coded as H102 (now Bo23) excelled for cold tolerance in the field and for agronomic traits. Therefore, Bo23 was further evaluated in seven trials conducted in early sowing in the southern Po Valley (Italy). The line again exhibited outstanding performance for cold tolerance and agronomic traits, both per se and as testcross. Bo23 was superior to B73 for most traits, indicating that its performance is also due to alleles of IABO78. This implies that the use of Bo23 in breeding for cold tolerance and agronomic traits can also contribute the beneficial genetic variation from its Italian parent.