Selection for Late and Early Maturity From Suwan 1 Maize Variety by 2 Cycles of S1 Recurrent Selection

Abstract

                Two cycles of S1 selection for earliness and lateness were performed from a maize variety, Suwan 1 (S) C9-F2. Selection criteria were based on silking date and yield with 10% selection intensity. There were 4 mazie populations formed from the two cycles of selection, late and early maturing populations from first and second cycles of selection. These four populations and two check varieties, Suwan 1 (S) C9-F2 (the base population) and Suwan 2(S) C7 (a recommended early variety) were yield tested.

               Two early populations from the first and second cycles of selection silked 1 and 5 day, respectively, earlier than Suwan 1 (S) C9-F2. Yields were 47 and 85 kilograms per rai, respectively, higher than Suwan 1 (S) C9-F2. In comparison with Suwan 2 (S) C7, the two early populations silked 5 and s days later than Suwan 2 (S) C7, but yields were 170 and 208 kilograms per rai higher. Since early population from the second cycle of selection had only  2 days silking date later than Suwan 2 (S) C7 but yield was much higher, this population had the potential to replace Suwan 2 (S) C7.

               Two late maturing populations from the first and second cycles of selection had silking date 1 and 2 days later than Suwan 1 (S) C9-F2, while grain yield was similar to that of Suwan 1 (S) C9-F2. Yield of late maturing populations were not greater than Suwan 1 (S) C9-F2 due to taller plant height which resulted in higher number of plant lodging.