Agronomic, genetic, and biochemical analysis of drought resistance in sorghum, and development of high yield potential sorghum hybrids for drought stress environments
Abstract
Three different studies were performed using sorghum (Sorghum bicolor L. Moench) lines previously screened for field drought resistance in Sudan Africa, and other lines selected for superior agronomic performance from intercrosses among drought resistant lines. In two rainout shelter tests in which moisture was carefully controlled to induce pre-flowering and post-flowering stress treatments, and by use of appropriate checks, genotypes were classified on the basis of their reaction to the stress treatments relative to the checks. HD-1, a hybrid from Sudan, was found to be tolerant to pre-flowering stress, while CS3541, K886, and M35-1 were tolerant to post-flowering stress. Two lines P898012 and P954035, were found to possess good levels of resistance to both reactions. A diallel analysis was performed using four lines with contrasting drought reactions, namely P898012, M35-1, TX7000, and TX7078. It was found that the drought resistant lines had higher betaine/amino acid ratios, and higher proportions of proline, alanine, and gln + glu, governed mostly by additive gene action. Line M35-1 also had high levels of pipecolic acid, governed by non-additive gene action. A third study testing the combining ability of drought resistant lines was performed using 16 R-lines, 4 A-lines, and 3 checks. The A-lines had been previously selected for resistance to post-flowering drought stress. Most of the R lines were known to have pre-flowering stress tolerance. HD-1, RS610, and A623 x TX430 were used as checks. The 64 hybrids, 16 R-lines, 4 B-lines, and 3 checks were planted in three locations: Two dryland and irrigated locations at Lubbock, Texas, and one at the Purdue University Agronomy Farm near West Lafayette, Indiana. Two lines, 954035 and CS3541, performed consistently superior to the others in hybrid combinations in all locations. Significant general combining ability (GCA) and specific combining ability (SCA) effects were observed for all traits except saddle effect (taller plants at ends of rows) seed set and lodging, implying both additive and non-additive gene effects are important. Grain yield was significantly negatively correlated to all the morphological characters implying it is possible to select for yield under marginal rainfall areas by simply using the morphological traits. (Abstract shortened with permission of author.)
Degree
Ph.D.
Advisors
Ejeta, Purdue University.
Subject Area
Agronomy
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.