Potential of Long-Ear Genetic Background to Improve Short-Season Maize Hybrids

Short-season maize hybrids may be improved by the introgression of novel germplasm containing useful alleles for enhancing grain yield. This thesis investigated the potential of the exotic germplasm BSLE(M-L)C30 [Long Ear (LE) genetics] to enhance the short-season germplasm pool. To assess the potential of this genetic background, 40 inbred lines were derived from BSLE(M-L)C30 and crossed to two short-season inbred lines to form 80 LE hybrids. In the first experiment, grain yield and yield related traits of the 80 LE hybrids were compared against five commercial hybrids. The top five LE hybrids within each tester background exhibited grain yield within 90% of the commercial hybrids. The results suggested that BSLE(M-L)C30 may contain useful alleles for grain yield. As the LE hybrids involving the Iodent tester were lower in grain moisture, it may be a trait that would be valuable in short-season hybrids. The second experiment examined the sink potential (floret number estimate), sink strength (kernel number and kernel weight) and grain yield in seven of the LE hybrids and a reference check under three plant densities. The seven LE hybrids exhibited greater sink potential and equivalent sink strength and grain yield to the check, suggesting that the LE germplasm can enhance sink potential without compromising sink strength under current commercial plant densities. The final experiment examined dry matter accumulation dynamics in two LE hybrids compared to two short-season check hybrids. One of the LE hybrids exhibited significantly greater dry matter at silking than the two checks, however, no differences were observed for dry matter at maturity. These results suggest that BSLE(M-L)C30 contains alleles which may enhance early season dry matter accumulation. In conclusion, there is strong evidence to suggest that BSLE(M-L)C30 is a useful source of novel alleles to improve the short-season maize hybrids.