Phenology of Sorghum Flowering

Abstract

Understanding the phenology of flowering, the time when sorghum, Sorghum bicolor (L.) Moench, is vulnerable to oviposition by the sorghum midge, Contarinia sorghicola (Coquillett), would improve the capability of managing this key sorghum insect pest and aid in developing control recommendations. Daily number of flowering spikelets per individual panicle of ‘DeKalb 50’, and per panicle in field populations of ‘WAC 715DR’, ‘Funk 522DR’, and ‘DeKalb 59E’ sorghum, were calculated from measurements of centimeters of panicle in flower. The rate of flowering of individual panicles of sorghum increased from Days 1 to 3 and then declined, with each panicle completing flowering in approximately 8 d. The most spikelets (1300) per panicle flowered the third day after flowering began on a panicle. Panicles in a uniformly growing field were flowering approximately 13 d irrespective of hybrid, with most spikelets (388 per panicle) flowering the seventh day after flowering began in the field. Almost 48% of the variability in the number of spikelets per panicle was due to sorghum hybrid and length of panicle. Panicle length and number of spikelets were positively correlated, with 42% of the variability in the number of spikelets attributable to panicle length. Mean panicle length was 26.9 cm. Mean number of spikelets was 2725 per panicle. Accurate assessment of the flowering duration of sorghum is critical to understanding the relationship between sorghum midge abundance and sorghum grain loss.